Working with Kydex Thermoplastic
What is Kydex?
Kydex is a thermoplastic sheet marketed for specialty applications. The manufacturers offer an extensive choice of colors and textures.
About Kydex, LLC
Kydex was first created in 1965 by Rohm and Haas Company. The sheet was UL listed as a fire rated material. Initial application plans were aircraft interiors. The product was impact and chemical resistant and could be thermoformed. That combined with the fact that it can come in custom colors made it a natural fit for aviation. In 1987 Kleerdex Company purchased Kydex and later became Kydex, LLC. By the early 1990s Kydex product line expanded to include mass transit, electrical enclosures, medical products, and furniture. Over the years Kydex added granite, carbon fiber, metallic, and wood grain designs.
On their website, Kydex lists aviation interiors, medical device components, mass transit interiors, building interiors, furniture and fixtures, industrial and equipment housings, and recreation and hobby as applications. The product comes in fire-rated sheets, wood grain, Microban Antimicrobial Product Protection, lamination and membrane pressed applications, and pearlescent tones.
Fabrication has many options and tools. Kydex sheets can be braked formed, laser cut, hot stamped, perforated, punched, fastened (with mechanical fasteners), routed, and welded. Sheets can be cut and machined with wood working and sheet metal shop tools. Circular saws, jig saws, and routers can be used. Composition, thickness, and material temperature will affect the cutting speed and tool type. Light surface scratches can be reduced in appearance with a simple wipe of Armor All. Deeper scratches can be buffed out with a rubbing compound. Crack repair can be done using solvent and Kydex sheet shavings. A heat gun can be used to shape the material. A heat gun will allow you to shape one part of the Kydex, while the rest stays rigid. (Wear your welding gloves when using this technique.) I've read of hobbyists using a toaster oven to heat their Kydex sheets. (I hope they don't use the same oven for cooking!)
Ultrasonic welding can be done to assemble Kydex. Sound waves at frequencies around 30-40kHz vibrate the plastic, mechanical vibration. The surface is heated and melted by the high frequency vibration. The touching surfaces are joined as pressure is applied. The welder tip or horn is applied to the rear surface and the finished surface is left flawless, without degradation or burning. Welding times are short and applicable to mass production. Pressure and voltage must be well controlled. Timing and pressure are affected by material thickness. Spot welding can also be done.
For best results the surfaces must be clean and weld times cannot be excessive. Temperatures over 400 degrees Fahrenheit will burn and degrade the product. The parts should be supported so they won't slip. Hot gas welding or adhesives can also be used to join Kydex sheets.
Hot gas welding can be done. It does however, emit potentially hazardous fumes. Welding should only be done with proper ventilation. Otherwise thermoplastic welding techniques apply.