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New technologies for inline moulding provide economic benefits |
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In line moulding has two new technologies for thin wall moulding with in line labels. One is called super light injection moulding technology (SLIM); developed Veriplast Solutions, and successfully used in a margarine tub for Unilever. SLIM combines Trexel�s MuCell microcellular foaming process with Veriplast�s extra thin label, a downgauged IML has significantly thinner than the market standards. It provides additional environmental benefits with a 30% reduction in the CO2 consumption compared to standard labels. The label is a 5 layer, 38 micron PP film, half as thick as typical IMLs. The thin label allows for a perfect bonding with lower injection temperature and pressure, the use of smaller tonnage machines and a 10% weight reduction in the final product.
SLIM combines simultaneous plastic and gas injection. Gas expands when the pressure is released during the injection process. The gas replaces part of the plastic, which means a reduction of up to 10% in packaging weight without affecting the quality:
• SLIM keeps the same rigidity and resistance to breakage, and also maintains a perfect outer surface for printing.
• SLIM's advantages over injection and thermoforming by way of excellent surface finish and greater rigidity.
• SLIM packaging is better for the environment due to its reduced carbon footprint.
Extra Slim Labels
Extra Slim Labels can be printed in flexography or rotogravure. Strong technical knowledge and ability allows our process to ensure the label remains flat throughout the manufacturing process (printing and cutting) and during the IML process of our customers. This technological "breakthrough" allows Veriplast to maintain a consistently high printing definition which is very precise. The label thickness of 38� not only has a favourable impact on weight but also optimizes due to lower weight:
• Transport costs (increased labels per pack).
• Change over costs on injection machine (more labels on same height).
• Reduction of plastic consumption to meet our ISO 14001 commitment.
Veriplast has used this technology to produce a 500 g margarine tub in a 4+4 stack mould on a 385 ton press. The same product was previously moulded on a 550 tonne machine. With MuCell, melt viscosity has been reduced by up to 60%, moulding pressure by 50% and injection pressure by 15%. Additional benefits for customers in Europe are the savings from Eco Tax costs. In Germany for a standard 15 g tub, the 10% weight reduction obtained as a result of SLIM saves EUR200, 000 in Eco Tax for every 100 million tubs.
TRIM (Thin Recess Injection Moulding)
Another lightweight packaging technology comes from Canada-based StackTeck. Known as TRIM (Thin Recess Injection Moulding), it uses an advanced approach to part design to enable thinning out of the part wall section beyond the conventional approach used for thin wall packaging moulded while processing polyolefins with high melt flows. Conventional thin wall part design normally assumes a maximum L/T ratio of 300 (i.e. ratio of flow length to average wall thickness). Using the patent-pending TRIM, it has been demonstrated in the production of a 32 oz. rectangular, container design, that large areas of the part can be thinned out, which correspond to an L/T ratio of over 500. Part weight savings that can be achieved using this technology are in the range of 20-40%.
The 32 oz. container had a flow length of 5.74 in. and with thin recess areas covering half of the part�s side wall and bottom, a thin panel thickness of 0.011 in. was achieved.
The injection speed and pressure used to fill the part were normal, by thin wall packaging standards, and it is expected that thin wall moulders can adopt this technology using existing injection moulding machines. A filling time of 0.2 seconds was achieved at a moderate fill pressure, using a 35 MFR PP grade supplied by Basell. The TRIM technology is being showcased on StackTeck�s IML pilot cell at its facility in Canada. The IML pilot cell is a joint effort by StackTeck, Netstal (Synergy 3500 injection moulding machine) and CBW (robots) to provide a prototyping and pilot programme vehicle to the industry for IML applications. |
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