reground

20:32 Sep 14, 2009 

Even a perfectly ground block, with the right coating for the job, can be foiled by poor drawing practices. If an operator forgets to turn on the coolant system or turns it on too late, the thermal shock can break off the coating. The initial string-up of the machine should be done slowly and carefully to prevent the wire gripper from crashing into the face of the block and damaging the coating. It is also possible to wrap the gripper with carpet or rubber to soften the blow

20:21 Sep 14, 2009 

Another spray process, High Velocity Oxygen Fuel (HVOF), shoots melted metal powder particles faster than the speed of sound, creating thicker and denser coatings that impinge into the substrate material (1/4" minimum wall thickness). Tungsten carbide coatings can be applied by HVOF up to 0.080" thick, yielding a surface that can be reground several times. Although it is the most expensive coating (other than sleeve jobs) for initial application, the regrinds typically make it more economical in the long run. Like ceramic, it is 4-5 times longer lasting than metalizing; however, it is less brittle and can be used to draw high carbon steels and hard stainless steels without cracking. Tungsten carbide can also be sprayed on pulleys, sheaves, and rollers.