CAM system supports 5-axis machining strategies
Germany-based HF-Zerspanungstechnik has reduced machining and programming times by merging two CAM systems into one. In an increasingly competitive environment, the company can now make full use of its 5-axis machining capabilities. By Dr. Thomas Tosse.
What began in 1996 in Saaldorf, Germany, as an individual enterprise on a farm now presents itself as an efficient supply business. Since 2011 HF-Zerspanungstechnik has been occupying a 1300 m² light-filled hall and 300 m² of office space. Owner CAD/CAMFritz Huber has always invested in the right technology and conveys his own vigour and enthusiasm to the team spirit of the 14-member workforce. In a relaxed, performance-oriented atmosphere, the team works a two shift schedule on machines such as a DMU 50 and a DMU 125P from DMG MORI, and B300 and a Hermle C42U.
Investment in technology, CNC machines pays off
There are also various lathes, such as a Gildemeister CTX 410 V6 with driven tools, Y-axis and counter spindle, as well as a DMT Kern CD 480 and a Wenzel LH87 3D coordinate measuring machine. Huber procured all milling machines with the iTNC530 control from Heidenhain: "For me they were exemplary in quality and user-friendliness from the beginning." Equipped with an automatic switch-off function, the machines are also suitable for lights-out operation.
HF-Zerspanungstechnik accepts commissions from many different sources. For a long-term customer, for instance, HFZ supplies welding electrodes for welding foil from which blood or infusion bags are made. These high-precision tools need to be completely measured, recorded and assembled.
Part of the turnover is generated as a supplier to the motor-racing industry. With self-designed moulds for carbon fibre parts - such as structural components for monocoque racing cars and components and assemblies such as wishbones and lateral control arms for GT3 vehicles. HFZ works as a main supplier to various well-known companies. Other focal points are the parts for mechanical engineering and mould making where high demands are made on surface quality as well as the accuracy. In terms of materials processed, 80% are non-ferrous metals and the rest plastics or high-strength aluminium for the aircraft industry.
5-axis simultaneous milling for mould makers
In the past, this broad range of tasks has been handled with two different CAM systems: "In many assignments the preparation work takes as long as the machining on the machine,” Huber said. "Some of our parts programming is very time-consuming."
In 2011, new customers in the mould making sector triggered a growth spurt and 5-axis simultaneous milling became increasingly important, forcing the company to take a good look at their CAM strategy. Besides the two existing systems, the company evaluated the CAD/CAM system Hyper Mill/Hyper-CAD from Open Mind. In demonstrations it quickly became apparent that the different requirements could most efficiently be met with this system. "In addition to the wide range of functions and the good price/performance ratio, we also saw an advantage in the well-matched products from Open Mind and Heidenhain," Huber said.
Meanwhile, the two CAM workstations are now manned over two shifts. There is no distinction between machine operator and NC programmers, Huber explained. "Here, every employee has the time and the know-how to write the programs for his machine on the CAM workstation and make changes at the machine itself," he said. "As a result , knowledge of current tool technologies and possible cutting speeds and feed rates always feeds back into the NC programs."
Experienced employees discovered the first advantage of using a single CAM system through the common tool management offered by Hyper Mill. "We aim to reduce the set-up times by using large capacity tool magazines on the machines, automatic tool removal and automatic zero point clamping," Huber said.
Converting 3D strategies to 5-axis tool orientation
HFZ sees further benefits from the functions in 5-axis milling. 3D strategies are converted to 5-axis tool orientation by the 5-axis module in Hyper Mill – up to the fully automatic calculation of the tool orientation for machining with a uniform tolerance. "We were given approximately 15 different cycles and we could try them all in direct use," said Hermann Thanbichler, NC programmer. "This enables us to always find an efficient path to the required surface finish."
The high feed rates of HSC machining inevitably require higher axis acceleration on curved workpiece contours. For each machining task it must be ensured that there is no deterioration in quality due to machine vibration even during highly dynamic tool movements. Motion control for 5-axis machining places particularly high demands on the machine control.
At the same time machining times must be kept to a minimum whilst achieving excellent surface finish and complying with the specified contour accuracy. The iTNC530 offers various functions for multi-side and five-axis machining that are harmoniously supported by the post processor. One example is the plane function: Programs for contours and drilling on inclined surfaces are often very complex and involve a lot of computation and programming. With the plane function machining is programmed as usual at the main level. The TNC then executes the machining in the tilted system.
Another advantage for the user is in clearly structured NC programs. Moreover, due to the space restrictions in 5-axis machining, 3D simulation of the machining sequence is an indispensable aid: "We often use this feature to check whether a particular 5-axis machining task is at all possible with the given spatial conditions of the machine, the required tools and fixtures," Huber explained.
Everything runs smoothly at HF-Zerspanungstechnik, from data acquisition by the Hyper-CAD system, into which all of the customers' 3D models have now been uploaded and prepared for milling, up to the optimisation of the kinematics by the iTNC530, Huber said. "We are very pleased with the interaction of Open Mind and Heidenhain," he concluded. "We have optimised our processes in order to remain competitive. We have made progress in shortening programming and machining times."