MACHINABILITY OF DUCTILE IRON CASTINGSductile.org/researchpdfs/doc20.pdf · MACHINABILITY OF...

RESEARCH PROJECT No. 20

MACHINABILITY OF DUCTILE IRON CASTINGS

TESTING BY MACHINING RESEARCH, INC.

REPORT PREPARED BY ROBERT J. CHRIST

SOCIETY

Issued by the Ductile Iron Society for the use of its Member Companies - Not for General Distribution

DUCTILE IRON SOCIETY 28938 Lorain Road

North Olmsted, Ohio 44070 21 6-734-8040

JULY 1993

Ductile Iron Society

Research Re ort Project No. f20

Machinability of Ductile Iron Castings

Testin Done by Machining 53 esearch, Inc.

Florence, Kentucky

Re ort Prepared by fobert J. Christ

Introduction

Summary of Findings

Conclusions

Machinability Test Results

Investigational Procedure Material Sources Machinability Test Procedures Machine Tooling Cutting Tools Machining practices Metallurgical Studies

Analyses of Machinability Data Face Milling Turning Drilling

Metallurgical Evaluations General Observations Effect of Inclusions on Machinability

Acknowledgements

References

Tables 1-5, Index

Figures 1-69, Index

Appendices A. Tool Wear Data B. Representative Micrographs and EDS Inclusion Identification Plots

Machinability of Ductile Iron Castings DIS Project P20

Tables and Figures Index

Tables Topic Pages

1 Index, Tool Life vs. Cutting Speed for Various Feeds 4

2 Description of Foundry Practices 13

3 Chemical Analyses of Machinability Bars 14

4 EDS-SEM Inclusion Analyses 58

5 Hardness of Inclusions in Ductile Iron 59

1A - 3D Appendix A - Raw Machinability Data 70 - 83

Figures Topic Pages

1-25 Tool Life Curves - Face Milling 15 -39

26 - 32 Tool Life Curves - Turning 40 - 46

33 - 36 Tool Life Curves - Drilling 47 - 50

37 - 40 Machinability Test Bars 51 - 52

41 - 44 Machine Tooling Used in Investigations 53 - 54

45 - 46 Tool Wear Characteristics 55

47 - 48 Examples of Ferritic Skin 56 - 57

49 - 58 Microstructures, Test Bars Used for Inclusion Analyses 60 - 69

B1 -B9 Appendix B - Additional Examples of Microstructures 84 - 93

B 10 - B 16 Appendix B - Typical SEM-EDS Inclusion Identification Plots 94 - 100

Machinability of Ductile Iron Castings

Ductile Iron Society Project P20

INTRODUCTION

The current study, which analyzes factors affecting machinability of ductile iron castings, is an extension of earlier studies. This earlier work was conducted at the Georgia Institute of Technology and is covered in DIS Research Report No. P14 - October 1987. While the previous work showed how microstructure affects machinability , and developed quantitative relationships to show tool wear rates versus pearlite content, graphite quality, and casting hardness, the study was limited to only turning operations. Additionally, this study was limited since it did not include an indepth assessment of all the factors affecting machinability .

In the current expanded study, machinability data is developed which:

Covers turning, milling and drilling operations.

Compares machinability of the as-cast skin of castings, to sub-skin machinability.

Develops tool life data for pearlitic ductile iron castings meeting ASTM Grade 80-55-06 and ferritic ductile iron conforming to ASTM Grade 65-45-12, both produced in as-cast conditions.

Covers irons cast in three different DIS member foundries identified simply as A, B, and C, to determine the relationship of production practice to machinability. All irons were supplied and evaluated in the as- cast condition.

Investigates the effect of microstructure and inclusions on tool life.

Results are presented in the form of curves that forecast tool life at different cutting speeds and tool feeds. This permits the user of this data to deterrmne trade-offs between maximum tool life and maximum rates of metal removal.

Microstructures and inclusions are shown to be the major factors affecting machinability in terms of tool life. Foundry practice and process controls in a foundry determine what microstructures and degree of iron cleanliness are developed in any grade of ductile iron, and hence, the machining characteristics.

This study demonstrates that machinability of any grade of ductile iron, whether in face milling, turning or drilling operations, is very much influenced by the total manufacturing and control practices of an individual foundry. Therefore, to use the data in this report to estimate the effect of variables on tool life, the user must equate particular castings to that of a similar product produced by one of the contributing foundries in the current study.

Three DIS member foundries contributed the machinability test castings, using their respective regular production practices. There were two sources each of pearlitic and ferritic grades. Machinability tests were then conducted and analyzed by Machining Research, Inc., Florence, Kentucky, under a contract funded by the Ductile Iron Society. Other contributors to completion of this work are listed in the Acknowledgements section of this report.

SUMMARY OF FINDINGS

The machinability test results for all the metal cutting studies are plotted as tool life curves in Figures 1-36. The curves can be used to forecast machinability at different cutting speeds and feed rates for ferritic and pearlitic type ductile irons produced by processes similar to those used by the contributing foundries.

Throughout the study, the various investigators referred to 80-55-06 iron as "pearlitic" and the 65-45- 12 iron as "ferritic" and these terms are used throughout the report. However, the ferritic iron does contain some pearlite and the pearlitic, some ferrite. The as-cast ferritic irons at 156-163 Brine11 Hardness are typical of that

grade. The pearlitic irons at 187 Brinell hardness and 223 Brinell hardness represent castings at the minimum and mid range for that grade.

Face Milling

As Cast Skin

Significant observations and conclusions from the current study follow:

General

1. Tool life data for the as-cast skin was considerably more erratic than the core or sub-surface metal in both turning and face milling. This is due to large variations in microstructures between foundries, the castings in a single pour, and between the surface and near surface characteristics. There are variations in the degree and depth of the "as-cast skin," degree of embedded sand, if any, and a varying depth and intensity of the increased ferrite surface layer. A "ferritic skin" is common on many ductile iron castings and one would expect a more ferritic material to have a higher machinability. However, all test castings were shot cleaned. Variations in intensity of peening will produce variations in the degree of surface work hardening, and work hardening is known to reduce machinability . For all machining operations, when differences in tool life could not be attributed to variations in matrix microstructure (i.., percent pearlite, graphite size or distribution), the iron showing reduced machinability had a higher inclusion content throughout the section. Irons produced by the in-mold process had the highest inclusion contents. In a few cases, as discussed below, this may have contributed to reduced tool life. Inclusions are partially dissolved or unreacted ferrosilicon or magnesium ferrosilicon alloys, slag particles or refractory metal complexes produced during melt down of the charge materials. Particularly injurious are titanium inclusion complexes. The source of these are discussed elsewhere.

While there was no consistent difference in tool life between ferritic irons from foundries "A" and "B," the as-cast skin had better machinability than the sub-surface material. Probable reasons are, both groups had a virtually pearlite free skin, and a lower inclusion content than in the sub- surface.

2. For the pearlitic grade, Foundry "A" iron at a lower hardness of 187 Brinell was more machinable than foundry "B" iron at 223 Brinell. This is an expected result.

3. For the pearlitic irons, the as-cast skin was more difficult to machine than the sub- surface for foundry "B" irons. The reverse occurred for the foundry "A" iron. The reason for the difference is probably a difference in pearlite content or quantity of inclusions.

Under Skin

1. For both the ferritic and pearlitic irons, foundry "B" irons were slightly better in machinability over the foundry "C" ferritic iron and foundry "A" pearlitic iron, respectively. However, as a group, the ferritic irons are more machinable than the pearlitics.

Turning

As Cast Skia

1. The as-cast skin of the pearlitic and ferritic cylindrical castings used in turning studies was more difficult to machine than the under skin or core metal, an expected result as discussed under "General" above.

2. In an exception to the above, there was very little difference in tool life results between skin and sub-surface material for foundry "C" ferritic iron.

Under Skin Recommendations for best machinability of any grade of ductile iron are:

1. The ferritic irons were more machinable than pearlitic irons over the entire range of . hsure casting surfafes are free from all speeds and feed rates, a normal condition. embedded abrasive material.

