INSTRUMENTATION • ELECTRONICS
OPTIMISING ACTUATOR DESIGN
Gerard Bush explains the key considerations in actuator design for food and beverage production
F
ood and beverage manufacturers are requiring cleaner, safer machine designs from their OEM machine builders. As the linear mover in many
production applications, it’s crucial that actuators are designed to ensure optimum hygiene, preventing the build-up of bacteria with the ability to withstand aggressive washdowns. When specifying an electric actuator, it’s also vital that they ensure lasting use without the need for extensive, time-consuming maintenance. Within food and beverage production, when linear motion is required, actuators are commonly present. As such, linear actuators are used in applications from packaging to handling the product itself, with processes such as forming, cutting, and slicing. Te trend from manufacturers to increasingly require cleaner, safer designs from their OEM machine builders,
particularly within higher-risk processing environments, such as meat, cheese, dairy, seafood and poultry, is in turn pushing this demand to machine component manufacturers. For actuator designs, this means they must be optimised for hygienic use, while ensuring accurate performance, reliability, and long-life. Te design entry benchmark is to
ensure legal compliance. Depending on geographical markets and end use, typically this will include adherence to the European Hygienic Engineering Design Group (EHEDG), as well as the 3A sanitary standards that represent the United States Department of Agriculture (USDA) and the Food & Drug Administration (FDA). However, before looking at the specifics of actuator design, the first consideration is how the actuator should integrate with the wider machine to optimise hygiene. Open-frame machine architecture enables optimisation of the clean in place (CIP) principles, ensuring visibility for effective cleaning, as well as the ability to clean all required areas, in particular those in contact with or proximity to the product.
FOOD-GRADE QUALITIES Coinciding with open machine design, the actuator requires stainless steel construction, with 316 stainless steel considered ‘food grade’ for its qualities in resistance to corrosion. Actuators such as Tolomatic’s RSH design can withstand regular washdown with aggressive chemicals without developing corrosion blemishes that could harbour bacteria. In
addition, the design
Tolomatic RSH hygienic electric rod style actuators
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form must avoid crevices and sharper angles that can
accumulate bacteria and debris. Instead,
rounded edges prevent food particles from collecting and pooling, while sanitary solutions can easily drain away after washdown.
Combined with stainless steel
construction, robust seals are required to ensure that an actuator achieves an IP69K rating, signifying protection against dust and water ingress, including high pressure water jets used during washdown. Surrounding the actuator’s thrust rod, seals prevent ingress that would otherwise cause corrosion and harbour bacteria. To minimise maintenance downtime and ensure actuator long-life, seals must also be durable to withstand washdown conditions. Polyurethane seals are suitable for most applications, with high tolerance of abrasives such as salt and sugar, but for use with the most abrasive caustic
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