Energy chains in machines for micro-assembly of electrical components

Energy chains and chainflex cables with up to 20 million movement cycles per day

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

Profile

  • What was needed: Energy chains of the E6 series and E2 series, chainflex cables of the series, among others, CF 2, CF10, CF 11, CF 27 and CFPE as protective conductor
  • Requirements: At least 5 years of maintenance-free operation of the machines and components, up to 20 million movement cycles per day, low-friction and low-vibration operation of the energy supply system at both high and low speeds, compactness of the solution
  • Industry: Machine tool manufacturing
  • Success for the customer: Detailed engineering for the customer with regard to planning the bend radii, internal separation of the cables, strain relief, etc., maintenance-free energy supply system, extremely long service life despite continuous load, selected materials of the cables guarantee extremely long service life, particularly quiet and low-vibration (E6) chains.
Other products for machine tools
Häcker machines High performance in a small installation space: Häcker develops and manufactures machines for micro-assembly, e.g. of sensors and electronic components.

Problem

The core competence of Häcker Automation GmbH, a company founded eleven years ago by Gerrit Häcker, is manufacturing for highly integrated production in the micrometre range. For the European passport, for example, Häcker's 18-axis machine glues an ultra-thin transponder wire, which ensures machine readability, onto a substrate. But even in cars there are sensors, e.g. for electronic braking and stabilisation systems (ABS, ESP etc.), which were 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. Thus, selected partners and high-quality individual components must be found for the machines.
This also applies to the energy and data cables that lead to the gripping, assembly or dosing units via the x, y and z axes. One of the development goals of Häcker is to be able to operate the machines maintenance-free for five years. The machines complete 5 to 7 million cycles per year in one-shift operation, and up to 20 million in 24-hour operation. That means that all moving components, including the cables, must in extreme cases be developed for 100 million movement cycles without maintenance or even replacement.
In addition, the energy supply systems must operate with little friction and free of vibrations at both high and low speeds. But compactness also plays an important role in the machines: As the installation mostly takes place on a work area of 500 x 500 mm, it is one of the maxims of the Häcker designers not to gift any installation space for the energy chain.

Solution

Häcker found this demanding requirement profile in the cable range from igus after other previously used cables did not meet the high requirements and tended to fail. There is a reason why this did not happen with the igus cables. Because the signal and energy cables of the chainflex series were specially developed for use in energy chains and are characterised by an extremely long service life when subjected to constant stress from the movements of the energy supply. New conductor materials and special jacket materials are used with them - with the result that the cables have a long service life when used in energy chains compared to conventional cables. The dreaded "corkscrew" with subsequent core breakage are avoided by the basic structure of the chainflex cables. 
Häcker uses, among other things, chainflex cables of the series CF 2, CF 10, CF 11, CF 27 and CFPE as protective conductors - and its selection has been confirmed a success, because up to now, despite the high requirements and the millions of movements, there are actually no failures.
However, Häcker Automation also places high demands on the abrasion behaviour of the chain, as the machines mostly work in cleanrooms. Under these conditions, the energy chains of the E6 series from igus, which Häcker uses for the linear guides of the x, y and z axes, have proven themselves today. These chains are characterised by a very quiet, low-vibration operation - an essential requirement in micro-assembly. And they are extremely durable.
"The cables must be optimally guided in the chain - especially when the chain is tightly packed. The bend radii 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 fastened either: A lot of detailed engineering is required here, in which igus supported us very well."
 
Jens Beyer, Technician at Häcker Automation GmbH
energy chain View of the work table of a machine being assembled - the energy chains for the x, y and z axes are clearly visible.
Energy chains Energy chains are also partially integrated in the individual drive and function modules.

Design of the energy supply system: detailed work is required

It is not only the chain itself that guarantees a long service life of the energy supply system. This always requires detailed work, 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 radii 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 fastened either: A lot of detailed engineering is required here, in which igus supported us very well." With success: Even energy chain systems with the smallest unrolling ranges of only 50 mm, which are used, for example, in the movement system for the dosing stroke, achieve the extremely long service life required by Häcker.
 
This is also remarkable because the cables and the energy supply systems are heavily stressed due to the high speeds. But the design work that igus has done for Häcker ensures the high availability over long periods. Convincing problem solutions were also developed for special requirements - for example, after tests in the laboratory, igus was able to offer an energy chain-compatible PE cable with a 1.5 mm2 cross section for the energy chain systems at Häcker.   
 
The detailed work includes the chain fastenings, which were constructively integrated into the energy supply system, and the selection of the cables. 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 purchased harnessed as readycable from igus: Then the assembly personnel in Schwarzhausen do not have to carry out the harnessing work and can connect the complete cable set, including plug connections, straight away. This saves time, and that is what counts at Häcker: a throughput of only ten days is estimated for the construction of a machine.
energy chain Orderly movement: The arrangement of the cables in the energy chain requires a lot of detailed work.
energy chain The fastening of the chain and cables must also be optimally solved in terms of design in order to meet the high demands on availability and durability.