What Is a Rotary Grinder?
A rotary grinder is a machine that places a workpiece, the object, to be processed, on a rotating round table and grinds it with a grinding wheel.
Rotary grinders are characterized by their suitability for grinding workpieces with relatively large areas and by their ability to grind numerous workpieces by placing them on the table at once. Generally, in surface grinding, grinding is done by the grinder moving to the left or right, while the type of grinder that rotates is distinguished by the term rotary grinder.
Uses of Rotary Grinders
Rotary grinders are used for efficiently grinding multiple workpieces with relatively large cross sections at a time. Specific workpieces include large quantities of substrates, wafers, and plates.
However, the throughput related to workpiece grinding depends greatly on the size of the rotary grinder’s table and the size of the rotating grinding wheel, so it is important to check the specifications of each manufacturer carefully.
Principle of Rotary Grinders
The principle of rotary grinder is to grind a large surface of a workpiece at once by placing multiple workpieces side by side on a large rotating round table and applying a rotating grinding wheel such as a diamond cup from the top surface.
Since this method allows a relatively large grinding area to be secured, it is more efficient and quicker than conventional surface grinding, in which grinding is carried out by moving the workpiece from side to side.
However, the disadvantages of this method are that it is relatively difficult to achieve accuracy and that it sometimes requires time for preparation, such as setting the workpiece. However, since it is a grinding method that can process large quantities of workpieces at a time, it is necessary to use a rotary grinder according to the purpose and application of the grinder.
Other Information About Rotary Grinders
1. Difference Between Grinding and Polishing
In general, the term “grinding” refers to the process of physically shaving the surface of a workpiece to remove material, while “polishing” refers to the process of polishing the surface of a workpiece to bring out its mirror-like surface. However, in some industries, the two are used without distinguishing between the two, in which case the term “polishing” is generally used to encompass grinding.
The process of polishing out a mirror surface, which is inherent to polishing, is also known as lapping or buffing, and often utilizes proprietary abrasives as well as grinding wheels.
2. Difference Between Rotary Grinder and Lapping Machine
Lapping machines are similar in their configuration to rotary grinders in that they are machines that set multiple workpieces on a rotating table and grind them. However, lapping machines are often used when the workpieces need to be ground to a high precision and mirror finish level.
The lapping machine has a method of sandwiches the workpiece between the upper and lower ref plates and uses the “principle of three-sided grinding” to improve the precision of its flat surface. Another major feature of the lapping process is that a liquid abrasive is poured into the workpiece to polish it, which is different from the method used to process workpieces on rotary grinders.
However, this method requires time and labor for polishing and finishing, so it is not suitable for mass processing in a short period of time, like rotary grinders.
3. Example of Grinding Accuracy Improvement on a Next-Generation Rotary Grinder
Some manufacturers of rotary grinders, with their technological innovations, are dealing with the next generation of high-end models that aim to achieve the accuracy of a lapping machine while still being a rotary grinder. Although their mechanisms are very complex, the following examples of improvements have been applied to increase grinding accuracy and finish to mirror level while still having the features of a rotary grinder.
- Permanent electromagnet, a chuck that is not affected by heat, is activated after the workpiece is set.
- Equipped with a function to monitor and FB the amount of grinding wheel cutting
- Applies technology to control the inclination of the table on which the workpiece is mounted with extremely high precision
This is an example of a next-generation rotary grinder with a processing speed and workability closer to that of grinding than to that of polishing, which is unique to rotary grinders.