Energy chains in machines for micro-assembly of electrical components

energy chain and chainflex®-cable with up to 20 million movement cycles per day

Several million work cycles per year with maximum precision in the micrometre range and five years of maintenance-free operation: Häcker Automation GmbH develops and manufactures machines for micro-assembly that meet the highest requirements. The Schwarzhausen-based company also leaves nothing to chance when it comes to partner companies and components. Today, cables and energy chains from igus® are used for the energy and data supply.

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Problem

The core expertise of Häcker Automation GmbH, founded eleven years ago by Gerrit Häcker, lies in manufacturing for highly integrated production in the micrometre range. For the European passport, for example, Häcker's 18-axis machine glues a wafer-thin transponder wire, which ensures machine readability, onto a substrate. But there are also sensors in cars, e.g. for electronic braking and stabilisation systems (ABS, ESP etc.), which are produced on Häcker machines.
These machines produce around 15 million sensors per year - with an error rate of well below 1 ppm (parts per million). At the same time, customers expect extremely high availability of the machines, which run in three-shift operation throughout the year. Selected partners and high-quality individual components must therefore be found for the machines.
This also applies to the energy and data cables that lead to the gripper, assembly or dosing units via the x-, y- and z-axis. One of Häcker's development goals is to be able to operate the machines maintenance-free for five years. In single-shift operation, the machines complete 5 to 7 million cycles per year; in 24-hour operation, it can be up to 20 million. This means that all moving components, including the cables, must be designed for 100 million movement cycles without maintenance or replacement in extreme cases.
In addition, the energy supply systems must run smoothly and vibration-free at both high and low speeds. Compactness also plays an important role in the machines: As the assembly operations usually take place in a working area of 500 x 500 mm, it is a maxim of the Häcker designers not to "give away" any installation space for the energy chain.

Solution

Häcker found this demanding requirement profile in the igus® cable programme after previously using other cables that tended to fail and did not meet the high demands. There is a reason why this did not happen with the igus® cables. The signal and energy cables in the chainflex® series were specially developed for use in energy chains and are characterised by an extremely long service life under continuous load due to movements with the energy supply system. New conductor materials as well as special sheath materials are used in them - with the result that the cables achieve a multiple downtime when used in energy chains compared to conventional cables. The dreaded "corkscrew" with subsequent core rupture is avoided by the basic design of the chainflex® cable.
Häcker uses chainflex® -cable series CF 2, CF 10, CF 11, CF 27 and CFPE, among others, as protective conductors - and sees its choice confirmed, as no failures have actually occurred to date despite the high requirements and millions of movements.
However, Häcker Automation also places high demands on the abrasion behaviour of the chain, as the machines mostly operate in cleanrooms. Under these conditions, the E6-series energy chain from igus®, which Häcker uses for the linear guide of the x-, y- and z-axis, has proven itself. These chains are characterised by very smooth, low vibration running - an essential requirement in micro-assembly. And they are extremely durable.

System E6

chainflex® cables

"The cables must be optimally guided in the chain - especially when the chain is tightly packed. The bend radius must be taken into account as well as the internal separation and effective strain relief. The cables must not show any movement in the chain, but they must not be fixed either: A lot of detailed engineering is required here, in which igus® provided us with excellent support."

Jens Beyer, technician at Häcker Automation GmbH

Designing the cable carrier

system: detailed work is required It is not just the chain itself that guarantees a long service life

for the cable carrier system. Detailed work is also always required here, which igus® and Häcker did together. Jens Beyer: "The cables must be optimally guided in the chain - especially when the chain is tightly packed. The bend radius must be taken into account as well as the interior separation and effective strain relief. The cables must not show any movement in the chain, but they must not be fixed either: A lot of detailed engineering is required here, in which igus® provided us with excellent support." With success: Even energy chain systems with the smallest unwinding ranges of just 50 mm, which are used in the movement system for the dosing stroke, for example, achieve the extremely long service life required by Häcker. This is also remarkable because the cables and energy supply systems are subjected to high stresses due to the high speeds. But the design work that igus® has carried out for Häcker guarantees high availability over long periods of time. Convincing solutions were also developed for special requirements - for example, igus® was able to offer an energy chain-compatible PE cable with a 1.5 mm2 cross section for the energy chain system at Häcker following tests in the laboratory. The detailed

work includes the chain fastening, which is structurally integrated into the energy chain system, and the selection of the cable. The high demands on service life make it necessary that only tested components are installed. This applies to the energy chain as well as to the cables, which are supplied ready-made as readycable® from igus® : Then the assembly personnel in Schwarzhausen do not have to do the assembly work and can connect the complete cable set including plug connections directly. This saves time, and that is what counts at Häcker: only a throughput of ten days is estimated for the construction of a machine.

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