Mounting the LCD and touch panel directly against the chassis front panel is not recommended. The panel specifications for all of our display modules show how the LCD and touch panel is to be mounted. It must have a gasket. We do offer silicon foam gaskets for some of our modules.
You will need to use a “soft” gasket and plan on some tension on the display module mounting tabs, but you should not plan on flexing the tabs. You will need to use stand-offs or spacers between the front bezel and the display module to ensure that you can apply enough pressure to compress the gasket to get a seal, but not so much pressure as to flex the mounting tabs. The standoffs will also provide a secure mounting for the display module. We use a black silicone foam product called “HT-800“. We use the version with adhesive on one side (on the touch-panel side), then press the other side of the customer’s chassis on assembly.
Find general information on gaskets and sealing, it shares a lot of knowledge and talks about compression sealing with regards to the HT-800.
Review general guidelines for gaskets and standard sealing environments.