Re: CNC Grinding

--- In CAD_CAM_EDM_DRO@yahoogroups.com, docsys@m... wrote:

> I am looking at setting up a grinder for CNC control and was

wondering

> how to compensate for wear of the grinding wheel.
>
> Can the wear of the wheel be taken into account so the ground parts
> will have the same dimensions? If so, how can this be achieved?

As Marcus indicated wheel wear is not the main issue. You are more
likely to be needing to compensate for temperature variations as the
wheel head warms up. It is not unusual for this to affect size
(diameter) by a couple thousandths during a typical warmup.

For cylindrical ( and ID) grinding, you will want precise control
over the table angle to control taper within less than 1/10 of your
likely finished tolerance. +0/-.001 would require at least .0001
increment on taper control at the extremes of the machine table
swing, and at least .0001 increment on the diameter. Anything less
and you will most likely be hitting desired tolerance only by luck.

For surface grinding it is less critical, as the table can be ground
flat and the work sitting on the table can be ground parallel to the
table, hence no doubling of the increments for diameter
measurements. This process, however, is not a good candidate for CNC
as the hydromechanical systems available on the used equipment market
are very inexpensive, and very accurate. I recently saw some Parker
surface grinders ( one of the best) available for under $2500. I
cried/wept/sighed in relief, knowing what some of these machines cost
just a decade or so in the past, and that I didn't pay the price then.

One common application for CNC is to run the dresser for form
grinding. These will typically use a shadowgraph for precise
measurement of the form and pregaging of the dressing diamond. This
then lends itself to automatic wheel compensation. These systems
still often use automated gaging to determine size adjustments and
even video inspection systems in high volume applications to detect
corner breakdown.

Fred Smith - IMService