One of the adverse effect of roll forming/cold working is tension bend cracking. During roll forming/cold working process of metallic coated steel sheet, the amount of strain(metal deformation) that occurs in the area of tension bends causes cracking of the metallic coating. The cracking is restricted to metallic coating; the steel is not cracked.TBC is a result of wrong selection of roll forming line and raw material.
BMPL overcomes the problem of TBC through its unparalleled latest technology roll forming lines and proper selection of steel material. BMPL roll forming lines are carefully engineered and customised to overcome this problem. These PLC controlled lines incorporates many rollforming stands instead of few stands, consisting of rolls designed from high grade chrome plated steel, which provides smoother and gradual transition and shaping of steel, without abrading the coating. In addition to this, while selecting the steel sheet important factors like thickness and strength of steel,thickness of metallic coating and paint system are carefully studied.
During heavy rainfall, water has a tendency to penetrate through overlaps due to capillary action. To prevent this action, an air gap is required between overlaps of sheets. In BMPL profile sheets this air gap is maintained by providing an anti capillary groove at side crest of sheets, thereby ensuring leak proof sheeting.
BMPL sheets are designed to provide complete overlapping of underlying crest to provide 100% leak proof installation and easy alignment of sheets unlike other non-technically designed sheets which provide only half overlapping of crest due to which there is always a chance of leakage in heavy rainfall and also installer finds it very hard to align the sheets during overlapping.