Glebar Centerless Grinder Issues, any help appreciated

I'm having issues with premature work rest blade failure in out Glebar TF9 DHD machine. After a new set up we're only getting days to a week run on the blade before the it wears through at the back edge of the work and reg wheels. We are sending a .0068" wire into a paddle stop where it's being plunge ground to a .0048" barrel OD. Set ups on this machine used to run for weeks now a week is amazing. Glebar thought it was a coolant issue, running Cimtech 500, and said that for further assistance they would need $250/hr for tech support. Have changed some consumables in the last month while this has been happening. Work wheel and reg wheel due to wear, diamond to try and fix the issue, and changed coolant and did tank clean per preventive maintenance schedule. Nothing has produced different results. One thought was an interaction between the way oil, Lubriplate SPO-222 and the coolant. Had to change to the SPO-222 a little over a year ago because of vendor issues with our old way oil but it was spec'd out to be comparable and has ran without these issues during that year. Any thought on this would be helpful.
THanks

Have you tried a new workrest blade or checked the hardness in the vicinity of the wear? Changed the angle of the blade? Any change in wire specs? Same workwheel and regulating wheel spec's? Correct workrest height? Proper angles when the regulating wheel was redressed? Did you "test fit" the regulating wheel to thee workwheel prior to setting your stock removal amount? Is your workrest blade fluttering? Regulating wheel rpm adjusted for changed regulating wheel diameter? Changes in regulating wheel dressing technique, different diamond, depth of cut, traverse rate? Someone had a "better" way to set up and run the machine? Same operator/setup man? All dirt, debris, gooey coolant removed from the blade reference surfaces? Bearings checked? Workwheel arbor to bronze sleeve fit?

We use the same machine. On a couple of occasions we completely stripped the machine and reassembled to track down our problems. I'll keep thinking...

Another thought:
Our machine is fitted with a hydraulic motor and double u-joint link driving the regulating wheel. At small diameters (<.030") the link is at a significant angle with respect to the motor's output shaft and the input shaft of the wheel. The angle imparts weird force profiles on the machine as the joints kink and unkink. The resulting displacements can wreak havoc on the machine and/or the workpiece especially as play develops with age.
And another:
Are you using the "default" 30 degree angle on the workrest blade? Increasing the angle weakens the blade but improves roundness while flattening the angle stiffens the blade but MAY compromise roundness.

The think the simplest solution to the problem it what Glebar said but it is not the amount of coolant it is the lubricity of the coolant. It sounds like you are probably running a Stainless steel part correct? If it is stainless I have to increase my coolant concentration up to about 8-10 with a Refractometer. With your coolant you have a refractometer factor of 1.8 to one. So I would up your coolant up to 5.5 to 6.0 and see if this helps out. I would not change anything until you have prove that this in not the problem and it is the cheapest way to start with.

Brucecu, we use a new work rest blade for every set up. I have not tried checking the hardness in the vicinity of the wear I will do that. No angles, heights, feeds, have been changed. Dressing angle stop knob had been found to be loosened around 6 months ago and dressing angle was, checked, adjusted, and knob was reset. Specs should be the same, we have an IQC department that verifies all in coming material and has not had any issues with the wire. Not sure what you mean by "test fit", please explain. Everything had been the same for set up since 2004 when the machine arrived. I've only been in the room for 3 years, the guy before me was in there 20 years and brought in most of the machines we have. He trained me on the set up procedure and it was written to the operators manual we have from Glebar. The Glebar Tech was the one who suggested a different set up procedure. He said they no longer burn in the regulating wheel, or only do in minimally. Our procedure has us burn it in .002". Blade is spring steel, torqued to 30in/lbs. should not be fluttering. Bearings sound alright and don't feel any wobble in the spindles. Plus we only have two machines that run this product and we have a high demand right now. So unless it completely dies I'm not going to be able to tear down whole machine. No sleeve on our machine wheel bore is sized to spindle dia. I'll discuss results of new set up in response to your second post.

brucecu said:

Have you tried a new workrest blade or checked the hardness in the vicinity of the wear? Changed the angle of the blade? Any change in wire specs? Same workwheel and regulating wheel spec's? Correct workrest height? Proper angles when the regulating wheel was redressed? Did you "test fit" the regulating wheel to thee workwheel prior to setting your stock removal amount? Is your workrest blade fluttering? Regulating wheel rpm adjusted for changed regulating wheel diameter? Changes in regulating wheel dressing technique, different diamond, depth of cut, traverse rate? Someone had a "better" way to set up and run the machine? Same operator/setup man? All dirt, debris, gooey coolant removed from the blade reference surfaces? Bearings checked? Workwheel arbor to bronze sleeve fit?

We use the same machine. On a couple of occasions we completely stripped the machine and reassembled to track down our problems. I'll keep thinking...

