Today, test, measurement and inspection tools operate closer to production, which requires that they be more flexible, more portable and more rugged. Instron Corp.'s newest tool--a handheld mechanical tester that combines the functions of push-pull force measurement tests with those of tension-compression tests--was developed with those needs in mind.

The tester traces its genesis to a request to Instron (Canton, MA) from General Motors Corp (Detroit), which needed a tool to test weather stripping after it had been installed on a car. "If the weather stripping is not put on correctly, or if it is not what was specified, the door won't close when it is slammed," observes Lorenzo Majno, Instron business development manager. "This handheld tester collects force and deflection data from the weather strip on the vehicle. The data produces a characteristic curve that allows GM workers to check the quality of the products that their vendors are providing."

To develop the tester, Instron engineers tore down a DeWalt 14.4-volt drill, gutted it and outfitted the unit with an electromechanical drive system. The result is a shaft that moves in and out of the drill-shaped body and allows the handheld tester to convert between two test modes: push-pull and tension-compression. In the push-pull mode, the force is reacted against the object itself, and tests for parameters such as the force required to pull a connector off a PC board. In the second mode, the force is reacted against a built-in crosshead, enabling tension and compression tests. In both operational modes, the tester applies load or displacement at known, repeatable speeds to ensure consistent testing and results.

The handheld tester is rated at 50 pounds of capacity and the precision screw drive works in a two-inch range. It works at variable speeds of up to 10 inches per minute.

The handheld device has been used for applications in a variety of industries, including automotive, electric components, medical devices and even in the food industry for determining the freshness of tomatoes.

Other capabilities include force-to-activate testing, which measures the amount of force required to activate such things as switches, latches and push buttons. The tester can further perform wire connection tests to check the strength of a solder joint, and can also test for crush and puncture resistance.

Bring it
"Traditionally, this type of testing had to be done in the lab," Majno says. "This tool allows people in a variety of industries to perform testing on the shop floor or out at their customers' facilities. This lets them bring the lab to the product, instead of bringing the product to the lab."

Data is captured via a Handspring Visor, a personal digital assistant from Handspring Inc. (Mountain View, CA) that is equipped with a data acquisition card. The PDA is mounted to the top of the pistol grip tool and provides a live display of load and position, peak load retention, XY graph and calibration data that can be downloaded to a PC or network. Additionally, operator instructions and job parameters can be uploaded to the tester.

The mechanical tester can be customized with grips, fixtures and application software for specialized testing requirements. Custom fixtures, which screw onto the end of the tool, can be built by Instron or by the customer. The PDA can be customized to track and produce graphs that are important to an application. Depending on the degree of customization required, the tool typically costs between $5,000 and $10,000 per unit.

Technology Contact
For more information about the Instron Handheld Mechanical tester, contact:
Instron Corp.
100 Royall St.
Canton, MA 02021 (800) 564-8378 Fax: (781) 575-5725