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product development | Mouldmaking

A 3D CAD representation of the gear assembly part shown in the main image (ejector side)

Using its current range of powdered layer building materials Faßnacht says it is able to manufacture compo- nents with hardness levels of up to 52HRC. And the use of relatively large cooling bores means that blockages are not an issue provided good mould maintenance routines are employed.

“We keep away from extreme

cooling channels,” says Faßnacht . “Our cooling channels have a

diameter of 5 mm. This means that moulds are absolutely process-reliable.”

As well as the reduction in moulding cycle times, placing the cooling channels close to the mould surface also improves overall thermal control and this can help to reduce warpage in the moulded part. And aside from the benefi t in mould cooling performance, the improved thermal effi ciency of the mould also presents an opportunity to heat the cavity surface.

Shorter moulding cycles mean greater added value, says Wolfgang Faßnacht

Cyclical regulation of the mould surface temperature is being increasingly used as part of heat-cool or “variotherm” moulding techniques for production of parts requiring a very high-gloss surface fi nish. Such variotherm systems allow injection of the molten polymer into the mould at an elevated temperature, followed by rapid cooling of the fi lled cavity once it has been fi lled with molten polymer. The technique can eliminate weld lines as well as allowing a high gloss surface to be achieved even when processing glass reinforced polymers. It can either use the sequential introduction of hot and cold thermal media into a single set of cooling channels or can employ the use of two separate heating and cooling circuits in the mould. In

both cases, placement of the channels in close proximity to the mould surface results in optimum results. Production of conformal

cooling inserts is not the sole area of application for the LaserCusing technology.

“Firstly, there are the inserts with conformal cooling to achieve shorter cycles in injection

moulding. Here it is possible to cool in a sensible way. Secondly, there are contour inserts for round parts which are more complicated and expensive to manufacture with traditional

methods. With the generative metal additive manufac- turing process, we are able to save time in the design and manufacturing phase and it is also easier to incorporate requests for changes to be made,” says Faßnacht.

Key benefi ts of the LaserCusing production tech- nique include eliminating the need to machine recesses and grooves for O-rings due to the more integrated production possibilities. Further time and cost savings can be made by using hybrid constructions, according to Faßnacht. This might involve forming the part of the insert that carries the cooling-channel design and cavity surface onto a prefabricated steel base element, which can be pre-drilled with the required coolant feed and drain holes. The LaserCusing technique allows the two components to be fused together and this hybrid method has already proven to be the fastest and most economical method in many cases, he says.

Faßnacht says he sees considerable growth ahead

for additive manufacturing technology in the mould- making industry, pointing out that the company is already supplying inserts to other mould makers on a contract basis. “Mould making is increasingly heading in this direction - the subject is openly discussed today,” he says.

More information Founded in 1990, W. Faßnacht Formenbau specialises in high performance moulds for production of multi- component and thin wall parts, including fi lm insert moulding. It has been using additive build technologies for construction of mould inserts since 2008.  Concept Laser is part of the Hofmann Innovation Group. The company develops and manufactures its own range of LaserCusing machines for production of additive built metal components. 

44 INJECTION WORLD | January/February 2013

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