Automation for the nation

Automation for the nation

ZeroClamp GmbH in Icking on Lake Starnberg develops and builds high-grade automation systems for conventional (metal-cutting) machine tools. The Bavarian specialist firmly believes that the future of production is operator-free. Just how realistic this vision is can be seen from the wire-cutting of high-precision components made of hardenable stainless steels.

The future of production is operator-free.

“The lack of skilled staff will be the biggest challenge for the domestic manufacturing industry in the coming years,” Klaus Hofmann predicts. He is the Managing Director of ZeroClamp GmbH in Icking. He founded his company devoted to the automation of machine tools in 2006. As he reports, a number of circumstances led to this decision. Prior to this he was the design engineering manager of a branch of an internationally renowned machine tool manufacturer. When the closure of this branch was announced, he seized the opportunity with both hands. His previous employer sweetened his redundancy with a financially attractive settlement, and he used this as his seed capital. The rapid success of the newly founded company is due in large part to the varied and pioneering ideas of its founder. “Innovation is my hobby. The automation of conventional machine tools has always had a strong fascination for me,” Hofmann explains. In his opinion, smaller and medium-size manufacturing businesses in Germany will have to automate their processes much more in the near future. “Demographic change accompanied by the shortage of skilled manpower will have a major impact on German machine manufacture in the next five to ten years. Many companies will search for skilled manpower in vain, and the only alternative then will be automation,” Hofmann continues. In addition, automated production will yield definite benefits. Throughput times will be shortened, quality will improve noticeably and costs will be cut.

Overcoming manpower shortages with automation

ZeroClamp’s product spectrum is consistently based on this realisation. In Icking, the specialist designs and builds everything that is necessary for the operator-free operation of metal-cutting machine tools. This particularly includes special robots built on the Scara principle. Served by flexibly configured buffer stores, these load and unload machine tools directly with blanks and/or palletised workpieces. They can also flexibly replace tools and fixtures. The ZeroClamp approach differs markedly from other automation strategies. Hofmann stresses: “Our system does without elaborate pallets. Our robots hold the workpieces with special, usually slim grippers. The excess material of the workpieces needed anyway for clamping them in the jaws of self-centring and multiple clamping devices is absolutely sufficient for this.” Another advantage of this special robot design is the ease of programming. The operator guides the robot manually into the required positions that are taught to the CNC control at the press of a button. Throughout the work space, the robot uses exclusively Cartesian coordinates (x, y and z).

Innovation as a hobby.

For its comprehensive automation solutions, ZeroClamp also produces high-precision zero-point clamping systems and heavy-duty multiple and self-centring clamping systems. The zero-point clamping systems also come with a number of distinct advantages. These concern particularly the clamping mechanism in the chucks. For example, pneumatic pressure of just 5 bar is sufficient to ventilate the clamping system. The clamping pin centres the workpiece with repeatable 2.5 µm accuracy and is tensioned with clamping elements developed by Hofmann himself, consisting essentially of a package of cup springs and an elastically pre-loaded conical ring. The latter locks the clamping bolt precisely centred in the chuck. The pre-loading of the spring package is released with the aid of a pressure ring that works pneumatically. A key advantage of this principle is the heavy-duty, simple design with just a small number of moving parts. This zero-point clamping system can consequently operate totally wear-free for a very long time. Single or multiple compact dirt- and swarf-tight chucks can be installed in face plates, clamping plates and work tables on turning and milling centres.

EDM the method of choice for series of high-precision components

Of course, the spring packages and segments of the conical rings for the zero-point clamping system have to be machined with accuracy to within a few µm. The same also applies to clamps that guide and hold the clamping units on the base rails for multiple and self-centring clamping devices. These components are mainly made of hardenable and stainless steel. Cup springs, for example, are machined from circular blanks just a few tenths of a millimetre thick, into which radial grooves are worked. Conical rings are composed of segments cut out of pre-turned rings. Grooves for the elastic pre-loading elements have to be additionally worked into the segments.
An additional special challenge is that ZeroClamp requires all these components in large series. “In Icking we produce several thousand zero-point clamping systems and multiple and self-centring clamping devices per year. Producing sufficient quantities of components for this confronted us on our own site with the demand for cost-effective production with little operator involvement,” Hofmann reports. While making use of its home-grown automation strategies, the ZeroClamp automation specialists also appreciate the advantages of a special machining process like wire EDM. “We wire-cut a large number of components in packages. High productivity and cost-effectiveness are two of the immediate special benefits of this technology. In addition, wire EDM is performed reliably and without supervision. This frees up production capacity and productivity without cost-intensive and increasingly scarce skilled staff,” Hofmann explains. In this respect, the wire-cutting process satisfies his expectations of cost-effective production with minimal human supervision.

Futuristic technology from Mitsubishi Electric

There are good reasons why Hofmann prefers to wire-cut on machines from Mitsubishi Electric. Much like the automation systems of his own company, he sees the machines of the Japanese corporation as the embodiment of trail-blazing technologies. Hofmann praises the direct drive using Tubular Shaft Motors for its dependability and robustness and, when combined with optical measuring systems, high precision. Because of this high precision, he intends soon to start wire-cutting guide elements for clamping bars to their final size instead of grinding them as at present. This will significantly reduce throughput time. The wire EDM machines also work unmanned during night shifts.

Because of their high dependability and availability, the wire-cutting machines from Mitsubishi Electric have paid for themselves at ­ZeroClamp within a very short time. “We tool what are now four wire-cut EDMs from Mitsubishi Electric during supervised shifts. We then let them run totally unsupervised in the second and even third shifts. So far we haven’t had any breakdowns or waste. The Mitsubishi Electric technology is innovative while also being truly mature and absolutely workshop-compatible,” says Hofmann stressing the advantages. Its high dependability is also attributable to the innovative wire threader. In the event of a breakage, the machine reliably finds the kerf and threads the wire with precision.

The manufacturer of automation systems in Icking has been working with a BA8 for over four years and for about a year with an MV1200S in addition. Six months ago, ZeroClamp invested in two more MV2400Ss and, in doing so, replaced machines from another manufacturer. The wire-cutting machines are programmed at an external NX CAD-CAM system from Siemens. So that the MV1200S and the two MV2400S machines can run unsupervised for much of the time, they have large wire stations with 20 kg wire spools. The MV2400S is due to be retrofitted soon with a fourth NC axis in order to extend the machining range. There are also plans to automate one of the MV2400Ss with a robot and buffer store from ZeroClamp.

Zero breakdowns, or waste.

Reliable processes on dependable machines

ZeroClamp mainly wire-cuts components in series. To generate the CNC programs, the programmers and machine operators in Icking draw on their own expertise as well as resorting repeatedly to the data sets integrated in the Advance Plus CNC controls from Mitsubishi Electric. After this, the machining processes are streamlined. They then run so reliably that the wire EDM machines can operate unmanned. Hofmann has so far done without additional software, such as mcAnywhere Contact. He sums up his experience as follows: “The wire-cutting machines from Mitsubishi Electric are an assurance of total dependability and process security. We don’t therefore have any problem with foregoing these extras for monitoring.” Should any questions nevertheless arise concerning the working, control or maintenance of the machines, the Mitsubishi Electric after-sales service is always available. Here, too, Hofmann has nothing but praise: “Via the hotline, you always get expert advice from competent employees within only thirty minutes.”

 

Interview