A fast and cost-effective route to producing prototypes of electronics enclosures is a process developed in Europe that combines CAD with CNC machining to fabricate plastic sheet. The process is growing rapidly for lots of 50 to 200, in part because of its low costs compared to making injection molds. Some companies are using the process to make production runs as high as 10,000. Prototypes can typically be produced in three to 21 days.
The most commonly used materials are flame-retardant ABS and other styrenic alloys.
It’s most economical to produce square housings with flat sides with this process, but it is possible to make curved to complex shapes. One drawback compared to injection molding is the need for greater tolerances. Tolerances on feature alignment and product dimensions are ±008 inches or .2 mm, according to one of the manufacturers. Maximum size is about 20 x15 x15 inches.
Printed circuit boards can be attached with snap-on, screw-in or other fastening options.
Plastronic Enclosures of Piscataway, NJ, has installed new, larger processing machinery that yields improved economics. “We can get parts to customers quickly because we use 4 ft x 8 ft sheets, which means shorter production cycles,” says President Daniel L. Cucchiara. Plastronic’s roots go back to 1993, when it became the first U.S. company to design and manufacture tool-less enclosures.
PEI says its approach, called Digital Design and Manufacturing, includes unique developments in Pro-E that allow more contours, radii and complexity. “We’re finding that the volumes are increasing,” says Cucchiara. “Five years ago, the norms would have been between 25 and 100. Now, 250 to 500 is becoming more the average.” The growth in competition is helping spur growth, he says. Average design time for enclosures is four to six hours. PEI focuses on UL-certified materials, such as ABS/PVC.
ClickFold Plastics of Charlotte, NC, is doubling production floor space due to a more than doubling in backlog growth over the last six months. “One example is a cover for connector housings,” says CEO and Founder Patrick Oltmanns. “The part is pretty large, so the mold would be expensive. Yet the part is simple. “It’s a perfect candidate for plastics fabrication.” ClickFold has a lot of business in medical enclosures, which typically have runs of less than 10,000. ClickFold also sees strong growth in demand for enclosures that were previously made from sheet metal. “For the same amount of money, they can get a box that weighs less and they don’t have to worry about painting,” says Oltmanns.
Another major player in the United States is a company located north of Seattle, WA called Tool-less Plastics Solutions, which is part of a French company called LTP. The tool-less process was invented by French engineer Jean Claude Antoine, who needed low volumes of plastic housings for stage lighting. He started LTP and gradually automated the process, borrowing production ideas from the sheet metal and cabinet-making industries. Jack Hill, marketing manager for Tool-less, said that styrenics, such as high-impact polystyrene, were at one time a very dominant material used in the process because of their cost advantage over ABS. “The price differential has narrowed,” however, and ABS is gaining share. Another material used is Kydex, an acrylic/PVC sheet. According to Hill, one new development at Tool-less is better capabilities to make curved sections.