Gripping advice: Turning Performance

By Michael Larson

Continuing advances in materials, geometries, coatings, and toolholding capabilities have resulted in vastly improved cutting performance and tool life, albeit along with adding significantly to manufacturers’ expenditures on tooling. What is less generally discussed is the other side of the equation: namely, that in order to achieve optimization in performance, tool life and return on investment, high-precision workholding systems are indispensable. At Hainbuch America Corp. in Germantown, Wisconsin, a comprehensive line of products is engineered to address highly specific turning requirements for both ID and OD machining. And the company urges shops to keep the following considerations in mind because of their impact on the most effective tooling equation.

Performance over extended life

Whether the tool is designed for high metal removal rates or surface finish in the micron range, the rigidity of the workpiece and repeatability over the parts run are essential. Standard chucks supplied with new turning centers frequently lack the strength and capability to prevent the misalignment that results in chatter, which in turn causes out-of-tolerance parts and excessive tool wear. This is especially true in complex operations such as ID turning and threading. As more manufacturers have incorporated the use of high-value specialized tooling, the need for stability and repeatability becomes a major economic factor.

Image courtesy of Hainbuch America

Precision

As parts have become more complex, and materials harder to machine, precision and repeatability are indispensable, both to part quality and to the need for higher speeds and feeds over the production run. When used for higher production of multiple parts, standard chucks tend to age fast, and the effects of wear may not become apparent until problems surface. An increasing number of shops and manufacturers who have experienced the problems associated with wear on older legacy machines have realized substantial savings by adding high-precision workholding equipment in place of the older traditional chucks. In some cases, new equipment has resulted in “better than new” repeatability and increased tooling performance, while negating the need for new machine purchases.

Quick-change capability and flexibility

The need to transfer a part from one machine to another or, in the case of multi-spindle machines, from one workstation to another can frequently result in misalignment. Further, successfully transferring parts requires expertise and experience on the part of the machine operator. Look for workholding systems designed for fast and foolproof change-over, whether changing from different parts in the same spindle or moving the workpiece for a secondary operation. Changes can be accomplished in a matter of seconds with maximum repeatability and require no special operator training. An example of this is Hainbuch’s new MAXXOS hexagonal mandrel that maximizes transmission forces, results in less tool wear, and delivers up to 57% higher rigidity with a possible achievable runout of ±2 µm.