By Jon Hunter
I use several different machines at the shop to accomplish the extreme level of precision required for the tight tolerances that engineers specify. For example the job I am working on now requires the use of a surface grinder. A surface grinder is a machine that generally uses a magnet to hold the parts to a hydraulically driven table. The table is pushed back and forth by a small hydraulic cylinder.
The grinding part of the machine consists of an electric motor, a grinding wheel, and a guard. Those parts are all on a big tower that moves perpendicular to the stroke of the table. That same assembly moves up and down on the tower to remove excess material from a part. To cool the parts it uses a water-soluble oil solution that is pumped through a hose, which ends up very close to the grinding wheel.
I am working on pieces of steel that need to be flat and parallel to each other to about a tenth of the width of a human hair. So the first thing I do when I get the part is clean it with isopropyl alcohol. Next I run a flat stone along the large surfaces to remove all remaining contaminants. Then I measure the part for flatness and parallelism and determine which of the two larger sides is bowed up.
When this is done I start preparing the grinder. I use the isopropyl alcohol to clean the magnetic surface and I use the flat stone to remove any remaining contaminants. After that is all completed I place the part on the magnetic surface bowed side up. I use a special type of glue that seeps into irregularities in the surface facing the magnet were the metal does not actually touch the magnet. This keeps those spots from being sucked down by the magnet, which would cause the other side of the part to distort. I then turn on the hydraulics, the grinding wheel motor, the magnet and the coolant pump.
I adjust the grinding wheel height so that it is just above the part, start the table movement by pushing a lever, and start the coolant flowing over the part. I feed the wheel down until it touches the part then I grind it to proper size. After that I stop the table, and turn off the coolant. I remove the part from the grinder and proceed to clean and measure it again.
That is what I do for a living. I hope you have found this article interesting and slightly informative.