Click to expand...

This machine has electric direct drive motors, only dressing system is hydraulic. Our other manual load machines have the hydraulic motor and universals. But yeah when we get down to small wheel dia/extreme angle in shaft link we have issues on those machines. The other mechanic actually drilled and tapped new mounting holes in the casting for the hydraulic motor on a couple of the machines that it was causing the most issues for production. I'm not sure what the degree of the angle is. On the scale template the regulating wheel is tipped up in the front to 1.5R and the dresser is set to the corresponding 1.5R with a left to right angle from front to back.

As I mentioned in the previous post the glebar tech support suggested only touching off the reg wheel or burning in only .0005" instead of the .002" we had been. At the end of the set up everything looked good, there was no discoloration on the work wheel, which we had been getting lately. Machine ran well for two hours then operator called for a broken wire. When I backed off the work wheel I found the back end of the work wheel was discolored with some kind of build up and had issues with wire feeding through. I ended up having to redress the work wheel .002 and bring it back into position. This fixed the feed issue, but it again made the back of the blade appear to be thinner than it should. This usually means the blade will wear through at this point in the next couple of days. I believe from this experience that an issue with the coolant concentration or amount of tramp oil in the coolant may be the culprit that is leading to the build up on the wheel. I would think this would explain the gradual degradation of the blade over the few days after a set up. The more wires that are ground, the more build up on the wheel, the more the blade is worn out, until the back of the blade breaks down. Let me know if you think this sounds correct. Thanks for the response, your help is appreciated.

brucecu said:

Another thought:
Our machine is fitted with a hydraulic motor and double u-joint link driving the regulating wheel. At small diameters (<.030") the link is at a significant angle with respect to the motor's output shaft and the input shaft of the wheel. The angle imparts weird force profiles on the machine as the joints kink and unkink. The resulting displacements can wreak havoc on the machine and/or the workpiece especially as play develops with age.
And another:
Are you using the "default" 30 degree angle on the workrest blade? Increasing the angle weakens the blade but improves roundness while flattening the angle stiffens the blade but MAY compromise roundness.

Click to expand...

Donovan, yes we are running stainless. We are running around 8 right now but I could try kicking it up towards 10. As I said in my second response to Bruce, after performing the set up as suggested by the glebar tech I found that the build up we were getting on the work wheel started after about two hours of run time. Previously I was seeing discoloration on the wheel during the sizing process. Would increasing the lubricity of the coolant help with fines build up on the wheel? The Glebar tech had suggested to lower the concentration. I reached out to Cimcool for they're thoughts but have not hear a response.
THanks, Dan

never worked with something that small

sounds to me like your part is spinning up

like regwheel aint biteing

can you see a sharpy mark?

if it is spinning lower concentration,rougher dress on reg wheel

more angle on blade

DocZen said:

Donovan, yes we are running stainless. We are running around 8 right now but I could try kicking it up towards 10. As I said in my second response to Bruce, after performing the set up as suggested by the glebar tech I found that the build up we were getting on the work wheel started after about two hours of run time. Previously I was seeing discoloration on the wheel during the sizing process. Would increasing the lubricity of the coolant help with fines build up on the wheel? The Glebar tech had suggested to lower the concentration. I reached out to Cimcool for they're thoughts but have not hear a response.
THanks, Dan

Click to expand...

What do you mean by fines build up? There is stainless material stuck to the Grinding wheel? When that happens to me I have the wrong wheel on the machine. What type of wheel are you using? I still think it is a coolant problem.

Donovan said:

What do you mean by fines build up? There is stainless material stuck to the Grinding wheel? When that happens to me I have the wrong wheel on the machine. What type of wheel are you using? I still think it is a coolant problem.

Click to expand...

Perhaps you should add filtration to your coolant system if it doesn't already have it. And if it does, either check for bypass leaks, or consider going to a finer filter element.

I guess I'm making an assumption to say that it is fines. We're getting a black discoloration on the back half of the wheel that turns gray over time and becomes present on the regulating wheel as well. We're using a green wheel, I believe it's silicone carbide. We get them directly from Glebar and only have a part number from them. I was told they're just Norton wheels that they true up and face the part info off of, but we've never had success with trying to source our own. The previous mechanic had one of the wheels sent out to other suppliers to be analyzed and was assured the one they sent him was the exact some composition but they would not achieve the same results. So we just use the ones from Glebar.

For the last 14 working days on one machine and 7 on the other there have been no issues and they are holding up. Blades look thinner than they should but they're not breaking down in the back. I'm going to see what happens on after the next set up. Right now the coolant is 7.2% concentration and I'm doing my best to keep tramp oil out of the coolant. Thinking about flushing all the coolant lines next time they go down and see if that helps. I'll let everyone know if I find a definitive problem and fix for it. Thanks again.