Ready-to-install handling system for electrical metal processing

Ready-to-install handling system for electrical metal processing
Marginal Column

July 2017


EMAG has developed a new machine type for electrochemical metal processing. The core of the system is a ready-to-install 6-axis handling system from Rexroth – short cycles, precise over a long stroke and corrosion-resistant in salt spray atmosphere.

The medium-sized EMAG Group from Salach in Württemberg is a specialist in vertical production machines and systems. One of the company’s main focus areas is electrochemical metal processing (ECM) – precision technology that is exceptionally effective in the manufacture of complex components from demanding materials.

ECM is increasingly replacing cutting methods in the automotive industry, as well as in medical, and aerospace technology. The requirements in terms of flexibility and automation of the systems are increasing accordingly. EMAG has responded with a new machine concept with a modular construction, which combines the entire process chain including pre-cleaning, electrochemical processing, post-cleaning, and testing. The systems can perform ECM processes in parallel, which cuts cycle times. They are also precise, compact, robust, and reliable.

Small space, long stroke

The new ECM system is based on the 6-axis handling system from Rexroth, which is made up of adapted standard modules from the company’s own linear motion technology range. Two 3-axis systems mounted back-to-back make up the basic construction. Type MKR-145 linear modules with belt drive operate on the longitudinal axis. All in all, the design concept has halved the installation space compared to predecessors. “We want maximum stroke by minimum foot print”, says Alexander Noller, head of mechanical design for the ECM machines at EMAG. Another key specification was the corrosion resistance of the components, as they are exposed to salt spray in the process chamber. For the profile bodies of the linear modules, Rexroth uses anodized aluminum with a chrome plated ball screw drive. The profiled rails and runner blocks are also made of corrosion resistant materials.

Easy installation, double service life

To reduce the installation work for EMAG, the handling systems – including trays for cable management, energy chains, and motors – are pre-assembled. In addition, they feature positive-locking connection technology that not only simplifies the initial installation but also any subsequent re-installation. The ball rail systems based on patented high precision technology double the life of the system.

Better than ±0.25 micrometers

“In order to achieve short cycle times, we need high dynamics and maximum precision on the long stroke of the longitudinal axis,” says Noller, describing one of the most important requirements. Rexroth met this requirement with the belt drive in the MKR linear module, which reaches up to five meters per second over longer distances. To maintain the precision of the axes when the toothed belt is extended or compressed, the integrated IMS measuring system is used. It operates with a repeatability better than ±0.25 micrometers. Even contamination and salt spray do not influence this precision. A further advantage of IMS: It makes external measuring systems unnecessary, once again saving installation and commissioning work. This is because there are no measuring systems on the two 3-axis linear modules, whose parallelism would have to be adjusted. In addition to the incremental IMS-I version, Rexroth also offers an absolute value version IMS-A. As soon as the system is switched on, it precisely detects the absolute position of the axis and reports it to the control without a homing cycle. Buffer batteries requiring regular replacement are not needed.

Fast configuration

The first machine from the new series is already in production. Workpieces are threaded onto tiny needles and guided through several ECM operations. But EMAG is thinking ahead. “We are currently working on the next machine, which features a longer working area,” Alexander Noller says. Once again, he can rely on the scalable handling system concept as no design modifications are required for this development step. Only the configuration will be changed. Noller summarizes: “Rexroth has achieved the goals regarding compactness, cost and flexibility laid out at the start of the project and we can focus completely on expanding the new machine series.”