2. For all irons, the tool life curves followed the conventional pattern of high speednow Minimize soft skin (higher ferrite at as-cast tool life, and low speedlonger tool life. surface) effects by proper molding material

formulations, and avoidance of decarburizing 3. For the ferritic irons, foundry "C" iron was types of mold coatings.

slightly more machinable than foundry "B" iron. Only possible explanation is a slightly . The more ferritic the microstructure, the high inclusion content and more segregated better the machinability. Thus, ferritic ductile pearlitic content in the "B" material. iron is considerably more machinable than a

partially ferritic grade. For all grades, the 4. For the pearlitic irons, foundry "A" iron had lower the pearlitic content, the better the

better machinability than foundry "B" iron. machinability . The higher ferritellower hardness for the "A" ironaccounts forthis normalbehavior. Tune all steps in the casting process to

minimize inclusions in the finished product. Drilling Machinability decreases as inclusion content

increases. Cell boundary carbides and

1. The foundry "C" ferritic iron had titanium inclusions are particularly harmful.

better wdrillabilityn than the Additional studies are desirable to determine

"B" iron over the full feed range of 0.003- best practices for elimination of various types

0.009 inches per drill revolution. ~ i ~ h ~ ~ of inclusions. The main contributors are

inclusion content in "B" iron is the reason. unreacted treatment products and inoculants,

(Hardnesslpearlitic contents are equal.) slag dross and certain abrasive elements introduced in the melting operation by charge

2. Foundry "B" pearlitic iron had better materials.

drillability compared to the foundry "A" pearlitic iron overall feed rates, except at MACHINABILITY TEST RESULTS the maximum. This was expected based on comparing hardness, pearlite content, and Machinability results covering 260 individual inclusion ratings. tests of tool life versus cutting speeds and feeds

are plotted in Figures 1-36. This represents an enormous amount of data and requires detailed

CONCLUSIONS and separate examination of each type of metal cutting operation. All raw machinability data is included in Appendix A. Relationships

While the information in this rePo' allows between the various are different for estimation of effects of metallurgical factors face milling, drilling and turning. They are and changes in machine settings On affected by ductile iron grade, metallurgy from machinability ratings for ductile iron castings, a specific foundry, and whether cutting through

interactions constraio hard and fast the =-cast &in or into the sub-surface metal, relationships. If a foundry or machine shop requires precise studies to compare the trade- offs between tool life, productivity and related Below is a quick reference table. A detailed

machining costs, a specific evaluation program analysis of all plotted data is covered in the is best established between the producer and the sections "Analyses of Machinability Data" and

machining center. "Metallurgical Evaluations. "

3

Table 1

Machining Iron Aspect Operation Grade Evaluated Figures

Face Milling All Removal of as-cast skin 1-2

Face Milling Femtic Removal of as-cast skin 3-4

Face Milling Femtic Comparison of as-cast 5-8 skin vs. sub-skin

Face Milling Pearlitic Removal of as-cast skin 9-10

Face Milling Pearlitic Comparison of as-cast 1 1-14 skin vs. sub-skin

Face Milling All Below skin, effect of 15-17 feed rates

Face Milling Femtic Below skin, effect of 18-21 feed rate

Face Milling Pearlitic Below skin, effect of 22-25 feed rate

Turning All Removal of as-cast skin 26

Turning Femtic Comparison of as-cast 27 skin vs. sub-skin

Turning Pearlitic Comparison of as-cast 28 skin vs. sub-skin

Turning All Below skin, effect of 29-32 feed rates

Drilling* All Below skin, effect of 33-36 feed rates

*Note: There are no tests on drilling through the as-cast skin since milling was performed prior to drilling.

INVESTIGATIONAL PROCEDURE

whereas foundry "B" used a double ingate runner system. The latter was found necessary to eliminate solidification shrinkage. Photographs of the raw castings with the gating system removed are included in Figures 37 and 38. Foundries produced the castings to conform to the following ASTM grade designations:

ASTM Grade Microstructural Type

80-55-06 Predominately pearlitic 65-45-12 Predominatelv ferritic

Castings were requested to be produced in sufficient quantities in each foundry to provide all the material for the current study, and according to the following matrix:

~reatment -

Foundrv Method* Grade Pearlitic Ferritic

A Tundish X B In mold X X C Omn ladle X

* For further discussion of casting practices, see Table 2.

Castings were degated, gates ground and shot or grit blast cleaned prior to delivery to the Machining Research Center.

Machinability Test Procedures Material Sources

Three DIS member foundries, identified as foundries A, B and C, were commissioned to provide castings produced by their respective normal production practices. The castings were of two types: an 8 inch (203 mm) outside diameter (O.D.) by 6.5 inch (165 mm) inside diameter (I.D.) and 18 inch (457 mm) long tubular casting for turning studies; and a 2 inch (51 mm) by 4inch (101 mm) by 18inch (457 mm) rectangular casting for the milling and drilling studies. Each foundry used an appropriate casting gating system representing the metal feeding system best suited to the particular foundry's operations. The most significant differences in the gating practices of the foundries was that foundries "A" and "C" employed single casting gating systems;

The method used to evaluate the machinability of the various ductile irons was to conduct a series of tool life tests for each of the three different machining operations. Tool life in every test was defined by the tool wear on the insert or the drill. The tool wear was measured by observing the cutting edge under 20X magnification. Wear was measured periodically throughout each test run. When the tool wear reached apredetermined limit, the test was stopped and the cutting time, or holes drilled to that point, were recorded as the tool life for that particular test. The wear limit was selected by Machining Research, Inc., based upon experience of useful tool life.

Many machining operations require cutting through the as-cast surface or skin of a casting. On the other hand, the basic machinability of a cast material is normally represented in the literature by machining data on sub-surface metal. The latter represents a more uniform distribution of hardness andmicrostructure, and therefore have a more predictable and uniform response to metal cutting operations. However, the as-cast skin has an oxide layer, which may also contain embedded sand, slag or other exogenous compounds. These would be expected to accelerate tool wear rates.

The following machining test matrix was followed for each of the two iron grades, ferritic and pearlitic:

Turning: Skin and below skin Milling: Skin and below skin Drilling: Below skin only.

The same test pieces were used for both milling and drilling studies, with the drilling tests performed after completion of both the skin and below skin milling operations.

Skin Turning Tests

The tubes for the turning tests were approximately 8 inch outside diameter (O.D.), 6-112 inch inside diameter (I.D.), and 18 inch long. The gate (notched) end of the tube was securely gripped in the machining center on the I.D. with the hydraulic three-jaw chuck. The other end of the tube was supported by a bull nose (large diameter) live center in the hydraulic quill of the tailstock. The tailstock end of each tube was squared off with a cutofflgrooving tool. Figure 39 shows examples of the turning test cylinder castings in both the before and after test condition. The eccentricity of each tube had to be measured to insure completely cleaning up all the as-cast surface in one pass. Since the eccentricity was not the same for all the tubular castings, the depth of cut for the cleanup or skin test was not uniform. The skin cut was stopped at 6 inch, 12 inch, and 18 inch, lengths of cut to measure the wear on the "cleanup" tool. This test was performed to indicate the difference between the machinability of the as-cast surface versus the sub-skin region of the castings.

See Figures 4 1 and 42 illustrate the Horizontal Machining Center at Machining Research, Inc., used for the turning studies.

Skin Face Milling

The castings for the face milling (and drilling) tests were 2 inch thick and 4 inch wide, and 18 inch long. The face mill cutter was clamped into the spindle of the CNC machining center (see Figure 43). The cutter (in Figure 44) has a capacity of five inserts, but only one insert at a time was used in the mill since the amount of as-cast surface to be removed was limited. The width of cut in these skin tests was maintained at 2 inches. One pass was made on each of the 2 inch x 18 inch faces on each casting. Two passes (2 inch each) were made on each of the 4 inch x 18 inch faces on each casting. The depth of cut was a minimum of 0.050 inches (1.27 mm), depending on any irregularities in the surfaces of the castings.

There were no skin tests conducted in the drilling operation. Figure 40 illustrates examples of the milling/drilling test pieces in the as-cast, milled, and finally drilled condition.

Sub-skin T u r u Sub-skin Face Milling

The test procedure was essentially the same for the turning and the face milling tests. A new insert, designated as the test tool, was placed in the tool holder or face mill. Unlike the skin tests, where only one pass was possible, as many passes as possible were made in the sub- skin tests. Repeated passes at a constant depth of cut were made on the castings with all the as- cast skin removed. Periodically, after each pass or several passes, the insert was removed from the holder and the cutting edge was inspected and the wear was measured and recorded on the data sheet for that operation. Figure 45 illustrates the typical pattern of wear observed on the inserts used in the turning and face milling tests. Each test was continued until the wear on the insert measured 0.015 inch (0.38 mm) uniform wear or 0.030 inch (0.76 rnm) localized (peak) wear. The recorded tool life was the time required to develop the specified wear on the insert at a specific combination of cutting speed and feed.

At the conclusion of each test, the next set of test conditions was determined. The feed levels that were used were selected to cover the range from rough to finish machining conditions. The selection of cutting speeds for each test series was somewhat subjective, but basically was determined by the machinability of a particular grade of iron, from a specific foundry. Generally, the ferritic irons, which should be "easier-to-machine" are expected to be machined at higher speeds than the pearlitic irons. The first test speeds are usually deliberately very high to give a short tool life. This rationale is used to control the level of tool life obtained. By systematically lowering the cutting speed, the length of cutting time (to reach the target amount of wear) is restricted to a reasonable time frame, based on Machining Research, Inc., experience.

The tool life values, the speeds, and the feeds are placed in aregression analysis calculation to model the tool life. As more test data are incorporated into the model, the ability to predict the tool life becomes more accurate. The correlation ratios to the model reveals how accurately the model predicts the actual tool life from the machinability tests. A variety of tool life curves can then be produced from the model to show the effect of speed and feed on tool life. The tool life curves shown in the figures in this report illustrate this relationship and how well the data fits the relationship. Since machinability data normally follows the traditional Taylor equation, repeat tests were unnecessary unless this trend was not observed. If a test point did not fit this pattern, the test was repeated to verify the result. Statistical replication tests were not performed since historical data has shown the repeatability of machinability data to be generally k10 percent.

Sub-Skin D r r U . .

