Food Contact: How Springs and Wire Forms Fit into Hygienic Design
When a designer selects materials for food-processing machinery, attention almost always focuses on surfaces that come into direct contact with the product. But a food-processing line is a system, and systems must also be assessed at their less visible points: springs inside valves, rings in closure systems, and wire forms (metal components shaped to a specific profile to fit particular geometries) in dosing mechanisms.
Constant humidity, frequent washdown cycles, aggressive detergents, temperature fluctuations and corrosion risk. These are normal operating conditions in a food-processing plant—and the same conditions that even the smallest metal components must withstand, despite often being overlooked in discussions of food contact.
The EHEDG guidelines (European Hygienic Engineering & Design Group, the European consortium founded in 1989 to develop hygienic design criteria for the food industry) set out requirements for the entire system: materials, geometries, surfaces, ease of cleaning and prevention of accumulation points. The key principle is that equipment is hygienic when every part is designed not to become a problem—not only the main surfaces, but also the functional components that ensure movement, sealing and adjustment. To date, EHEDG has published 42 technical documents containing standardised protocols for assessing component cleanability, sanitisation and bacteria-tightness.
For a spring or wire form, this raises practical questions: can the material withstand washdown cycles without degrading? Does the geometry allow effective cleaning? Does the surface finish prevent residues from accumulating? Does the component retain its dimensional characteristics over time?
Springs, rings and wire forms are used in many of the subsystems that make up food-processing machinery. They operate in valve opening and closing mechanisms, actuator spring-return systems, dosing devices and dispensers, as well as locking and adjustment systems. In some cases, they form part of electromechanical subassemblies in which precision and cycle repeatability are primary requirements.
Their function is often invisible when compared with the complete machine, but it is critical. If a spring loses its elastic properties after repeated washdown cycles, or if a wire form deforms because of corrosion, the performance of the entire subsystem becomes unpredictable. In a food-processing plant, unpredictable operation leads to downtime, unplanned maintenance and the risk of non-compliance.
Food-Contact Metal Components: Designing for the Operating Environment
Selecting the material for a component intended to operate in food-contact environments is not a standalone decision. Regulation (EC) No 1935/2004 requires all materials intended to come into contact with food—or with systems that process it—to be sufficiently inert so that they do not transfer substances to food in quantities that could endanger human health or alter its characteristics. For metal components, the critical mechanism is migration: the transfer of substances from the material to food through direct or indirect contact. The Regulation requires this transfer to remain below specified limits and compliance to be demonstrated through traceable technical documentation.
Compliance, however, is not limited to material selection. The EDQM (European Directorate for the Quality of Medicines & HealthCare) technical guide on FCM (Food Contact Materials) documentation explains that a robust compliance dossier requires structured information: materials used, manufacturing processes, traceability and technical declarations. For food machinery manufacturers, working with suppliers capable of providing clear, readily integrable technical documentation reduces time and uncertainty during audits and qualification.
A supplier of metal components for food-contact applications must understand where each component will operate, the stresses it will be exposed to and the function it must maintain over time. This requires technical dialogue before production begins and often improves the component itself: a more suitable material, optimised geometry and a surface finish consistent with the planned sanitation cycles.
The quality of a food-processing plant is built at system level. A system is reliable when every part, even the smallest, has been designed with a clear understanding of where and how it will operate.
