Murr Elektronik: Commissioning made easy

July 16, 2019

Maschinenfabrik Berthold Hermle AG is one of the market leaders for metalworking centers. The machines from Baden-Württemberg are used for production all over the world. They rely on Murrelektronik’s Cube67 modular fieldbus system for the electrical installation. It makes automation concepts leaner and faster and, by extension, more effective. Cube67’s Machine Option Management (MOM) is particularly advantageous for Hermle. It has allowed them to reduce the development, maintenance and software support efforts for connecting different options on a machine.

Hermle AG is based in Gosheim, Germany. The town, at the highest point of the Swabian Alps, has traditionally been a hub for metalworking. The company, which has been listed on the German stock exchange since 1990, uses the slogan “better milling”. The company’s milling machines and machining centers are exceptionally powerful and particularly innovative. Over 26,000 Hermle machines have been successfully installed worldwide. The machining centers are used to manufacture everything from large complex components to small high-tech ones. The milling equipment is used in a wide range of industries ranging from medical technology to classic tool and mold making to aerospace technology.

Hermle’s customers choose the machining center that best meets their needs. The individual systems are modular, so they can be mixed and matched in a variety of combinations. A customer might choose milling spindles with different speeds and tool holders or tool magazine extensions for more than 500 magazine places or perhaps a comprehensive modular system for workpiece automation.

Hermle uses Murrelektronik’s Cube67 modular IO system for the machine’s electrical installation. The individual Cube modules are compact, robust and fully potted. They are mounted directly on the machine without terminal boxes or switch cabinets. A bus node makes the connection to the higher-level fieldbus system. At the same time, it is the starting point for the installation which extends into the machining center. The Cube67 IO modules are installed close to the process allowing Hermle to connect the sensors and actuators with the shortest possible M12 cordsets. The modules are daisy chained to each other with an easy-to-recognize green jacketed system cable that transmits both power and data. This simplifies the installation and reduces the space needed for routing cable.

Maximum standardization with Machine Option Management (MOM)

Hermle customers can design their machines the way they want them thanks to the numerous options available. Because the Cube67 system comes with Machine Option Management (MOM), Hermle ‘s commissioning process is remarkably uniform regardless of the options chosen. With MOM, the project planning for the machining center’s hardware and software is done virtually on the basis of a standardized full extension. During commissioning, the machines are then configured according to their actual equipment. Often, parts of the finished machine are not assembled at the Gosheim facility, but at the customer’s site. One example of this are the coolant systems. They often transported directly from the supplier to the end user. “In order to be able to put the machine into operation, the commissioning has additional test equipment. This allows it to simulate the final configuration,” says Hans-Peter Marquart, head of electrical design at Hermle. This means that the company puts the machines into operation in the configuration that will later be used by the operator. Individual options can be “switched on and off” as required. When done this way, machine configuration is very quick and, because it contains all tested modules, process reliability is also high. Hans-Peter Marquart explains why this is important: “We deliver our machines all over the world including South America and China”. Commissioning is carried out according to the plug-and-play principle – quickly and without any risk of programming errors. For Hermle, the biggest advantage of MOM is that it does not maintain its own software for each machine and can therefore be used individually.

A striking advantage for Hermle are the multifunctional M12 ports on the Cube67 Digital IO modules. For each PIN 2 and PIN 4, the user can define whether they are to be used as inputs or outputs. This opens up a wide range of design possibilities. For example, you may need an output in installation areas that are primarily made up of sensors but at another point in the machining center you may have the opposite need – an input in an area filled with outputs. Without multifunctional ports, two modules would have to be placed in each of these areas making for an expensive and complex solution. Cube67 integrates one module at a time, on which the ports are set accordingly. This is a huge advantage for assembly and commissioning – fewer modules are required which lowers both the amount the space needed and the assembly costs.

In addition to “standard modules”, Hermle also uses function modules. An encoder module is used to measure the flow of the hydraulics on the pallet system. It counts the pulses on site” and transmits the process value to the controller where it is further processed and evaluated.

End customers also benefit from using Cube67 because of the pin level diagnostics. Hermle and its control manufacturers have developed masks that visualize the diagnostic data. These let the end customer immediately see if a fault is occurring at a point on the machining center. This allows troubleshooting can be carried out quickly resulting in higher machine availability and greater cost-effectiveness.

Hermle is currently working on the change from PROFIBUS to PROFINET. Going forward their machining centers will be equipped with PROFINET. The Cube system, with the bus node as an interface to the higher-level network, is worth its weight in gold. IO-Link devices will be able to be integrated with very little effort. Hans-Peter Marquart says that “we don’t want to change the architecture itself but optimize it further.” With Cube67, we can change out the bus node while continuing to use the installation that spreads out under it.

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