The rectangular castings for the face milling tests were also used in the drilling tests. The milling tests on eachcasting were stoppedwhen the workpiece was 1-114 inch thick, leaving a 1-114 inch x 4 inch x 18 inch rectangle. Both 4 inch x 18 inch faces were drilled on each piece. Each drilling produced a 112 inch (12.7 mm) deep blind hole. A blind hole is one that does not break through the exit side of the workpiece. The general test procedure for the

drilling tests was the same as that used in the turning and milling tests. The tool life in drilling is expressed as the number of holes drilled before the wear on the drill reaches 0.0 15 inch (0.38 mm). Figure 46 illustrates the wear location on the drill. The maximum wear usually occurs at the intersection of the cutting edge and the margin (primary peripheral clearance) of the drill.

Machine Tooling

Face milling and drilling tests were performed on a new Tongil TNV-80 three-axis machining center (Figure 43). This machine has a 24 hp (3 1.8 kW), 8000 rpm spindle and a 30 position tool changer. A Fanuc Model OM, CNC controller provides accurate positioning and repeatability. Each workpiece casting was securely clamped in two Kurt 8 inch heavy duty precision vises, keyed and bolted to the table of the machine.

The turning tests were performed on a new Tongil THN-4 horizontal CNC turning center equipped with a 35 hp (46.4 kW), 4500 rpm spindle motor (Figure 41). The controller is a user-friendly Fanuc Model OT-B CNC with color graphics display.

A TekSoft CAD/CAM system provides DNC capability for both machine tools.

Cutting Tools

All turning tests were conducted using the same style tool holder and the same grade of coated carbide inserts. The tool holder was a Kennametal brand, DSRNL- 124B style using grade KC 850, SNMA 432 inserts. The KC 850 grade is a titanium nitride coated, multi-layered carbide.

The tool holder provided double negative 5 degree back rake and side rake angles. Side and end cutting edge angles were 15 degrees. The tool holder was clamped in a VDI tool block in one of the ten stations of the indexing turret.

Milling tests were made with a4 inch (102 mm) diameter, five tooth cutter containing only one insert. The geometry on this cutter provided

double negative 5 degree axial and radial rake angles and a 15 degree lead angle. The cutter utilized the same inserts as the turning tool.

Both the turning and the face milling tests were stopped when the wear on the cutting edge of the inserts reached 0.015 inch (0.38 mm) uniformwearor0.030 inch (0.76 mm)localized wear.

Tools used in the drilling tests were Cleveland brand two fluted, high speed steel twist drills. The geometry was the standard 118 degree plain point jobbers style.

0.009 inch per revolution (ipr). These are 0.076,O. 127,O. 178, and 0.229 &rev, respectively. The 114 inch (6.3 mm) diameter holes were drilled 112 inch (12.7 mm) deep, blind (not breaking through the bottom of the piece).

The as-cast skin was removed from the tubular castings in one continuous pass on each casting. The cutting speed was varied from 400 to 900 fprn (123-274 dmin), but the feed was constant at 0.005 ipr (0.127 &rev).

Sub-Skin Turning Machining Practices

The cutting speed in the face milling operation on the pearlitic irons was varied from 650 feet per minute (fprn) to 1000 feet per minute (198-305 dmin), and the feed from 0.005 inch (0.127 rnrn) pertooth to0.015 inch (0.381 mm) per tooth. The speed range on the ferritic irons was from 1000 fprn to 1500 fprn (305-457 dmin). The depth of cut was maintained at 0.050 inch (1.27 mm). The tests were all performed dry, with no cutting fluid.

The 2 inch x 18 inch faces were machined first, on all the castings. Then a 2 inch wide pass was made twice on the 4 inch x 18 inch faces on each casting. The cutter and workpiece were always aligned so that the cutting setup was in a climb milling mode.

Sub-Skin Face M d h g . . The cutting speed was varied from 300 fprn to 1000 fprn (91-305 dmin), and the feed from 0.005 inch per tooth to 0.015 inch per tooth. The depth of cut was maintained at 0.050 inch. The tests were all performed dry, with no cutting fluid. The 4 inch face was machined in these tests. The 4 inch x 18 inch remnants from this test were used for the drilling tests.

All the drilling data were taken under the as- cast skin. The cutting speed varied from 200 to 500 fprn (6 1- 152 mlmin). Four levels of feed rate were used: 0.003, 0.005, 0.007, and

The cutting speed was varied from 400 to 1000 fprn (122-305 dmin) and the feed rate from 0.005 to 0.020 ipr (0.127-508 &rev). The depth of cut was constant at 0.050 inch.

Metallurgical Studies

Typical samples from each type of iron and each foundry source were analyzed for microstructure, hardness, chemical composition, and inclusion types and amount. Additionally, when individual machinability results for a given set of test parameters were different from what would be normal for the particular iron, these samples were further analyzed by scanning electron microscopy and x-ray spectrometry to explain the abnormal machining behavior. Finally, the specific processes used to produce castings in each foundry were examined in an attempt to explain the basis for the microstructures or types of inclusions in test pieces. Foundry process descriptions can be found in the Table 2.

ANALYSES OF MACHINABILITY DATA

Each of the three types of machining operations are analyzed separately, with the analyses based on the model curves in Figures 1-36. Machinability testing always results in some data scatter. Experience has shown that this scatter can be normalized by modeling the individual data points to produce trend curves of tool life versus speed, for any given feed rate, according to the Taylor equation, as described in the Investigational Procedure Section.

For each type of metal removal operation (except for drilling), the analyses first addresses machining through the as-cast skin, followed by the machining characteristics of the sub-skin material. The differences between skin cutting and sub-surface material machinability are then examined.

Face Milling

Milline Casting Skin

Figures 1-14 cover face milling the as-cast surfaces of the rectangular castings. The scatter in this data reflects variations in the metallurgical character of an as-cast skin on ductile iron castings. The skin characteristics will vary between foundries, grades, producers, and foundry molding practices. For example, the skin will have variations in the thickness of the oxide surface layer, burnted in exogenous material, degree of degraded graphite, inclusion content and pearlite content.

Figures 1 and 2 compare all four irons at two feed rates, 0.005 and 0.010 ipt (inches per turn of milling cutter). At the higher feed rate, speed has less effect on tool life, and the data converges.

The two ferritic irons, which had quite similar hardness values, are compared in Figures 3 and 4. There is no consistent difference between the two. Figures 5-8 compare machinability between the as-cast skin and the sub-surface metal for the two ferritic irons, at two different feed rates. For foundry B, Figure 5 shows the unusual condition where the skin has better machinability than the sub-skin. However, at the higher feed rate in Figure 6, the situation is reversed. This is a data scatter effect and indicates neither iron may have a machinability advantage over the other. Figures 7 and 8 show the same comparison for the "C" ferritic iron. At the lower feed rate in Figure 7, the as-cast skin has better machinability than the sub-skin material, whereas in Figure 8 for a higher feed rate, there was little difference.

Fi~ures 9- 14 examine the skin machinability of the two pearlitic irons. These two irons had significant differences in core hardness and in the pearlitelferrite ratios, with iron "B"

averaging 223 Brinell hardness, and iron "A" averaging 187 Brinell hardness. The metallurgical effects are discussed further in a subsequent section.

In Figures 9 and 10, for feed rates of 0.005 ipt and 0.010 ipt, respectively, foundry " A material had better skin machinability than the "B". Figures 1 1 - 14 compare skin versus sub- skin machinability, Figures 1 1 and 12 for "B" iron, and Figures 13 and 14 for "A" iron. For foundry "B" iron, which was the harder of the two, the sub-surface material tended to machine better than the skin at low speed, but there was no difference at higher cutting speeds. Whereas for the "A" pearlitic iron, the skin had consistently better machinability than the sub- surface iron. This is believed due to the fact that the "A" pearlitic iron castings had a much deeper ferritic skin than on the "B" material. This is normal since low pearlitic content irons tend to have deeper ferritic skins.

Fi-mes 15-17 compare the millability of both ferritic and both pearlitic irons at three increasing feed rates. At the higher feeds, Figures 15 and 16, the ferritic irons have substantially better machinability than the pearlitic irons. Additionally, iron "B" exhibits increased tool life in both the ferritic and pearlitic conditions, compared to the irons from foundries "C" and "A", respectively. However, at the highest feed rate, 0.015 ipt, shown in Figure 17, ferritic iron "B" exhibited the reverse - higher machinability.

Figures 18-2 1 comparemachinability ofthe two ferritic irons at increasing feed rates from 0.005 to 0.020 ipt. In all cases, ferritic iron from foundry"BU has superior machinability. Because of the exponential nature of the tool weadspeed relationship, the numerical difference in tool life between the different irons is accelerated as cutting speeds are reduced.

Figures 22-25 cover the comparisons of pearlitic irons from foundries "B" and "A". Except at the higher speeds and at the lowest feed in Figure 22, rnachinability of the two irons is similar, with iron "B" being only slightly better than iron "A".

Turning

C a s w k i n Removal

Figure 26 compares the machinability of the four irons, two ferritic and two pearlitic, that were cast into cylinders. The ferritic irons have better machinability than the pearlitics. At all but the highest turning speeds for the ferritics, foundry "C" is better than foundry "B". Whereas for the pearlitics, foundry "B" is superior to foundry "A". In Figure 27, there is little difference between skin and sub-skin machinability of foundry "C" ferritic iron. But for foundry "B" ferritic, sub-surface material was more machinable than the casting skin. In Figure 28 for the pearlitic irons, ignoring an exceptional data point at cutting speed 800, the skin of foundry "A" iron machined poorly compared to the below skin. In the case of foundry "B", the situation is slightly reversed, particularly at the higher turning speeds.

