VIEWPOINTS INDUSTRY LEADER OPINION & ANALYSIS Harnessing the Power of Underused CAM Capabilities v
achine builders, cutting tool vendors, workholding solu- tions designers and many others have been stepping up to the plate to deliver CNC manufacturing solutions capable of delivering substantial increases in productivity without sacrifi cing quality. CAD/CAM software developers have been working in tandem with these suppliers to integrate these emerging hardware capabilities into their CNC programming environments. A number of OEMs and job shops are encouraging their engineers, programmers and programmer/machinists to take advantage of these hardware and software developments. Where these improve- ments have been installed, shops frequently realize increases in CNC manufacturing productivity ranging from 25% to 300%. The use of fi ve-axis equipment for 3+2 machining springs quickly to mind. Many manufacturers still shy away from pur- chasing fi ve-axis mills because of the perceived complexity of this manufacturing process and the fairly steep learning curve for becoming a competent fi ve-axis programmer. This is a justifi able concern for those contemplating the manufacturing of parts that require continuous fi ve-axis machining, but not the case for the majority of shops that only need to produce prismatic parts with features on multiple sides. Many three-axis programmers fi nd it easy to make the transi-
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tion to fi ve-axis 3+2 work because these programs are essen- tially a compilation of three-axis routines written in various work planes that are readily defi ned within the CAD/CAM environment. The 3+2 approach makes it easier to visualize the complete part for more accurate tool presentation, eliminates the creation of multiple workholding solutions and eliminates the time and stacking errors of multiple setups. Best of all, the work of mul- tiple machines can be performed many times faster and more accurately within the compact footprint of a single machine. Employing C-axis lathes to make prismatic parts is an analo- gous situation. The 3D milling capabilities of today’s CAD/CAM software for lathes is so comprehensive that C-axis lathes can be a superior choice for making a range of small parts that have only a small amount of turning content or none at all. The rotary axis is used for positioning so that multisided prismatic parts can be produced from continuously fed bar stock. This application, with a very low CNC programming learning curve, can produce spectacular productivity improvements.
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AdvancedManufacturing.org | December 2016
Then there is the case of constant chip-load machining. Con- ventional CNC machining strategies constrain productivity based on worst-case conditions. Programmers dial back feeds and speeds to keep the tool from becoming buried in the corners. This approach sacrifi ces enormous amounts of productivity compared with strategies incorporating modern roughing toolpaths adjusting tool movements based on material conditions immediately ahead of the cutting tool. These CAM programs keep the tool cutting safely and rapidly based on a few simple cutting parameters, the most important of which is the cutting tool manufacturer’s chip- load recommendation for the material in question. Keep the chip load constant and the tool will cut safely at any speed or stepover.
Unfortunately, far too many manufacturing businesses remain on the sidelines of the productivity improvement game.
It usually takes an experienced programmer about an afternoon of tutoring and experimenting to learn the basics of this strategy. Then a little more time may need to be invested making some test cuts as the constant chip load toolpaths are adapted to new appli- cations and materials. The ROI on these time investments typically occur within days and the payback continues unceasingly. Unfortunately, far too many manufacturing businesses remain on the sidelines of the productivity improvement game because their managers fi nd themselves faced with too many day-to-day challenges coupled with insuffi cient manpower resources. While this problem is widespread and one we can all relate to, the fact re- mains that some companies that are equally constrained are fi nding the time to improve their CNC manufacturing productivity anyway. Those who have adopted a “you can’t get there from here” point of view will almost certainly prove themselves to be right. On the other hand, those who want to fi nd a better way can take encouragement from those who have already set out on this path. They also will discover that there are many machine build- ers, cutting tool vendors and CAD/CAM representatives who are ready, willing and able to help. Each discipline has characteristics when combined appropriately with each other that offers the maximum effi ciency for your job. All you need to do is ask.
Brian Summers Vice President
CNC Software Inc.
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