Dials Are No Longer A Traditional Concept
The addition of automatic tool changers (ATCs) brought more flexibility to the dial-transfer machine.
You really cannot beat a fast-acting and precisely locating rotary transfer table machine for progressing a large quantity of complex components in the shortest cycle time. "Fine, so let the high volume guys buy them!" I hear you say. "They are inflexible, and when the jobs are life-expired, you junk the machine."
Well, that attitude is what 1984 novelist George Orwell would have called ‘Oldthink'. OK, so what is the ‘Newthink' behind dial transfer machines? That is easy: You do not junk them at the end of a production run, nor do you have to hitch a two-axis CNC lathe to one when some OD turning is needed. For that matter, you can add grinding, welding and riveting if the job suits.
The catalyst for change in dial-transfer systems was CNC. Two-axis and three-axis machining heads were developed by two German companies, Alfing Kessler Sondermaschinen (AKS) of Aalen-Wasseralfingen and Witzig und Frank (now in the Thyssen Group) of Offenburg, back in the early 1980s. The companies developed modular fixturing systems that effected a quick changeover, initially among ‘like' families of components. The addition of automatic tool changers (ATCs) brought more flexibility to the dial-transfer machine.
Other companies who took advantage of the flexible dial machine idea included the Italian builders Giuliani Division of IGMI and IMAS Transfer Division of Dell Orto, as well as Eubama.
The idea of having a machining center with two horizontal, independently acting spindles occurred to Honsberg Lamb in the early 1990s.
While two spindles worked simultaneously, one could be undergoing ATC. AKS and Heckert thought this idea was good too, as did German dial-transfer machine builder Ketterer Maschinenbau.
According to the company, Ketterer devised the Duo-Flex, a twin-spindle head that enabled more flexibility and higher productivity when putting small and medium volumes through its dial machines. The twin spindles were independently driven and controlled. Axis traverse rate was 60 m/min.
There were still some problems, such as how to turn, circumferentially groove or grind an OD. There were a variety of answers.
One or two dial transfer builders designed turning and cylindrical grinding units that work well, but still entail letting go the component from a fixture, transferring it to the unit and back again. Those accumulated re-clamping errors could be important.
Instead, Giuliani and Eubama decided to wrap the dial around a horizontal axis and feed it with bar. In one sense, you could say the multi-spindle automatic had been re-invented—but not quite. The parted-off billet is chucked in a central carrier, with five or more stations.
Giuliani's Proflex is described as a sliding headstock system accepting bar up to 36 mm (over 1 3/8 inch) diameter. It can deploy up to 26 high frequency (HF) machine spindles and a four-tool carriage to machine one job, or 24 HF spindles and a six-tool carriage to do two jobs simultaneously.
Proflex can also be conceived to machine from fixed bar or coil stock. Similarly, the Eubama S series accepts bar up to 25 mm (say 1 inch) diameter. These two companies also make the more traditional dial transfer machines, of totally modular build, with pick-and-place billet/casting loading or with bar feeders. The Eubama KE Series of dial transfer machines is regarded as a standard series—just like buying a CNC lathe—and does jobs that require turning, threading, boring, cross-drilling and PCD drilling.
Of its Proflex, Giuliani says that the user can begin with a basic machine and add spindle units and modules as new jobs come in. The machines have the production advantages of more traditional dial transfer machine concepts. They minimize downtime and ensure accuracy, because in-cycle the component is rarely let go between operations.