SCHUNK has Tightened te Balance Specification on All Toolholders to Ensure That Our Customers Can Yield the Finest Results.
How does balance effect the metal cutting process? The answer is simple, out-of-balance creates vibration, vibration causes chatter, and chatter causes many problems such as poor surface finish, inability to hold size, and reduction in tool life.
Balance is categorized in our industry by applying a balance grade, GX.X. - dependant on the component's influence on the full machine system. Previously, the standard grade for a fine balanced tool toolholder was G6.3 and the grade for the machine spindle was G2.5. In recent years there has been a shift to a tighter balance requirement, due to the ever-increasing machine tool spindle speeds. The new standards for these high-speed systems are G2.5 for the toolholder and G1.0 for the machine spindle.
Achieving this balance is not simple. This quantum change in balance grade coupled with the increasing speed requirement has required all precision toolholder manufactures to improve process. In the end, the results for end-users that require precision at high speeds will be obvious.
It becomes clear that the allowable out-of-balance in g-mm is greater with the higher mass and lower speed of the holder. This gives us a wider range when fine balancing the toolholders. When the mass is low and the speed is high, the allowable out-of-balance is reduced and the challenge to fine balance becomes more difficult and in some cases approaches 1 g-mm.
Ten years ago, there was very little discussion regarding the balance of the toolholder, but numerous machine tool manufactures mandated the use of fine balanced holders and now we are all familiar with the need. This mandate from the machine builders was in an effort to protect the machine spindle bearings, but the result encouraged a focus on the needs of precision toolholder systems - SCHUNK's forte since 1978. This will allow the users far more benefits than just increased spindle bearing life. Now, they can expect improved finish, increased tool life, and better cutting accuracy, and more.
