Compact energy chains in Alzmetall machining centres

• What was needed: ready-made readychain® systems from igus® consisting of energy chain E4/4 Light and associated chainflex® cable, iglidur®bearings
• Requirements: High travel speeds and accelerations, compact installation situation requires tight bend radius, continuous load
• Industry: Machine tool construction
• Success for the customer: The energy chain E4/4 light offers particularly compact external dimensions and at the same time is built particularly robust, the readychain® system saves assembly time and costs and makes installation considerably easier for the customer

Alzmetall GmbH in Altenmarkt, which is known as the market leader in the metalworking industry, has built up a range of machining centres in the upper quality and performance segment since the 1980s. 
In 2001, the GS 800 was added to the machining centre product family, which was expanded in 2005 with the GS 1000 and finally extended downwards in September 2006 with the GS series. Hans Jürgen Gizler: Head of Sales for CNC machining centres: "We offer the new GS 650 for users who demand precision and performance that cannot be met by conventional frame designs". The machine is designed as a genuine gantry system and is offered exclusively with highly dynamic and maintenance-free torque drives.
High accuracies (Tp=0.007) and high machining speeds are ideal for use in single part production and series production, in tool and mould making and in general mechanical engineering.
Integration into automated production systems is possible with a gantry robot solution - the machine can be fully craned from above - as well as with a pallet changer or an articulated robot for loading from the front - e.g. with a pallet changer. For example, with a zero-point clamping system.
For other components, the company relies on outsourcing, i.e. co-operation with high-performance suppliers - for example, for the energy supply systems that supply the spindle with energy, data and coolant.
The high requirements are a direct result of the high performance that the machine delivers. In rapid traverse, the spindle travels at up to 60 m/sec and achieves a maximum acceleration of 10 m/sec2. In free space, acceleration values of up to 17 m/sec2 are even required. However, a high number of movement cycles under continuous load also place high demands on the quality of the cable and cable routing.

For the GS 800, Alzmetall used pre-assembled readychain® cable assemblies from igus® for the first time. As the co-operation has proved successful, the GS 650 will also be equipped with readychain® systems.
This choice not only reduces assembly time, but also contributes to the longevity of the energy supply system. This is because the chainflex® cables have been specially developed for use in energy chains: they allow a small bend radius - which also permits compact installation situations - and are characterised by a long service life even under continuous movement stress. This is an important criterion for Alzmetall, as the machines have a very solid design. The spindle, which operates at up to 30,000 rpm, requires a total of 50 to 60 power and signal cables - including electric cables for servo drives, hydraulic hoses for the tool clamp, encoder and measuring system cables as well as supply lines for cooling lubricant and a compressed air supply for blowing out the spindle. The readychain® systems save valuable assembly time.
The energy chain system of the GS 650 ensures manoeuvrability in three axes. The x-axis moves separately, while the y- and z-axes are superimposed. Assembly is extremely simple, as all three chains end in a junction box, which igus® also supplies. The x-axis has a horizontal design and uses the upper machine cover as a support, on which it is supported by a bridge: a design detail that saves space and ensures optimum guidance of the chain. 
When developing the energy supply system for the GS 650, the project engineers benefited from the fact that a new energy chain series had just been launched on the market at that time: The E 4/4 Light is characterised by very compact external dimensions; the chain is 20 mm narrower with the same capacity. It was precisely these 20 mm that ensured that the chain remained within the contours of the machine during all movements. And despite the compact type and the narrow bend radius, the chains and with them the cable move at high speed.