5-axis portal milling Zimmermann offers improved designs for heavy machining

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More dynamic milling, greater precision and lower energy consumption are the key aims of Zimmermann’s improved FZU/FZP42 portal machines. Their thermo-symmetrical design is intended to support complex 5-axis machining of large, heavy workpieces without sacrificing accuracy or surface quality.

With the FZU/FZP42 machine line, Zimmermann offers users efficient 5-axis portal milling machines for heavy workpiece machining. The specific aspect of these improved machines is a thermo-symmetrical design, incorporating a centrally-guided Z-slide. This particular construction, as well as the guide layout, increases machine stability, while also saving weight — resulting in a more dynamic, productive and energy-efficient machine.

“We have developed suitable machine designs for light processing, such as composite materials or aluminum used in aerospace, as well as for highly dynamic heavy machining,” reports Cornelius Kiesel, president at Zimmermann Inc. in Detroit, the U.S. operation of F. Zimmermann in Germany. While further developing its machine portfolio in the last several months, heavy machining for automotive, other transportation and off-highway are gaining an even higher priority in the company’s market targets. At the same time, Zimmermann is on the cutting-edge in its traditional segments, explains Frieder Gaenzle, CEO of F. Zimmermann. “We are focusing less on classic heavy machining, using large tools and high material removal rates per cut. Instead, the FZU/FZP42 model range provides tool and mold makers with a 5-axis system for highly complex components, which enables more dynamic milling of free-form surfaces.”

Dynamic heavy machining is precisely the challenge in this new market segment. Because the more difficult it is to process the materials, the higher the requirements for rigidity in the machine, Kiesel further notes. Weighting in at several tons on average, the machines are quite massive. How can this massive design deliver great dynamics, so that users can work even more productively?

“Our machines mill out contours with a maximum speed of 60 m/min and may accelerate with 3 m/s2, if needed. “This resembles a motorcyclist, accelerating in a curve to run it more dynamically,” says Kiesel. Despite the acceleration, the machines must be able achieve very high accuracy as well as high-quality surfaces. “This connection of dynamics and heavy machining may be compared to a truck, loaded with stones, performing in a Formula 1 race,” Kiesel muses.

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Thermo-symmetry for more precision

In order to achieve this result, Zimmermann is setting up its complete machine portfolio thermo(load)-symmetrically. This occurs because changing ambient temperatures, as well as processing temperatures, inevitably influence machine geometry featuring a portal design. The idea behind a thermo-symmetrical design is based on the ability to substantially absorb incurring thermal influences, achieved by the design of the machine structure itself. Considering this factor, Zimmermann engineering has appropriately designed and intelligently arranged the machine structure and drive unit components and guides, as well as other components responsible for accuracy, for all machines in this newly developed portfolio. In this way, the machine structure may expand in directions that are non-critical.

The centrally guided Z-slide of the portal in double-bridge construction has a large cross-section which makes it especially stable. Using this design, Zimmermann achieves a very high degree of rigidity. Since there is no possible one-sided temperature rise, accuracy is greatly increased, as well. With this structural design, the machine manufacturer constructively reduces the effects of error-inducing variables to a minimum. Due to the fact that less leverage forces apply in comparison to a serial design with a classic guide layout, Zimmermann has increased rigidity of the FZU/FZP, without having to increase the cross- sections of the components. Because less mass needs to be moved, the machine works faster and more dynamically. “Moving less mass also requires less energy. This results in clear cost benefits”, states Kiesel. Additionally, the thermo-symmetrical design makes it possible to omit complex cooling circuits, which also has a positive impact on cost reduction.

By offering the new FZU/FZP42 machine lines, Zimmermann seeks to gain a better foothold in heavy machining. For a long time, the machine manufacturer only occasionally sold systems in this market segment. This has changed following these new developments. “We are already seeing the first successes in the market, says Kiesel. “We were able to sell three ‘heavy’ machines in the first quarter alone.” The company’s customers are equally convinced about the technical data and the price-performance ratio. “A particular customer only wanted to purchase one of our machines for post-processing, since they were already using a heavy machining system provided by a competitor. During the discussions, they then spontaneously decided on a second machine from Zimmermann,” notes Kiesel.

Among the new customers for this line is an automotive manufacturer, who required a new machine for their tool making, in order to process large sheet-metal forming tools and to replace older systems. In the end, Zimmermann was able to successfully assert itself against the competition with its FZU42 machine. The customer realized that this innovative machine concept will enable them to meet their requirements to a high machining accuracy with excellent surfaces on their tools. The high tool weights of up to 40 tons do not pose a problem for the FZU42 system, because the components are not being moved. The movement system, consisting of the portal, Z-slide and milling head, can operate with consistently high dynamics, regardless of the tool weight.

Flexible setup

“We were able to successfully impress the customer with our concept and our price-performance ratio,” says Kiesel. Another important aspect adds to this scenario. The FZU system does not require a solid machine foundation and can therefore be placed flexibly on the factory floor. Extensive construction, which creates high costs and disrupts manufacturing, are completely eliminated.

“We continue to develop and are able to find the right answers for many applications, concludes Frieder Gaenzle. “We have the right overall package. We offer these improved machine concepts in all market segments. Besides the machine structural upsides, these improvements include fitting mounts for the spindles, milling heads for the tools and an extensive service package for our customers.”

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