[hacdlux]

i have several jobs in my shop that are basic tierods. its a long running job
example: 1/4" bar with 1/4-28 thread x .500 long each end from 3-13" in length in 316 stainless

machine is a tsugami ss 26(might move to a tsugami b0 in the long term)

the current process is having blanks cut to length and have an operator load in a lathe barfeed push to stop, chamfer, thread, deburr; flip and repeat(an aswome late in the day punt program)

i had the brilliant idea to run them in our swiss that had some spindle time availible(normal machine is over boooked)

problems arose when the chips from the threading tool would wrap around the part and get jammed between the guide bushing and the thread, ruining the part.

i currently use a right hand carmex laydown insert and have tried applying hp coolant to blast the chips off.

i have temporarily achieved semi reliable production by loading my chucker kit and using my sub to pull for length, making it he most complicated transfer i have had to program for a swiss so far.

i would like to be able to run the guide bushing for increased rigidity and speed but need it to be reliable.

a few ideas I've had:

thread rolling= faster but more expensive

shim a left hand holder out and not have to retract into gb=might work but different thread inserts than the rest of the shop and less rigidity

make a dog leg holder= same inserts, still less rigid

if there is a simple tool or programming change that would be awesome, i cant imagine i'm the first one to have this problem

long term goal is to get a long parts catcher and run as a full production automatic process

[gizmo_454]

Good morning hacdlux,

I have had this issue for a few years now. I have run many parts where the threaded OD was the OD of the bar. One was threaded the entire 16" length of the part! (They wouldn't accept all-thread for one reason or another!) Sometimes it's not bad, sometimes you can pull all of your hair out. The material you are cutting is the biggest factor. Something like mild steel or easy alloys, (4140), are easier to take care of the chips than stainless, just like in normal turning. 316 stainless is a booger, for sure.

Some things I found that helps, but doesn't always solve the problem:

The biggest help was using an insert with multiple points on it. I think Iscar calls theirs "twin-thread" but other manufacturers have similar style inserts. They seem to help with chip control and it takes half the number of passes of a standard insert. The only drawback to them is that they are typically only available for course thread pitches of 20 TPI or less. Being long running or returning work, it may warrant spending the extra money to order specials for the finer thread pitches. Again, this helps, but is not a cure-all.

I tried the HP coolant in our Tsugami B0326 on the 16" long part previously mentioned and that only made a slight improvement, if any. Granted, this part was 316 stainless. You can experiment with different nozzle directions to help get the best benefit from it, but it might take a while.

If the twin thread inserts are not available for your needs, try any and all inserts from different manufacturers with different chip breakers. This will definitely take a while, but if you find the right insert, it can virtually solve your problem.

For threads with a length of engagement as short as yours, I would possibly try running them in one of our E-, or M-series Citizens, as they are a 3-path control. Then you can just tell path 1 to stick the material out there and path 2 can thread it. This works wonders if you have a 3 path machine.

You can also try the dog-leg on the threading tool. For the size of the parts you are talking about, rigidity should not be a problem with the holder. I would be more worried about the bar you are threading. But even then, you are only talking about 2 times diameter, so that shouldn't pose a problem.

Also, being in the Tsugami SS26, your holders are horizontal like those in our B0326. Try experimenting with orientation of the holder. Try it on the back gang where the holder is upside down. This way gravity can help pull the chip down, away from the bar you are threading.

There are many ways to skin a cat. If you have the patience, and have the time and materials to be persistent enough to try, you will get it figured out. Good luck and have fun!

Mike

[ghyman]

My "late-in-the-day-punt" ideas sometimes give happy little surprises; I had a similar problem on a Citizen several years ago - the fix was surprisingly simple.

Use an opposite-handed threading tool, run the spindle in reverse, and cut the thread starting at the opposite end from where you are now. (Some machines have the Z+ and Z- directions reversed, so I am being careful not to say the wrong direction!) This will let the chips fall at the end of every pass, as the bar will be clear of the tool.

Just a thought. It's worked well for me ever since I first tried it.

[chunkymonkey]

Thread roll will give you stronger and faster thread. It's only more expensive up front. You will make your ROI in time saved very fast. How much do you think you have spent trying to fix the shaving issue?

[MCImes]

Ditto to the ideas:
1. Thread rolling will produce no chips and a faster cycle. As said, the investment up front is more expensive, but if its a long running job its easy to annuitize the cost over thousands of parts

2. Flip the tool upside down and thread from back to front (from Z+ towards Z-). This should push chips off the end and naturally unthread themselves

[gizmo_454]

Ghyman,

That is a magnificent little idea! I never thought of that! I'll have to give that a try next time! Thanks!

Mike

[hacdlux]

thank you gentleman,
im going to get a left hand single point on order,
i just sent a reguest to landis for their ez rollers
and my operator just came in to tell me the single point insert blew off....grrrr