When we use an automatic metallographic polishing machine, the sample is placed in a fixture (fixture), which is installed on the power head. When in use, the power head descends and the sample is polished on the rotary table.

 Generally speaking, the power head rotates, but it is necessary to further clarify: why does it rotate? Which direction is it rotating in? What is the speed chosen? How to match with other parameters?

First question: Why rotate?

If it does not rotate, the problem is not significant because during manual polishing, the sample cannot rotate even if held by hand. However, manual polishing without rotation is limited by technical conditions, and in addition, manual polishing generally needs to rotate 90 degrees between each process. Also, if the power head does not rotate, it cannot be used as a whole polishing cloth like manual polishing, and can only be polished along one trajectory.

In this way, for an automatic metallographic polishing machine with non rotating power head, in order to achieve the same effect as manual polishing, it is necessary to manually adjust the polishing angle and position of the sample, which loses the significance of using an automatic polishing machine.

Second question: In which direction does it rotate?

It is recommended to rotate in the same direction as the turntable, as there are several benefits to doing so. Firstly, compared to reverse rotation, the system is more uniform and stable during startup and operation, and secondly, it is less likely to cause eccentric wear. In addition, co rotating is also beneficial for throwing the ground particles out of the turntable. Of course, rotating in the same direction also has its drawbacks. The polishing time will become longer, and the polishing agent is easily thrown out during polishing. Therefore, it is generally recommended to adopt a compromise solution.

During the metallographic sandpaper polishing stage, it rotates in the same direction, ensuring uniform and stable wear without deviation. When sanding with sandpaper, the diameter of the grinding particles is large, and rotating in the same direction will not cause too long grinding and polishing time. Reverse rotation during the polishing stage improves efficiency and helps maintain the polishing agent. When polishing, the grinding amount is very small, so efficiency is more important. Of course, there is no problem with the entire process rotating in the same direction.

Third question: What is the speed to choose?

The recommended speed is generally between 60-90 rpm/min, which can be adjusted based on usage experience. When the speed is very low, the motor will step and shake, but when the speed is high, it is not conducive to maintaining uniformity and stability of the system.

Fourth question: How to match with other parameters?

Other parameters here include: rotary speed, loading force, sandpaper thickness, polishing cloth selection, polishing agent type, and so on. Suggest checking the recommended parameters in the sample preparation manual and adjusting them based on actual usage.

In summary, the power head should rotate; Rotate in the same direction as the turntable; Select a speed of 60-90 rpm/min.

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