Julius Blum GmbH, an Austrian manufacturer of top-quality slides, hinges and other products for kitchen units, uses 3-axis and 5-axis machining centres from Roeders to help maintain the company’s international reputation as an innovator and technology leader. UK and Ireland agent for the German machine builder, Hurco Europe, explains the benefits.
Three of the high-speed machining centres, which incorporate jig grinding capability, are in an automated cell devoted to manufacturing injection mould tools for producing plastic parts used in Blum’s products. A Fanuc robot on a linear track interconnects the machines with a washing station, a coordinate-measuring machine and several storage systems for tools and workpiece pallets.
Gerhard Gorbach, operation resources manager of number 3 plant at Blum headquarters in Hoechst said, “Our products are designed to offer customers perfect motion quality and to maintain this characteristic throughout the full life cycle of the furniture they have been built into.
“To maintain quality, we manufacture almost all of our component parts in-house, right down to the plastic bearings in the drawer slides. Every aspect of our products, however marginal some might seem, influences the customer’s overall impression.”
Ralf Hildebrand, manager of the grinding department added, “Product quality is only one factor for achieving success.
“The other is cost efficiency. The only way we can achieve that is to extend the quality ethos to the machines we use as well as to our practices on the shop floor, in the metrology department and all the way along to the packing section.”
Helmut Böhler, manager of the toolroom explained, “Our department works on the same principles as the main factory, but flexibility needs to be even higher.
“Batch size is low and frequently one-off. To maximise utilisation of our machines, we look to automation and also to reducing in the number of component set-ups.
“We try to integrate cycles that were previously performed sequentially on one or more machines into a single operation, such as the high-speed milling and jig grinding of prismatically shaped components.
“The approach is not only more efficient and less costly but also increases accuracy due to fewer reclampings.”
Since 2003, Blum has relied on high-speed milling centres from Roeders. In the early days, they were used for producing highly accurate EDM electrodes in copper or graphite. With the more recent machining centres, the focus shifted to hard milling and jig grinding on a single platform.
Workpiece datuming is carried out automatically within the machine by a measuring probe. The part does not have to be fixtured accurately, saving time, as its position and orientation are allowed for in the control, which automatically recalculates the NC program. Periodic in-process measurement of key parameters allows tool offsets to be sent to the machine control to ensure machined parts stay within tolerance.
As they are automated, the Roeders machines can be used with minimal operator involvement, especially as grinding tools can be exchanged in a similar way to the milling cutters and drills.
In the Blum toolroom, the mix of jobs involves not only complex geometries that need to be programmed off-line but also simpler parts that can easily be programmed directly at the machine. The suitability of the Roeders RMS6 CNC system to accommodate both approaches was an important criterion.
Moreover, as it was developed in-house, the control software is able to be easily and promptly upgraded. Blum has already benefitted by taking advantage of recently improved cycles for helical and rapid traverse jig grinding. All Roeders machines at Hoechst are updated inexpensively to the latest software release, ensuring that the same post processor may be used and that jobs cay be swapped seamlessly.
The high speed machining centres are built for top performance in terms of metal removal rate as well as accuracy. Drawing tolerances for injection mould tools are especially tight, typically ± 5 µm for dimensions and ± 3 µm on bore diameters.
The machines feature linear motors in all axes, linear scales for absolute positional feedback to within 50 nm, patented weight compensation in the Z-axis and fast movement in all axes without stick-slip on reversal, ensuring accurate interpolation. Temperature control of the liquid recirculating through the machine elements is to within ± 0.1 K, ensuring excellent thermal stability.