Sub-surface Turning

Fi~ures 29-32 cover sub-surface turning of all four irons at increasing tool feeds of 0.05,O. 10, 0.15, and 0.20 ipt.

Ferritic irons are substantially superior in machinability to the pearlitics. The superiority increases with feed rate. At the three lowest feeds, 0.05,0.010 and 0.15 ipt, the "C" ferritic out performs the "B" ferritic iron. At all feed rates, the foundry "A" pearlitic ductile at 187 BHN machines somewhat better than the foundry "B" iron which has a hardness of 223 BHN. For sub-skin machining of the pearlitics, "A" is better than "B" for turning but "B" is better than "A" for face milling.

Drilling

Drilling tests were conducted only on sub-skin material, and on each of the four irons at feed rates of 0.003, 0.005, 0.007 and 0.009 i.p.r. (inches of feed per revolution of the drill). Drilling tests were made with a soluble oil type cutting fluid, which is almost always necessary in drilling of ductile iron in order to prevent early catastrophic failures of the drill bit.

Fi~ures 33-36 include results for both ferritic and both pearlitic irons. Note the scales are

different than those employed for face milling and turning. Ferritic irons exhibited far superior drillability , compared to pearlitic irons, as measured by the number of holes drilled before loss of the drill cutting edges. The curves tend to be quite steep, particularly for the harder pearlitic materials. Drilling operations are ultra sensitive to drill speeds. Very small reductions in speed can often increase number of holes drilled by 5 to 10 times. For the ferritic materials, "C" iron drills at significantly higher speeds than "B" iron, even though the sub-surface or core hardness of the two irons are very similar.

The pearlitic irons present a different case. Except for the highest feed rate of 0.009 i.p.r., "B" iron is more drillable than "A" iron, yet the "B" iron has a bulk hardness of 223 BHN, and the "A" material is only 187 BHN.

A subsequent section on Metallurgical Characteristic of Iron, provides explanations for some of the unexpected differences in machinability of the various irons.

METALLURGICAL EVALUATIONS

All previously published works demonstrate that machinability, whether milling, drilling or turning is a function of the microstructure. The higher the ferrite content, the correspondingly lower the hardness, the better is the machinability. Thus, the more ferritic grade 65-45- 12 should have better machinability than grade 80-55-06. The current work reinforces this observation. However, abnormalities occur in the current data at certain feed settings. Some examples are:

1. In several cases, apearlitic grade, machined better than the ferritic.

2. For a given foundry source, either pearlitic or ferritic, in some instances, the skin had higher and sometimes lower machinability than the sub-surface - an unexpected variation.

3. Two irons with similar hardness and similar matrix microstructures (ratio of ferrite to pearlite) had markedly different machinability ratings.

4. Occasionally, reversals of the above cases occur between turning, face milling and drilling. (One would expect if one iron had superior machinability over a second in turning, the same relationship should also occur for face milling or drilling). The reasons for these abnormalities could not be identified.

To determine relationships of structures to machinability results, the following were evaluated:

Microstructures of typical samples for each of the four irons, at the as-cast skin and in the sub-skin. See Figures 47 and 48.

Photomicrographs to illustrate graphite size and distribution; percent pearlitelferrite, uniformity of structures and inclusion concentrations.

Selectively, further studies of microstructures for unexplained or unanticipated abnormalities in machinability from what would be considered normal behavior.

Conduct energy dispersive x-ray spectroscopy (EDS) by scanning electron microscopy (SEM) of individual inclusions for amount and composition.

Collect information on foundry production practice for each iron in an attempt to relate practice to structure to machining test results.

Figures 47-56 are microstructures which include unetched micrographs to reveal inclusions. Table 4 is a spreadsheet relating specific points on the machinability curves (Figures 1-36), to these figures, and providing pairs of comparisons of amounts and types of EDS identified inclusions to the machinability results.

Additional examples of high inclusion content test pieces are included in Appendix B, along with some examples of EDS type plots for inclusions. These micro numbers are also listed in Figures 1-36, however, SEM-EDS analyses were not performed on Appendix B micros.

EDS can only identify individual elements. Each inclusion is complex. By separate analyses of numerous different appearing

inclusions in each sample, and from the analyst's knowledge of the compounds most likely to be formed in the ductile iron process, the source or origin of each compound can be identified.

General Observations on Microstructural Variations

Although castings from a given source should have been produced in a single cast, variations in matrix microstructures from the beginning to the end of a pour are expected. This is normal due to treatment and inoculation fade and falling pouring temperatures. This is a probable explanation for much of the data scatter in a specific series of tests.

2. Both pearlitic and ferritic grades have a "soft skin", i.e., an increase in ferrite content over that of the sub-surface. The depth and degree or surface ferrite enrichment varies between foundries, and between castings produced in a single pour. This is typical and normal in ductile iron production. (See Figures 47 and 48.)

3. Pearlitic grades showed a more pronounced ferrite increase in the skin over ferritic irons.

4. Part of the abnormal machining results between the skin cut and sub-skin machinability is a result of 1, 2, and 3 above.

However, all castings were shot cleaned before machinability testing. This introduces an uncontrolled amount of work hardening that could affect the current machining test results. The erratic behavior in turning and face milling of the as-cast skin is probably a result of the shot peening effect.

When differences in machinability between two irons cannot be explained by matrix structural differences alone, the lower machinability relates to increased inclusion amounts. Additionally, irons containing titanium inclusions, or undissolved ferrosilicon particles, are particularly prone to reduce tool life.

6. Irons produced by the in-mold process, compared to those produced by ladle treatment, have a finer average nodule size; a mixture of coarse primary nodules and very fine secondary nodules; and a very non-uniform distribution of ferrite and pearlite. These irons also tend to have higher inclusion concentrations.

7. Many of the EDS micros contain complex inclusions high in titanium (Ti). Ti inclusions are frequently reported to be extremely detrimental to machinability because of abrasive wear on cutting tools (Tic and TiN compounds are much harder than carbide tool inserts). Irons from foundries A and B each had numerous Ti containing inclusions. Sources of high Ti are pig iron, steel scrap contaminated with high strength- low alloy steels (these contain Ti, V, and Cb plus higher P than low carbon sheet and plate), or from melt down furnace linings. Several sources have suggested that direct arc melting is particularly prone to reducing Ti from a high Ti furnace lining. It is also possible that painted scrap can contribute Ti to the melt because Ti pigments are the backbone of many automotive coatings.

8. Whereas the two ferritic irons were similar in hardness and matrix ferrite content, but the pearlitic irons were not. Iron "A" at 187 Brinell hardness averaged 40% ferrite in the core, whereas, iron "B" at 223 Brinell hardness averaged only 20% ferrite in the core. Additionally, the average nodule size of the "B" iron is one-half of that of the "A" iron.

Interactions of each of the eight factors above therefore account for differences in machinability between pairs of test results. Individual assignable causes are therefore difficult to determine. Only general observations are noted. As the curves in Figures 1-36 illustrate, tool wear data becomes compressed at the lower cutting speeds when using the highest tool feed rates. Thus, small metallurgical variations may be less important on tool life if a machining philosophy of "maximum feed with allowable speed" is practiced in the machine shop.

Effect of Inclusions on Machinability

When differences in machinability , whether for face milling, drilling or turning, could not be accounted for, based on hardness or matrix microstructures, microsamples were analyzed by EDSSEM for amount and type of inclusions and graphite size and distribution. These micros are identified by number on the appropriate curves in Figures 1-36. A total of 38 micros were prepared in all. An analyses of 5 pairs (2 micros each) for effect of inclusion on machinability behavior are summarized in Table 4. All inclusions were of a complex compound type.

The results show that when differences in machinability are not accountable based on matrix microstructure, the poorest machinability is assignable to the test sample having the highest inclusion content. The data further shows that iron "B" in both the pearlitic and ferritic grades tends to have the highest inclusion content.

Iron "B" is produced by the "treatment in the mold" process, which could account for the higher inclusion content, compared to irons "A" and "C" which are nodulized by ladle metallurgy.

The analyses of the inclusions indicate that their source is the treatment reaction products, unreacted alloy, undissolved ferrosilicon inoculants, and slag carried into the mold by the iron stream. None of the samples exhibited magnesium or cerium sulfides as was frequently found in the previous DIS Project P16 on inclusions. This could be due to the low sulfur base iron at each of the three foundries.

Table 5 is a list of typical hardness values for various binary inclusions found in ductile irons. There is no available data on the more complex inclusions, consisting of 5-8 elements, found in many of the machinability samples. However. the hardness values would probably exceed 1500 DPH. The extreme high hardnesses of the oxide and nitride type inclusions are expected to have a major impact on reducing tool life in all types of machining operations.

It is therefore extremely critical that good metal casting practices demand that only the cleanest iron enters the mold cavity. For the in-mold treatment process, it is equally critical that all treatment alloy be totally dissolved and reacted in the molten iron before casting solidification.

