Adopting Complementary Technologies For High-Speed Machining
Lots of times, a great deal of manufacturers' attention is directed toward machine tool technology. This is because many believe that it has the greatest potential to provide significant benefits. Unfortunately, some manufacturers become too narrowly focused and overlook essential advancements in other areas.
In today’s rapidly changing market, embracing and implementing new technology is extremely important to achieving success. Most manufacturers realize this and constantly monitor the evolution of technology to find additional competitive advantages. Lots of times, a great deal of their attention is directed toward machine tool technology. This is because many believe that it has the greatest potential to provide significant benefits. Unfortunately, some manufacturers become too narrowly focused and overlook essential advancements in other areas.
It is true in almost any situation that a chain is only as strong as its weakest link. A car with a powerful engine and inefficient transmission will obviously suffer limited performance. A streamlined, state-of-the-art production line will only produce finished parts as quickly as its most outdated process. Likewise, it is impossible for a machine tool to achieve an overall level of performance beyond what is allowed by its least capable component.
As machine tool technology has advanced in recent years, the potential for suboptimal performance has grown because of a “weak link.” In an effort to boost productivity, many manufacturers have invested in machines with greatly increased spindle speeds. The mere purchase of such a machine does not guarantee higher levels of performance, though. In fact, without a total approach to maximizing the machining process, the addition of a high-speed spindle machine can even result in a negative effect to overall productivity.
Older and low-quality toolholders typically fail to make maximum contact with the spindle pocket. When used with a high-speed spindle, this will result in increased chatter, forcing the operator to sacrifice either accuracy or higher productivity. Furthermore, a poor fit will cause additional wear on the spindle, meaning that the spindle will have to be repaired or replaced with much greater frequency. Not only will a company be forced to pay for work on the spindle, but it will also lose productivity because of the time the machine is down.
Toolholders designated for use with high-speed spindles should provide the maximum amount of contact with the spindle pocket. As machine technology has advanced, so has the design of toolholders. The resulting increase in surface contact reduces chatter, improves spindle life and boosts accuracy by holding tighter TIR.
To get a maximum return on investment from a high-speed machine, a manufacturer must choose tooling and processes that can support the machine’s increased levels of performance. At a bare minimum, this means selecting toolholders that are pre-balanced out of the box. Most of today’s toolholders are pre-balanced to 2.5 g at anywhere from 15,000 to 25,000 rpm. While these ratings will guarantee adequate performance in many operations, manufacturers that really want to maximize the benefit of a high-speed spindle machine should go a step further.
Since pre-balanced toolholders are balanced while completely bare, the introduction of a tool into the equation will have a negative effect. The effect may be small, but it can cause several types of problems. Even minimal unbalanced forces place additional strain on spindle bearings, causing reduced spindle life. A small amount of unbalance can also introduce vibration to the cut, which hurts both surface finish and tool life.
Ideally, tool assemblies should be individually balanced for applications running at speeds of 10,000 rpm or higher. Once a pull stud collet nut and tool have been added, a toolholder’s pre-balance rating is no longer viable. At lower speeds, the difference is often small enough that it can be safely ignored. When working with high-speed spindles, though, the effects can increase quickly, influencing productivity and quality. Balancing total assemblies helps a company ensure that it is getting the absolute greatest possible return from its investment in technology.
The rapid rate of innovation allows for the constant improvement of metalworking operations. As a significant technological breakthrough, high-speed machining holds the potential to provide incredible benefits. At the same time, the technology demands a much higher level of attention to supporting components within the process. When American manufacturers upgrade to increase their global competitiveness, it is vital that they remember that machining is very much like a chain. To guarantee success, they must pay attention to the strength of every link, whether it be the machine, tooling, toolholding, workholding or other components within the machining process.