An innovative production process gives to this range of cold drawn round bars from 15 to 32 mm (to be extended up to 45 mm) special characteristics: a perfect bar end and a very high surface quality.
The production in 6 meter bars, sawn in half in line, eliminates the typical dimensionalvariations of the extremities, due to the usual shearing with traditional products. This newprocess allows the end of the bars to have both shape and size identical to the rest of the bar.Thanks to the perfect shape of the sawn end, a small chamfer of a few millimeters is enough toprevent any problem during bar loading, avoiding waste. Even production of the first piece takenfrom each bar is no longer a problem. For easier bar gripping, the other end is finished with a30° chamfer 4-6 mm deep with milling of the middle circle. Eddy current controls are guaranteedeven in the first 5 centimeters of the bar, usually not controllable according to the standard, asthey are performed on the 6 meter bar before cutting.
MAB70® can be supplied in the CIRCOGRAPH + DEFECTOMAT version, with guarantee ofsurface integrity much higher than Class 3. Thanks to the simultaneous use of both controldevices, we are able to monitor both longitudinal defects (cracks, grooves, overlapping, etc.)and trasversal defcts (scales, pits, isolated fores, etc.). At the same time it is possible to checkthe first 5 centimeters of the extremity like the rest of the bar, the maximum permittedpercentage of material with discontinuity depth higher than the one allowed by Class 3 isreduced more than tenfold, falling from 1% to 0.1%. This value is actually lower than the 0.2%permitted for Class 4.
For easier bar gripping, the other end is finished with a 30° chamfer 4-6 mm deep with milling of the central bar.
It is not technically possible to guarantee “zero defects” in the cold drawing process, but thanksto the MAB70® CIRCOGRAPH + DEFECTOMAT version we are very close to this outcome. This isproven by the data collected in more than two years of trials by some major producers of verydelicate components for the Automotive and Hydraulic industries.