Three at a time

There's always excitement in the manufacturing fraternity when a new method is developed, particularly if it brings about sizeable benefits in process as well as costs. Röchling Automotive of Germany has introduced JectBonding. a new process that bonds an injection moulded part with a blow mould while the moulding of both is still in progress. Until now blow moulded and injection moulded elements were formed in separate processes and later on bonded by welding in a third step. Those three production steps are now integrated into one single production phase

Either the injection moulding and bonding takes place at about the same time as the blow moulding within the same tool or after the blowing in a second one. Yet both options have synchronous injection moulding and bonding in common. This is the unique selling proposition of both, an approach branded JectBonding.

In comparison with the multi-step process, the main advantages are simplifying, cutting the corner and avoiding defects. While welding as a bonding method always produces some defects, Jectbonding minimises them. Depending on parts geometry and material, the much more robust process allows for more reliable cost fundamentals. The combining of process steps creates even further cost-cutting potential. A win-win situation for OEMs and suppliers.

JectBonding in a separate tool is already in application at charge air tubes of the Opel Corsa and Vectra for several engines. It will also be applied for the future Vectra. "The method is already series proven and will therefore be used for further parts," explains Gernot Henb of the Opel thermal-development.

JectBonding within the blow mould debuts globally with the charge air tubes for the new Volkswagen common-rail engines. "Further projects will follow," says a statement from the Volkswagen development department.

Beyond the cost advantages, the technical and functional superiority is crucial for market success. In comparison with the mechanical welding seam, JectBonding realises over 20 percent more adhesive force due to the additional chemical bonding on the molecular level. This is also expressed in a higher value look. What's more, the geometry is exactly always the same due to maximum repeat accuracy.

JectBonding within same blowing mould

This describes a process without a change of tools. The functional extensions are JectBonded directly within the blow mould. During this the blow moulded part has not yet cooled down. Thus, the adhesive strength is improved.

Process stability is top-notch, because no changing of the tools is necessary. Yet, the challenging construction of the combined blowing and injection moulding tool allows only for a limited number of functional elements. On the other side, these can be produced simultaneously, which cuts cycle time.

JectBonding with a separate tool

In this process a blow formed part is extended with attachments by means of injection moulding in a separate injection tool. The material injected melts the surface of the carrier part, establishing a firm bond between lug and pipe on molecule structure level. Due to the exactly controlled temperature and pressure phases, there is no loss of material properties and the joint is chemically and mechanically stable.

JectBonding with a separate tool additionally allows for more freedom of design regarding carrier and attachments enabling the realisation of complex geometries. Moreover, a big number of attachments can be JectBonded with a single separate tool. So, facility expenses and cycle times are reduced in comparison with welding. More the attachments, the bigger the advantages of this JectBonding option.