display / touch / bonding solutions
Food and beverage production is a wet environment by design. Equipment is sprayed, foamed and wiped down on a schedule, and any display mounted on that equipment has to survive the cleaning regime as well as the process.
This guide covers the selection questions that follow: what each cleaning regime demands of a display, how sealing and mounting create or avoid harbourage points, which materials survive which chemistry, and what documentation a food producer's quality team is likely to ask for. Ingress protection ratings themselves are defined elsewhere; the subject here is hygienic design and selection.
Displays appear in four broad positions. An operator panel on a filling or packaging machine is touched continuously through the shift. A line status board is read from a distance and rarely touched. A washdown-adjacent HMI sits where cleaning is most aggressive, often on a machine frame. And a service interface is used only by maintenance staff, but is frequently the unit that gets sprayed while a neighbour is being cleaned.
The positions differ in how much cleaning they see, how close they are to product, and whether a person has to touch them with wet or gloved hands. Sorting the intended position into one of these four categories is what determines the sealing, the materials and the mounting method that follow.
Cleaning regimes vary more than the ratings used to describe them. A wipe-down with a cloth and a mild detergent is a different exposure from a high-pressure spray; a foam or gel cleaner that sits on the surface is different again, because contact time matters as much as chemistry.
| Cleaning regime | What the display must resist | Sealing consequence | Material consequence |
|---|---|---|---|
| Wipe-down with detergent | Repeated abrasion and cleaning agents | Smooth front, no joints to trap residue | Coatings and printed borders must resist wiping |
| Hand spray or hose | Directed water with moderate pressure | Sealed front assembly and connectors | Gaskets rated for the cleaning temperature |
| High-pressure spray | Water and steam at close range | Sealing verified as an assembly, not per component | Metals and elastomers chosen for the temperature |
| Foam or gel cleaners | Extended chemical contact | Chemically resistant gasket and bonding materials | Compatibility list, not a single rating |
The consequence is that two sites with the same nominal protection requirement can need different materials. The regime, the cleaning agent and the contact time are the inputs; the rating is only a shorthand for part of the answer.
Hygienic design is mostly about what a surface does with liquid and residue. A display mounted into a panel with a raised gasket, a recessed screw head or a horizontal ledge gives material somewhere to collect, and cleaning has to remove it from there every time.
Three principles apply to displays specifically. The front should be flat or angled so that liquid runs off rather than standing. The junction between glass, gasket and housing should be a single compressible interface rather than a stack of parts with steps between them. And where the unit has a cable exit, it should be sealed at the point where it leaves the enclosure rather than further along the cable.
Mounting from the rear, into a frame that carries the sealing, is usually the arrangement that keeps the front surface simple. It also means that the sealing function belongs to one part, which is easier to validate and easier to replace.
Four materials are exposed on a washdown display: the front glass, the coatings on it, the gaskets and the housing around it. Each has a compatibility list rather than a single value, and the lists differ.
Glass is chemically durable but its coatings are not, so the useful question is which treatment the glass carries and what the site's cleaning agent does to it. Gaskets and bonding materials vary far more: two elastomers with similar mechanical ratings can behave very differently after repeated contact with a caustic foam. Stainless steel housings resist corrosion but can develop crevice corrosion where a fitting traps residue, which is a design issue rather than a materials one.
Two practical steps: obtain the compatibility list for the exact cleaning agents the site uses, and include the printed graphics and any adhesive label in the assessment, because those are usually the first items to fail. Cleaning compatibility for touch surfaces is discussed further in hygiene, disinfection and chemical resistance.
Repeated cleaning subjects a display to cycles rather than to a constant condition. A warm machine is washed with cooler water, or a cold room contains a display that is sprayed with a warm cleaning solution, and the assembly expands and contracts with each cycle.
Thermal cycling is where sealing design is tested in practice. A gasket that compresses correctly at installation can take a set after hundreds of cycles, and a bonded front glass experiences shear at the bond line. Where a cleaning schedule runs several times a day, the number of cycles in a year is large, and the assembly should be selected for cycling rather than for a single wash.
The same cycling affects the display's own readability: a panel that has been cooled by a spray can take time to return to normal response, and where the operator needs to read it immediately after cleaning, that time is part of the specification.
Operators on a food line wear gloves, and their hands are frequently wet. Both conditions reduce the capacitance change a touch sensor sees, and both make precise targets harder to hit. The controls should therefore be larger than on an equivalent dry application, and the touch layer should be specified for the glove and water case rather than tuned for a bare fingertip.
Three settings matter: a glove mode or a lower detection threshold with its own filtering, a droplet-rejection behaviour that does not suppress a legitimate press, and a wake behaviour that responds to the first touch rather than the second. The operational background is covered in gloved and wet operation.
Where the display is used to acknowledge a step in a process, the interface should confirm the press visibly and unmistakably. A missed acknowledgement costs more than a large button does.
A food producer's quality team will ask how the equipment can be cleaned and how that is demonstrated. For a display, the useful documents are the material compatibility list for the cleaning agents in use, the sealing concept with its test method, and the surface finish specification.
Where the display forms part of a machine that is validated as a whole, the display's contribution is usually the cleanability of its front surface and the absence of places where residue can collect. A written description of the front assembly — flatness, joint design, materials, and how it is cleaned — answers most of the questions before they arrive.
The certificates and quality documentation a supplier can provide are summarised on the quality and certification page, and the general principles of ingress protection are explained in water and dust protection ratings.
Maintenance is the point at which a hygienic design is usually broken. A unit that has to be opened in place, with its rear panel removed inside a production area, creates a risk every time it is serviced.
The design responses are familiar from other washdown equipment. Put the serviceable parts on the dry side of a wall or panel. Where that is not possible, make the unit removable as a sealed assembly so that a replacement can be fitted without opening anything in the production area. And specify the connections so they can be made and unmade without tools that are difficult to clean.
Whichever route is chosen, the service procedure should be written down and given to the customer, because the arrangement a design assumes is not necessarily the arrangement a maintenance team will use.
The list below is intended to be completed with the site's own values: the cleaning regime and agents; the cleaning temperature and cycle frequency; the sealing concept for the front assembly; the materials and their compatibility; the touch behaviour with gloves and water; the display's readable state immediately after cleaning; the mounting arrangement and its service access; and the documentation set to be supplied.
Two items on that list are frequently left out and later cause the most difficulty: the contact time of the cleaning agent, and the number of cleaning cycles per day. Both change the specification more than the nominal protection level does.
If a project is specifying a display for a washdown area, describe the cleaning regime and the mounting position and we will set out which of these items the specification has to fix. Panels for this type of equipment are listed in the industrial LCD display range.
Not automatically. The rating describes the assembly's behaviour under a defined test, while the cleaning regime, the chemistry and the contact time decide how long the materials last. Both belong in the specification.
Often, provided the front assembly is designed for cleaning rather than only for protection. The panel's own sealing is rarely the deciding factor; the housing, gasket and mounting are.
By treating the post-cleaning state as a specified condition: how quickly the display returns to normal response, how the water on the front affects touch, and whether the operator needs to read it during that period at all.
Harsh Environments and Rugged Displays
By continuing to use the site you agree to our privacy policy Terms and Conditions.
