Early science fiction writers guessed wrong when they speculated about the look of automation. They made their robots resemble humans, with two legs for walking and two arms for working. One problem with this picture is that a human body is a general-purpose instrument, while the purpose of any piece of automation is specific. We use one type of programmable machine to move an object from place to place and a separate type of programmable machine to mill a workpiece. These different machines have different shapes to suit their different purposes.
A similar, larger misconception still at work today is the idea that automating some process or function has to involve the addition of any machine at all. The robots and other components of a lightly attended production line may carry a part through all of the same stops and motions that human workers would, but is this the only way to achieve automation? If the objective is to reduce the reliance on human effort and human oversight, then anything that serves that objective deserves to be called by that name. In this light, “automation” may take the form of a change in procedures instead of a new piece of programmable equipment. Automation may take the form of an idea.
How we think about automation is relevant right now because the effective use of automation will determine the eventual success or failure of many shops receiving this magazine. Skilled employees able to perform challenging tasks on the shop floor are becoming steadily more difficult for these shops to find, and cost pressure from competitors using cheaper labor overseas is making all manufacturing labor more difficult to employ. That makes the efficient use of personnel an increasingly important measure of manufacturing effectiveness. The worth of the process is determined by how much value it can return for every dollar that has to be spent on people.
Modern Machine Shop has always applied exactly this standard to our coverage of High Speed Machining. HSM is not necessarily a superior method of machining, nor is it an evolutionary step that describes where all machining is headed. Instead, HSM is one tool among many that are available to metalworking shops. It just so happens that HSM involves many different technologies and addresses a range of challenges—these are the reasons it deserves a special issue. But whether HSM is used to reduce assembly in aerospace production or to reduce EDM and polishing in tool-and-die work, the fundamental principle is the same. The speed, strategically applied, allows the machining center by itself to take the place of multiple machines or stations. This approach—consolidating two steps into one—is arguably a more elegant way to automate than to leave the two steps as they are and install a robot between them.
Speed Is Just The Start
What is high speed machining? The term cannot be defined in terms of any particular speed. Achieving a high value of “rpm” or “sfm” is not the objective in itself. Instead, high speed machining describes the way the speed is used.
In high speed machining, the speed is an enabler. Production methods that would have been slow and expensive at lower speeds become practical when a fast spindle is combined with precise axis moves at high feed rates. With the machining center taking on a larger role thanks to the changed production method, a process that used to be cumbersome becomes more flexible and efficient.
The cases mentioned above provide examples. In aerospace machining, high speeds and feed rates make it practical to mill complex aircraft parts in one piece that formerly had to be assembled from smaller components.
In die/mold machining, high speed cutting makes it practical to use small tools and light depths of cut, so slots and intricate details can be produced through milling instead of EDM. Also, the smooth finish right off the machine may make it possible to eliminate manual polishing.
Both of these applications require not only speed but also the process able to put it to use. That process involves tooling, control and programming considerations that are distinct from the demands of conventional cutting. That process may even involve a more sophisticated understanding of the machine’s behavior at different speeds (as illustrated in this article).
High speed machining is a broad topic getting broader. The fact that there are now so many accomplished practitioners of HSM in addition to its beginning users demands a breadth of coverage it would be impossible to achieve using the printed issue alone. Complementing our coverage of HSM in print is our High Speed Machining Online Supplement, which is available at www.mmsonline.com/hsm.
The issue in print profiles HSM users and emerging technologies. The Online Supplement takes a more comprehensive view than this, providing information likely to be of value to any shop still wrestling with HSM’s fundamentals. Presentations online capture the basics of HSM, describing its rationale in different industries, as well as the machine, tooling and programming elements that contribute to effective HSM processes.
One brand new feature of the Online Supplement is potentially valuable to current and beginning users alike. A database of high speed machining product information allows users to search for those products that offer the specific features they need for their own HSM applications.
This is our fourth special issue on high speed machining, and much of the technology and technique has matured since the first special issue 6 years ago. The process for high speed machining of dies and molds, for example, is now widely practiced and well understood.
And yet there are still new developments to report. You can find a selection of these in this collection of articles:
- Micro Milling At 1/2 Million RPM
- Understanding Surface Location Error
- Surpassing The Speed Limit In CGI
- Lending A Hand To The Handbook
The concepts and technologies described here will be new to almost every shop. What these new ideas show is that, while high speed machining may be standard practice in many places, the way HSM will look in the future remains a worthy subject for speculation.