DuPont Engineering Design Electronic Magazine
in food processing
By Glen Barber
Sales Manager at DuPont Performance Polymers UK
One of the first commercial applications of food-contact-approved, metal-detectable DuPont™ Delrin® in Europe reflects the enhanced potential for metal replacement in food processing applications.
The use of high performance thermoplastics to replace metal in the food processing industry applications bring with it the potential to produce lighter, lower cost and corrosion resistant components often with superior performance. Their adoption to date, however, has been limited for fear of broken or loose plastic parts contaminating the food and not being detected by existing metal detection systems.
It is against this background that DuPont Performance Polymers recently introduced new DuPont™ Delrin® FG400MTD acetal resin with the aim of opening up more applications in food processing. Made with a proprietary metal filler, it can be detected by most metal-sensing equipment in the unlikely event of a part’s entry into the process stream. The new, food-contact-approved resin shares the established attributes of Delrin® that have led to a wide range of applications such as conveyors, including low wear and friction and a combination of mechanical properties highly suitable for conveyor components.
One of the first customers to benefit from this new grade is Miles Platts of Leicester (England), a leading manufacturer of thermoplastic coil bobbins with a long history of partnership with DuPont. It had approached Ishida Europe, a provider of food and non-food weighing and packaging solutions – to identify opportunities for metal to plastic replacement projects using engineering polymers. The outcome was the substitution of stainless steel food hoppers, used for the accurate dispensing of ‘sticky’ foodstuffs, with Delrin® FG400MTD in an innovative design that combined the low friction capability of the material with a low surface contact area, thereby significantly improving the feeding of high-adhesion foodstuffs.
Because the food hoppers undergo a series of cleaning operations, including aqueous washes in acids and alkaline mixtures, the chemical resistance of the new material was seen as a critical factor. Miles Platts molded test trays in metal-detectable Delrin® which were exposed to the end-users cleaning regime over periods of 20 to 80 hours. DuPont subsequently carried out a series of extensive analysis tests using scanning electron microscopy to demonstrate the retention of the material’s properties.
DuPont in the UK also carried out extensive moldflow analysis of the design and made a number of recommendations in terms of gate design to optimize processing and part performance. Upon approval of the design by Ishida, Miles Platts commissioned production tools to be manufactured in China. Engineers from DuPont's technical center in China attended several trials at the tool maker together with Miles Platts staff. Commercial production of the hoppers started in the UK in 2009, with Miles Platts becoming the first customer in the UK – and only the second in Europe – to use Delrin® FG400MTD.
ContactMiles Platts Limited
Unit Z, Blaby Industrial Estate
Leicester LE8 4GZ