- Huyett Marketing Department
- 11/18/2020
Grinding, also called surface grinding, is a machining operation in which material is removed using a powered abrasive wheel, stone, belt, paste, sheet, compound, etc. to realize fine finish tolerances and surface finishes. While there are a number of ways to grind parts, grinding is a more precise method of tolerance modification.
Parts are laid on a table that has a chuck or holder. The holder uses magnets to hold parts on the table, or in the case of non‑magnetic materials like stainless steel, a vacuum chuck or adhesive is used. The magnetism of the chuck has limitations based on the size of the workpiece as well as the holding power around the outer edges of the chuck (about 1" in total).
The table reciprocates, or moves back and forth, beneath an abrasive turning wheel. As the table moves back and forth, the entire table moves so that over time, the grinding wheel passes over the entire surface area of the table. This process, while slow, is precise. With each pass, as much as 0.001" of material is removed. The maximum thickness to be removed using this process is 0.008". Otherwise, milling should be used.
In order to develop a constant datum point, a minimum amount of material is needed, which is 0.001" for part lengths under 4". For parts over 4" in length, a minimum removal of 0.003" is required. Cold‑drawn steel has some permissible twist that is revealed in longer length parts. The extra stock allows the grinder to pass through the twists so that a common datum point is achieved. Under the best of circumstances, a tolerance of 0.0005" can be held using this method, although a maximum of +/-0.0005" (0.001" total) is recommended.
