TEXTURES

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GUIDELINES:

The finer textures (.002" or less) are difficult to form. Coarser textures allow for better replication and they also cover many mold or sheet imperfections.

OVERVIEW:

Texture has a direct effect on the ability to evacuate the air between the sheet and the mold during the forming cycle. Some textures actually trap air causing voids in the texture of the part. There are many texture patterns available which are thermoformable.

SPECIFICS:

When the air is evacuated between the mold and sheet there is a need for a clear path for the air to move away. While the sheet is suspended above the mold this is not a problem. When the sheet touches the mold the air is trapped and needs a way to move toward an evacuation hole. In the instance of a texture that is designed to imitate a splatter paint finish, the mold will actually have on its surface a series of small recesses that, once the material covers them, will not allow the air to escape. Because of the trapped air, the sheet will not conform to the textured recess and the part will have a flat or ill-defined surface.

The ideal texture will be a continuous pattern of interconnecting ridges or recesses. This pattern allows for the air to move along a path to a nearby evacuation hole. Cast aluminum molds have a rougher surface finish and usually a coarser pattern is required to cover up those imperfections. The size of the evacuation holes will also determine the type of texture required. A .060" hole with a .003" deep texture will stand out. Typical evacuation holes are .015" to .035". Very fine textures with depths of .002" or less will highlight holes of this size.