Burnishing Tools Information
Burnishing tools are used to impart a gloss or fine surface finish, often in processes that involve the cold working of metal surfaces. Burnishing tools are also used for the sizing and finishing of surfaces.
The first noticeable difference between abrading and burnishing a surface to accomplish this peak and valley reduction is that the former removes metal from the part while the latter does not. Abrasive finishing cuts or tears away the peaks in the surface, thereby bringing the average peak and valley distances closer together. But Cogsdill says that this also leaves sharp projections in the contact plane of the machined surface. Burnishing doesn’t have this problem. At first glance, a burnished part looks as if the metal surface has been smeared smooth. But that would be incorrect. The burnishing tool’s polished and hardened rollers actually perform cold flowing of the surface and subsurface material, which results in a controlled plastic deformation of the part.
Which Parts Work for Roller Burnishing?
In the slideshow above, there is a photo of a sample part, with the unfinished surface on the left and the finished surface on the right. There are a couple things to note here. First, roller burnishing is fast and repeatable; the finish seen above was accomplished in less than 2 seconds. Cogsdill counts the fact that its tools can size, finish and work-harden parts in a single seconds-long operation as a principal benefit over grinding, honing or lapping.
How to Burnish Metal
Burnishing is the process of polishing metal to give it a smooth shiny finish. It is often used on soft metals such as brass or aluminum and is an alternative to diamond dragging.
Trophy brass is usually lacquered with a thin layer of paint or plastic that must be abraded to expose the underlying metal without actually engraving it. The following steps will show how to burnish metal.
-
Select a burnisher. This is a special engraving tool with a blunt end instead of the usual sharpened tip, illustrating its purpose of polishing metal without cutting into it. The spindle motor causes the burnisher to rotate rapidly and will provide a smoother appearance than diamond dragging.
-
Set up the engraver for burnishing. Install the light touch burnishing adapter and insert the burnisher into a solid collet or top load spindle just like any other cutter.
-
Remove the nose cone and micrometer. They are not needed for burnishing and removing them will provide a better view while burnishing.
-
Loosen the set screw and position the burnisher so that it extends at least 1/4 inch past the spindle and tighten the set screw.
-
Push the burnisher with your finger to see if it hangs up. If it does, loosen the set screw slightly and rotate the burnisher 30 degrees. Repeat this until the burnisher moves back and forth. The idea is to have the set screw as tight as possible and still allow the burnisher to move freely.
Different Deep Hole Drilling Tools and Technologies
Gundrilling is a deep hole drilling process that uses a long, thin cutting tool to produce holes at high depth-to-diameter ratios. Gundrilling is typically effective in diameters from 1 – 50 mm [~0.04 – 2.00 in]. A gundrill differs from a conventional twist drill by its unique head geometry; a standard gundrill has a single effective cutting edge that removes chips as it advances into the workpiece.