Project Management

Lyle Jenkins, Technical Director Ductile Iron Society

Final Report Review Team ACKNOWLEDGEMENTS

Most of the research conducted in this project was sponsored and funded by the Ductile Iron Society. However, a number of DIS member organizations and individuals voluntarily contributed time and resources to successful completion of the current study on machinability. Both groups of contributors are recognized below.

DIS Funded Research

Machining Research, Inc. Planning and conducting Florence, KY all machinability tests, and

&ta analyses.

Metcut Microstructural sample Cincinnati, OH preparation.

Zexel, Inc. Scanning electron Decatur, IL microscopy and energy

dispersive spectrography analyses of inclusions.

Robert Christ Data analyses and Consultant preparation of final report.

DIS Member Voluntary Contributors

Cast-Fab Technologies, Inc. Castings for Cincinnati, OH rnachinability study.

Harvard Industries, Inc. Castings for Albion, MI machinability study.

Teledyne Casting Service Castings for LaPorte, IN machinability study.

Deere & Company Metallographic work Moline, IL and iron analyses.

Lyle Jenkins P.H. Mani Prem Mohla

Project Monitoring by DIS Research Committees

Initially: Special Properties Subcommittee, Tom Prucha, Chairman

Subsequently: P20 Project Monitoring Committee, Prem Mohla, Chairman

REFERENCES

1. DIS Research Report Project No. 14, "An Investigation of Factors Affecting The Machinability of Ductile Irons," The Ductile Iron Society, October 1987.

2. DIS Research Report Project No. 16, "Characteristics of Inclusions in Ductile Iron Castings," The Ductile Iron Society, August 1989.

3. John D. Christopher, "Machinability of Ductile Iron," Final Report of Machining Research, Inc., on DIS Project P20, November 1992, on file at the Ductile Iron Society.

4. Svetlana Reznikov, "DataBase of SEM and EDS Analyses of Inclusions in Machinability Test Coupons for DIS Project P20," Zexel Environmental Engineering Laboratory, March 1993, on file at the Ductile Iron Society.

Table 2

Description of Foundry Processes Used to Prepare Machinability Samples I

*Note: Iron held at the molding line in a rod furnace to maintain tem~erature ~ r i o r to in mold - casting.

Foundry B Foundry C

20T direct arc Channel induction

33% returns 4040% returns (uncleaned) (mixed cleaned and

uncleaned) 26-35% bushlings 510% sore1 pig 40-33% ductile iron 4550% steel scrap Borings Crushed electrode

carbon raiser 1% other (50% FeSi, FeMn, electrode carbon raiser) Cu added in the charge for pearlitic grade

CaC, + 1 % petroleum None Coke

In mold 4T open ladle 5.5% Mg-Fe-Si with 5% Mg-Fe-Si 1 % balanced rare earths

NO cover, no rare earths

None - In mold which 0.5% of 75% FeSi, in also provides inocula- pouring ladle tion

Ferritic and pearlitic Ferritic

lOOT channel* None

Melt method

Charge

Desulfurization of base iron

Treatment

Inoculation

Grades produced for this study

Duplexing

Foundry A

10T coreless induction

30% returns (uncleaned)

35% slitter steel 35% sore1 pig Sic as required

Petroleum coke carbon raiser

None

Coke to control S to 0.007%

Tundish 5% Mg-Fe-Si with rare earths

1.5% steel punchings cover

Pretreat, 0.30% of 75% FeSi in tundish

Inoculate, 0.40% of 75% FeSi in pouring ladle

Pearlitic

None

Table 3

Chemical Analyses and Brinell Hardness of Cylindrical and Rectangle Machinability Bars

Iron Brinell* Composition, Wt 9% Foundry Type Hardness Si Mn P S Ni Cr Mo Cu Mg Ce Ti V Sn C**

A Pearlitic 187 2.64 0.34 0.020 0.009 0.06 0.05 ~0.01 0.10 0.055 0.022 0.011 0.015 0.005 3.46

B Pearlitic 223 2.47 0.48 0.022 0.008 0.02 0.04 ~0.01 0.58 0.053 0.003 0.014 ~0.01 0.003 NA

B Ferritic 163 2.32 0.39 0.025 0.006 0.03 0.05 4.01 0.24 0.040 0.002 0.030 4.01 0.002 NA

C Ferritic 156 2.55 0.27 0.025 0.005 0.03 0.04 4.01 0.03 0.058 0.023 0.016 4.01 0.001 3.50

* These are general hardness values. At the extreme surface of the as cast skin, hardness values were estimated to be 10-15 Brinell Hardness c numbers lower, due to the increased ferritic skin found on all test castings. .b **NA = not available.

Face Milling - Skin All Ductile Iron Grades

130

120

110

100

90

80

70 Tool Life minutes

60

50

40

30

20 . #

10

0

200 400 600 800 1000 1200 1400 1600

Cutting Speed-Feet per minute -

-face mill: 4" diameter, single tooth cutting tool: Kennametal grade KC850 insert style: SNMA-432 -feed: 0.005 ipt depth of cut: 0.050" -width of cut: 2.0" milling setup: climb cutting fluid: dry

---tool life end point: 0.015" uniform wear.

FIGURE 1

Face Milling - Skin All Ductile Iron Grades

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600

Cutting Speed-Feet per minute

face mill: 4" diameter, single tooth ---cutting tool: Kennametal grade KC850 -

insert style: SNMA-432 feed: 0.010 ipt depth of cut: 0.050"

- width of cut: 2.0" milling setup: clin-b - cutting fluid: dry tool life end point: 0.015" uniform wear

Face Milling - Skin Ferritic Ductile Iron

130

120

110

100

90

80

70 Tool L i f e

minutes 60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600

C u t t i n g Speed-Feet per m inu te

insert style: SW-432 feed: 0.005 i p t depth o f cut: 0.050" width o f cut: 2.0"

- -

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I I I I I I I I I I

Face Milling - Skin Ferritic Ductile Iron

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- -- - - - - - - ce mill: 4" diameter, single tooth

cutting tool: Kennarnetal grade KC850 insert style: SNMA-432 feed: 0.010 ipt depth of cut: 0.050" width of cut: 2.0" milling setup: climb

L

FIGURE 4

Face Milling Foundry "B" Ferritic Ductile Iron 163 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- - - - - - -

face mill: 4" dianeter, single tooth - - cutting tool: Kernmetal grade KC850

insert style: SNclA-432 -

- feed: 0.005 ipt -

- depth of cut: 0.050" w i d t h of cut: 2.0" - milling setup: clinb cutting fluid: dry

--tool life end point: 0.015" uniform wear- - -

- - - -

* -

TI,, 1 1 1 1 1 1 1 l l t l l l l 1 , 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I 1 I ,

Face Milling Foundry "B" Ferritic Ductile Iron 163 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


-

- -

face mil 1: 4" diameter, single tooth cutting tool: Kernemeta1 grade KC850 insert style: SNCIA-432 feed: 0.010 ipt

- - -

Face Milling Foundry "C" Femtic Ductile Iron 156 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


insert style: SM4432 feed: 0.005 ipt

- depth of cut: 0.050" - - width of cut: 2.0"

'milling setup: clinb -

cutting fluid: &y tool life end point: 0.015" uniform wear -

- *

- - - - \ - -

-

- -

- - - Y

- 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ~ 1 1

Face Milling Foundry "C" Femtic Ductile Iron 156 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


depth of cut: 0.050"

w F i g u r e 8

Face Milling Skin Pearlitic Ductile Iron

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- I I I I I - face mill: 4" dianeter, single tooth - - ,cutting tool: Kennametal grade KC850 - insert style: SNC1A-432

feed: 0.005 ipt depth of cut: 0.050"

- width of cut: 2.0" milling setup: climb cutting fluid: &y tool life end point: 0.015" uniform wear

- - - - -

-

- - - -

FIGURE 9

Face Milling Skin Pearlitic Ductile Iron

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


nsert style: SNFIA-432 feed: 0.010 ipt depth of cut: 0.050" width o f cut: 2.0" milling setup: c l i h

-

- - -

- -

- \

- - GOUNDRY "A" - - - -

-

-

1 1 1 1 1 1 1 1 1 1 1 , 1 1 4 1 1 1 1 * 1 1 ' * l l l s l l l 1 1 1 1 1 1 1 1 1 1 1 * 1 1 -

Face Milling Foundry "B" Pearlitic Ductile Iron 223 BHN Skin 'Versus Sub-Skin

120

110

100

90

80


60

50

40

30

20

10

200 400 600 800 1000 1200 1400 1600


- -

- - - - - -

face mill: 4" dimeter, single bth - 'cutting tool: Kemcmetal grade KC850 - insert style: SNMA-432 - - feed: 0.005 ipt - , - depth of cut: 0.050"

- 2 w i d t h of cut: 2.0" - - milling setup: clinb cutting fluid: dry - - tool life end point: 0.015" uniform wear

- - - \ -

SUB SKIN

- - 7 - -

1 1 1 1 1 1 1 1 1 , 1 1 # ( , 1 1 1 1 1 ,

Face Milling Foundry "B" Pearlitic Ductile Iron 223 BHN Skin Versus Sub-Skin

130 - -face mill: 4" diameter, single tooth cutting tool : Kennamtal grade KC850 -

- 120

insert style: SHYA432 'feed: 0.010 ipt

- depth of cut: 0.050"

