automotive | Product development Right: The
Hofmann-built rotary two
component mould in
production at Hella’s Signal Lighting facility in Slovakia
from distortion,” says Voßwinkel. During the development process the complex prism geometry was continually modified in order to achieve the optimum balance between the requirements of mould manufacturing and lighting design. “The higher the requirements for a component are set, the more conservative the view of the production team concern- ing stable processes,” Voßwinkel says. The transparent PMMA Edgelight components are
manufactured by Hella on rotary tools using a two-com- ponent moulding process. The thick-wall parts are moulded in Altuglas HT121 or Plexiglass 8N PMMA resin at the Hella Signal Lighting plant in Slovakia. Each mould produces a left and right-hand component in each cycle. The big challenge, according to Hofmann, is to achieve the correct geometrical form and cleanliness required to allow the light to perform to its design intensity.
Eliminating distortion Hofmann developed a contour which allows the maximum light output at the point of emission while at the same time being manageable from a production technology point of view. This applied not only to manufacture of the production tools but also to the demoulding characteristics of the light module. “The function of the light module demands the complete absence of distortion in the component, which is a challenge for us as tool designers, and for production at Hella”, says Voßwinkel. The basic principle of the Edgelight design is to feed
Below:
Component parts for the Porsche Macan’s distinctive rear lighting unit
light from an LED diode strip to be guided through the thick section guide to achieve precise light ‘bundling’ at the point of exit. The light is fed in to the Edgelight strip from LEDs mounted on a circuit board using collimator optics. Deflection optics within the Edgelight strip reflect the light internally to guide it in the required
direction while output coupling optics emit the beam in the required direction. The PMMA grades selected for the part both provide very good surface finish to the precision optical surfaces, which is essential in achieving the required performance. Precision model making also played a key part in the
development of the Porsche lighting system. Hofmann used a variety of techniques to manufacture the required optical prototypes, including PMMA casting and machining. This allowed the light entry and exit geometries to be optimised to achieve the best possible performance. The company also used more traditional prototyping
technologies such as sterolithography and laser sintering to develop the fully-functional parts for incorporation into pre-production vehicles used for pre-launch marketing, dealer presentations and trade shows. In total, Hofmann delivered 300 functional lighting sets prior to production start-up.
About the car: Launched at the end of last year, the Porsche Macan is a compact premium 5-door SUV. The company has a targeted annual production of around 80,000 units. ❙
www.hofmann-innovation.com
16 INJECTION WORLD | June 2014
www.injectionworld.com
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