Prevention of grinding burns

Grinding burn is one of the most common grinding defects on workpiece, especially for high-precision grinding. Grinding burns can be contributed to a lot of reasons. In order to avoid workpiece loss caused by grinding burns, this paper briefly analyzes the causes of grinding burns and the measures to prevent grinding burns.

I. Reducing the generation of grinding heat

In the process of machining the workpiece, due to the characteristics of machining, friction causes temperature rising on workpiece surface, which is particularly obvious in the process of grinding; this heating phenomenon is also the direct cause of the grinding burns. Below measures can be taken to alleviate heating during grinding.

1. Controlling the grinding feed rate and feed amount

In the process of grinding, precision and efficiency is a pair of contradictions. In order to improve the surface quality of the work piece, the grinding feed rate need be reduced. However, in mass production, as to achieve the specified processing efficiency, the risk of burns and other undesirable phenomena on the workpiece surface is often increased.

In order to completely eliminate grinding burns, the grinding feed rate must be reduced, but in order to compensate the loss of processing efficiency due to the reduction of feed rate, usually ① reducing the stock removal of workpiece properly and ②adjusting the feed speed of each grinding steps(increasing feed speed in the "rough grinding" step, and decreasing the feed speed in the " finish grinding" step) will be taken. In brief, it can prevent grinding burns through reducing grinding feed amount and adjusting the grinding feed rate in different grinding steps without reducing grinding efficiency

2. Selecting grinding wheels

In production, in order to obtain a better grinding surface, the grinding wheel with coarser grit size is often selected, but this restricts the grinding efficiency of the grinding wheel. In order to avoid the loss of excessive processing efficiency due to t coarser grit size of the grinding wheel, the grinding wheel with finer grit size, soft hardness and relatively loose organization can be usually selected within the allowed range. Larger porous grinding wheel should be used as far as possible to keep the grinding wheel sharp for grinding. Coolant with better lubricity can also be selected to further reduce the friction between the grinding wheel grains and the workpiece surface.

3. Reducing the contact surface between grinding wheel and workpiece

The grinding process of grinding wheel is actually a kind of multi-cutting edge cutting at the same time, each cutting edge will generate heat due to friction in the process of grinding. So the more cutting edges cut at the same time, the more heat will be generated in the unit time or unit feed distance. It’s difficult to cool in a narrow space rapidly. As a result, the surface temperature of the workpiece will rise sharply which will cause burns. Therefore, reducing the contact surface between the grinding wheel and the workpiece will effectively reduce the generation of cutting heat and avoid burns.

II. Accelerating conduction of grinding heat

In the process of grinding, except controlling the heat generated by grinding, the generated heat can be conducted more quickly and effectively. Therefore, measures can be taken to make the grinding heat transfer out as soon as possible in the production.

1. Change of cooling mode

On the basis of normal cooling, the spray position and mode of coolant can be adjusted appropriately, such as internal cooling, high pressure cooling, spray cooling, etc.; and the cleanliness of the coolant can also help reduce the temperature of the workpiece surface.

2. Coolant temperature

In the process of processing, the coolant circulation system of the equipment is cooled by the temperature controller, which reduces the temperature during processing.

In summary, in the nowadays with increasing workpiece accuracy, the method of giving up production efficiency to obtain higher processing accuracy has long been unable to meet the needs of manufacturers. The manufacturers pay more attention to improving grinding quality, reducing burns and keep the production efficiency unchanged. Only reducing burns effectively and improve accuracy through careful observation and tries can adapt to the requirements of future equipment manufacturing.