Innovation | thin wall packaging
A new energy effi cient injection moulding and forming technology aims to challenge thermoforming in production of deep-draw thin wall packaging. Chris Smith reports
Forming an alternative option
A novel plastics forming technology based on the use of injection moulded fl at or contoured preforms could make the performance and cost effi ciency benefi ts of two-stage injection stretch blow moulding available to producers and users of thin wall packaging items such as tubs and pots. The Ecoform processing technology – under
development by UK-based GR8 Engineering – is a two-step technique comprising initial injection mould- ing of a custom-designed fl at or contoured preform followed by a secondary stretch-blow forming phase. Stretch-blow forming allows a high degree of biaxial orientation to be achieved in the moulded part, according to system developer Peter Clarke, with a resulting improvement in key physical properties in the resin and a high degree of wall thickness control. The stretch-blow forming process shares some similarities with the stretch blow moulding techniques used in the PET bottle sector, says Clarke. In particular, it lends itself to being integrated in-line with the injection moulding machine to create a single-step production system. Alternatively, it can be used as the second stage in a two-step process, which could present packaging producers with the option of buying in preforms and forming them at the fi lling point, as many PET bottlers do. This could yield signifi cant savings in inventory, logistics and warehousing, he says.
www.injectionworld.com The most immediate attraction of the Ecoform
technique to packaging producers, however, is the potential reduction in energy use. Thermoforming is a well-proven technology for high volume production of thin wall packaging items. However, that volume comes at a price, according to Clarke. “Thermoforming is a high energy, high waste, high maintenance process that can only compete in the thin lid and tray market using sheet less than 300 microns,” he says. Clarke says the key benefi t of the Ecoform technol- ogy is that it eliminates the need to heat plastic that is not required in the fi nal part. In conventional thermo- forming, typically only 50% to 65% of the heated sheet material is converted to product. Conversion rates depend on the shape of the part being produced, with round containers creating up to 50% sheet waste while rectangular parts produce up to 35% waste. Additional energy is then put into this skeletal waste material during granulation prior to reprocessing. In addition, Clarke says thermoformed part design-
ers are often forced to “over-engineer” the design, creating parts with a much thicker base and rim than is actually required in order to obtain the strength needed in the sidewall, which is where most of the thinning of the sheet takes place during the forming process. “Depending on the shape of the container, you may have to heat up to two tonnes of plastic to make one
October 2012 | INJECTION WORLD 41 The EcoForm
process applies injection-
stretch blow
technology to the deep-draw tub market
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