If you've specified a bright bar with a tight diametrical tolerance — say h6 or h7 — chances are it needs to pass through a centerless grinder. Centerless grinding is one of the most important finishing processes in bright bar manufacturing, and understanding how it works helps you specify the right product for your application.
How Centerless Grinding Works
Unlike conventional cylindrical grinding, centerless grinding does not hold the workpiece between centers. Instead, the bar rests on a work-rest blade between two wheels:
- A grinding wheel that removes material
- A regulating wheel that controls the bar's rotation and feed rate
Because the bar isn't clamped between centers, long lengths of bar stock can be fed through continuously, making the process efficient for high-volume production of round bars.
Why It Matters
- Tighter tolerances. Centerless grinding routinely holds tolerances of h6 to h9, tighter than cold drawing or peeling alone can achieve.
- Better roundness. The support geometry reduces out-of-round error compared to bars that are only turned or drawn.
- Superior surface finish. Ground bars typically achieve a surface roughness of Ra 0.4–0.8 μm, important for components like hydraulic cylinder rods and precision shafts where surface quality affects seal life and wear.
When You Need a Ground Bar vs. a Drawn Bar
If your application involves sliding fits, seals, bearings, or any function where surface finish and roundness directly affect performance, a Bright Ground Bar is usually the right choice. For general engineering components where cost matters more than sub-micron tolerances, a standard cold-drawn Bright Bar is often sufficient.
Not sure which one your drawing calls for? Get in touch with your specification and our team will recommend the right product and tolerance class.