How It Works 

Percussion welding creates an electric arc between two pieces held at a pre-defined gap, then thrusts the molten surfaces together. The arc comes from a capacitor discharge, and the percussive phase is the rapid movement that closes the gap and forges the bond.

No filler, flux or solder is used, so there is no need to crimp or solder. It can join a variety of metals, including aluminum, brass, copper, steel and titanium, and it is used for dissimilar combinations that are difficult to join by other means.

The stages are shown in the diagram on this page and described step by step below.

Every weld follows the same four stages. The steps below are the whole cycle, from loading to bond.

The heating time is measured in milliseconds. In that time the arc melts only the two facing surfaces, and the parts are thrust together immediately, so very little heat reaches the metal around the joint.

The heat-affected zone (HAZ) is therefore minimal, with little or no negative effect on the materials, and the risk of distortion is reduced. That is what makes it practical to weld small components, wires and other fine work next to insulation, plating or sensitive features.

To compare how far heat spreads at different heating times for your metal, use the HAZ calculator.

A percussion welding station has three parts, each with a clear job at the four stages:

• Model 726 Bench Fixture holds the wire in a moveable wireholder and the workpiece in a stationary holder, sets the pre-defined gap, and applies the rapid motion of the percussive phase. It is triggered by a foot pedal or a hand switch.
• Model 858 Percussion Welder supplies the energy for the arc and controls the timing and speed.
• Percussion Weld Monitor (optional) records the current waveform of each weld and checks it against a learned signature.

Details are on the 858, 726 and actuator pages.

A weld is defined by a small set of settings, which makes it easy to document and repeat. On the 858 front panel the operator sets:

• Actuator speed, delay and weld energy voltage, on dials.
• Mode (regular or heavy duty), pulse (long or short) and polarity, on switches.
• Capacitance, selected from three banks.

The settings that suit a given pair of materials are in our lab data: 131 schedules across 33 materials. They are starting points, not guarantees. Open the Parameter Finder to see them, then validate on your own parts and change one setting at a time.

A weld can be checked in three ways, from quickest to most informative:

• Visual inspection of the joint, often under a microscope for fine wire.
• Mechanical testing, such as a pull test. In pull tests the wire often breaks before the weld.
• The Percussion Weld Monitor, which compares each weld with a learned signature on maximum current, point of contact and waveform, and gives a Pass/Fail result.

The monitor is used for both process development and production monitoring. See the Percussion Weld Monitor page.

• A short learning curve. The process is quick to learn and easy to operate, and operators can start producing welds with minimal training.
• Versatile metal joining. Aluminum, brass, copper, steel and titanium, including direct welds between dissimilar metals, across industries from automotive to aerospace.
• A minimal heat-affected zone. The short heating time reduces the risk of material distortion.
• No consumable electrodes or filler. That reduces waste, and post-weld cleanup is minimal.

The video walkthrough on this page shows step by step how the 726 Bench Fixture is operated. We can run the same demonstration with your parts at our lab in Denver.