The Huichon Machine Tool Factory of the Democratic People’s Republic of Korea has made ultraprecision stone surface plates of various sizes enjoying popularity among users for their good mechanical operation. They are quite different from the cast iron surface plate which is difficult to process precisely and easy to deform in high temperature. The latter also makes errors because of changed circumstances in inspection and calibration of products. The stone plates are more than two times the cast iron plates in hardness and resistance to abrasion and more than 35 times in resistance to heat. And they keep their shapes unchanged for a long time because they have a few factors of shrinkage and expansion. The nonmagnetic stone plates, which are unaffected by surroundings, bear well with acid and water and produce less vibration and noise. They, ensuring precision of 0.0025 mm per one square meter, have already been introduced into different economic sectors.
Precision rocks, what will they think of next? |