Guiding fiber-optic cables reliably

"A fiber-optic cable for our hardening systems can cost up to EUR 20,000", declares PhD.-Eng. Eckehard Hensel, Managing Director of ALOtec GmbH, located in Kesselsdorf near Dresden. "To prevent it from breaking, which interrupts processes that can result in quality defects on the component to be hardened, the cable must be reliably and effectively protected." This is accomplished with energy supply systems made by igus® GmbH, Cologne. The triflex® R product range, which provides movement in all directions, is used in this case. triflex® R is now available in its third generation. The chain was specifically developed for demanding 6 axes robot applications. It is able to address any requirements profile in rough industrial environments, ranging from large welding robots to small palletizing robots.

Advantages of laser beam hardening

ALOtec GmbH was founded in 1998 as an offshoot from the Dresden-based Fraunhofer Institute for Materials and Radiation Technology (IWS). Since then, the focus has been on the production of laser hardening systems to customer specifications. They are proving themselves in the machinery building, tooling and mold-making industries. Reference systems are located in Germany and Europe, as well as the US and India. "We also offer laser hardening as a service on our own laser hardening systems", the Managing Director explains. The company has established itself in the market with a total of twelve employees.

Laser hardening, or laser beam hardening has been in use by industry for approximately ten years. Among others, this boundary layer process also uses directly radiating and fiber-coupled high-performance diode lasers (HPDL). These operate in a relative short-wave spectrum. This results in notably more efficient energy absorption in the material when compared to other laser beam sources.

The laser hardening process involves a highly targeted, or partial, application of thermal energy into the component. The amount of thermal energy is significantly lower than with other processes. The benefit is that the component exhibits non-significant warping. This consequently limits, or even eliminates post-machining on the hardened component. In addition to high energy-efficiency, other benefits of laser hardening include short processing cycles, which makes the hardened components readily available for subsequent processing steps. Other features include the significant environmental compatibility and cleanliness. Coolant media, such as oil or water, are unnecessary. The only condition is the direct, unrestricted access of the laser beam to the component surface.

The laser hardening process involves a highly targeted, or partial, application of thermal energy into the component. The amount of thermal energy is significantly lower than with other processes. The benefit is that the component exhibits non-significant warping. This consequently limits, or even eliminates post-machining on the hardened component. In addition to high energy-efficiency, other benefits of laser hardening include short processing cycles, which makes the hardened components readily available for subsequent processing steps. Other features include the significant environmental compatibility and cleanliness. Coolant media, such as oil or water, are unnecessary. The only condition is the direct, unrestricted access of the laser beam to the component surface.

A real-world example

Basically, any surface made from steel castings, construction, alloyed and tool steels, but also various cast iron grades, such as cast iron with flake or spheroidal graphite can be hardened. For instance, the grooves on the outrunner of an electrical motor, which also functions as the traction wheel on an elevator, were hardened on location on a mobile hardening system as service. Grooves are machined into the traction wheel into which the elevator cable is clamped and retained. To prevent the grooves from wearing too quickly, the groove flanks are once again hardened on both sides.

Finding the solution step by step

These energy supply systems have been in use in all hardening systems since 2006. We developed today's solution step by step", igus®' technical sales consultant, Matthias Gebauer, states in retrospect. "In addition, other intermediate sizes have been introduced over the years, so that today, the corresponding chain cross-sections and chain-lengths are available for the various requirements from the factory. These only need to be adjusted to the individual situation. “Originally, the enclosed triflex® TRC.100 was the energy supply system of choice. But this created problems for the quick replacement of cables. "This is why we ultimately decided to go with the open energy supply system", Eckehard Hensel elaborates. Corresponding sample shipments have moved the decision forward. "The samples, the personal support, the immediate availability of all components have made a convincing case for us. In addition, all change requirements were responded to promptly. Today, we are able to provide high system reliability." “Of course, selecting the smaller multi-dimensionally moving energy supply systems also has had an impact of the overall system concept. Eckehard Hensel summarizes in conclusion: "The systems are basically very compact in their design. Among other factors, this is made possible by the energy supply systems. The hardening systems must operate impeccably over time. Their engineering is mature. And we are able to prove this. In spite of the high mechanical loads, we have not experienced a single failure of a fiber-optic cable world-wide!"