Producing large parts with precision is not easy. But how do you produce the smallest components, such as gears and screws for the watch industry or contact pins for connectors, with micron-level accuracy and in large quantities? Swiss companies Esco and Affolter achieve this feat in their CNC machines with TwinCAT CNC and servo drive technology from Beckhoff.
In Watch Valley, a region between Basel and Geneva, an ecosystem has developed over several centuries around the watch industry and the smallest precision components for micromechanical devices. Machine builders such as Esco and Affolter are an important part of this ecosystem. Their CNC machines are used to manufacture the smallest gears, screws, shafts and other components at maximum precision, laying the foundation for the famous precision of Swiss watch movements.
Esco specialises in lathes for the production of parts with high accuracy and impeccable quality in medium and large quantities. Unlike conventional automatic lathes, Esco machines are characterised by the operating principle of stationary material and rotating tools. This allows the machines to process ring or bar material in a fully automated process, without interruptions.
Esco has been relying on PC-based control for the automation of its machines since the beginning of 2020, for which it uses TwinCAT 3 from Beckhoff. “The control and drive technology from our previous suppliers were at the end of their life cycle and we needed future-proof CNC technology that could be easily configured for our different series,” says Vincent Fankhauser, sales manager at Esco.
This is where Beckhoff Solution Provider, Affolter comes into play. The company manufactures gear hobbing machines, and as a contract manufacturer produces intricate parts for the watch industry and other sectors on around 350 machines. Managing director, Vincent Affolter says: “We were always proud of our own control solution, which we developed ourselves for our machines, and then had the electronics manufactured.” The central component of the control system was an FPGA that calculated all setpoints for all axes in parallel, within microseconds. But when the electronic components became unavailable, Affolter was no longer able to maintain its control system, let alone develop it further and integrate additional requirements such as IT connectivity. Fortunately for Affolter, the performance of PC technologies was increasing rapidly.
“When analysing possible control system suppliers, we quickly found what we were looking for at Beckhoff and started initial tests with PC-based control,” says Affolter. One of his priorities was to retain the flexibility for in-house innovations without the company having to again develop hardware itself. “This is provided by the open control platform from Beckhoff,” adds Philippe Abt from sales at Beckhoff Switzerland. PC-based control and TwinCAT CNC now form the basis for a control platform that Vincent Affolter uses in its own CNC machines and makes available to machine builders such as Esco as a Beckhoff Solution Provider.
When adapting the CNC solution to the Esco machines, the flexibility of PC-based control became apparent. Due to the required machine cycle, there was no time to waste when processing the CNC tasks. “Due to the modular system architecture of TwinCAT CNC, it was possible to achieve the short cycle times required by Esco by configuring it accordingly,” recalls Abt. In order to reduce the computing times for the tasks, any functions that were not required were removed.
The jointly adapted control concept based on TwinCAT 3 and a C6920 control cabinet Industrial PC works in all Esco machine series, and forms the basis for the long-term and safe migration of all CNC machines to PC-based control. Esco has delivered around 150 machines with TwinCAT CNC-based control technology in various configurations since 2020. As Fankhauser says: “We are now much more flexible and can put together exactly the computing power and drive configuration we need from the entire portfolio, including safety. With an Escomatic D6 Twin, for example, there are twelve servo axes to be controlled and three CNC channels to be calculated.”
The One Cable Technology (OCT) in the drive technology saves space in the control cabinet and in the machine, since only one thin motor cable needs to be routed. The issue of signal interference in the feedback systems has also been eliminated since the switch to OCT.
Affolter and Esco are currently working on integrating tool monitoring and inline quality control. The roadmap also includes the connection of their CNC machines to MES and ERP systems via universal machine technology interface (umati) and OPC UA. With PC-based control as an open and modular control system, this is set to be another success.
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| www: | www.beckhoff.com |
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