Post on 06-Apr-2018
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Lesson Title: Lathe Operations
Lesson Duration: 4 hours
Industry Competencies: Participants will:
research and discuss theoretical and background information about engine lathesand turning operations
select cutting speeds and feeds, and calculate the RPM appropriate to a specific
material/cutting tool combination
link the basic theory of turning to tool geometry (chip formation)
describe the relative motions of the lathe and describe the interactions of various
subsystems, including the machine tool, machine controls, drive mechanisms,cutting tools, tool holder, work piece, and work holder
demonstrate safe operating procedures for each machine tool used (Comp. 2)
develop a list of lathe and turning operations, and identify the sequence ofoperations needed to make a specific product (Comp. 4)
use hand tools to support the setup and operation of lathe machinery (Comp. 5) operate lathes at an introductory level (Comp. 6)
select cutting speeds and feeds, and calculate the RPM appropriate to a specific
material/cutting tool combination (Comp. 7)
apply basic precision measurement instruments before, during, and after turning
operations to ensure that product specifications and tolerances are met (Comp. 9).
Specific Objectives: Participants will:
read schematics and engineering sketches accurately
measure accurately using SI and US systems and tools
employ all personal and environmental safety requirements collaborate successfully to solve machining problems
set up and use the lathe properly.
Assessment(s):
Rubric for Evaluating the Transfer Activity
Participant: Date:
Participant
Deliverable
Participant
Task with
Competency
Highly
CompetentCompetent
Needs
Improvement
Safe Operation ofmachinery
Operate machinetools in a safe and
proper manner.
Use hand tools to
support setup of
machinery.
(Comp. 1, 3, 4, 5)
Machinery andtools are operated
safely and in
accordance with
manufacturer's
instructions.
Safe and properoperating
procedures are not
followed.
Process Planning
Sheet: Making
Develop a list of
machining
Sketch of part is
detailed and
Sheet includes a
sketch of the part
Sheet is inaccurate
or incomplete.
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Parts for the
Robotic Gripper
operations and
identify the
sequence of
operations needed
to make the part.
(Comp. 2, 10)
professionally
presented. List of
operations shows
an indepth
understanding of
the process.
and complete list
of operations, in a
correct sequence
required to produce
the part.
Inspection Sheet:Making Parts for
the Robotic
Gripper
Record partmeasurements
before, during, and
after machining
and ensure thatspecifications have
been met. (Comp.
6, 9)
Examination ofpart tolerances on
inspection sheet
shows variation
from tolerancesspecified on
engineering
drawing.
Measurements ofpart to determine
conformance to
engineering
drawing areaccurately done
and recorded on
inspection sheet.
Sheet is inaccurateor incomplete.
Part Make a part within
tolerances.
(Comp. 4, 5, 7, 8)
Part is within
tolerances
specified on
engineering
drawing. Part
moves well with
parts made byother teams.
Part achieves the
correct basic
geometry of part as
specified on the
engineering
drawing.
Part is not
attempted, or is not
completed, or basic
geometry of part is
incorrect.
Overall Assessment Highly Competent CompetentNeeds
Improvement
Competency
or Task
Highly
Competent Competent
Needs
Improvement
Measurements areaccurate using both US
and SI devices.
All measurements aremade accurately with
full understanding and
ability to use
measurement tools.
All measurements aremade with appropriate
tool and are accurate.
One or moremeasurements are
incorrect and ability to
use appropriate tools is
not consistent.
Conversions within theUS system are accurate. All conversions areaccurate with full
understanding and
appropriate units
indicated.
All conversions areaccurate with
appropriate units
indicated.
One or more of theconversions is
inaccurate and units are
not displayed correctly.
Conversions with the SI
system are accurate.
All conversions are
accurate with full
understanding and
appropriate units
indicated.
All conversions are
accurate with
appropriate units
indicated.
One or more of the
conversions is
inaccurate and units are
not displayed correctly.
Conversions between
the US and SI systemsare accurate.
All conversions are
accurate with fullunderstanding and
appropriate units
indicated.
All conversions are
accurate withappropriate units
indicated.
One or more of the
conversions isinaccurate and units are
not displayed correctly.
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Competency
or Task
Highly
Competent Competent
Needs
Improvement
Write clearly and
effectively on a specific
topic.
Topic is fully addressed
with highly effective
supporting information
with no errors ingrammar, punctuation,
or spelling.
Topic is fully addressed
with adequate
supporting information
and no errors ingrammar, punctuation,
or spelling.
Topic is not addressed
or poorly supported with
one or more errors in
grammar, spelling, andpunctuation.
Speak clearly and
present information
about a specific topic.
