High Speed Milling: A Competitive Necessity

The use of high speed milling in moldmaking shops is no longer viewed as merely providing a firm with a competitive advantage. It is a disruptive technology that is becoming a competitive necessity. It is now being employed extensively, and those mold shops not effectively implementing this technology could fall by the wayside in the highly competitive worldwide marketplace.

In a recent CIMdata survey of moldmakers worldwide, 9 percent of the moldmakers stated that the use of high speed machining is required to remain competitive, with only 5 percent not accepting this assertion. Moreover, only 5 percent of the survey respondents forecast that the use of high speed machining would remain steady. The remaining 95 percent expect usage to increase. More than 55 percent of the moldmakers project the use to increase moderately, and even more telling is that more than 35 percent believe there will be a dramatic increase in usage. It is clearly an important technology that will become even more so in the future. More than 70 percent of the users surveyed had implemented high speed machining, so most of the moldmakers were basing their responses on actual experiences. The remaining respondents provided a projection based on their knowledge of the technology.

Usage will increase because users are obtaining or expecting to receive significant productivity gains from the implementation of high speed milling. This is typically the result of higher quality parts being produced with smoother surface finish, less time spent at the machine tool and a sizeable reduction in the amount of handwork that is often required to finish a part. In the CIMdata survey, two-thirds of the respondents stated that they are receiving or counting on a reduction of at least 16 percent in overall production time as a result of high speed machining. Further, one-quarter of the moldmakers are getting or anticipating a reduction of more than 25 percent, and 15 percent are obtaining or forecasting a reduction in overall production time of greater than 35 percent. Clearly, benefits of this magnitude are substantial and can greatly impact competitiveness.

North American moldmakers are more bullish on the positive impact of high speed machining than their European counterparts are. For example, whereas 30 percent of American moldmakers surveyed are receiving or expecting decreases of 25 percent or more in overall production time, only 15 percent of European moldmakers are obtaining or anticipating a similar benefit. Correspondingly, nearly 45 percent of European firms were obtaining or expecting reductions in overall production time of only 15 percent or less. Approximately 30 percent of North American moldmakers took this more conservative view. Japanese moldmakers tend to be more positive than Europeans, but less sanguine than Americans. The rationale for these distinctions by geography is not clear, although it could be related to the extent of knowledge gained from using the technology.

To support high speed milling, the CAM programming software must provide fast and efficient transfer of data and smooth tool movement to generate a constant chip load as well as support those machine tool features necessary to produce gouge-free, high surface finish parts. CAD/CAM and CAM-centric software vendors focusing on the mold marketplace are responding to these demands by introducing software changes that are specifically designed to support high speed milling.

IBM/Dassault considers the three primary criteria for high speed milling to be constant engagement of the cutter, no sharp corners and use of climb milling. In CATIA Version 5, the full tool is never in the material, all internal corners are rounded and a loop can be added to an external corner.

Delcam has embedded at least 12 significant features in PowerMILL that are specifically related to support of high speed machining. This includes support of spline output employing either a B-spline or a NURBS curve and placement of arcs on the end of lace cuts with various parameters used to define the transition path.

In UG CAM from UGS, standard processes are available that use a hierarchy of templates for targeted applications such as mold machining. A hierarchy of templates is provided for different processing levels including setup, group sequence and operational sequence. A specific machining template for high speed contouring is included within UG CAM.

Vero International provides support for high speed milling through the use of a dedicated application within the Visi Advanced Machining module. Some of the features included are automatic reduction of output points, residual roughing to maintain a constant tool load and minimum/maximum control of surface finish.