At Freudenberg Anlagen- und Werkzeugtechnik GmbH’s factory, workpieces need only be mounted once on a System 3R reference system to send them speeding through all the machining processes concerned. This increases not only component precision, but also total production capacity.
In preparation for World Expo 2010 in Shanghai, a tunnel is now being built under the Yangtze River. The tunnel boring machines from Herrenknecht have seals from Merkel Freudenberg Fluidtechnik. Because the 3,500 kW output of the machines’ engines generates a torque of over 39,000 kNm, enormous loads have to be withstood by the 6 m diameter (!) seals on the shafts. However, the dimensions are not always so large. More than 80,000 different seals from Freudenberg work their magic in machines, vehicles and plants in all kinds of industries worldwide.
MacroHP pneumatic table chuck – an interface for exact positioning of workpieces.
In Laudenbach, Freudenberg manufactures, amongst other things, moulding tools for elastomer seals. Moulding tools are a prerequisite for the mass production of high-precision sealing elements that have complex geometries. Reference systems from System 3R play a major part in Freudenberg’s tool production. The company uses two System 3R reference systems in its tool machines. In the table chucks, the references give a defined interface. This ensures that workpieces are positioned exactly and that the zero point is strictly observed in all machining operations. So that they can be rapidly switched between various machines, while maintaining high precision, each workpiece remains on its pallet to the end of the very last operation.
The Macro system has three pallet sizes: 52 x 52; 70 x 70; and, Ø 116 mm.
The Macro system is used in certain machines. Here, the pallet’s references are ground directly in. They are also in the same plane. There are no loose parts that have to be checked or adjusted before starting. The user simply mounts the desired clamping element (magnet, vice or raster plate) to the pallet. Other machines use the Dynafix system, which is larger. The use of two different reference systems is attributable to the different dimensions of the components that have to be machined.
Two Fehlmann machines are served by a WorkMaster robot from System 3R. The modular handling concept comprises a changer unit and several rack magazines that can handle chaotic loading. Manfred Cech, head of tool manufacture at Freudenberg Anlagen- und Werkzeugtechnik GmbH, relates: “Although both these machines are used for components of different sizes, the robot wouldn’t be fully employed serving only a single machine. By switching between various gripping devices, it can serve both machines alternately.”
On the software side, WorkShopManager watches over the various machining operations in the process chain. The system administers: machining programs; measured values for the workpiece’s position on the pallet; and, the pallet’s position in the magazine. Before machining commences, it also monitors that the necessary cutting tools are available.
At Freudenberg’s, a single WorkMaster serves both the Fehlmann machines. The result is high productivity and great flexibility.
The WorkCenter program provides the base. All the data required for manufacturing to take place is established here. CellManager is responsible for the automated communication between the machines and the robot. In accordance with a list of priorities, it also automatically starts the next job. Providing information on, for example, tools and their degree of wear, the program tells the operator which jobs can be carried out with the available resources. Via CellManager Remote, the operator can monitor cell status from an external computer. Finally, AlarmServer ensures that any error messages from the cell are relayed via e-mail or SMS.
The magazines with workpieces waiting for the next machining operation. WorkMaster’s modular magazines are adapted to each user’s specific requirements.
“WorkShopManager gives dependable and interruption-free processing throughout our unmanned night shifts,” comments Dr. Eng. Mario Kordt, technical head of tool manufacture. “The operator prepares the shift the day before by determining which workpieces are to be machined and in which order. He or she then loads the robot magazine in accordance with this plan.”
Without reference systems, the elastomer seals could not be produced with the required precision. “In all important respects, the end product’s quality is determined by the quality of the press tools,” opines Manfred Cech. “A determining factor here is that, right through to the end of the final machining operation, each workpiece is mounted on its pallet once and once only. Over the entire process, we achieve a system accuracy of 3 µm. This would have been impossible with repeated setting up of the workpiece. Furthermore, during retoolings, there is always the risk of damaging delicate components.”
The reference systems give the users clear advantages as regards efficient use of machines. An ongoing machine operation can be easily interrupted in order to, for example, take a tool out of production and have it repaired.
Using a reference system, workpieces and their fixtures can be measured in a measuring machine (even between machining operations) without sacrificing the required system accuracy.
“Presetting can be done outside the machine. This markedly reduces tooling times and gives optimum productivity. On top of that, the operator can use the saved time to prepare the unmanned shifts,” explains Manfred Cech. For Freudenberg, it is a further plus that, from table chucks and pallets to complete robot systems and software, System 3R supplies all that is necessary.
“Given our high manufacturing precision, it is important that mechanics, software and machine control are perfectly in tune with each other,” emphasises Mario Kordt. “Naturally enough, the simplest way of achieving this is to source most of the components from a single manufacturer. Nonetheless, it is the precision and flexibility throughout the entire process chain that are the main reasons for our use of reference systems from System 3R.”
“In the near future, we will be developing a plant for laser machining,” reveals Manfred Cech. “This will be based on a five-axis milling machine with a rotatable table. To achieve a repetition accuracy of around 2 µm, we will be using the Dynafix system that we already have.”
Mario Kordt agrees: “Rather than being obliged to buy a special palletisation system for each newly acquired machine, we can simply continue to use our existing equipment. System 3R is our standard. Our employees are thoroughly at home with the reference system and it has served us extremely well.”
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Precision production in brief
Macro
Automation in brief
WorkMaster
WorkShopManager