Cold Drawn Seamless Cylinder Tubes

Seamless cold drawn cylinder tubes produced by ALTA spa have very high mechanical properties and are eventually available also n special steel grades. Dimensional tolerances, surface quality and roundness tolerance are as per UNI ISO EN10305-1 standards and cover a wide size rage as per customer demand.

Final surface resulting in the cold drawn tubes is caused by the condition of the mother tube, because during its hot drilling the tube gains spiral shape (pic A) which is maintained even if reduced, after rolling and drawing (pic B).

Traditional finishing processes of honing and rolling follow this spiral trend, obtaining the requested tolerance and without modifying the spiral shape which is in direct opposition with the principal of concentricity for the specific group: PISTON TUBE/PISTON/TUBE.

Picture c, is demonstrating the extreme straightness of the inside finish, known as “ALTA finish”. The machining of a tube with a reduced inside stock allowance, is generating raw material spots (in the picture the darker spots) those areas are outside of the maximum tolerated straightness, due to the spiral shape of the tube.

To avoid these problems ALTA sources tubes with a higher stock allowance, over and above the norm (up to 3 mm in diameter) removing the necessary material, allowing a better straightness, roundness and surface cleaning finish, against the traditional systems