Machine Design

Fast prototypes shaped from sheets

The more latitude designers have defining a part's final form, the greater the strength and quality available without increasing cost.

Prototype tools can form Kydex sheet but a more-durable epoxy or fiberreinforced-plastic mold is needed for trial production.

The shape of this prototype part was hand sculpted. Once the design is approved, it will be used to thermoform developmental parts of Kydex thermoplastic sheet which will undergo further refinements.

Panel with structural ribs is thermoformed from Kydex thermoplastic sheet. After forming, it can be trimmed manually or with automated routing equipment.

Thermoformed component incorporates indentations, stiffeners, and other details that conform to clearance and attachment specs. Designers used wood and body filler materials to build the design before casting a mold for larger-volume production.

So says Claude Gidman, an industrial designer at Gidman Design Assoc. Ltd., Toronto. "Failing to take advantage of creative shaping opportunities for product enclosures, for example, can result in product housings that are bland, ineffective functionally, and less appealing to customers they target," he maintains.

One method Gidman Design relies on to hammer out concept designs is to fabricate prototypes and tooling from sheets of a thermoplastic alloy that readily shapes via thermoforming. Kydex thermoplastic sheets, from Kleerdex Co. LLC, Bloomsburg, Pa., work well for prototyping, says Gidman. The material can be heat fabricated or thermoformed into complex shapes, making it suitable for designs where it houses, supports, protects, or decorates products. It can also be stamped or pressed like sheet metal to create covers and enclosures, but without the need for surface treatment, complex tooling, or painting. It is rigid, durable, fire rated, resists impacts and numerous chemicals, and comes in a range of standard and custom colors, sizes, thicknesses, and surface textures. Kydex sheets also meet or surpass code requirements for such applications as most transportation interiors, Gidman says.

So long as they are properly designed, tooled, and formed, parts fabricated with the material don't thin out at the edges. Product developers can thus use the sheets in a relatively inexpensive process like thermoforming to improve and test designs. It's also suitable for pilot production to test out ideas for more expensive processes such as injection molding.

The sheets can also be thermoformed into tooling at minimum expense, says Gidman. "We've made tooling durable enough for molding over 20 parts." Gidman's team can repeatedly modify the Kydex molds with pieces of wood and bodyfiller to develop different shapes for testing.

Additionally, from prototyping it's a simple step to thermoform parts from Kydex sheets in quantities of 50, 100, or into the thousands, says Gidman. Higher volumes, however, need epoxy or reinforced tooling. Epoxy tooling can be made by casting resin into the back sides of prototype parts made from Kydex sheet, says Gidman. This takes much less time than conventional methods of building epoxy tooling from patterns based on drawings or CAD, he says.

As with any material, there is a learning curve when working with Kydex sheet, Gidman says. Its chemical resistance, for example, makes it reject most adhesives, so double-sided tapes and glues are mandatory when attaching fasteners and other hardware in applications including seat parts and some types of covers and shrouds. The right thermoforming temperature depends on various factors such as part shape, he notes, and only comes from trial-and-error. Deep draws are possible, providing the shaping and lead-up tooling is prepared appropriately and according to how the sheet behaves when formed, Gidman adds.

All in all, designers able to work with this sheet for prototyping are more versatile and more effective, Gidman says. "It is possible to quickly and economically create unique, creative forms."

Kleerdex Co. LLC,
(570) 387-6997,

TAGS: 3D Printing
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