Page 86 - MetalForming-Oct-2018-issue

Metal Sanding
and Grinding
Identify problems caused by incorrect belt tensioning, and find out here how to fix them.
BY DOUGLAS JENSEN
Abrasive metal-finishing belts of all sizes require tension to oper- ate. Although some machines use spring pressure to create belt ten- sion, and some wide-belt sheet- and coil-polishing equipment employ hydraulic belt-tensioning cylinders, the vast majority of belt-sanding and -grinding machines use pneumatic belt-tensioning cylinders.
For quality and productivity when belt sanding or grinding workpieces,
Douglas Jensen is senior application engineer with Norton|Saint-Gobain Abrasives, Worcester, MA; tel. 508/795- 5000, www.nortonabrasives.com.
the importance of appropriate abrasive belt tension cannot be over-empha- sized. In many cases, problems relate directly to the amount of tension applied to belts. However, problems related to high or low belt tension often are caused by something unrelated to the tensioning function itself. How can you determine the direct cause, and how can you fix it?
As a general rule, set belt tension at the point where the abrasive belt does not slip on the drive wheel (nar- row belts) or roll (wide belts) when it engages during the sanding/grinding process. But where is that point? And, even if that point is found, it can change easily as the abrasive belt wears and more friction develops between the part and the face of the belt as the operator applies more pressure. A complicating factor: Machines using abrasive belts feature a significant amount of design
For quality and productivity when belt sanding or grinding, the importance of appropriate abrasive belt tension cannot be over- emphasized.
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MetalForming/October 2018
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FABRICATION
Belt Tips for Better