5-axis machining A wide range of workpieces with 5 axis

From Andrea Jäger

The manufacturer and developer of modular clamping, positioning and measuring equipment Witte Barskamp uses Mazak machines for most of its production. A new addition is robotised with an automated system.

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Alufix Meisterbock with cubing elements.
Alufix Meisterbock with cubing elements.
(Source: Mazak)

Horst Witte began his professional career as a plant manager at a contract manufacturer that mainly produced parts for the aerospace industry. When he went into business for himself, he took with him the good contacts he had in the industry as well as his unique ability to find new solutions and machining options and turn them into future-proof products.

An old forge in Bleckede, two machines and a local agricultural machinery mechanic, whom Witte quickly retrained as a universal milling cutter, formed the initial foundation. At first, smaller parts for aircraft and satellites, small series, individual parts and prototypes were produced. Enquiries from the automotive industry for complete devices and the entry into the project business followed. The forge soon became too small. The move to modern, large halls at the current company location in Barskamp finally marked the broader positioning of the company and the expansion of the business fields.

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As early as 1973, Horst Witte had developed his first own product, the RKD radius and ball joint, and had it protected as a utility model. In the same year, he presented his first vacuum clamping system for workpieces for the semiconductor, paper and printing industries and for mechanical engineering at the EMO in Hanover. The Alufix modular clamping system, developed in 1987 and patented in 1988, is now indispensable in metrology and in all industries where dimensional quality monitoring plays a decisive role, such as the automotive industry, aerospace, medical technology or prototype and model construction.

Difficult aluminium components are a speciality

The parts machined at Witte are mostly made of aluminium, a material that requires a high degree of expertise due to the inherent internal stresses. Aluminium is easy to machine in itself, but for clamping the often unstable workpieces such as thin-walled sheet metal, special clamping devices such as vacuum plates are often necessary to prevent the workpieces from warping. The contract manufacturing division is still a cornerstone of the Witte company today. Its speciality is the precision machining of large-area and difficult aluminium components for the aerospace industry, including extremely thin sheets of high-strength aluminium alloy.

At the company's location in Barskamp, the production department has access to state-of-the-art machinery, including more than 40 CNC machining centres and CNC lathes, vacuum clamping technology developed in-house for large components, and air-conditioned measuring rooms with a temperature stability of ± 0.5 degrees celsius. Over the years, 23 of these machines have come from the manufacturer Mazak, 15 of which are still in operation every day in two shifts.

The first fully automated Mazak machine, the Variaxis i-600 5-axis machining centre with robot automation, moved in during January 2021. This was preceded by the strategic orientation towards 5-axis machining. 5-axis machining enables a significantly wider range of workpieces. Even highly complex components can be machined on five sides in just one set-up, as the cutting tool can approach the workpiece from any direction. For machining the sixth axis, a robot takes the workpiece out of the machine, turns it around and puts it back in. The result is a finished workpiece with higher accuracy.

Complete machining of complex workpieces

The machines of the Variaxis series are ideal for the complete machining of complex workpieces due to the combination of high spindle power and enormous torsional rigidity. The cast construction, designed for maximum torsional rigidity, guarantees outstanding machining results without sacrificing performance or accuracy. This is due, among other things, to the robust spindle, which is optionally available with a maximum speed of 12,000, 18,000 and 30,000 min-1, the linear roller guides on all linear axes and the trunnion-mounted table with one roller gear each for the A and C axes.

The Variaxis is equipped with Mazatrol Smooth control technology in the Smooth X variant for 5-axis machining. With this control, manufacturing and automation systems can be managed centrally. The basic philosophy is the same in all Mazatrol control generations. For daily operations, this simply means that all employees can operate all Mazak machines equally. At Witte, programming is done either directly on the machine or with the Smooth CAM RS. Solid CAM, among others, is used as an external programming system.

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The Smooth X is not only intuitive to operate and fast, it also contains many useful programming functions, such as Intelligent Pocket Milling. This function can save 60 percent machining time compared to conventional pocket milling with tool path compensation. New functions such as Seamless Corner Control, Variable Acceleration Control and Smooth Machining Control are also extremely useful when programming in the finest increments, such as machining with 5-axis simultaneous control and free-form machining in mould making.

Save on personnel and avoid long delivery times

From the beginning, there was no doubt that the Variaxis i-600 should be automated. Automated machining not only saves on personnel, which is already in short supply, but is also more economical overall and helps to avoid long delivery times. “We knew that our range of parts was suitable for automated production,” explains Jens Düffert. “Only the type of automation still needed to be clarified.” The alternatives up for discussion were automation by pallet changers or a robot system. The decision in favour of the robot was made, among other things, for reasons of space. With a pallet changer, the changeover to the 6th side described above would also have been more complicated. And the experience in practice? “The processing costs have been halved in some cases,” Andreas Witte reports. “In addition, there is an enormous amount of time saved due to the lack of reclamping.” He further adds: “The automatic operation makes us more flexible because low-man late, night and weekend shifts are possible.”

At Witte, the automated Variaxis i-600 is not the only smart solution from Mazak. The FF 5000/40 horizontal machining centre was designed for optimised high-volume production in the automotive industry and offers here a special solution generated from the Mazak standard programme for head machining of cuboid bars with lengths of up to 5000 millimetres. The prerequisite and special feature of the machine is the fixed table, the travel of the Z-axis originates from the spindle. The clamping technology for the machine was designed by Witte production manager Thomas Freer. As with all machine investments made by Witte, the supporting advice came from the team at Mager & Wedemayer Werkzeugmaschinen GmbH.

For the future, Witte is planning an increased range of products in the field of measurement and quality assurance. The latest new developments are remote-controlled or autonomously manoeuvring floor conveyor vehicles which, as feeding and positioning solutions for integrated or downstream metrological quality checks, also ensure high precision and economic efficiency in automated processes.

With these driverless transport systems based on Witte's aluminium structural panels in sandwich design, systems in the automation chain can be connected, organisational gaps closed and processes accelerated.

Witte attaches great importance to future-oriented sustainability. This includes, for example, the unlimited reusability (retooling) of the Alufix modular system and, internally, the consistent recycling of metal waste in addition to the use of energy-efficient equipment and machines. Aluminium can be completely recycled without any loss of quality. In the process, only 5 percent of the energy required for new production is consumed. Witte Barskamp GmbH & Co. KG was awarded the title of “Ökoprofit-Betrieb” (“eco-profit company”) by the state of Lower Saxony in 2010.

* Andrea Jäger is a freelance writer. Further information: Yamazaki Mazak Deutschland GmbH, Sabrina Röckle, Head of Communications, Tel. +49 7161 675-235, sroeckle@mazak.de

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