Topic is fully addressed
with highly effective
supporting information
with a clear voice,
excellent syntax,
excellent grammar, and
superb volume.
Topic is fully addressed
with adequate
supporting information
in a clear voice with
effective grammar and
pronunciation.
Topic is not addressed
or poorly attempted with
inadequate supporting
information, low voice,
and one or more errors
in grammar.
Production of a PartCompetency
or Task
Highly
Competent Competent
Needs
ImprovementMachine Operation
Analysis
All machine operations
were followed with high
level of quality and
superb detail.
All machine operations
were followed with high
level of quality.
One or more of the key
procedures were not
followed or poorly done.
Machine/Tool Use The actual machine and
related tool use wassuperb with no mistakes.
The actual machine and
related tool use wasdone well with required
detail.
There were one or more
instances of poor tooluse during the process.
Safety All safety rules were
followed exemplarywith assistance to
others.
All rules were followed
as directed.
One or more rules was
not followed whichestablished some risk.
Accuracy All parts were measuredand fabricated
accurately with exact
precision beyond any
tolerances.
All parts were measuredand fabricated
accurately within
acceptable tolerances.
One or more parts weremeasured wrong or
fabricated poorly outside
of required tolerances.
Resource(s):
Print Materials - Basic mathematics textbook and Machining textbook (to be identified)
Audiovisual -
Internet sites-Key word search - lathe, lathe operations, lathe safety, lathe manufacturers, lathe parts,
lathe attachments, lathe tooling.
Purpose of the Lesson:
To introduce participants to lathe machining operations, including safety, tooling, and
applications for manufacturing.
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Required Knowledge and Skills: Participants will:
perform basic operations in mathematics
measure accurately using SI and US tools and units
convert measurements between SI and US systems
read basic schematics and machine part drawings/sketches follow personal and environmental safety requirements.
Tools, Materials, Equipment Needed:
1 lathe
bar stock
1 pad of 3" x 5" Post-it Notes
1" x 6-1/2" bar stock
For the facing and center drilling portion of this activity, per participant:
setup tools
1 micrometer with collar
1 center drill reference chart in Machine Tool Practices
1 vernier caliper
same work piece used above
For the turning portion of this activity, per participant:
1 lathe
1 micrometer with collar
same work piece used above
Specific Safety Requirements:Everyone must wear safety glasses at all times during equipment demonstrations and
operator evaluations. Observe proper safety and operating procedures at all times. Dispose
of chips and other debris as required by your facility. Each participant must pass the Lathe
Safety Test and Operator Evaluation before being allowed to operate any lathe.Participants may not proceed until all safety knowledge is addressed. You must ensure that
participants can demonstrate safe and proper operating procedures before using equipment.
Lesson Elements: (5-E model)
Engagement:
In preparation for this activity, you should have assigned participants to research topicssuch as:
types of machine tools operations
types of tooling
ways of holding work
speeds
feed rates
tolerances
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surface finishes
measuring and measuring instruments.
At the beginning of this session, have the group decide how the discussion should proceed
(such as, work through a list or go around the room). Have them establish ground rules for
the discussion; for example, the person presenting information is allowed to finish beforethe rest of the group can ask questions or present differing opinions. Be sure to emphasize
the importance of respect for the ideas and information provided by others.
Review the parts of a lathe, either in this discussion or as part of the equipment
demonstration that follows.
Make sure that the discussion and/or demonstration includes the information that appears
on the quiz.
Exploration:
Before observing a lathe demonstration, participants should be required to visit one or morelathes available in the manufacturing laboratory and using a part identification worksheet
as shown below, they should identify and describe each machine part that has been labeledby the instructor with sticky notes or some other simple form of labeling.
Machine Part Number Machine Part Name Purpose or Description
Participants should view the following image and prepare a written description for lathe
machining operations. The written descriptions will be used to guide discussions led by theinstructor about what these machines can and cannot do.
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Another interesting exploration activity is to challenge participants to explore a variety ofLathe manufacturers and locate product descriptions and machine specifications for
comparison of machine capabilities and features. This research will help participants
understand the wide range or products and machine features depending on the scope ofproduction work needed by an organization. Participants can accomplish this asindependent or small team work. Examples are provided below to guide this research.
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YCL-1236/YCL-1340
Options: Taper Turning attachment Micro Carriage Stop
5-C Lever Collet Closer
2 axis Digital Readout
Birmingham YCL 12"dia x 36" Geared Head Bench Lathe Manufactured in China.
