[jmichaud1]

I am a machine tool instructor and recieved some donated stainless that I am unsure what type it is. I am trying to cut a segmented thread. I tested my program in brass and it ran great. I switched the material to the stainless and I am having trouble with the threading insert holding up. It is a 3/8-16 thread. I started at 1000 RPM with a .002/side depth of cut. I slowed it down to 500 and it got worse. Do I need to go faster? What do you think?

[CitizenBrian]

Can you give some more info? Threading insert being used, copy of the threading cycle, cutting oil being used. I would think 1000 rpm would be fine even for something hard like 304ss.

[jmichaud1]

I am cutting 303 SS. The threading insert is a NTK ZM3. I am using a G32 and steping down .002 per side at a time.

[CitizenBrian]

I don't see anything bad in your program jumping off the page at me. I think your best bet would be load the brass back in and watch the whole part cycle (no oil) and also listen closely. You might see and or hear the problem. In our L20's I have seen tools clip the top of the bar stock when indexing from tool to tool, if this was your problem you wouldn't get any tool breakage in brass but SS would be a different story.

[SirDenisNayland]

I always can't help but lol at code happy "instructors" who don't know what they're doing when it comes to actual machining.

[brawlerman]

Wow, That gave me a headache just looking at that code. Does everyone write their programs like that? I run 15 machines at a time and if my programs were that complicated I would lose my mind.:cheers:

[Ned-Dragon]

post drawing let us see it at least similar to it.

[jmichaud1]

Here is a picture of the screw. After I changed material to 303 stainless the part ran awesome. I will have to try a different grade insert so I can use up the other material I have. As far as the code for the segmented thread, is there an easier way? It took a little thinking on my part but the parts turned out nice. I'm getting the impression from a few that there is a better way.

[hacdlux]

i can take a wild stab at this, my guess is you have a very tough stainless thats not very machinable,and you hava a very sharp threading insert.

i would try a full profile insert, i had a similar job in 304l that broke swiss style inserts every other part, changed to a lay down and finished the job in one edge

[hongjianming]

I read the pregram, found the #127 value is longer, the guide bush can not support, so change te #127 value, test cut again.

[jmichaud1]

The program ran good. The #127 length gets close to running out of the guide bushing but I carefully measured everything and it works good. For the unknown material I think I'll try hacdlux's advice. What is a lay down insert? Does anyone have a vendor or insert number/information?

[hongjianming]

you know the material is tough, so the #123 must be geometric decreasing, programing like G76 function, or an alternating thread (zigzag),that is better.