Drying | materials preparation
Resin drying is an essential but energy- intensive necessity in many moulding applications. However, the latest drying technology developments promise to improve performance and cut energy use
Keeping moisture in check
Resin drying is a key element in the material prepara- tion process. It helps avoid visible product defects such as splaying as well as not-so-visible product perfor- mance impairment issues due to polymer degradation. And, provided drying is carried out effectively, it can reduce process variation. However, drying polymers is a relatively costly exercise and a key area of development in recent times has been to improve drying system control and optimise energy use to keep down cost. “Dehumidifi cation of the plastic is as important as the injection moulding,” says Paolo Gasparotto, business development manager at Moretto. “Water infl uences not only the appearance of the fi nal part but also the mechanical strength.” With its Eureka drying technology, the company has
targeted both energy effi ciency and consistency. Developed initially for the PET processing sector - where the company says drying energy is typically the second largest cost after the raw material bill - it claims a 56% reduction in drying energy consumption compared to current system technology. The Eureka system is built around three
core components: the X-Max zeolite-based dryer, OTX heat exchanger, and Flowmatik airfl ow management. These three stan- dalone technologies have been developed over more than a decade, says Gasparotto, but have only in the past two years been combined into the Eureka system, which
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takes each element in the drying process and integrates them in a way that allows each to function at the optimum level of effi ciency. “This explodes the concept of drying step-by-step,” he says. Modularity is at the core of the concept. The X-Max
Dryer, for example, is intended to be assembled by combining up to 10 active units sized to deliver the required airfl ow for a project (a minimum of three units is recommended to ensure
continual operation during zeolite regenera- tion). A newly–developed low energy consumption multi-stage blower is used in the X-Max system in place of the more usual side channel pumps, allowing signifi cant savings to be made in large capacity installations. The company has employed powerful
fl uid simulation software to optimise the geometry of the OTX hopper heat exchanger to maximise its effi ciency (Moretto has one of the most powerful super-comput- ers in Italy running the NASA-developed Star CCM simulation software). The result, the company claims, is that OTX hopper volumes are reduced in size by 40% without compromising the required four hour treatment time. “For the same size hopper we can give the customer 40% more capacity,” says Gasparotto. “Or for the same job we can use 40% of the
Main image: Resin dehu-
midifi cation can be a processor’s second largest cost, according to drying equipment
maker Moretto
Left: Maguire has added continuous throughput monitoring to its VPD vacuum dryer range
March 2015 | INJECTION WORLD 53
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