Programming Multi-Axis Lathes
This is one of those you-can't-solve-today's-problems-with-yesterday's-solutions kinds of stories. Or, to be more specific, you can't program today's multi-axis lathes with live tooling using software developed for more conventional CNC lathes and machining centers. Shops are finding that to take full advantage of today's sophisticated CNC turn/mill machines and Swiss-type lathes, they need an equally sophisticated CAM software package.
A case in point is AccuRounds (Avon, Massachusetts). The firm began about 20 years ago as a Swiss screw machine shop doing relatively simple, high-volume jobs. As more traditional markets gave way to newer ones, the firm shifted to complex, difficult-to-machine shafts, primarily for the computer and printing industries. Today, it combines precision machining and finish grinding of round mechanical components, ranging from miniature heat-treated pins for the bearing industry to large drive shafts for paper-feeding machines. It also provides sub-assembly operations for customers.
AccuRounds began replacing its cam-operated Swiss screw machines with CNC counterparts in the mid-'80s. At about the same time, the company rearranged the machines in the shop, going from the traditional departmental layout (production machines here, secondary machines there, and so on), to a number of family-of-parts machining cells. The firm presently has eight such cells, dedicated to long shafts (greater than 12 inches), small components, large components, prototypes and so forth.
The cells are built around one or more CNC machines (usually a CNC lathe or CNC screw machine). They also have manually operated secondary machines. The part machining operations are distributed among the secondary machines to reduce part cycle time. (AccuRounds is a firm believer that the best way to reduce cycle time is by balancing secondary operations within the machining cell.) Many of the secondary machines are portable and are moved in and out of the cells as job requirements dictate.
AccuRounds prospered with the cellular machining concept, but the market started to change again. Customers were asking the shop to quote increasingly sophisticated parts with tighter tolerances, tighter concentricities, more demanding surface finishes—and more hole making operations as well.
"Part shapes were becoming so complex that, in many cases, there was no way to rechuck turned parts in a second machine to do those hole making operations," explains Robert Martell, AccuRounds engineering manager. "It became even more of a problem when we were required to locate drilled or milled features relative to turned features, because it was difficult to set up the part at a particular angular orientation."