110 width of cut: 2.0"

- 'milling setyl: clink cutting fluid: b y

100 tool life end point: 0.015" uniform wear -

90 - -

80 - -

Tool Life - minutes - - ISM SKIN

I 1 1 1 1 1 1 1 1 I I I I I I I 1 t I U I I 1 1 1 1 1 1 ,

200 400 600 800 1000 1200 1400 1600

Cutting Speed-Feet per minute J

Face Milling Foundry "A" Pearlitic Ductile Iron 187 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- - - - - -

,face mill: 4" diameter, single tooth - cutting tool : Kernemeta1 grade KC850 -

insert style: M 3 2 feed: 0.005 ipt depth of cut: 0.050" width of cut: 2.0"

- - SUB SKIN

- - -

Face Milling Foundry "A" Pearlitic Ductile Iron 187 BHN Skin Versus Sub-Skin

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


cutting tool : Ksmanstrrl grade KC850 insert style: SH1A-432 feed: 0.010 ipt depth of cut: 0.050" width of cut: 2.0"

E milling sekup: clinb cutting fluid: b.y

--tool life end point: 0.015" uniform wear- - - 1 - - - - - - - - - -

- - -

1 1 1 1 1 l l 1 l l 1 1 1 1 1 1 1 1 l 1 1

FIGURE 14

Face Milling - Sub-Skin All Ductile Iron Grades

- face mill: 4" dicmeter, single tooth

130 L akting tool : Kernameta1 grade KC850 - insert style: SEMA-432 -

120 : feed: 0.005 ipt 'depth of cut: 0.050"

- width of art: 2.0" 110 : milling setup: clirh

cutting fluid: dry - tool life end point: 0.015" uniform weer

100 - 1

I

- - 90 -

-

Tool Life minutes

- 20 -

-

200 400 600 800 1000 1200 1400 1600



130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


insert style: SNYA432 feed: 0.010 ipt depth of cut: 0.050" width of cut: 2.0"

- - -

FQIURE 16


130

120

110

100

90

80


60

50

i 40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


I 1 - face mil 1: 4" diameter, single tooth

cutting tool: Kennmnetal grade KC850 insert style: SNMA-432 feed: 0.015 ipt - - FWNDRY "C" depth of art: 0.050" - FERRlTlC wi& of a: 2.0" -

I milling setup: clirrb - cutting fluid: 6y -

--FOUNDRY "8" tool life end point: 0.015" uniform wear

PEARLlTlC I I 1 I

Face Milling Fenitic Ductile Iron

130

-

120

110 face mill: 4" dianeter, single tooth cutting tool: Kernaneta1 g-ade KC850

100 1 'insert style: St+%-432 - feed: 0.005 ipt -

90 depth of cut: 0.050" width of cut: 2.0"

- milling setup: clinb

80 cutting fluid: &y tool life end point: 0.015" uniform wear -


60 -

50 - - -

40 - -

30

- 20

- - / \

10 - - - 0 - r 1 ' 1 8 - '

1 1 1 1 1 1 1 1 1 1 1 1 1 * 1 1 1 1 1 1 * I- * 1 1 * 1 1 1 ,

200 400 600 800 1000 1200 1400 1600


Face Milling Ferritic Ductile Iron

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- -

- Face mill: 4" diameter, single tooth

- Cutting tool: Kemcmetal grade KC850 Insert style: SMA432 -

0 Fesd: 0.010 ipt Depth of cut: 0.050"

1, Width of cut: 2.0" . Milling satup: clirh Cutting fluid: b y Tool life end point: 0.015" uniform wear

- - - - -

\ \

- - - -

Face Milling Ferritic Ductile Iron

130

120

110

100

90

80

70 Tool Li-fe minutes

60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- x I - face mil 1: 4" dianeter, single tooth - cutting tool: Kemanatal wade KC850

insert style: SMA-432 feed: 0.015 ipt -

- depth of art: 0.050" width of cut: 2.0" -mil ling settup: clinb

- cutting fluid: by - tool life and point: 0.015" miform wecr

L

-

- -.

- - - \ i

- - - - -

r l l k h l l l . l l 1 1 1 1 1 1 1 1 1 1 1 1 l l l l l l l . ~ l I I I 1 1 1 1 1 1 1 I I I I I I I

Face Milling Fenitic Ductile Iron

130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


- - I I I I I - - face mil 1 : 4" diameter, single tooth - cutting tool : Kernemeta1 grade KC850 - - insert style: SNW-432

- - feed: 0.020 ipt dapth of cut: 0.050" width of cut: 2.0" - milling setLp: clinb - - cutting fluid: &y - tool life 4 point: 0.015" uniform weer

- - - - - - -

-

- - A - - - - \

- - - -

- --

F O U N D R Y "c" -

-, 1 1 1 1 1 1 1 1 l 1 1 1 l 1 I 1 1 1 1 1 1 1 1 1 1 1 1 l 1 1 1 1 1 1 l l 1 1 1 1 1 l l l l l l l l

Face Milling Pearlitic Ductile Iron

I, face mill: 4" diameter, single tooth

130 cutting tool: Kennametal grade KC850 insert style: SNMA-432

120 feed: 0.005 ipt depth of cut: 0.050" width of cut: 2.0"

110 milling setup: clinb cutting fluid: dry tool life end point: 0.015" uniform wear

100 F

1

90

80

70 Tool Life minutes -

60

- 50

40 \4 30

20

FOUNDRY "A"

1 0 ---------------

0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ~ 1 1 * 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ( 1 1 1

200 400 600 800 1000 1200 1400 1600


FIGURE 22


130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


insert style: SNMA432 feed: 0.010 ipt depth of cut: 0.050" width of cut: 2.0" milling setup: climb


130 I 120 face mill: 4" diameter, single tooth

cutting tool: Kennametal grade KC850 insert style: SNM4-432

110 feed: 0.015 ipt depth of cut: 0.050" width of cut: 2.0"

100 milling setup: clih cutting fluid: dry

90 tool life end point: 0.015" uniform wear

80


60

50

40

30

20 --------

10

0 1 1 1 1 1 1 1 1 1 1 , 1 1 1 1 , 1 1 1 ' 1 1 1 1 1 l 1 1 l I 1 I I 1 I I l I 1 I I I 1 1 1 1 1 l 1 ,

200 400 600 800 1000 1200 1400 1600



130

120

110

100

90

80


60

50

40

30

20

10

0

200 400 600 800 1000 1200 1400 1600


1

face mill: 4" diameter, single tooth cutting tool: Kennarnetal grade KC850 insert style: SNMA-432

- feed: 0.020 ipt depth of cut: 0.050" width of cut: 2.0" milling setup: clirrb cutting fluid: dry

- t o o l life end point: 0.015" uniform wear A-

-

7 FOUNDRY "0"

I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I

Turning - Skin All Ductile Iron Grades

140

130

120

110

100

90

80

Tool L i f e 70 minutes

60

50

40

30

20

10

0

200 300 400 500 600 700 800 900 1000

C u t t i n g Speed-feet pe r m inu te

FIGURE 26

Turning - Ferritic Ductile Iron Skin Versus Under Skin

140

130

120

110

100

90

80

Tool Life 70 minutes

60

so

40

30

20

3 10

0

200 300 400 500 600 700 800 900 1000

Cutting Speed-feet per minute

Turning - Pearlitic Ductile Iron Skin Versus Under Skin

140

130

120

110

100

90

80


60

50

40

30

20

10

0

200 300 400 500 600 700 800 900 1000


FIGURE 28

Turning - Sub-Skin All Ductile Iron Grades

140

130

120

110

100

90

80

Tool L i f e 70 minutes

60

50

40

30

20

L

10

0

200 300 400 500 600 700 800 900 1000

C u t t i n g Speed-feet pe r m inu te


140

130

120

110

100

90

80


60

50

40

30

20

10 b

0

200 300 400 500 600 700 800 900 1000


FIGURE 30


140

130

120

110

100

90

80


60

50

40

30

20

10

0

200 300 400 500 600 700 800 900 1000


-

-

PEARL l T lC

I , , I I I 1 I I , , I I I I I I I

, I 1 , I ,


140

130

120

110

100

90

80

Tool L i f e m i n u t e s

60

50

40

30

20

10 /

0

200 300 400 500 600 700 800 900 1000

C u t t i n g Speed- fee t p e r m i n u t e

cutting tool : Kennametal KC850

FIGURE 32

Drilling All Ductile Iron Grades

1000

900

800

700

600

TOOL LIFE 500 HOLES

400 b,

300

200

100

0

150 200 250 300 350 400 450 500

CUTTING SPEED-FPM

Figure 33

DRILLS: CLEVELAND LIST 1800 -DIAMETER: 1/4" LENGTH: JOBBERS FEED: 0 .003 IPR ,DEPTH OF HOLE: 1 / 2 " , BLIND

-

TlNG FLUID: TRIM SOL 1:20 1


1000

900

800

700

600

TOOL L I F E 500

HOLES

400

300

200

100

0

150 200 250 300 350 400 450 500

CUTTING SPEED-FPM

Figure 34

4 8

Drilling AU Ductile Iron Grades

1000

900

800

700

600

TOOL L l F E 500

HOLES

400

300

200

100

, . 0

150 200 250 300 350 400 450 500

C U T T I N G SPEED-FPM

-

D R I L L S : CLEVELAND L I S T 1800 DIAMETER: 1/4"

L E N G T H : JOBBERS - FEED: 0.007 I P R

I DEPTH OF HOLE: 1/2", B L I N D - C U T T I N G F L U I D : T R I M SOL 1:20

L - TOOL L l F E END P O I N T : 0.015" WEAR


1 0 0 0

9 0 0

8 0 0

7 0 0

6 0 0

TOOL L l F E 5 0 0

HOLES

4 0 0

3 0 0

2 0 0

1 0 0

0

1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 4 5 0 5 0 0

CUTTING SPEED-FPM J

D R I L L S : CLEVELAND L I S T 1 8 0 0 D I AMETER : 1 / 4 " LENGTH: JOBBERS FEED: 0 . 0 0 9 IPR DEPTH OF HOLE: 1 / 2 " , B L l ND CUTTING F L U I D : T R I M SOL 1 : 2 0 TOOL L I F E END POINT: 0 . 0 1 5 " WEAR

FOUNDRY "0" PEARLlTlC FOUNDRY "CW/

>

x 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

I I

Figure 36

Figure 37. As-cast cylinder for turning studies, with the casting gating system removed.

