Centerless Grinding
Centerless grinding grinds the outside diameter of round parts without centres or chucking, supporting them between a grinding wheel, a regulating wheel and a work rest blade. It is fast and consistent for pins, rollers, bars and bushes in high volumes.
What it is
In through-feed grinding, straight parts pass continuously between the wheels, making it very productive for pins, dowels, bar stock and tubes. In in-feed (plunge) grinding, parts with heads or steps are ground in position.
Because the part is supported along its length, even long thin parts can be ground to tight size and straightness without centres.
Typical applications
- Dowel pins and needle rollers
- Precision bar and shafting
- Bushes and sleeves (outside diameter)
- Piston pins and valve stems
- Tubes and hydraulic rods
Suitable materials
- Hardened and case-hardened steels
- Alloy and tool steels
- Stainless steel
- Cast iron
- Brass, bronze and some plastics
Points to consider
- Through-feed suits plain diameters only; stepped parts need in-feed setups.
- Centerless grinding does not correct eccentricity between an OD and a bore; use cylindrical grinding on a mandrel if concentricity to a bore matters.
- It is most economical at volume because setup takes time.
- Straight bar stock can be supplied ground to h8/h9 or finer.
Frequently asked questions
What parts suit centerless grinding?
Plain cylindrical parts such as pins, rollers, bar, tubes and bushes, especially in medium to high volumes.
Can centerless grinding grind shouldered parts?
Yes, by in-feed (plunge) grinding, though through-feed is only for straight parts.
Does centerless grinding improve concentricity to a bore?
No. It references the outside diameter only. For OD-to-bore concentricity, grind on a mandrel between centres.