Boring Bar Solutions: Vibration Dampening
Learn how to help reduce the vibration that occurs when using a boring bar.

Boring bars come in a number of different designs and functions, from double clamp dimple bars to carbide shank micro-dex boring bars. The design of a boring bar largely determines its functionality and the type of cut it makes in the boring process, as well as its intended application. For example, Aluminum boring bars generally have shank sizes from .625 to 1 inch diameter, and are intended for use in aluminum, nonferrous metals, or plastic materials.

One common problem across all boring bar designs and applications is vibration. A boring bar can range in diameter, and its length is defined in respect to that measure. So, for example, if a boring bar is an inch in diameter, and has a six inch length, it’s said to have a six times stickout. When a boring bar is inserted into a socket or cavity to begin cutting, that stickout often gets far enough out from the lathe to start vibrating. The bar will then bang against what it’s supposed to be cutting, causing the chips cut out of the material to be larger than normal, potentially jamming the rotation of the bore.

There are a number of ways you can help reduce vibrations in your boring bar:

  • Choose the shortest possible adaptor.
  • Choose the largest diameter adaptor.
  • If possible, use a tapered adaptor to reduce deflection.
  • Choose a light cutting insert with positive cutting geometry.
  • Choose a small nose radius (no larger than .4mm).
  • Use sharp insert with relatively thin coatings.
  • Enter at a 90 degree angle.
  • Do not cut too deeply (no more than half the cutting edge length).

However, one simple solution is to select a bar specifically designed for vibration dampening. Vibration dampening bars can be tuned to reduce vibration and deflection within the boring space and depending on the material being cut. This makes things a lot easier on both the cutting machine and the material finish. Vibration dampening bars are made from multiple metals, and are designed specifically to have a soft exterior, but rigid center. The dampening mechanism itself is on the inside of the tool and is adjustable with a wrench.

It should be noted that vibration dampening bars require experience to use. Fine tuning a bar to reduce vibration as much as possible can be a rigorous process that takes patience and diligence. However, once the right tuning frequency is achieved, the payoff in terms of time and money saved can be worth it.