Centerless grinding

Centerless grinding is a processing method in which the workpiece is not fixed in a chuck or center, but is ground while rotating the outer periphery.Its major feature is that it enables high-precision, high-efficiency continuous production, making it particularly suitable for mass production.

We also handle centerless grinding, but we specialize in straight shapes made of stainless steel. In this article, we will introduce in detail the basic mechanism of centerless grinding, the main types, and our production track record.

What is centerless grinding?

Centerless grinding consists of three components: the grinding wheel Gw (Grinding Wheel) that cuts the workpiece, the regulating wheel Rw (Regulating Wheel) that transports the workpiece, and the blade that serves as the path for the workpiece.

The workpiece is located between the grinding wheel and the regulating wheel, and is supported on the V-plane formed by the outer surface of the regulating wheel and the top surface of the blade. When the workpiece is ground by the grinding wheel, the friction between the workpiece and the regulating wheel causes it to rotate at the same peripheral speed as the regulating wheel.

The surface of the workpiece is ground due to the difference in peripheral speed between the grinding wheel and the workpiece, and the cylindrical outer surface is formed by rotating according to the regulating wheel.This eliminates the need to attach and detach the workpiece to the spindle center and tailstock center, which is required in cylindrical grinding, thereby improving machining efficiency.

In addition, since the workpiece is supported over its entire length by the adjusting wheel and blade, high precision and heavy load processing is possible. In centerless grinding, the support position changes as the workpiece diameter changes as the processing progresses, and the center of rotation of the workpiece also moves.

It is this characteristic that makes it known as 'centerless'.

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What is grinding? An easy-to-understand explanation of the types, characteristics, and differences from cutting

Types of centerless grinding

There are two main types of centerless grinding. From here on, we will introduce the types of centerless grinding.

1. Through-feed grinding
2. Infeed grinding

Through-feed grinding

This method involves tilting the axis of the regulating wheel slightly vertically to generate a force (thrust) that advances in the axial direction, and grinding the workpiece as it passes between the grinding wheel and the regulating wheel. With this method, there is no restriction in the axial direction, and workpieces can be fed continuously, allowing for highly efficient processing.

Sanwa Needle Bearings specializes in straight stainless steel bearings, and can process them with an outer diameter tolerance of 0.1 μm or less.

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Sanwa Needle Bearing's pursuit of ultra-high precision

Infeed grinding

This is a grinding method in which the grinding wheel contacts the work surface simultaneously without feeding the workpiece in the axial direction.This is called "plunge grinding."
By using a blade and adjusting wheel that is suitable for the workpiece to support it, it can be used to process stepped or tapered workpieces.

Advantages of centerless grinding

There are four main advantages to centerless grinding.

①High precision and efficiency
Continuous processing is possible, enabling mass production of high-precision parts.

②Can handle a wide variety of products
It can accommodate a wide range of shapes, including straight, stepped, and tapered shapes.

3. High-precision roundness and cylindricity can be achieved
The workpiece is supported by a rigid blade and regulating wheel, ensuring stable machining.

④Reduce processes
Compared to center-type cylindrical grinding, there is no need to drill a center hole in the workpiece.

actual production

Here we will introduce some of the production results we have achieved.

Gasoline engine parts

Automobile meter pin