 | Thread Cutting by Dies and Taps - Course: Techniques for Machining of Material - Instruction Examples for Practical Vocational Training. |
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Instruction example 5.4. Piston
In this example thread cutting is undertaken in blind holes by means of taps.
Figure
Material
16 Cr Mo 4 (low-alloyed steel), alloy components: 0.16 % carbon, 1 % chrome, less than 1 % molybdenum, rest iron.
Dimensions
Ø 45 x 93
Tools
spiral drill Ø 17.5 mm, machine tap M 20, chucking spanner
Measuring and testing tools
vernier caliper, steel measure
Accessories
extendable chucking jaws, tap wrench, reducing collars, coolants and lubricants
Required previous knowledge
drawing comprehension, measuring and checking, thread cutting by hand, centring, boring, counter-boring
Workshop drawing explanations
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M 20: |
M = metric thread |
All surfaces have been machine-finished. |
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20 = nominal diameter | |
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Sequence of operations |
Remarks |
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1. Dimensional inspection | |
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2. Clamp workpiece |
Clamping in extendable jaws to Ø 38 mm |
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3. Clamp tool |
Fix spiral drill to tailstock by means of reducing collars |
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4. Set the cutting values for boring |
Spiral drill is made of quick-cutting steel v = 25 - 50 m min-1 |
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5. Undertake a Ø 17.5 x 38 mm bore |
Ensure proper cooling. Check bore depth with steel measure on the quill. Debur the workpiece. |
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6, Set the cutting values for thread cutting |
For steel v = 4 - 15 m min-1 heeding the material and thread size |
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7. Position tap |
Select machine tap. Position the railstock tap to centring of tap. |
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8. Cut the tap |
Ensure tap wrench support. Check on proper alignment through the
railstock tip. |
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9. Unload workpiece |
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10. Dimensional inspection | |
Piston
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