[100 experts interpret the quality of hundreds of products] Today's attention: Abrasives

Daily attention: Abrasives
Appearance expert: Liu Ping, Jiangxi Provincial Product Quality Supervision and Inspection Institute
Product introduction
Abrasives are made of ceramic, resin, rubber, rhombohedral and other binders with brown fused alumina, white corundum, chrome corundum, green silicon carbide, black silicon carbide and other abrasive consolidation (pressing, sintering or baking, molding and other processing techniques). A grinding tool, such as grinding wheel, grinding head, sand tile and grindstone, is a kind of metal or non-metal workpiece widely used in machinery manufacturing, geological drilling, aerospace, metallurgy, construction and other fields. Tools for roughing, semi-finishing and fine grinding, as well as grooving and cutting of the outer, inner, flat and various profiles are essential tools in modern industrial production.

Abrasives are mainly composed of a combination of binder and abrasive. Different proportions and different binders and abrasives of different particle sizes (called formulations) can be used to make various products with different performance (working speed, hardness, etc.) to meet different requirements. Workpiece processing requirements.

According to the use of abrasive tools, they can be mainly divided into two categories: one for grinding and grinding, the common ones are flat grinding wheels and boring wheels, and the other for cutting, such as resin (or rubber) thin grinding wheels, fiber reinforced. Resin cutting wheel.

Key indicators
1. Swing strength. According to national standards, when the grinding wheel reaches the specified test speed, the grinding wheel must not be broken for 30 seconds. At present, the unqualified grinding tools on the market mainly involve two reasons. First, the individual grinding wheel manufacturers have poor process control, low product quality, and fail to carry out factory inspection according to regulations. Second, many advanced The mechanical equipment not only processes the surface quality of the workpiece, but also has high processing efficiency. One of the methods to improve the processing efficiency of these equipment is to increase the grinding (or cutting) rate, that is, the rotation speed, so some grinding wheel manufacturers do not adjust the grinding wheel formula and In the case of the molding process, the ordinary rotating grinding wheel produced is randomly marked with the mark of the high-speed grinding wheel to occupy the market.

2. Static balance. The standard stipulates that grinding wheels with an outer diameter of 125 mm and larger, a working speed of 16 m/s and higher, and a single weight of 0.2 kg and larger shall be subjected to static balance inspection. Static balance is a measure of the uniformity of the tissue inside the grinding wheel, that is, the uniformity of the mixing of the abrasive and the binder. Since the grinding wheel is operated under high-speed rotation, the balance of the grinding wheel itself not only affects the surface quality of the machined parts, but more importantly, affects safety.

3. Aperture. The hole diameter is an index reflecting the installation of the grinding wheel and the mechanical equipment. The grinding wheel is a tool that is easy to replace and often replaced. The mandrel of the grinding wheel of the mechanical equipment is fixed and cannot be replaced at will. The matching clearance of the grinding wheel mounted on the mandrel of the equipment is specified according to the standard design and is designed as a standard part. If the aperture deviation is too small, it may not be installed or forced to be installed by tapping or hard extrusion. As a result, cracks may occur in the grinding wheel product during the installation process, and the strength of the grinding wheel may be damaged; if the aperture deviation is too large, an imbalance occurs after installation on the equipment. The result will be like a grinding wheel with a poor static balance. Large or small pore diameter deviations can cause the grinding wheel to rupture during use.

4. Hardness. Hardness is an indicator of the softness and hardness of the grinding tool. The hardness of the grinding tool plays a key role in the efficiency of cutting and grinding. The hardness of the hardness of the grinding tool is compatible with the material of the workpiece, and the hardness is not soft. High, hard hardness will cause burns on the workpiece.

Shopping guide
1. Look at the surface marking, check whether the surface of the grinding wheel has cracks, missing corners, etc., and whether the inner hole inlay layer is peeled off, and whether the plane of the inserting hole is flat. The national standard stipulates that at least seven indicators of the manufacturer's name, trademark, abrasive code, abrasive grain size, hardness, maximum working line speed and production date shall be indicated on the surface of the product. The industrial product production license number shall be on the outer packaging or on the instruction manual. And safety signs (QS). The complete product is marked, indicating that the enterprise is a formal enterprise with a certain scale. Even if there are problems in the process of use, the consumers are well documented.

2. Listen to the sound, use a small wooden hammer to gently tap the grinding wheel to listen to the sound response without dumb sound, there is a dumb sound indicating that there are fine cracks inside the grinding wheel.

3. Abrasives of resin, rubber and rhombohedral binder should pay attention to the date of production indicated on the surface. Since such abrasives are susceptible to moisture and freezing, the national standard stipulates that such abrasives should not be stored for more than one year.

4. It is forbidden to use abrasives with cracks, corners and other damage, matte sounds and exceeding the storage period.

5. Abrasives are fragile products. They should be protected from vibration and collision during transportation. Storage should be placed in the rack or box according to the shape and size. If stacked, the stacking height should not exceed 1.5m. Rubber and resin bond sheet grinding wheels should take measures to prevent deformation during storage and pay attention to moisture and frost.

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