Problem- Thread Mill Compensation

[bwollner]

The threads in our parts are changing as our thread mills wear, and it doesn't look good to our customers. We use go and no-go gages and on some machines we use variable gages, but we are relying on operators to judge how much to compensate for tool wear, and the process isn't repeatable or accurate. Is there a known way to determine this easily, such as a chart that gives average wear for different tool material and size and part material? I am working on an automatic measurement/adjustment system right now but it is quite costly and has never been successfully completed, and I would like to avoid it if possible.

[Daleb]

I had as simular problem when thread milling a stainless steel job. I added a pass and gave each pass a different wear offset to adjust how much materail each pass took. Everyone at my shop look at me as if I was crazy adding cycle time, but there were more parts ran at the end of the shift and without losing parts from all the scrap, we shipped more parts to the customer. I made up part of the cycle time by beening able to speed the cutter up because the cuts were lighter.

[psychomill]

The only "sure" way is to be able to measure the pitch diameter for its exact measurement. However, with that in mind, a common thing to do is to refer the pitch diameters on the gage. Usually, a plug gage will show the diameters on the handle (if you have one) and on the shanks of each plug. Ring gages will have them marked on the gages as well. All you need to do is figure out the difference between the two values by simple subtraction. Then when your threads start to go out, just simply comp an amount that doesn't exceed the subtracted diameter value of the gages....