Figure 38. As-cast rectangular log for milling and drilling studies, casting gating system removed.

Figure 39. Cylinder casting for turning studies. Right, as cast; left, machined in turning test.

Figure 40. Rectangular log casting. Left, as cast; middle, milled in milling test; right, log after drilling test.

Figure 41. "Tongil Turning Center," used for single tool turning tests.

Figure 42. Internal view in the turning center, with cylinder in position at completion of a test series.

Figure 43. Tongil Vertical Machining Center used for milling and drilling tests. Note both mill head and drill chucks.

Figure 44. Rectangular millingldrilling samples are held on the fixture mounted on the horizontal feed machine bed.

5 4

TOOL WEAR ON CARBIDE INSERTS

V I M A

VlEW A

DRILL WEAR

VlEW A

VlEW A

Figure 47. Exam les of typical increased ferrite skin, u er fi ures, corn ared to 8 ' f & ic core microstructures, for all irons. agni ication 10 ) tYP. J

Foundry "B," Pearlitic Skin Foundry "A," Pearlitic Skin

Foundry "B," Pearlitic Core Foundry "A," Pearlitic Core

56

Figure 48. Exam les of typical increased ferrite skin, up er fi ures, corn ared to typic S core microstructures, for all irons. ( Id '? agni ication 100 5 )

Foundry "C," Ferritic Skin

Foundry "B," Femtic Core

5 7

Foundry "C," Fenitic Core

Table 4

Summary of EDS-SEM Inclusion Analyses

Foundry1 Curve Micro Machinability Graphite Brinell Inclusion Analyses* Microstructural Iron Type Figure No. Number RatingtType Size, pm Hardness Amount Figure No.

"B" Pearlitic 35 113 Bestldrilling 36.7 223 FeSi, MgFeSi+Ti, MgO/FeSi Less 49

"A" Pearlitic 35 11 1 WorstMrilling 58.7 1 87 MgFeSi+Ti+Ca, MgOIFeSi, More 50 -

~&/Fe0/Ce-~a+% "B" Femtic 34 112 Worstldrilling 40.6 163 FeSi+Ti, FeMgFeSi+Ti, MgO, More 5 1

"C" Femtic 34 115 Bestldrilling 43.9 156 MgCeSiO, MgO, Less 52 MgFeSi+AYCe SiC+Ti,

Ln MgFeSi+Ti+Al

03 "B" Femtic 30 128 Worstlturning 34.2 149 MgFeSi+CeO+Ti, MgOJMgSi More 53

"C" Ferritic 30 130 Bestlturning 50.3 159 MgFeSi+MgO, FeSi, Ce Less 54 "B" Femtic 6 119 S1 betterlmilling 36.1 163 MgFeSi+Ti+Al, MgO-CeO+Ti, Equal 55

"C" Femtic 8 124 Sl worstlmilling 35.0 156 MgFeSi-CaLa, FeSiMgAl, Mo, 56 FeCaMgLaO complex

"B" Pearlitic 11 121 S1 worstlmilling 39.5 223 FeSi, MgFeSi Voluminous 57

"A" Pearlitic 13 1 16 S1 betterlmilling 76.3 187 MgFeSi+O+Sb, MoC, Voluminous 58 MgOFeSi+Al,Ti,Ce,Sb,FeCeAl SbCMg complex

Note additional examples, all EDS plottings, and SEM micros of inclusions, and graphite morphology are on file at DIS.

*Inclusions were often duplexed, showing up to 8 different elements in an aglomerate. Identification of constitution of the particular phases or intermetallic compounds was not included in the current investigation. See Reference 2 for further information on possible types of inclusions.

Table 5

Typical Hardness Values for Some Phases and Inclusions in Ductile Irons

Phase or Inclusion Diamond Pyramid Hardness (kg/mrn2) *

Graphite Soft, not measurable

Ferrite 130 - 150

Pearlite 250 - 300

Fe3C 700

Si02 800

MgO 1 100

MgFeSi 1200

MgO/Al,03 1400

TiN 1900

A120, 2500

Tic 2500

Sic 3000

TiCN 3OOO+ rl L

*Values reported by Goldschmidt.

Note: Many inclusions are complex, i.e., Mg-Ca-FeSi, combined with Ce, Al and Ti intermetallic compounds. These have a predictable composite hardness of at least that of the hardest of the constituents.

FIGURE 49: DRILLING DUCTILE IRON Foundry B - Pearlitic 223 BHN

Tool Life Holes: 190 at Cuttil ~eed: 200 feet oer minute

lOOX Unetched lOOX Etched in Nital

400X Unetched

6 0

FIGURE 50: DRILLING DUCTILE IRON Foundry A - Pearlitic 187 BHN

Tool Life Holes: 60 at Cutting Speed: 200 feet per minute

100X Unetched 100X Etched in Nital

400X Unetched

6 1

100X Unetched lOOX Etched in Nital

400X Unetched

6 2


400X Unetched

63

FIGURE 53: TURNING DUCTILE IRON Foundry B - Ferritic 149 BHN

Tool Life: 54 minutes at Cutting Speed: 600 feet per minute.


400X Unetched

6 4

FIGURE 54: TURNING DUCTILE IRON Foundry C - Ferritic 159 BHN

Tool Life: 102 minutes-at Cutt ing Speed: 600 feet per minute.


400X Unetched

65

FIGURE%: FACE MILLING AS-CAST Foundry B - Ferrit

Under Skin Tool Life: 99 minutes at Cut

I SKIN versus UNDER SKIN .ic 163 BHN .tinq Speed: 400 feet per minute.

lOOX Etched in Nital

400X Unetched

6 6

FIGURE^^: FACE MILLING AS-CAST SKIN versus UNDER SKIN Foundry C - Ferritic 156 RHN

Under Skin Tool Life: 89 minutes at Cutting Speed: 400 feet per minute.


400X Unetched

6 7

FIGURE 57: FACE MILLING AS-CAST SKIN versus UNDER SKIN Foundry B - Pearlitic 223 BHN


lOOX Unetched lOOX Etched in Nital 1

400X Unetched

6 8

FIGURE 58: FACE MILLING AS-CAST SKIN versus UNDER SKIN Foundry A - Pearlitic 187 BHN



400X Unetched

6 9

Appendix A

Tool Wear Data

The following tables contain all the tool wear versus machining parameters test data for each foundry, both grades of ductile iron, and for each of the three machining operations. This covered 11 1 face milling, 70 turning and 79 drilling individual tests for a total of 260. Excluding any replications, all data is plotted on the machinability tool life versus cutting speed curves in Figures 1-36 of the main body of this report.

The modeled tool life data in the last column of each table are calculated points for the curves in Figures 1-36. Method to determining these points is discussed in the Machinability Procedure section of the report.

