Circumferential & Seam Welds

A variety of product elements use precision welding as a joining stage of their manufacturing process. Many times these welds must be extremely reliable because of the nature of the product, and must be created without compromising the device's function due to excess heat or mechanical distortion.

Medical components such as cardiac pacemakers and pumps require several welds in their manufacture. These life-dependent seals must prevent external body fluids from getting into the device and prevent leakage of assembly internals into the patient's system. Batteries, capacitor cans, valves, switches, floats, solenoids, and many more devices require a weld around their periphery to complete their assembly. Diaphragms and metal bellows are joined with welding currents sometimes lower than one amp. Manufacturers of vacuum tubes, detonators, airbag components, cryogenic elements and a growing host of modern day products now consider precision welding as a less formidable challenge than in the past and are more commonly welded in production environments.

For low heat applications, an arc pulsation technique can be used. Arc pulsing involves using the welding power supply to rapidly alternate the weld current from a high (peak current) to a low (background current) value. The metal(s) under the arc melt and fuse together each time the arc is pulsed to the peak amperage. This method allows each molten pulse to cool and solidify. A hermetic seam weld is thus made from the creation of a series of overlapping spot welds.

The arc pulsation welding technique brings many benefits to the welding procedure, often improving weld quality and repeatability. In some cases materials and weld joints that are difficult to successfully weld with a non-pulsed arc can easily be welded with a pulsed arc technique. These methods can dramatically decrease heat input to the overall assembly and improve weld consistency to further enhance weld quality.

Arc weld programmers and precision motion devices provide increased weld control and the ability to use pulsed arc welding techniques. Arc gap setting devices provide the ability to set a repeatable electrode to work distance (the arc gap) prior to the commencement of each weld. High quality tungsten electrodes with suitable tip geometry can improve arc starting, arc stability and electrode tip life.

How to Develop Welding Parameters