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Moulds Cap moulds with multiple ejection systems In line with the diversified range of customer requirements, Swiss company Schöttli says it is able to supply a variety of cap moulds with slider or collet chucks removal concepts, for removing tamper evident (TE) banded caps. A popular alternative, sliding split moulds remove the TE band by opening the sliders, which are available with different geometries and are used for demoulding undercuts of moulded parts. Collet chuck moulds represent a smaller market segment, as only a few suppliers are able to manufacture them. Nonetheless, the market is growing steadily since it allows freedom of cap design and production on relatively small injection moulding machines. Collet chucks ensure that all bridges that connect to the TE band are demoulded in a geometrically identical

seeing a trend for processors using smaller collet chuck moulds moving to moulds with a higher number of cavities. Bottling specialists in the US, Europe and in China, meanwhile prefer caps with continuously gated TE bands that become operable by means of folding or slitting in downstream stations. This mould concept does not require demoulding by sliders or collet chucks. Nonetheless, demoulding of small undercuts also has to be ensured. The core must withstand the

manner because of the opening in six directions. This approach is beneficial for contract bottling companies as well as for consumers. The constant and even geometry of bridges has an advantage as it allows a virtually uninterrupted capping operation at the bottle filling line as the TE band is evenly distended during capping. During this process, all connecting bridges are subjected to an identical load, so that weak connections are not torn during capping. This is particularly important for the bottling process as it guarantees an errorfree closing procedure. The collet chucks have a lifespan of 5 million cycles, despite the fact that they are under high mechanical stress due to frequently changing loads. The company also says that processors who have opted for collet chucks as an alternative to slider systems stay with them. It is also

forces applied during stripping. Here, Schöttli adapts the forced ejection method where after injection moulding, the individual screw caps are routed past cutting knives that are rotating at high speed, in order to partially cut open the closed TE band. Up until recently, cap producers have been using compression moulding for the postfolding and slitting but are changing to injection moulding. But forced ejection is still preferred to allow the use of existing downstream equipment for folding and slitting.

Trialling overmoulded fibrereinforced preforms Austrian machinery producer Engel has installed an injection moulding cell, comprising its vertical insert 1800 H/500 L/400/90 machine, for the development of lightweight structural components at the Technical University of Chemnitz in Germany. The cell features Engel’s Organomelt technology where fibre-reinforced plastic preforms are thermoformed and then assembled into a component by overmoulding in a mould, a process that the company displayed at the K2010 show last year. The scientists at the university are collaborating with partners from the machine and plant engineering, automotive and aerospace industries, to introduce

A 96-cavity cap mould with collet chuck demoulding

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new processes for this technology that is targeted at the automotive and aerospace sectors. The cell is integrated with a Kuka articulated arm robot and features what Engel says is a unique combination of prepreg and injection moulding module. The prepreg module is positioned as an additional clamping unit above the rotary plate on the vertical injection machine and moulds the fibre prepregs into the right shape for back injection. The system supports a variety of process combinations such as injection-compression moulding, twocomponent moulding and microstructure foaming. The multiaxis robot provides an interface to future solutions.


Moulds Inspection system for barrier containers Teaming up with US coinjection systems specialist Kortec, German automation systems manufacturer Waldorf Technik has developed a multicomponent moulding system that allows for high-volume moulding of PP containers with an EVOH barrier. This is paired with a quality assessment equipment, Check´n Pack system, for inline verifying of the barrier layer’s consistency. The technology, which has been optimised for high volume processing using 32 or 64-cavity stack moulds to produce retortable thin three-layer structures (PP-EVOHPP plus tie layers), is

wall, bottom and injection point inspection. Waldorf says that the barrier packaging can be used for sensitive products such as fish, meat, fruit and pet food, which are usually retort or aseptically filled or in cans, with a shelf life of up to two years. It also says that by using its inspection system, processors can realise production and logistics savings of up to 40%. Waldorf also has another barrier solution it has developed that involves 3D in-line vacuum coating with various PVD or PECVD coatings provided by Germany-based Cavonic. The company says these coatings provide a low-cost

repeatable and does not negatively affect cycle times. Though co-injection is not new, the company says there was no system that could check if the EVOH layer was consistent throughout the complete body of a container. This is now possible with its in-line system that is said to provide 100% control of the complete EVOH layer, 100% inline extraction of rejects and is a fully automated process and logistics system. Stating that standard inspection systems have problems with EVOH, Waldorf goes on to say that its system allows 360 degree rim, 360 degree side

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option with solid barrier and similar hermetic property to glass. One of its major advantages is its suitability for existing injection moulding processes. The company says that laboratory tests have been successful and it is ready for the aseptic process, with the target of complete sterilisation. Its tests show that barrier against oxygen permeability currently achieves 99.15% after sterilisation. In addition, the combination of thinwall performance, barrier properties and low production costs make this technology, which can be adjusted to biodegradable polymers, an attractive proposition, says the company.

Mould  

IMA features issue March 2011

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