How To Solve Common Problems In Polishing

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When designing, mapping, or drawing a machine or component, you must draw a part drawing. The accuracy of the parts drawing directly affects the performance of the machine or component. So for the designer who draws the drawing of machining parts, the requirements are very high. This article will introduce the drawing method of machining parts in detail.

The polishing services of the cavity in the part manufacturing process is a very important process. It is related to the quality and life of the part, and also determines the quality of the part. Mastering the working principle and process of polishing, and choosing a reasonable polishing method can improve the quality and life of parts, and then improve the quality of products.

1.Excessive polishing

The biggest problem encountered in the daily polishing process is "over polishing", which means that the longer the polishing time, the worse the quality of the surface of the part. There are two phenomena of excessive polishing: "orange peel" and "pitting". Excessive polishing often occurs in mechanical polishing.

2. Reasons for "orange peel" on the workpiece

The irregular and rough surface is called "orange peel". There are many reasons for "orange peel". The most common reason is caused by overheating or carburizing of the part surface. Excessive polishing pressure and polishing time are caused The main reason for "orange peel". For example: polishing wheel polishing, the heat generated by the polishing wheel can easily cause "orange peel". Harder steels can withstand higher polishing pressures, and relatively soft steels are prone to over-polishing. Studies have shown that the time to produce over-polishing varies with the hardness of the steel.

3. Measures to eliminate the "orange peel" of the workpiece

When the surface quality is found to be poor, many people will increase the polishing pressure and prolong the polishing time, which often makes the surface quality worse.

The following methods can be used to remedy:

• (1) Remove the defective surface. The grain size of the grinding is slightly coarser than that of the previous sand number, and then the grinding is performed. The polishing strength is lower than the previous.
• (2) Perform stress relief at a temperature lower than the tempering temperature of 25 ° C. Grind with the finest sand number before polishing until satisfactory results are achieved, and finally polish with a lighter intensity.

4. Reasons for "pitting corrosion" on the workpiece surface

Due to some non-metallic impurities in the steel, usually hard and brittle oxides, they are pulled from the surface of the steel during the polishing process to form micropits or pitting corrosion. The main factors that cause "pitting corrosion" are the following:

• (1) The polishing pressure is too large, and the polishing time is too long.
• (2) The purity of the steel is insufficient, and the content of hard impurities is high.
• (3) The surface of the parts is rusted.
• (4) The black leather is not removed.

5.Measures to eliminate pitting of workpieces

• (1) Carefully re-grind the surface. The grain size of the sand is slightly coarser than the grain size used before. The soft and sharpened whetstone is used for the final step of grinding before the polishing process.
• (2) The softest polishing tool should be avoided when the size of the sand particles is less than 1 mm.
• (3) Use the shortest possible polishing time and minimum polishing intensity.

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