TABLE IA

Face Mrlling Ductl1.e Iron

Cutter: 4" dia. single tooth face mill, KC850, SNMA-432 inserts AR:-5' ECEA: 15' RELIEF: 5' RR:-5' CA: 45' NR: 0.0312

Depth of Cut: 0.050 inch Width of Cut: 2" setup: Cllmb Mllllng Cuttlng Fluid: Dry Tool Llfe End Polnt: 0.015" Unrform, 0.030" Locallzed Wear

FOUNDRY "B" FERRITIC DUCTILE IRON

Skin Data

Cutting Speed fpm

Feed

Ipt

Actual Modeled Tool Life Tool Life minutes minutes

Sub-surface Data

TABLE IB

Face Milling Ductile Iron

Cutter: 4" dra. slngle tooth face rnlll, KC850, SNMA-432 Inserts AR:-5" ECEA: 15' RELIEF: 5' RR:-5' CA: 45' NR: 0.0312

Depth of Cut: 0.050 lnch Wldth of Cut: 2" Setup: Cllmb Mlllrng Cuttlng Fluld: Dry Tool Llfe End Polnt: 0.015" Unlform, 0.030" Locallzed Wear

FOUNDRY "C" FERRITIC DUCTILE IRON

Skin Data

Cutting Feed Actual Modeled Speed Tool Life Tool Life fpm minutes minutes

Sub-surface Data

TABLE IC

Face Mllllns Ductlle Iron

Cutter: 4" dla. srngle tooth face mill, KC850, SNMA-432 lnserts AR:-5' ECEA: 15' RELIEF: 5' RR:-5' CA: 45' NR: 0.0312

Depth of Cut: 0.050 inch Width of Cut: 2" Setup: Climb Milling Cuttlng Fluid: Dry Tool Life End Point: 0.015" Uniform, 0.030" Localized Wear

FOUNDRY "B" PEARLITIC DUCTILE IRON

Skin Data

Cutting Speed fpm

Feed Actual Modeled Tool Life Tool Life

LF?? minutes minutes

Sub-surface Data

Cuttrng Speed fPm

TABLE IC (continued)


Sub-surface Data

Feed Actual Modeled Tool Llfe Tool Llfe

rPt mlnutes minutes

TABLE ID

Face Mlllrns Ductrle Iron

Cutter: 4" dla. single tooth face mill, KC850, SNMA-432 lnserts AR:-5" ECEA: 15' RELIEF: 5' 22:-5' CA: 45' NR: 0.0312

Depth of Cut: 0.050 lnch Width of Cut: 2" Setup: Cllmb Milling Cutting Fluid: Dry Tool Llfe End Point: 0.015" Unlform, 0.030" Localized Wear

FOUNDRY "A" PEARL ITIC DUCT1 LE IRON

Skin Data

Cutting Speed fpm

Feed Actual Tool Life minutes

Sub-surface Data

Modeled Tool Life minutes

TABLE IIA

Turnlna Ductlle Iron

Tool: Kennametal Grade KC850, SNMA-432 Inserts BR:-5' SCEA: 15' SR:-5' ECEA: 15' RELIEF: 5' NR: 0.031

Depth of Cut: 0.050 lnch Cuttlng Fluld: Dry Tool Llfe End Pornt: 0.015" Unlform Wear; 0.030" Localized Wear

FOUNDRY "B" FERRITIC DUCTILE IRON

Skin Data

Cutting Feed Actual Modeled Speed Tool Life Tool Life fPm g& minutes minutes

Sub-surface Data

Cutting Feed Actual Speed Tool Life fpm iPt minutes

Projected Tool Life minutes

TABLE IIB

Turnlnq Ductlle Iron

Tool: Kennametal Grade KC850, SNMA-432 inserts BR:-5" SCEA: 15' SR:-5' ECEA: 15' RELIEF: 5' NR: 0.031

Depth of Cut: 0.050 inch Cutting Fluid: Dry Tool Life End Point: 0.015" Uniform Wear; 0.030" Localized Wear


Skin Data

Cutting Feed Actual Modeled Speed Tool Life Tool Life fPm minutes minutes

Sub-surface Data

Cutting Speed fPm



TABLE IIC

Turnlns Ductlle Iron

Tool: Kennametal Grade KC850, SNMA-432 Inserts BR:-5" SCEA: 15' 8R:-5' ECEA: 15' RELIEF: 5' NR: 0.031

2epth of Cut: 0.050 lnch S1~ttlng Fluld: Dry Tool Llfe End Polnt: 0.015" Unlform Wear; 0.030" Locallzed Wear


Skin Data

Cutting Feed Actual Modeled Speed Tool Life Tool Life fpm l~& minutes . minutes

Sub-surface Data

Cutting Speed fPm



TABLE IID

Turnlns Ductile Iron

Tool: Kennanetal Grade KC850, SNMA-432 Inserts BR:-5' SCEA: 15' SR:-5' ECEA: 15' RELIEF: 5' NR: 0.031

Depth of Cut: 0.050 inch Cuttlng Fluid: Dry Tool Llfe End Point: 0.015" Uniform Wear; 0.030" Localized Wear

FOUNDRY "A" PEARLITIC DUCTILE IRON

Skin Data

Cutting Feed Actual Modeled Speed Tool Life Tool Life fpm 1_Pt minutes minutes

Sub-surface Data

Cutting Feed Actual Projected Speed Tool Life Tool Life fpm minutes minutes

TABLE I I I A

D r i l l i n g D u c t l l e I r o n

D r r l l : 114" d l a . HSS, 2 f l u t e j o b b e r s l e n g t h t w i s t d r i l l C l e v e l a n d T w l s t Dr l l l List No. 1800

H e l i x Ang le : 29' P o i n t A n g l e : 118 ' L l p R e l i e f : 1 2 ' P o i n t Type: P l a l n

Depth of H o l e : 0 . 5 i n c h , b l i n d C u t t l n g F l u l d : Tr im S o l , 1 : 2 0 Too l L i f e End P o i n t : 0 . 0 1 5 " Wear o n t h e c o r n e r o f t h e l l p

F O U N D R Y "B" FERRITIC DUCTILE I R O N

C u t t i n g Feed A c t u a l Modeled Speed Too l L i f e T o o l L i f e fpm l~& h o l e s h o l e s

TABLE IIIB

Drlllins Ductlle Iron

3rlll: 114" dia. HSS, 2 flute jobbers length twist drill Cleveland Twist Drill List No. 1800

Helix Angle: 29' Polnt Angle: 118' Llp Relief: 12' Point Type: Plaln

Cepth of Hole: 0.5 inch, blind Cutting Fluid: Trim Sol, 1:20 Tool Life End Point: 0.015" Wear on the corner of the lip


Cutting Speed fpm

Feed Actual Tool Life

holes

Modeled Tool Life holes

TABLE IIIC

Drlllins Ductile Iron

Drill: 114" dla. HSS, 2 flute jobbers length twist drill Cleveland Twist Drlll Llst No. 1800

Helix Angle: 29' Point Angle: 118' Llp Relief: 12' Polnt Type: Plain

Depth of Hole: 0.5 inch, blind Cuttlng Fluid: Trim Sol, 1:20 Tool Life End Point: 0.015" Wear on the corner of the lip


Cutting Speed fpm

Feed Actual Tool Life

holes

Modeled Tool Life holes

TABLE IIID

Drllllns Ductlle Iron

Drlll: 1/4" dia. HSS, 2 flute jobbers length twist drlll Cleveland Twlst Drlll List No. 1800

Helix Angle: 29' Point Angle: 118' Lip Rellef: 12' Polnt Type: Plaln

Depth of Hole: 0.5 inch, blind Cutting Fluid: Trim Sol, 1:20 Tool Life End Point: 0.015" Wear on the corner of the lip

FOUNDRY "A" PEARLITIC DUCTILE IRON

Cutting Feed Actual Modeled Speed Tool Life Tool Life fpm 1Pt holes holes

Appendix B

Micrographs and SEM-EDS Inclusion Plots

Appendix B contains additional examples of microstructures of various milling/drilling and turning test pieces to illustrate the diversity of microstructures and the large amounts of inclusions found in some of the test pieces. Note that the "ferritic" iron may contain matrix pearlitic contents up to 20%. Whereas the "pearlitic" irons, which ranged from 187-223 Brine11 Hardness contain up to 40% ferrite.

Figures B 1-B8 Micrographs of typical graphite morphology and inclusion contents.

Figures B 1GB 15 Examples of EDS plots identifying inclusions for irons "A", "B", and "C".

The balance of EDS plots and micrographs are on file at the Ductile Iron Society.

FIGURE B1: TURNING DUCTILE IRON Foundry A - Pearlitic 187 BHN

Tool Life: 11 minutes at Cutting Speed: 600 feet per minute.


400X Unetched

85

FIGURE B2 TURNING SAMPLE

Foundry A - Pearlitic


400X Unetched

8 6

FIGURE B3: DRILLING DUCTILE IRON Foundry B - Pearlitic 223 BHN

Tool Life Holes: 160 at Cutting Speed: 200 feet per minute


400X Unetched

87

TURNING SAMPLE FIGURE B4 - Pearlitic

100X Unetched 100X Etched in Nital

400X Unetched

FIGURE B5: TURNING AS-CAST SKIN DUCTILE IRON Foundry B - Ferritic 149 BHN

Tool Life: 19 minutes at Cutting Speed: 900 feet per minute


400X Unetched

8 9

FIGURE B6 MILLING-DRILLING SAMPLE Foundry B - Ferritic


400X Unetched

90

FIGURE B7

TURNING SAMPLE Foundry C - Ferritic


400X Unetched

9 1

FIGURE B8

MILLING-DRILLING SAMPLE Foundry C - F e r r i t i c

lOOX Unetchea lOOX Etched i n N i t a l

400X Unetched

9 2

FIGURE B 9 : TURNING AS-CAST SKIN DUCTILE IRON Foundry C - Ferritic 159 BHN

Tool Life: 24 minutes at Cutting Speed: 900 feet per minute

lOOX Etched in Nital

400X Unetched

93

FIGURE B 10

THU 21-JHN-93 11 : 56

FIGURE B 1 1

FIGURE B 12

FIGURE B 13

FIGURE B 14

Q , QQQ B- 5

20 EXEC (7-3 1) DHTA LHBEL

FIGURE B 15

Series I1 Zexel-Illinois Cupsot-.: Q.(3QQkeV = Q

Q . QQQ :ZQ EXEC f 7-5 j DATA LABEL

FIGURE B 16

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