Floor stand included
7" diameter max swing over carriage 2 HP, 220 volt, 1 phase main motor
9 speeds from 70 - 1400 RPM
Standard Equipment:
6" 3-jaw chuck
8" 4-jaw chuck
10" face plate 1-1/2" spindle bore
3 3/4" steady rest
follow rest Gap
4-way tool post
thread chasing dial
2 dead centers reducing sleave
full splash guard chip tray
Automatic longitudinal and cross feeding
Hardened and ground Spindle and Bedways
12" swing x 36" center distance Precision Geared Head Gap Bench type including floorstand: $2,495.
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Birmingham CT-1440G Precision Lathe $3595.
Manufactured in Taiwan. ** Uses 110 volt electrics **
Swing over bed 14" [355mm] Between Centers 40" [1016mm]
D1-4 with 1-1/2" Spindle Bore [38mm]
Width of Bed 7-5/32"
Lathe bed is made of high tensile cast iron in rigid construction structure, the bed way ishardened and ground.
The main spindle is equipped with 2 precision taper roller bearings.
Provides 12 spindle speeds from 70 to 1350 RPM, quick speed change by lever. All gears head stock with oil immersed lubrication design, provides vibration free V-
belt replacement
2HP motor has power suitable for heavy duty cutting. Includes heavy duty floor stand
along with full length splash guard as standard equipment.
In addition to complete lathe turning centers, participants can locate and review
information about various components and lathe parts such as the examples shown below-
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Birmingham Extended Range Precision Gap Bed Lathes
Swing diameter over bed - chose from 26" / 32" / 40"
Between centers: 40" / 60" / 80" / 120" / 160" / 200" Width of bed 21 21/32"
20 HP main motor (15 HP ON DL-26 series only)
67 kinds of inch threads 18 speeds from 7.5 to 1000 RPM
D1-11 camlock with 5-1/8" spindle bore on most lathe sizes Main spindle hardened and precision ground
Bed made of fine grain high tensible cast iron 4-way rapid travers to carriage and cross slide
Bed ways induction hardened and precision ground
All gears and shafts hardened and precision ground Spindle supported at 3-point by precision bearings
Automatic lubrication system in headstock and feed box
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Hydra-control multi-disc clutch for spindle turning and brake
Manufactured in China
After discussing the lathe, participants are ready to observe a brief demonstration of the
machines capabilities. This demonstration should include a review of the parts of the
machine, proper nomenclature, and any specific safety procedures. One interestingapproach to the actual machine lathe demonstration and related setups is to have
participants complete the setups and then prepare photos of those key configurations which
could be used in participant tutorials or remedial instructional episodes needed throughoutthe course.
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A detailed machine parts drawing should be provided by instructor for participants toreview. This example provided below is very detailed and may not be needed for a
foundations course, but it is good for participants to review such documents to see thescope of detail in a basic turret lathe, including the motor and drive assemblies as well as
the lathe bed and various controls and attachments.
Participants should be able to review a lathe parts drawing or photo with parts labeled as
shown below. It is suggested that participants prepare their own documents by
photographing and then drawing detailed drawings to be kept in their class notebooks or
journals. These must be kept for future reference and exam studies.
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Explain and demonstrate the following turning operations and concepts, which the
participants will perform in the Lathe Exercise:
operating speeds and feeds
facing and center drilling turning to tight tolerance
Explanation:
Identify and describe the various types of machine tools:
engine lathes
gap beds
chuckers
turret lathes (old technology)
CNC lathes
automatic screw machines
Discuss (written and oral) the following operations:
turn
face
bore
thread
knurl
drill
ream
taper
grove trepan
internal vs. external operations
Discuss these types of tooling:
tool geometry of turning tool
tool geometry of facing tool
tool geometry of threading tool
tool geometry of boring bars
tool material type (HSS/carbides/ceramics)
Describe these ways of holding work:
chucks (3-jaw universal vs. 4-jaw independent)
face plate (collets)
between centers
Discuss how to determine proper RPM for lathe work: (RPM = (cutting speed x 4)
diameter)
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Extension:
Lead participants in a discussion of the activity by asking questions such as:
Is the lathe the most efficient way to produce this part?
What other operations can be performed on the lathe?
Is it easy to turn a part to a tight tolerance?
When turning to a tight tolerance, what went wrong or was unexpected? How did
you correct the problems you encountered?
What are the economies of tight tolerances ( .001")?
How can you match your machining speeds and techniques, as well as your
measuring instruments, to the tolerances specified on the print?
1. Perform the following practice operations on the lathe:
Using pre-made Post-it Notes, label the parts of the lathe. Remove the Post-it Notes.
Practice changing speeds on the lathe. Practice operating automatic cross and longitudinal feeds.
2. Perform the following facing and center drilling operations on the lathe:
Load a tool and set it to center.
Select the proper center drill using the reference chart in Machine Tool Practices.
Face and center drill both ends of the work piece.
