Centreless grinding & centreless cylindrical grinding

What is centreless grinding and for which parts is it suitable?

Centreless grinding – also known as centreless grinding or centreless cylindrical grinding – is a process of external cylindrical grinding, in which the workpiece is not clamped. It rests freely on a support between the grinding wheel and the guide wheel, rotating about its own axis whilst being ground to size. The process is particularly suitable for the large-scale production of identical round parts: shafts, bolts, rollers, needles or bar steel can be machined using this method, ranging from a few millimetres to several metres in length, with maximum precision and the highest level of cost-effectiveness. Thanks to the continuous passage of the workpiece and the absence of clamping, cycle times are short and material removal rates are high – a decisive advantage wherever high production volumes with tight tolerances are required.

What is the difference between through-feed and plunge grinding?

There are two basic types of centreless grinding process. In through-feed grinding, the workpiece is fed axially through the machine – ideal for cylindrical parts without steps that are to be ground in large quantities. In plunge-feed grinding, the workpiece remains stationary in the axial direction; the grinding wheel is advanced radially. This method is suitable for profiled, stepped or conical workpieces where axial feed is not possible. Tyrolit offers suitable grinding and dressing wheels for both methods, as well as coordinated dressing tools.

Which materials can be machined using Tyrolit centreless grinding wheels?

Tyrolit centreless grinding wheels are designed for steel, stainless steel, HSS (high-speed steel), cemented carbide, nickel-based alloys, as well as titanium and titanium alloys. Steel and stainless steel are the most commonly used materials, for example in the grinding of bar steel in the steel industry or in the manufacture of drive shafts and bearing components in the automotive industry. HSS plays a central role in the tool and cutlery industries, where the precision and service life of the grinding tools directly determine the quality of the finished product. Tungsten carbide is covered by the CSS REGULATOR standard wheel. For nickel-based alloys and titanium – materials typically used in medical technology and aerospace – the CSS CENTERLESS grinding wheel is available.

What role does the regulating disc play in centreless grinding?

In centreless grinding, the regulating disc is far more than just a passive counter-bearing. It controls the rotational speed of the workpiece and – in through-feed grinding – also the axial feed. Its coefficient of friction and elasticity therefore directly determine the dimensional accuracy and surface quality of the finished components. Variations in the regulating disc are directly reflected in the grinding result. The CSS REGULATOR from Tyrolit are manufactured using a pressed process. A very high degree of compaction ensures consistent quality across the entire width of the disc. The special BR60/63 epoxy resin bond ensures reliable workpiece contact; the elastic bond matrix compensates for irregularities in the workpiece and maintains a constant contact pressure – even with long grinding discs.

Highlights from the Tyrolit centreless range

CSS CENTERLESS is the resin-bonded grinding wheel for grinding round bars. It impresses with maximum stock removal rates, reduced cycle times and the highest concentricity and dimensional accuracy – and forms part of the complete Tyrolit system comprising grinding wheel, dressing wheel and dressing tool, all from a single source.

STARTEC CG combines N-LW lightweight construction technology with diamond grains of the highest quality, raising the standard in centreless through-feed grinding to a new level. The damping lightweight backing body protects the machine spindle, reduces energy consumption and allows the use of coarser grit sizes whilst maintaining the same surface finish – which directly translates into higher material removal rates and longer tool life. The grinding coating can also be designed with a combination of grain sizes across the width of the wheel, enabling both roughing and finishing operations in a single pass. STARTEC CG is manufactured to individual customer specifications.

In which sectors do manufacturing companies rely on centreless grinding?

Centreless grinding is the method of choice wherever high-volume production of precision cylindrical parts is required. In the automotive industry, it is used to manufacture drive shafts, piston pins and bearing rings. The steel industry relies on centreless cylindrical grinding for bar stock grinding. In the tool and cutlery industry, this process is used to produce HSS tools with extremely tight tolerances. The medical technology sector utilises the process for implants and surgical instruments made from titanium and nickel-based alloys. Tyrolit supports manufacturing companies across all these sectors as a system partner – with coordinated grinding and regulating discs, as well as the associated dressing tools and the application expertise that a tool supplier alone cannot offer.