Viewpoints: The Growing Importance of Multitasking
By Ki Hyo Park
Hyundai WIA Machine America Corp.
Web site: www.hyundai-wiamachine.com/
The earliest multitasking mill/turn, turn/mill machine tools began showing up on the floors of job shops and industrial-scale production facilities in the early to mid 1980s. These were the result of the demand to do more with less—more operations, less setup and operator involvement.
An important driver in today’s multitasking environment are smaller lot sizes. The days of doing million-part production runs are few and far between. The challenge today is for shops of all sizes to machine as many part features as possible in a single setup on a single machine. Central to accomplishing this is a universal control to address the exploding range of machining technologies used in metalworking operations (turning, milling, drilling, grinding, hobbing, nibbling, punching, marking and more).
Benefits of doing more with less include compressing lead times, from days to hours, and reducing lot sizes with no cost penalty. Lots as small as one piece can be done efficiently and cost-effectively. Multitasking improves cash flow through higher throughput and shipment frequencies. It also slashes non-value added time, with fewer fixtures, tools and far less labor. Furthermore, it improves part accuracy by reducing tolerance stack ups between multiple fixturings.
What's more, multitasking reduces shop burden—fewer machine tools, reduced floor space and more cost-effective use of utilities. You can also run untended—one operator can run several machines, or you can run an entire third shift untended—which increases cutting time without the attendant labor costs. Bottom line: Doing more with less results in increased profitability.
Further, multitasking is an evolutionary process: When you think you have figured out how to do everything possible on a multitasking machine tool, someone comes up with another set of ideas for more applications.
Among those ideas is broaching features such as keyways, ID splines and fir-tree root forms on disks for aerospace engines and steam turbines. The broach for ID work is an axially oriented tool. The B-axis of the multitasking machine is oriented as if one were going to drill the ID. The brooch is inserted into the hole then pulled out to create the desired form.
A second example involves hobbing of propeller shafts for marine outboard motors. The propeller shaft is turned and hobbed out of 630 stainless for corrosion resistance. The way these shafts were made involved a multiple-step process: Turning on a lathe, dropping the shaft out, taking it to a vintage dedicated Barber Coleman hobbing machine (with very time-consuming, labor intensive setups), cutting the spline, then removing the part to a grinding operation. It used to take 3 min just in turning alone. Now turning and hobbing in one machine takes just 3 min, 40 sec. This example of multitasking technology with a hob assembly is doing away with some dedicated hobbing, while maintaining similar throughput and excellent quality with one machine performing the operations of two machines.
Yet another new application produces spur and helical gears. The process uses a disk-shaped milling tool that rolls radially following an involute path with simultaneous motion of the X–B or Y–B axes. Variations in the gear shapes are generated by the tool path, not by the tool geometry, so a simple tool can produce a range of different gear configurations.
Hyundai WIA not only develops and builds multitasking machines for the market as a whole, we also employ the latest technology in our own plants to manufacture engine, transmission and suspension components for our parent company, Hyundai Motors.
It’s not always about reducing labor costs or burden rates. Again, as a global manufacturer in both mature and developing markets, we’ve learned first-hand that in many cases multitasking machines are required to provide the consistency we need in machining components for the many finished goods we produce.
In the future there will undoubtedly be many more multitasking functions. However, a word of caution: Adding all of these capabilities in a single machine is one thing; knowing how to use them correctly is another. This requires the end-user to work very closely with the machine tool vendor. It’s often very difficult to come to terms with the reality of doing so much in a single machine. This is especially true if one is used to operating single-task machine tools. ME
This article was first published in the May 2012 edition of Manufacturing Engineering magazine. Click here for PDF.