Precision Measurement Flexible Manufacturing Copyright © Texas Education Agency, 2012. All rights...

Precision Measurement

Flexible Manufacturing

Copyright © Texas Education Agency, 2012. All rights reserved.

1

Measurement

All measurements are based on the Customary or Metric systems. Manufacturing requires the ability to understand all parts of standard measurements.


2

Customary and Metric Systems

• In manufacturing the system of measure is decided; and measuring tools are purchased for that system.

• Conversions are not done on the factory floor; some plans may have both systems listed on the drawing.

• For this lesson the customary system will be the measurement of choice.


3

Comparison of Customary and Metric Systems

Customary Metric

Fraction of an inch Millimeter 1mm

Inches Centimeter 10 mm 1cm

Foot 12 inches

Yards 36 inches 3 feet Meter 1000mm 100cm 1m

Customary Metric

1/16” 1.7mm

1 inches 25.5 Centimeter

Foot 12 inches 305cm

3.28 feet Meter 1000mm 100cm 1m


4

Customary System of Measurement


5

Divisions of an Inch

1

1/16 5/163/16 7/16 9/16 11/16 13/16 15/16

3/81/8 5/8 7/81/4 3/4

1/2 1 inch


6

Divisions Repeat

1 2

1/16 1/161/4 1/2 1/4 1/2 3/43/4

The division repeats between the whole numbers. Just add the number to the measurement. Example ¼” and 1 ¼”


7

Reading A Ruler

1 32

The block is 1”

Reading a ruler is looking at the marks and finding which mark lines up with the piece being measured.


8

Reading A Ruler

1 32

The block is 2 and 3/16”


9

Reading A Ruler

1 32



10

Reading A Ruler

1 32

The block is 3/4”


11

Reading A Ruler

1 32



12

More Inch Divisions• The inch is also subdivided into 1/32nd, 1/64th

and 1/128th.• Measurements this small are hard to read on a

ruler. Machinists use other measurement tools to measure these smaller dimensions.

• Measurements are changed into decimals instead of fractions.• Some parts have to be machined to sizes

smaller than the thickness of a human hair.Copyright © Texas Education Agency, 2012. All rights reserved.

13

Precision Measurement Tools

Micrometer Caliper

Digital Caliper


14

Measurement Tools

• Micrometer measures to 0.001 of an inch.• Calipers measure to 0.001 of an inch.• Digital Calipers measure to 0.0005 of an inch.• Micrometers and calipers can be standard or

metric system.• Digital Calipers can be switched between the

systems with the use of a button.


15

The Digital Caliper

• Measurement tool most used today.• The caliper will measure outside, inside, depth

and step dimensions.• Can be set to

decimals, metric and fractional readings.

• Easy to use and set.


16

Digital Caliper PartsInside Jaws Lock Knob

LCD Display Beam Graduations

Depth Gauge

Zero Adjusting Button

On / Off ButtonMode Button

Outside Jaws


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Digital Caliper Buttons

• On / Off Button - turns on the display• Zero Button - sets the caliper to zero• Mode Button - changes the display to read decimals, fractions and millimeters• LCD Display - displays the measurement with resolution of .0005, 1/64th or 0.1 mm


18

Digital Caliper Parts

• Outside Jaws• Inside Jaws• Depth Gauge• Beam Graduations• Lock Knob


19

Using a Digital Caliper

15/16

1.00

1.00

Outside Measurement

Inside Measurement

Depth Measurement


20

Reading a Digital Caliper

4.

4. .30

30

Press the On/Off button to turn the LCD display on. Set the mode to the type of reading you want (decimal, fractional or metric). Place the object to be measured inside the jaws of the caliper and the display will show the measurement.


21

Measurements

• Plans may give measurement in fractional numbers. These may need to be changed to decimals. The following slide shows some of the equivalents.

5/16

0.25011 1/2”

250

mm 1.75”


22

Fractions/Decimals/Metric Equivalents

Fractions Decimals Metric Fractions Decimals Metric

1/16 0.0625 1.568 mm 9/16 0.5625 14.288 mm

1/8 0.1250 3.175 mm 5/8 0.6250 15.875 mm

3/16 0.1875 4.763 mm 11/16 0.6875 17.463 mm

1/4 0.250 6.350 mm 3/4 0.75 19.050 mm

5/16 0.3125 7.938 mm 13/16 0.8125 20.638 mm

3/8 0.3750 9.525 mm 7/8 0.8750 22.225 mm

7/16 0.4375 11.112 mm 15/16 0.9375 23.813 mm

1/2 0.500 12.700 mm 1 1.000 25.400 mm


23

Feed and Speeds of Machining


24

Feed and Speeds of Machining

How deep can I

cut?

What is RPM?

What is surface speed?


25

Feed and Speeds of MachiningHow deep can I cut?

Depth of cut is how much the machine can cut in one pass of the cutter.

What is RPM?

Revolutions Per Minute is a measurement of speed.

What is surface speed?

This is the speed in feet per minute that is traveled as you turn something.


26

Machine Questions

• What is a Cutting Speed Chart?• How fast can I turn the part?


27

Cutting Speed Chart

A chart that gives the speed of a cutting tool moving down the length of the material being machined.Cutting speed is expressed in feet per minute or meters per minute.


28

Cutting Speed ChartMaterial Type Surface Feet per Minute Meters per Minute

Mild Steel 100-125 30-38

Cast Iron (medium) 60-80 18-24

Alloy Steels 65-120 20-37

Carbon Steel 70-130 21-40

Free Cutting Steel 115-225 35-69

Stainless Steels 75-130 23-40

Bronzes 80-150 80-150

Aluminum 250-350 75-210

Brass 300-700 90-210


29

Calculating RPMs• The lathe spindles or mill cutters rotation per

minute is figured by the cutting speed on the chart and the diameter of the material or the diameter of the cutter.

RPM = Cutting Speed (FPM) X 4 / Diameter

Cutting Speed (FPM) X 4

DiameterRPM =


30

Math Time!!!

• The diameter of the stock is 1.5 inches and the material is aluminum.

• Cutting Speed is 250(fpm)• Calculate the rpm needed to correctly turn the

piece of stock.RPM = 250 x 4 / 1.5RPM = 1000 / 1.5

RPM = 666.66


31

Math Time!!!

• Calculate the RPM for cutting a piece of mild steel 2.25 inches in diameter.

• Cutting Speed is 100(fpm)

RPM = 100 x 4 / 2.25RPM = 400 / 2.25

RPM = 177.77

32

Discussion

Why is it necessary to figure the revolutions per minute for the piece being turned?


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Precision Measurement Flexible Manufacturing Copyright © Texas Education Agency, 2012. All rights...

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