Use a caliper to measure the length of the work piece:
___________________________
Explain how the choice of measuring tools corresponds to blueprint tolerances and
whether a caliper is accurately calibrated.
3. Perform the following operations pertaining to turning to tight tolerance:
Set up the work piece between chuck and center.
Determine whether the lathe is equipped with a single- or double-depth micrometer.
Using Engineering Drawing: Lathe Exercise for reference, practice turning
diameters to size.
Discuss how to turn a diameter to a tolerance of .001".
Discuss how surface finish affects tight tolerance.
Use a micrometer to measure the diameters of the work piece.
Consider the micrometers tolerances, measuring range, usage, and calibration to
discuss why a part may be within tolerances though the micrometer may indicateotherwise:
The following planning sheet can be used to guide the practice exercises identified above.
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Process Planning Sheet: Lathe Exercise
Participant: Date:
Sketch of Part
Operations Materials & Equipment
Approved By:
The following is a part drawing for a thread cutting exercise that can be presented toparticipants as part of basic lathe skill development and refinement. The instructor can
offer other similar examples for participants to complete based on their class ability level.
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The following images are provided for the instructor to help guide participants in their
understanding of thread cutting operations-
Three Wire Method of measuring threads:
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Thread Nomenclature
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Screw Thread Lead and Pitch
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Enrichment:
Have participants investigate the history of lathe machines and prepare a timeline that
begins with crude devices such as the one shown below. Key machine features andinnovations should be highlighted in their timelines. This activity can be accomplished as
independent or collaborative work.
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Evaluation:
1. List two ways to face off a piece to a given dimension.Turn the compound 30 and feed in twice the amount that you want to cut. Turn the
compound 90 and feed in the same amount that you want to cut.
2. What is backlash and what adjustments do you have to make for backlash?
Backlash is play in the longitudinal or cross feed screw. In the backlash area, the
micrometer dial will change but the corresponding machine slide will not move. Aslong as you have removed the backlash and are moving the screw in the same direction,
you do not need to worry about backlash. To get rid of backlash when you change
directions, go two full turns past your position and then come back to your position.
3. Calculate the correct spindle speed for turning 2-1/2" diameter cold-rolled steel.
Use the formula:
cutting speed x 4 diameter of work piece
100 x 4 (2.5in.)160 RPM
4. What happens if you drill too deeply with a center drill?
If you drill too deeply, the bearing surface for the center will be a sharp edge instead of
a 60 angle. This will give a poor bearing surface.
5. You need to turn a work piece to a 0.547 0.002 diameter and you're turned down to
0.557. What are the last five steps you will take to hit the final size correctly?
a. Turn the micrometer collar to the desired cut.b. Start the cut for 1/8-1/4 inch.
c. Quickly move the cutter to the right of the work piece without changing the
micrometer collar.d. Measure whether you are cutting the desired diameter.
e. If so, continue the cut. If not, readjust the micrometer collar.
6. What is the difference between single-depth and double-depth cross feed
micrometer collars?
A single-depth micrometer collar cuts twice as deep as the reading on the micrometer
collar. A double-depth micrometer collar cuts the same amount as the reading on themicrometer collar.
7. Why do you need to center drill a work piece?To provide a bearing surface for a center or to provide a starting point for a drill since a
drill tends to walk when it starts the cut.
8. You have a 0.002 tolerance on your blueprint, but when you made the final cut, the
surface finish was very rough. Is this a problem? Why or why not?
Yes. If the surface finish is rough, the high points of the surface irregularities will wear
off quickly, changing the size of the work piece.
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9. What precaution should you take when turning between a chuck and a center? Explain.
The work piece can slip into the chuck jaws and move away from the tailstock center,leaving it unsupported at the tailstock end. This unsupported end can whip around,
causing a hazard for the lathe operator. Also, the chuck jaws may not align the work
piece with the tailstock center.
10. What is a good feed rate for a roughing cut on the lathe? Explain. The feed rate for
roughing should be 1/5 to 1/10 of the depth of cut.
11. What is a good feed rate for a finishing cut on the lathe? Explain. Finishing feeds
should be .003 to .005 for steel.
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The following inspection sheet can be used to evaluate all Lathe exercises.
Inspection Sheet: Lathe Exercise
Participant: Date:
Description Required Sizes Machined Sizes
Acceptable
Within
Tolerance
Yes No
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Enrichment:
1. Look up recommended feed rates from technical manuals for tool suppliers.
2. Discuss the quick-change gear box.3. Use two or three different feed rates to explain how feed rate affects surface finish.
4. Discuss the typical tolerances for various lathe operations and tooling.
5. Describe the typical finishes generated on lathes.6. Discuss the use of graduated dials, compound rest stops, digital readouts, and gauges.