Precision cold drawn tube is the carbon, alloy or stainless steel pipe with high precision sizes. Usually it has been made through hot rolling or cold drawn (cold rolling) processes. So precision pipe is a kind of seamless pipe.International standard for precision pipe is DIN 2391, which is applied with European standard.As a matter of fact, more steel pipe standard could applied for the precision pipe. Includes DIN2445, EN10305, DIN1630, DIN1629, ASTM A106, ASTM A179, JIS G3445Materials available with 10#, 20#, 35, 45, 40Cr, 25Mn. 37Mn5, St35(E235), St37.4, St45(E255), St52(E355) and etc.
For hot rolling precision steel pipe, tolerance of OD is +/- 0.1%.For cold drawn precision tubes, tolerance allowed in below conditions:
Diameters 6mm to 10mm, normal tolerance condition +/- 0.2%, premium tolerance condition +/- 0.15%.
10mm to 30mm, normal tolerance condition +/- 0.4%, premium tolerance condition +/- 0.2%.
30mm to 50mm, normal tolerance condition +/- 0.45%, premium tolerance condition +/-0.3%.
For outer diameters above 50mm, normal tolerance condition +/- 0.1%, premium tolerance condition +/- 0.8%.
Manufacturing process of the precision steel tubes
During manufacturing processes, the key point is to do the annealing for raw materials.
Precision steel pipe manufacturing flow chart:
Raw Material Inspection – Remove Oxide Layer – Visual Inspection – Heating – Hot Rolling – Pickling and Passivation (Phosphating) – Grinding – Lubrication and Drying – Cold Rolling (Internal and external extraction) – Remove Oil – Ends Cutting – Inspection – Marking – Packing and Storage
As we know, most of precision steel tube has cold drawn and hot rolled process. On the contrast, cold rolling will be more complicated. Not only the pipe need to be continuous rolled by three roller, but also the test have to be done after extrusion, so to guarantee the quality of the precision pipe materials.
Manufacturing methods of seamless precision tubes includes hot rolling and cold drawn. More over it could be manufactured in welding processes. it is widely used for manufacturing the pneumatic parts and hydraulic cylinder barrels.