Hand Surface Grinder VS Ordinary Surface Grinder

Grinding is a method of micro-precision cutting of the surface of a workpiece on a grinding machine with a grinding wheel or other abrasive tool at a high linear speed. Grinding is one of the main methods of parts finishing, with machining accuracy of up to 0.01mm, dimensional tolerances of up to IT5 ~ IT6 and surface roughness Ra can reach 0.2 ~ 0.8μm. The following describes the differences in machining methods and ranges between hand surface grinder and ordinary surface grinder.

Machining Range and Methods of Hand Surface Grinder

Hand Surface Grinder Processing Range:

In the manufacturing and processing of mold parts, this type of grinder, due to the small size of the machine table, flexible manual operation, digital cutting feed, and processing of mold parts with high precision, is commonly used in a variety of flat surfaces, beveled surfaces, grooves, grinding finish machining.

Hand Surface Grinder Machining Range:

1. Measure the mold parts to be machined, determine the grinding dosage, wipe the datum and the surface of the grinding machine table to make it fit, and turn on the switch of the electromagnetic suction cup to suck the machined parts firmly. If the part is relatively small, use the flat vise to clamp, adjust the position and suck firmly on the table.
2. According to the grinding requirements of the machined parts, select the grain size and shape of the grinding wheel accordingly, and adjust the grinding position. 
3. Test cutting. As the grinding process is a finishing process, the grinding dosage is very small, so the trial cutting is very important, to carefully observe the trial cutting sparks, to prevent accidents caused by excessive cutting. 
4. The cutting process to strictly control the amount of grinding, roughing, and finishing processing is completed by cutting. In the process of machining, needs to detect the size of the mold parts promptly, according to the actual test results to guide the processing, to ensure that the accuracy of the mold parts is in line with the drawing requirements.

Machining Range and Methods of Ordinary Surface Grinder

Ordinary Surface Grinder Processing Range:

Ordinary surface grinder and hand crank surface grinder processing principle and function are the same, hand crank surface grinder grinding wheel is smaller, according to the mold parts of the plane, inclined surface, curved surface and other machining requirements to choose, processing precision is high. Ordinary surface grinder is mainly used for processing the plane and groove of larger mold parts, automatic tool walking, high processing efficiency, dimensional accuracy is slightly lower than the hand-operated surface grinder, and it is more difficult to process the surface of non-planar parts.

Ordinary Surface Grinder Selection of Grinding Wheels:

The hardness of the grinding wheel refers to the ease with which abrasive grains can be dislodged from the grinding wheel under the action of external forces. The hardness of the grinding wheel has a great influence on the grinding productivity and grinding surface quality.

If the grinding wheel is too hard, the abrasive grains can not be dislodged after grinding blunt, the grinding efficiency is very low, the work surface is very rough, and may be burned, if the grinding wheel is too soft, the abrasive grains have been dislodged from the grinding wheel, the grinding wheel loss is large, the shape is not easy to maintain, affecting the quality of the workpiece. Select the appropriate hardness of the grinding wheel, the abrasive grain grinding blunt due to the increase in grinding force and falls off on its own, so that the new sharp abrasive grains are exposed, the wheel has self-sharpening, then the grinding efficiency is high, the surface quality of the workpiece is good, the loss of the wheel is also small.

Grinding soft materials to choose a harder wheel, grinding hard materials to choose a soft wheel, grinding soft and toughness of non-ferrous metals, wheel hardness should be selected softer, grinding poor thermal conductivity of the material should be selected softer wheel, face grinding than the circumferential grinding, wheel hardness should be softer.

In the same grinding conditions, the resin bonded wheel than the ceramic bonded wheel hardness to be higher than the level of 1 ~ 2, wheel rotation speed when the wheel rotation speed is high, the hardness of the wheel can be selected soft 1 ~ 2 levels, grinding with coolant than dry grinding wheel hardness is higher than 1 ~ 2 levels. The choice of the bond should be considered according to the grinding method, the use of speed and surface processing requirements, and other conditions.

Wheel size refers to the size of the grinding wheel in the size of the abrasive particles, The abrasive particle size selection principle is: rough grinding, should be used in the abrasive particles of the larger grinding wheel, to improve productivity, fine grinding, should be used in the abrasive particles of the smaller grinding wheel, to obtain a smaller surface roughness.

Selection of Grit Size for Common Grinding Wheels

Grinding Temperature:

Grinding due to high cutting speed, cutting thickness is very small, and the cutting edge is very blunt, so the power consumed to remove the unit volume of the cutting layer is about 10 to 20 times that of the turning, milling, and other cutting processing methods, and most of the energy consumed by grinding is transformed into heat, so that the grinding area forms a high-temperature region.

Usually the grinding temperature is the average temperature of the grinding area during the grinding process, which is about 400~1000℃. The grinding temperature affects the abrasion of abrasive grains and the adhesion of abrasive chips and abrasive grains, which can cause work hardening, burns and cracks on the surface of the workpiece, and cause the workpiece to thermally expand, warp and form internal stresses. For this reason, a large amount of cutting fluid needs to be used for cooling during grinding and to flush away the abrasive chips and broken down abrasive grains to ensure the precision of the grinding process of the parts.

Ordinary Surface Grinder Machining Range:

1. The general surface machining method is similar to that of the hand surface grinder, using the magnetic table of the grinder to suck the parts for machining. If it is beveled grinding processing, you can use the manual feed method to complete the processing.
2. Detect the blank to be ground, adjust the angle of the sine gauge or universal precision vise, and clamp the blank to be ground firmly. 
3. Place the jaws of the vise in the direction parallel to the table movement and tilt the angle of the sine gauge in the direction of starting grinding to ensure a smooth grinding process.
4. During the grinding process, the amount of tool eating should be small, divided into roughing and finishing, and pay attention to the timely detection of the angle to ensure that the grinding accuracy meets the requirements of the drawings.

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