CNC grinding
CNC grinding is a finishing process in which a rotating abrasive wheel removes small amounts of material to achieve precise dimensions, form and fine surface finish. It is mainly used on hardened steel parts such as shafts, pins, hydraulic spools and guide surfaces, after turning or milling and heat treatment.
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Typical parts
- Shafts with bearing seats and sealing surfaces
- Pins, bolts and rollers
- Hydraulic spools, pistons and piston rods
- Guide rails and wear plates
- Tool and fixture components
Quantities
- Centreless grinding for large quantities
Inspection
- Micrometers, bore gauges or air gauges
- CMM for first articles
- Roundness and cylindricity on a form tester
- Roughness and hardness if specified
- Grinding burn check
Documents
- Dimensional report
- Heat treatment record
- EN 10204 3.1 certificate
How CNC grinding works
A grinding wheel made of abrasive grains rotates at high speed and removes fine chips from the workpiece. Because the depth of cut is small, grinding achieves tighter dimensions and finer surfaces than turning or milling, and works on hardened material.
Cylindrical grinding
(OD and ID) for shafts, bores and bearing seats, with the part held between centres or in a chuck.
Centreless grinding
for pins, rollers and bars, without centre holes, suited to large quantities.
Surface grinding
for flat faces of plates, guides and tool components.
Dimensional and surface inspection
Ground diameters are measured with micrometers, bore gauges or air gauges, and on a coordinate measuring machine (CMM) for first articles. Roundness and cylindricity are measured on a form tester, surface roughness with a profilometer, and hardness on the finished part where the drawing specifies it. Grinding burn can be checked by etching or other agreed methods.
Standard documents are a dimensional report, a heat treatment record and a material certificate to EN 10204 3.1. More on the quality page.
Materials for CNC grinding
Case-hardening steel
- 16MnCr5
- 20MnCr5
Quenched and tempered steel
- C45
- 42CrMo4
Stainless steel
- 1.4301
- 1.4404
Tool steel
- 1.2379
- 1.2842
There is no fixed size or tolerance limit. Send us your drawing and we will define the right production route and confirm feasibility.
Is this the right process?
When CNC grinding is the right choice
- The part is hardened and still needs machining to final size
- Fits, bearing seats or sealing surfaces need tighter tolerances or finer surfaces than turning gives
- Form and position tolerances such as roundness, cylindricity or flatness are critical
When another process is better
- Unhardened parts without tight fits: CNC turning or CNC milling alone is cheaper
- Hardened parts with complex internal contours or sharp corners: EDM
Related pages
- CNC turningCNC turned parts in steel, stainless steel, aluminium and brass from machine shops in Türkiye: shafts, pins, bushings and flanges, with dimensional reports.
- CNC millingCNC milled parts in steel, stainless steel and aluminium from machine shops in Türkiye: housings, plates, brackets and machined castings, with CMM reports.
- Secondary operationsHeat treatment, galvanising, powder coating, KTL e-coating, painting and assembly for cast, forged and machined parts, managed by QProcess in the same order.
- ForgingClosed-die and open-die steel forgings, rolled rings and shafts from forges in Türkiye, supplied raw, heat treated or machined, with EN 10204 3.1 certificates.
- Other industriesCast, forged, machined and plastic parts for pumps and valves, hydraulics, rail, material handling, industrial automation, robotics and marine equipment.
- Agricultural machineryGearbox housings, PTO shafts, hubs, brackets, counterweights and wear parts for agricultural machinery manufacturers, produced by manufacturers in Türkiye.
- Machinery and equipmentMachine bases, housings, shafts, gear blanks, guides and plastic wear parts for machinery and equipment manufacturers, produced by manufacturers in Türkiye.
Frequently asked questions
Why are parts ground after hardening?
Hardening causes small distortions and makes steel too hard for most cutting tools. Grinding removes the distortion and brings bearing seats, fits and sealing surfaces to final size and finish on the hardened part.
What is the difference between cylindrical and centreless grinding?
In cylindrical grinding the part is held between centres or in a chuck, which suits shafts with shoulders and several diameters. In centreless grinding the part is supported on a work rest between two wheels, which suits pins, rollers and plain bars in large quantities.
Which surface roughness can grinding achieve?
There is no fixed value we state in advance. Send us your drawing with the surface requirements and we will select a machine shop whose equipment fits the part and confirm feasibility.
Send your drawing. You get a quotation in 3 to 5 working days.
Your drawings are handled confidentially; NDA on request.