Layer milling at the press of a button with WorkNC-LMP

Kegelmann Technik, a supplier of prototypes and low volume parts in cast aluminium and plastics, is a great supporter of modern technology, particularly those of benefit to its customers. Over a year ago, the company added a layer milling centre (LMC) to its equipment, which WorkNC-LMP, can programme almost at the touch of a button.

<< I was impressed by the zest for innovation at Sescoi, whose development team are always slightly ahead of the game. >>
Stephan Kegelmann, Kegelmann Technik GmbH

Long before rapid prototyping was recognised in Germany, Stephan Kegelmann was aware of potential benefits in the generative milling processes. He established Kegelmann Technik GmbH in 1989, with just one SLA machine The business has expanded considerably since then and is very customer focused.

For some time major customers, particularly from the automotive industry, have sought partners who could take on everything from development to the finished part. Stephan Kegelmann outlined the company philosophy - “We want to offer the customer a wide range of services, and faster than our competitors, so must have a comprehensive spectrum of inhouse technologies.”

In 2001, he saw F. Zimmermann’s LMP technology, a new layer milling process. The machine operates by successively milling plastic or aluminium plates. After each machining pass, a new plate is bonded to the previous one ready for the next machining pass, combining the advantages of generative rapid prototyping processes with conventional milling. The benefits for Kegelmann Technik were that the machine could run unmanned, and little work was required in plate preparation and magazine loading. Stephan Kegelmann commented, “This means I can manufacture highly complicated components efficiently which is precisely what I need today.”

It was also important that the machine should be easy to programme, so he turned to Sescoi of Neu-Isenburg, and its special programme for LMP. Since the beginning of the 1990’s he has been using Sescoi’s WorkNC CAM software. He now has five WorkNC workstations, as he finds it ideal for his needs. He enthused, “I was impressed by the zest for innovation at Sescoi, whose development team are always slightly ahead of the game and devote a great deal of energy to progressive projects.”

For fully automatic division of the model into layers, as well as all the specialised strategies, including machining of adhesive grooves, layer heights and surface roughening, Sescoi developed a new module WorkNC-LMP. With this, programming the layer milling centres – as is usual with WorkNC – is accomplished practically at the push of a button. The programmer enters all the parameters for the layer milling process, i.e. the size, thickness and number of plates, time and pressure for the bonding process and the vacuum level. The programmer then determines which milling and bonding paths must be generated, calculated and postprocessed and finally graphically verifies the toolpaths. The module automatically creates all the information required for optimum utilisation of the machine. Finally, WorkNC-LMP produces the code, necessary to control the machine entirely automatically.

F. Zimmermann, Sescoi and Kegelmann collaborated closely on this project. Stephan Kegelmann praised the team, “I’m delighted with the progress. Sescoi have increased the calculating power and implemented an improved rest material strategy.” Christian Frey, SLS/SLA operator at Kegelmann Technik, is responsible for the layer milling. He looks after the complete LMC process, producing very complex parts including radiator grilles, sculpted interior components such as central consoles, air conditioning apertures and glove compartments. The machine is ideal for components with deep geometry, where the excessive tool lengths makes machining from a block impractical. Christian Frey comments, “We often need to achieve a minimum corner radius of 1 or 0.5mm. For large models I simply cannot mill this from solid as a small cutter is incapable of reaching the required depth - building up in layers is the only way. Previously, individual conventionally produced plates had to be bonded together, with the risk of adhesive contamination. With the LMC there is no danger of this, it operates unmanned and is much faster.“

He continued, “With this software I only need short programming times, it rarely takes more than two hours. Once I have set up a programming strategy, it is the same for every layer. In addition, I do not have to worry about checking for any collisions as there are none, WorkNC-LMP totally prevents them.”

Stephan Kegelmann anticipates further advantages from WorkNC’s new five-axis programming, “We can cut deeper with the same cutter lengths and obtain a better finish. As all our machines are five-axis, that suits us very well. Additionally, WorkNC’s excellent 5-axis collision control makes machining safer which we find particularly important.”