Flat during Grinding

Machine is: Koyo C4520F (Centerless Grinder)
Blade is looking good. Grinding Wheel and Regulating Wheel are new on the machine.

We are grinding the whole parts but sometimes we have a flat surface on the whole ground diameters.

Process is: Loader is picking part up - RW is staying during Grinding on same Position - Loader moves part on blade - GW is starting with grinding; after finishing the GW is moving back & Loader is going up to Home Position.


When we check the part we see a flat on the part sometimes.

Don't know why and how to prevent the flat.

Need Help please

How straight are your parts to begin with?

when ts are coming from the turning machine they are very straigt on all diameters, but they have roundness issues because the channel of the barfeederguide is 39mm and the material is only 21mm.

the technician told me, that i have maybe to much pressure during the grinding on the part/rw.

the spot came up after some month when the machine was running.

i think the spot is coming after the part will rise up from the blade and the gw is still at the grinding position.

It sounds like you are trying to take off too much in the first few passes considering the material condition. Take less amounts for the first two or three times to "true up" the material.

This is pretty common problem on the Centre less grinders where the loader is used. Basically it is created by the regulating wheel when the part is sitting idle after the grinding cycle is done. Usually happens when the line is running slow and the grinder is waiting for a raw part to come in. so one method to reduce this kind of problem is to modify the loader PLC program. Change the logic on loader to offload the finished part if there is no new raw part to load after 5 sec wait. if there is a part available then continue the regular cycle. Other thing you can check is that regulating wheel is not injecting the spin to the part more than 30RPM. Try this and let me know.

Dal.