Ceepackaging

Technology

Venting the extrusion mould

As the mould closes around the parison and is inflated and pressed to the cavity wall by air blown into it, air is trapped between the parison and the two mould halves. This trapped air must be removed. In order to expedite this venting process, conventional moulds are often equipped with vents at the parting line for expelling any trapped air, sometimes with the help of vacuum. The downside of this method is the fact that air can only be removed locally and the introduction of a vacuum leaves small marks on the finished part.

Specialist fhw-moulds has developed a new solution for this problem: the extrusion mould for a 20 litre jerry can is now vented in all four corners of the mould and vacuum can be used to increase the ventilation effect. The vent is cut across the entire height of the mould corner so as to eliminate the occurrence of marks on the finished part. This way, entrapped air can be removed quickly and effectively.

During extrusion blow moulding, cycle times are highly dependent on mould cooling times. The new mould design with corner venting allows significant cuts in cycle times. “Thanks to optimized cycle times, the additional costs for this special mould have a very short payback time,” Jean Ingenbrand, Managing Director of fhw-moulds points out. An additional benefit of this solution is that exchangeable corners can accommodate different designs of hollow plastic products, which translates into more versatility and cost-efficiency for blow moulders.

fhw-moulds in short

fhw-moulds GmbH, Bottrop/Germany specializes in the production of extrusion blow moulds. The specialist has been designing and engineering customized high-tech moulds for more than forty years and offers the experience that comes with operating more than 5,000 systems in the international market.

Since 2008, the company conducts its business under the name of fhw-moulds, formerly known as Friedrich H. Weischede Formenbau GmbH. The name change inaugurated a new generation of management: At the head of the company are Jean Ingenbrand, managing partner, and metal expert André Enselmann, who joined management in 2010. The mould specialist with more than forty employees offers customers a complete service package for the perfect customized blow mould, from initial idea, design, prototyping and mould engineering right through to mould sampling.

www.fhw-moulds.de

Photo: While corner vents ensure better air removal and shorter cycle times, they also accommodate different designs and more versatility for blow moulders
Photo by fhw-moulds GmbH,
Bottrop, Germany