In the drag finishing process, workpieces are clamped in specially designed holders. These holders are dragged in a circular motion through a process drum containing grinding or polishing granualate. This high-speed motion generates high contact pressure between the workpiece and the media, which quickly produces perfect results in the form of high-precision edge rounding, smoothing or a mirror-finish with results equivalent to those obtained by manual polishing.

One of the main applications for OTEC’s drag finishing machines is in the tool making industry. Some of the parts that can be processed using drag finishing include:

• carbide cutters, thread-cutting dies, inserts and small broaches – processing these parts in a drag finishing or stream finishing machine reduces the risk of chipping. Precision rounding of the cutting edges and polishing the chip flutes increases tool life and improves cutting performance.

• PVD and DLC coated workpieces – Stamping, forming and cutting tools are often coated with a carbide material in order to reduce wear. As a result, droplets can form on the surface of the tool. The drag finishing process selectively removes these droplets. Lubricant can be retained in the tiny holes and depressions left behind. This gives an improved film of lubricant on the surface of the tool, resulting in much less friction and reducing wear dramatically.

• finishing of stamping and forming tools – the quality of stamping and forming tools can be improved considerably with the OTEC finishing process. Surface finishing lowers the coefficient of friction and thereby reduces wear at the surface of the tool. Polishing the forming surfaces can considerably increase the life of stamping and forming tools and improve tool performance. Smoothing the roughness peaks reduces the forces required and gives better flow characteristics during forming. In order to ensure that the quality of tools remains constant, regular repolishing is absolutely essential. Finishing in OTEC machines not only cuts down on expensive manual finishing work, but also delivers absolutely reliable and reproducible results.