Suitable insert for CDS tubing.

[Springer]

Guys,

I have a small job (100 off) to make a simple bush, the customer has supplied the material and therein lies the problem!

He has given me lengths of 31.75mm x 19.00mm cold drawn seamless tubing/ CDS and they need to be parted to 70mm long and the ID opened up to 21.00mm. It very much an agricultural part as the drawings dont have any tolerances but I tend to work to +/- 0.1mm as that is plenty good enough.

My problem is Ive tried about half a dozen different inserts that I have and I cant get this stuff to cut nicely, its very gummy then seems to have hard spots in it, the chips wont break unless you push the tool really hard but then everything turns purple very quickly, its not a nice material to work with.

Its not so much the fact Ive got 100 to do this time, its going to become a regular order so Im trying to get a decent workflow in place.

I was hoping to bore the ID in one pass as 1.0mm DOC is usually fine on my machine (Harrison M300) but Im not having much luck.

I have considered setting up a drill and drilling the bore using the carriage but I would need to buy something, maybe a U-Drill or spade drill with inserts?

Any thoughts?

 

[pcd]

the chips wont break unless you push the tool really hard but then everything turns purple very quickly

What turns purple? If you mean the chips that sounds like a good thing.

I cant get this stuff to cut nicely, its very gummy then seems to have hard spots in it

Is the problem that you're getting a finish that looks like this?

 

[Springer]

The chips turn purple but dont break, tried lots of speeds and feeds.

It just feels like Im using a blunt tool with all the different inserts Ive tried but they are all good. Ive tried DCMT and CCMT in different grades, in most materials a 1mm DOC is childs play but this tubing is horrible.

 

[atex57]

Try using an insert made for aluminum. Can't run as fast or hard but it might made it chip better. Yah, tubing is nasty.

Ed.

 

[neilho]

The customer supplied the material, eh? Been there, done that. :-) Maybe time to have a talk with the customer ? Has this material been successfully turned into bushings before or is this left over from another job, an economy move?

My $.02: I'd be looking for a different material, with the customer's blessing, of course. Labor is more expensive than material.

 

[Springer]

The customer supplied the material, eh? Been there, done that. :-) Maybe time to have a talk with the customer ? Has this material been successfully turned into bushings before or is this left over from another job, an economy move?

My $.02: I'd be looking for a different material, with the customer's blessing, of course. Labor is more expensive than material.

Yes the same material has been used for years, they are a new company to me but they have been getting these bushes made for a long time. They provided me with samples made for them by someone else who made a decent job of it.

Ive just had an intro into this company and its only the fourth job Ive done for them but the first using this tubing.

The reason Ive get the work is because Im local and my business took a big hit recently so a friend introduced me to them as I need the work. They pay a fair rate which Im happy with, I just need to find the right insert.

 

[4GSR]

I feel your pain here, too. I find it just as easy as disconnecting the feed on the lathe as the stringers get long, the re-engage the feed. Doesn't ball up as bad. Yeah, look like crap for roughing, then leave .010-.020 for a finish pass. This generally works for me.

 

[bigjon61]

I go down this road often with basically the same size of bushings for one of our customer. Tell them to order the right material or you will order it and charge them. You won't have very good luck with a spade drill

 

[kenton]

I'm not sure if you have access to Haas's tooling but I have been impressed with their HMU chipbreaker inserts. I have been using them on manual machines and they seem to do a real good job breaking chips on gummy material.

CCMT3251-HMU / CCMT09T304-HMU, Carbide Turning Insert, 80° Rhombic, Grade HTS25 - Pack of 5

CCMT3251-HMU / CCMT09T304-HMU, Carbide Turning Insert, 80° Rhombic, Grade HTS25 - Pack of 5

www.haascnc.com