An unfortunate truth in the world of product assembly is that it often costs more to install a handle in a piece of sheet metal than the handle itself. That's because an assembler needs time to align the parts, insert two or more screws, place the tool bit on each fastener, and drive them home. A new technology developed by DIRAK Inc. (Chantilly, VA) promises to make the process of installing handles, hinges and other hardware dramatically faster and simpler.

The company's Snap-Line hardware installs in sheet metal without screws or tools. Each latch or hinge has a housing with a spring-loaded set of wings that snap into position to hold the part firmly in the panel. Before installation, the wedge-shaped wings protrude from the housing. They retract as the part is installed. When the part is fully seated, the wings slide instantly back into place behind the panel, securing the part in place with an audible snap. The part will remain securely attached to the panel despite severe vibration and heavy loads.

"We've done tests with some of our customers, and they have reduced their hardware installation time by up to 90 percent using Snap-Line hardware," says Dr. Klaus Bergmann, product development manager with DIRAK.

The spring-loaded mechanism self-adjusts to the load required for each application, and the hardware is available for sheet metal ranging from 0.8 to 5 millimeters thick. It also compensates for misalignments. Because the hardware is installed without tools, it can be located in areas that would otherwise be difficult to access.

The Snap-Line mechanism holds hardware in place as securely as threaded fasteners, says Dr. Bergmann. "It depends on the strength of the panel, the thickness of the material, and the size of the snaps, but typically, it takes 4,000 newtons to tear a Snap-Line hinge completely out from the panel. The panel will bend or break before the fastener does," he says.

An added benefit of the snap-fit installation is that it won't accidentally damage the product. There's no danger of a tool bit slipping and scratching a finished surface. And, because there are no screws, nuts or washers, there's no risk of loose hardware falling out and damaging sensitive equipment.

Snap-Line hardware can be removed for replacement or maintenance. When a special key is inserted into the housing and turned, the wings retract and the part can be slid out from the panel.

The Snap-Line family of hardware includes hinges, handles, latches, swing handles, rod-latch systems, and panel fasteners. Like DIRAK's standard line of hardware, Snap-Line hardware is symmetrical, which means that if engineers suddenly decide that a door should open to the left instead of to the right, the existing hardware doesn't have to be scrapped.

Before Snap-Line hardware can be installed, square or rectangular holes have to be punched into the sheet metal panels. "This shouldn't be a problem, because most panels are already machined, stamped and bent with automated equipment," says Dr. Bergmann. "The holes can be made with a simple punch tool."

For more information on snap-fit hinges, latches and other hardware, visit, or eInquiry 20.