What Tolerance Can You Actually Hold? A Buyer’s Guide to Surface Grinding Specs

Picking the wrong service on a quote can cost you time, money, or a part that doesn’t meet spec.

Most buyers ask for “surface grinding” without specifying which kind. That’s a problem, because Blanchard and Mattison grinding solve different jobs.

Blanchard grinding

is a rotary process: the worktable turns counterclockwise while the abrasive wheel spins clockwise. It was invented in 1909 by the Blanchard Machine Company, and it’s still the fastest way to remove heavy stock from a rough workpiece while keeping thickness and surface finish consistent across the whole part. If you’re starting with a forging, a casting, or oversized bar stock and need it flattened and sized fast, Blanchard is the right call.

Mattison grinding

is a reciprocating process — the table moves back and forth under the wheel instead of rotating. It’s not built for aggressive stock removal. It’s built for precision. Mattison grinding routinely holds tolerances in the tenths of thousandths and delivers a noticeably finer surface finish than Blanchard alone. It’s almost always the last step before a part ships, not the first.

Bottom line: In practice, a lot of parts see both: Blanchard first to knock down stock and flatten the blank fast, Mattison second to hit final tolerance and finish. Specifying “Blanchard” when you mean “flat and fast” and “Mattison” when you mean “tight and fine” gets your quote priced right the first time — and gets your part ground right the first time.

You got questions?
Visit nelsongrinding.com or call 714-738-5588.

Keep on Grinding!