| Ultrasonic metal spotwelders can be equipped with special tooling for wire-harness assembly. |
Ultrasonic metal welding holds distinct advantages over mechanical-assembly devices and soldering, according to engineers at Electro-Canada, Toronto, (www.electrocanada.com), a manufacturer of wire harnesses for automotive and off-highway industries.
Building harnesses requires a positive, permanent means of attaching wires to connectors. Mechanical connections and soldering are messy, time consuming, and do not always provide the necessary bond integrity, says Tibor Maknyik, the company's manufacturing manager. A switch to ultrasonic-welding improved connections and cut costs.
Electro-Canada uses a WS-2014D welder from Sonobond, West Chester, Pa. (www.sonobond-ultrasonic.com), with specialized tooling for processing wire. The device uses a vertical, vibrating reed, driven by a transducer and horn perpendicular to the reed. This provides a low-amplitude, high-impedance connection that directs energy in a shear mode -- essential for ultrasonic metal welding. Also, the unit applies force directly to parts being welded, an advantage over cantilevered lateral-drive systems, says Janet Devine, Sonobond's president.
The WS-2014D spot welds in a single pulse and, although welding rate depends on the material and thickness, most welds take less than 1.5 sec, says Devine.Sonobond's durable tooling also reduces downtime and improves productivity, says Maknyik. Heat-treated tool-steel Taper Lock tips last for up to 300,000 welds. They also cost under $1,000, one-quarter to one-third that of competing products, he says.
The tooling is easily and quickly replaced and requires no recalibration. Installation is similar to inserting a Morse tapered drill bit in a drill press, which ensures the tip is always aligned.
Electro-Canada uses Sonobond's standard 1,500-W power supply with an optional energy monitor. The operator selects the energy level (W-sec) and weld duration. The monitor/controller measures energy usage and indicates defective welds. In addition, a custom-designed sonic-cutout switch stops the machine immediately after the weld cycle completes, which helps extend tooling life.