By rronald

February 24, 2023, 10:28 am

Threadmill questions

Trying to get feeds and speed for threadmilling. I have a few questions.

I've entered MIC-6 Cast Aluminum as the material (since there isn't an option for ATP-5 tool plate). I'm doing a 6mm thread. 1mm pitch. 4 flutes and a single point (thread). Tip diameter is 4.85mm.

1) I've set DOC to 1mm since it only cuts one thread at a time and the depth of one thread is the pitch. Correct?

2) The distance between the the minor diameter and the major diameter is also about 1mm. Since this is being cut with a helix and only half the material is removed from each side of the cut, I've divided the cut in half and set WOC to .5mm. Correct?

The recommended Speed is 24K RPM (limited by my spindle speed). My vendor recommend a lower SFM, so I will adjust that downward (don't think it's relevant to these questions).

3) The recommended feed provides a chip load of .014 mm. This is only half the minimimum chip load recommended by the vendor. More relevant, it's less than 1/2 the chipload shown in HSMAdvisor's Manufacturer Speeds and Feeds (shown as .0370 mm). I'm confused about why the displayed manufacterer feed rate isn't being recommended?

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Eldar Gerfanov (Admin)

February 27, 2023, 10:35 pm


1. Yes that is correct.

2. Yes that's correct.

3. Internal threading requires you to compensate the feed rate for the internal circular interpolation factor. I think your manufacturer usually gives you the chip load without that compensation applied. HSMAdvisor does that for you.

But given the workpiece being aluminum, it might not matter anyway.

Here is more info on the subject: https://www.harveyperformance.com/in-the-loupe/machining-circular-tool-paths/

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