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| Layer milling for Rapid Prototyping | | Faster to prototypes | Time is money This saying often hangs over the heads of developers and decision makers in the automotive industry like DamoclesÂ’ sword. Time-to-market is one of the decisive factors for the success of a new model. An innovative layer milling technique for Rapid Prototyping or Rapid Tooling promises considerable time saving in the development process. The system is controlled by Sinumerik 840D.
DaimlerChrysler has already got it. Since October 2001 the first version of the new machine has been working in the model construction of the automobile manufacturer in Sindelfingen. "Our goal is", according to the engineer responsible, Dipl.-Ing. Edib Kocan, "to be able to make the prototype tools more economically than previously with the 5-axis milling technique."
Trend towards Rapid Tooling
In addition to simple demonstration models up to 200 prototype parts are required from one prototype tool in the course of a development cycle, and that in the quality of real components. The trend is moving clearly away from Rapid Prototyping in the direction of Rapid Tooling, i.e. the manufacture of tools and molds for prototypes and pilot series parts. The major disadvantage of the previous Rapid Prototyping methods: They allow fast manufacturing of complex demonstration models but the surface quality, mechanical strength or temperature resistance come nowhere near those of the milled workpieces.
However, with conventional milling machines special requirements such as complex geometries with slim cavities, extreme recesses and ribbings can only be implemented with great time and effort. Especially the development of milling strategies and the programming of components with extreme recesses and free forms as are often the case in mold construction often lead to difficulties, for example the additionally required swivel axes on the mill increase the danger of collision. And long, protruding tools reduce the surface quality. Tiresome reworking is the rule.
Faster, better, cheaper
The new layer milling technique LMP wants to offer a way out of the dilemma time versus quality. The technique was developed by the renowned milling and grinding machine manufacturer F. Zimmermann in Denkendorf near Stuttgart who has been supplying machines for model construction for almost 50 years.
The basic concept of the new technique from the Swabian company and the integrated production unit LMC (Layer Milling Center) developed for it is the layer milling of the form. The fully automatic LMC joins the raw material plate by plate with a gluing process. Since the milling device operates from bottom to top, the chips fall down where they can be sucked off. The gluing surface for the next plate stays clean so that there is no need for reworking.
The whole process is controlled down to the finest detail by a Sinumerik 840D from Siemens which harmonizes optimally with the Simodrive 611D drives. Two Intel Pentium processors at the heart of the Sinumerik and their operating system Microsoft Windows (also in the NT version) simplify the free programmability and the make the new layer milling center LMC capable of communication in a computerized production environment.
Also for complex forms
Even complex forms with large recesses or thin walls are no problem for the new layer milling machine from Denkendorf because only short tools are necessary. The gluing process is by now so sophisticated that the finished workpieces have an impressively high mechanical strength. In accuracy and surface quality the LMC achieves the values common in conventional milling centers. But faster.
Expandable and future-oriented
Edib Kocan quotes time savings of up to 30 percent. The LMC therefore ideally combines the advantages of the existing Rapid Prototyping method and the conventional milling but detours the disadvantages of the previous alternatives. After several test runs and revisions, the patented technique with the LMC which won the Euromold Award has since reached series maturity. People at DaimlerChrysler are more than pleased and consider LMP to be absolutely future-safe. |  |
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