Centerless grinding issues

[MaynardC1890]

I am having random issues with scratch marks on the pieces coming out of my centerless grinders. In particular 3 distinct parts are all having this issue across sealing surfaces. I feel like the issue may be pieces of the grinding wheel or some of the metal removed at the previous process is sticking to the parts and causing issue at the next grind process. All three machining centers share a coolant reservoir which is filtered. My question, is it possible the coolant fluid is too viscous and allowing those particles to stick to the parts and transfer to the next grinder where they are scoring the parts? any other recommendations or things I could look into to try and stop these scratches?

 

[looslib]

Are the scratches coming from the same machine or different machines?



"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli

 

[MaynardC1890]

From what I have witnessed the marks are coming from all 3 processes but are being cleaned up in the next. I feel that I am getting Swarf stuck on the parts from the previous processes and its not being cleaned off by the coolant nozzles. The scratches are miniscule but unfortunately this is a sealing surface under a lot of pressure and our customer is extremely picky. We are working on getting some relief in that area but im looking for anything that might be useful in clearing the chip from the part.

 

[btrueblood]

What material, and in what condition, and what prior machining is done? Is it possible that the prior machining is leaving embedded chips behind, and the grinder wheels are loosening them so they fall out?

Do you have an intermediate wash process prior to the parts going to the grinder?

"All three machining centers share a coolant reservoir which is filtered" - so the grinders share a reservoir, or do the grinders share with another process (mill, lathe)? I'd assume the grinders would need a higher level of cleanliness/filtration due to the smaller typical chip/particle size being taken off the workpiece. It's an obvious question, but not answered: have you checked the filters for damage/holes?

 

[BrianE22]

Not to take traffic away from here but there might be more grinding specialists here:

https://www.practicalmachinist.com/vb/abrasive-machining/

I'm sure they'll want a picture showing the problem.

 

[mfgenggear]

with out the OP telling us the condition of the parts, ask by btrueblood, this is a shot in the dark with out the proper information.
soft parts are gummy and will not obtain a proper finish. also parts need a roughing operation, then grinding off .0005 stock total.
roughing the parts is critical. straight grind will result in bad results. out of round, and bad finish.
ask the engineer sales engineer at your grinding wheel supplier if the correct wheels are being used. type of material, if it is thru harden or case harden, or soft will make a diffrence in what type of wheels, grit, composition, center grinding machine are better suited for this type of operation. edit also there may be more dresses required, to maintain the cutting action of the wheels, surface finish.

 

[enginesrus]

Sounds to me its the device that supports the parts feeding in or out of the grind wheels, I would think the finish on that is very critical.

 

[Tmoose]

From OP's profile - My last login was on Tuesday, February 8, 2022.

I guess he solved the problem.