5.1 Milling cutters can be divided into two groups: according to design or method of sharpening - NSC Mechanical Technology Automotive - Question 5 - 2017 - Paper 1

1. High Abrasive Resistance: A good milling cutter should be able to withstand wear and tear due to its interaction with tough materials.

2. Red Hardness: The cutting edge must maintain its hardness even under high temperatures generated during cutting operations.

To perform the screw-cutting procedure using the compound-slide method, follow these steps:

1. Adjust the Tool: Set the compound slide to an angle of 30° to the right and accurately position the cutting tool in the tool post.
2. Check Thread Requirements: Use the index plate of the quick-change gearbox to check the necessary pitch of the thread.
3. Zero the Dial: Start the lathe and set the cutting tool to touch the workpiece, ensuring the dial is set to zero on both cross feed and compound slide.
4. Make Initial Cuts: Move the cutting tool a small distance to clear the end of the workpiece and advance the compound slide by 0.05 mm.
5. Engage Half-Nuts: With the lathe turning, engage half-nuts for threading, starting the first cut.
6. Withdraw Tool: After the first pass, disengage the half-nut lever and check if the thread pitch is correct, confirming the thread form.
7. Repeat Process: Continue to make successive cuts until completing the full thread.

Form cutters or profile cutters are applicable for machining the gear.

To calculate the indexing needed for milling 33 teeth:

1. Determine Full Turns: With a full turn around the gear consisting of 360°, divide this by the number of teeth: $1 \text{ Full turn} + \frac{360°}{33} \text{ teeth}$

A - Side and face milling cutter B - Vice fixed jaw C - Parallels D - Work piece E - Collars and spacers F - Work table G - Dividing head H - Handwheel

A - Major/Crest diameter B - Pitch diameter C - Minor or Root diameter