... tube, polygonal tube, single and double groove pipe and so on TypeSpecification (mm)MaterialTolerance ranges(mm)Hardness rangesRound tubeΦ5-Φ325Cr12M0V ... precise; 10 years experience in RD, the fingerprints, mechanical pattern, on the corner, concave angle phenomena, and to form tolerance of ... roundness in les than 0.05mm, square tube on the angle does not exceed ±0.05mm. High Hardness ...