Grinding & Custom Shafting


Grinding is a process in which small abrasive particles are embedded into a grinding wheel, belt, cylinder or stone to accomplish material removal. It is commonly used for removing small amounts of material at a time, allowing smooth and accurate tolerances of 0.001” or less. There are numerous ways to achieve a desired diametrical tolerance, such as centerless grinding, lathe turning and grinding between centers.

  • Centerless Grinding
    In the process of centerless grinding, a bar is placed horizontally on rollers and is fed into actual grinding component. Material is removed along the bar’s previous straightness.
  • Lathe Turning
    The process of lathe turning involves bracing a bar horizontally between one or two centers (depending on the length). The bar is then rotated by these centers while a machine tool cuts into the material removing stock and achieves the desired tolerance or custom shape.
  • Grinding Between Centers
    Grinding between centers is the most accurate process of the three, in which the bar is suspended horizontally and braced on each end by centers. The grinding roller then meets the material and follows the length of the bar, removing stock accurately. When grinding between centers the actual grinding component determines the outcome, resulting in the tightest diametrical tolerance attainable.

Key Terms

In the stainless and nickel industry there are certain terms associated with particular tolerances:

  • “TG&P” Turned Ground and Polished: refers to any type of material that has been turned ground and polished. There is not an industry standard for this type of material. It is custom with any size and any tolerance.
  • “BSQ” Boat Shaft Quality: refers to a type of shafting commonly used in the marine industry. There are specific tolerances and finishes required to meet BSQ standards, although the tolerances are not typically as tight as PSQ. In the marine industry, BSQ is also known by many other names; for example AQUAMET® 17 is the same thing as 17-4 BSQ.
  • “BQ” Bearing Quality: refers to a type of bar that has a custom diametrical tolerance with no other requirements such as ovality, finish, straightness or length.
  • “PSQ” Pump Shaft Quality: refers to a type of shafting that is generally used in rotating industries. There are industry standards for PSQ materials, such as specific diametrical tolerance, finish and ovality.
  • Fan Shaft Quality: refers to a type of shafting used in the fan industries. These applications require an even tighter tolerance than PSQ material, due to the increase of bearings used with the shaft.

Aquamet® is a trademark of Armco.
The information above is not warranted, guaranteed, or for design purposes.

The information above is not warranted, guaranteed, or for design purposes.

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