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Published: September 23, 2010
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Benefiting from Multicomponent Injection Moulding

The moulding technique can help device firms cut costs and reduce assembly operations


A sandwich container and cap made by means of two-component moulding technology offers better barrier properties than conventional pharmaceutical packaging containers.

Because of its versatility and ability to enhance product functionality and cut costs, multicomponent injection moulding is growing in popularity with medical device and pharmaceutical companies. Among the most-impressive benefits of the moulding technique is its ability to optimise the barrier properties of packaging containers. For instance, by using two-component sandwich moulding with two hard polymers, Raumedic (Münchberg, Germany; www.raumedic.com) was able to create a pharmaceutical drug container and cap with a 70% reduction in the water vapour permeation rate compared with similar containers on the market.

Sandwich moulding, which is illustrated in the figure on this page, is performed in four steps. First, the external barrier layer, or “skin,” of the component is injected into a mould. Next, using a special needle system, another polymer is injected into the skin. As the core fills, it pushes the skin outwards. Finally, the polymer that was used for the skin is injected a second time, filling the mould completely. The moulding procedure can be used to create components with a wall thickness of less than 1.5 mm and a middle layer as thin as 0.3 mm.
 
Fusing the hard with the soft
The metal cannulae is directly moulded using two-component injection moulding technology. The soft component of the device has an additional sealing function.

Another common application of multicomponent injection moulding is the melding of hard and soft thermoplastic polymers into a single component. An array of polymers can be used, enabling device firms to tailor components to specific design, functionality and sterilisation requirements. Owing to its ability to fuse hard and soft components, the moulding method also helps streamline production of many components that otherwise would have to be manually assembled.

 
A local anaesthesia catheter coupling that Raumedic produced using this technique integrated the sealing elements into the assembly in a single step, eliminating the need for manual postassembly and its associated costs. When moulding the coupling, the injection mould tool was used with rotary technology to provide a defined mould rotation of 180° and subsequent transport to two stations. The hard component was moulded at the first station. Afterwards, a soft-sealing element was injected directly onto the hard component at the second station. The soft and hard components react chemically, making them practically inseparable. The moulding technique also enabled the couplings to be designed so that they offer a visual and acoustic signal when they are closed, thus ensuring a secure connection.
 
Metal insert moulding
Multicomponent moulding also can be used to join hard and soft thermoplastic polymers to a metal insert for applications such as injection devices. Raumedic developed a technology for an ophthalmologic application that required the insertion of metal components into cannulae. Metal cannulae are directly moulded first with a soft polymer and then with a hard one. The soft component of the product improves the device’s sealing capability while the hard one provides stability. The adhesion between the metal insert and the thermoplastic is similar to what it would have been if they had been glued together.
 
Looking forward
Multicomponent injection moulding technology will give rise to new opportunities for manufacturing novel medical and pharmaceutical devices in the near future. Applications such as injection pens and inhalers are likely to be among the first devices to benefit from the technology. Another likely application of the moulding method is its use in the integration of anticounterfeiting technologies such as custom chips into medical products. Multicomponent injection moulding technology will probably be increasingly used in conjunction with fully automatic assembly
 and handling systems. 
 
Dr Thomas Jakob
is Director, Business Unit Moulding/Pharma Solutions, Raumedic,
Münchberg, Germany
tel. +49 9252 3590
thomas.jakob@raumedic.com
www.raumedic.com 

 


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