[scook179351]

Hello all,
I'm wondering if all the people here are using SMQ material in their swiss turns or regular bar stock. Whenever we try to use regular bar stock here, the parts are not always round because of the material not being round. I'm having a hard time convincing people here that we need SMQ material to make round parts.
thanks.

[cogsman1]

On a "Swiss" machine you are using the stock as part of the support system during cutting. When you adjust the guide bushing it must be tight enough to prevent the bar from escaping away from the cutting tool. When your bar stock size is changing you must set the bushing to the bigger size to prevent the stock from getting jammed as it tries to pass through. Now when the smaller portion of the bar is in the bushing the stock will escape for the cut. The "rule of thumb" is 60% of the stock condition will very likely be found in your part, out of round, varying size... You will also get finish problems from this. So if your stock runs .001" out of round your part will be up to .0006" out of round. Not always but very likely. Remember "Garbage in, garbage out"
There are special collet systems to help prevent this by using an "adjustable" guide bushing. Citizen has one that work pretty well. Recent design changes have solved early problems.
These systems are expensive but, add up the cost of scrap, broken tools, down time missed deliveries and lost customers then decide if the cost is worth it.

[scook179351]

Thanks for the quick reply. I understand how it all works, I needed support for other people so that I can get ppl here to buy the correct material. I couldn't find anything online about this problem, so any input here is great.

[yoopertool]

In the shop I work in we have found that the machine and operator safety well outweighs the extra cost of SMQ material. We run some smaller diameter heat treated bar stock and if it jams up in the bushing it is likely to start flexing break while turning 8000RPM. No good ever comes from having chunks of .1875" stock whipping around at 8k. We check our material diameters before the delivery man even leaves because if the diamter is out of round or varying much more than .0005" we send it right back. Companies want swiss lathes because they want precision parts run quickly, but if they dont provide the proper material they are going to end up with bad parts, remaking orders, and alot of upset operators. Good luck!

[PixMan]

I'm not familiar with the term "SMQ", could someone please educate me?

FWIW, for the past 10+ years of programming and setting up CNC Swiss machines, my employers have all switched over to Ugine for stainless steel. It comes in with less than a few "tenths" out-of-round, and end-to-end size is controlled within the same tolerance. Their Ugima 303XL is fantastic for cutting qualities too, tools last seemingly forever.

I've used sub-3mm diameter OSG List 1100 EX-Gold HSS (coated, non-coolant-thru) drills in it for over 6 or 7000 parts, pushing them pretty hard.

[PixMan]

I'm not familiar with the term "SMQ", could someone please educate me? <snip>

Oops, figured it out.....Screw Machine Quality. My bad. I thought everyone in this side of the business bought that, unless you have a Tsugami or Maier that can run in chucker mode.

[Pecker]

Cogs is right. You always get what you pay for. If you skim on material cost, you will get less quality. You will chase ur tail on getting proper bushing tightness. We run Tsugami, Nomura, and Citizens. JUNK MATERIAL = JUNK PARTS. Ask the powers that be if they would like to explain to the customers why their parts are late or poor quality due to the extra "pennies" for material.

[cogsman1]

FYI, You can also get Citizen "Non-Guide Bushing" machines.

[Tinmuk]

I agree with PixMan, Ugima is the only thing we put in our Citizens. Almost every part we make has +/-.0001 tolerance on the diameters. One part we make is .0469 +.0001-.0000 at each end and .063+/-.0001 in the middle. We can hold that on our L-20 using Ugima material.

You have to use very good guide bushings and adjust them properly as well. Don't buy used or no-name guide bushings, Get the absolute best you can. The upfront price is insignificant when you amortize it over thousands of parts.