How we hold tolerances
Most grinding is done by abrasive wheels that rotate at high speed or by power-driven cloth or paper belts coated with an abrasive. The same methods are used in precision grinding but with extreme precision in the grinding process. Precision grinding means very close tolerances. 0.00002″ can be achieved only if the proper machinery is used. The machinery needed for precision grinding must be constructed very accurately, with very heavy rigid frames to assure permanency of alignment. Another essential factor in achieving precise tolerances is accurately balancing rotating parts to avoid vibration and mounting spindles with inaccurate bearings. Controls are also provided to ensure that all movements of machine components used to determine critical dimensions are made accurately.
Holding Tolerance for
Blanchard grinding is very similar to rotary-type surface grinding. For the most part, the only difference between rotary-type surface grinding and Blanchard grinding is that Blanchard grinding is generally done on a larger scale. It is also common with Blanchard grinding for one to reach more precise tolerances. Typical applications for Blanchard grinding are with parts too large to be ground or machined in any other manner and require exact tolerances.
Holding Tolerance for Surface (Mattison) Grinding
Flat grinding, a.k.a. surface grinding, produces a smooth, accurate, flat surface on machine parts, tools, and dies. Flat grinding machines may have the wheel’s axis either horizontal or vertical to the surface of the work. The workpiece is attached to a movable table with a horizontal-type flat grinder. As that table is advanced across the flat grinding wheel, the part will automatically or manually be ground entirely.
The vertical-type flat grinder uses a cup-shaped wheel. These flat grinding machines often have a large rotating table attached to the work. The workpiece is forced into the grinding wheel as the table slowly rotates.