Resistance measurements for control of laser metal wire deposition

• Tool-workpiece distance within laser metal wire deposition can be derived from resistance measurements.
• A distance estimation is formed from an empirical regression model.
• The distance estimation based on resistance measurements is successfully used for height control.
• Resistance monitoring is easy to implement together with hot-wire deposition technology.

A method for controlling robotized laser metal wire deposition on-line by electrical resistance metering is proposed. The concept of measuring the combined resistance of the wire and the weld pool is introduced and evaluated for automatic control purposes. Droplet formation, detachment of the wire from the weld pool and stubbing can be hard to avoid during processing due to the sensitive process and short reaction times needed for making on-line adjustments. The implemented system shows a possible route for automatic control of the process wherein such problems can be avoided automatically. The method proves to successfully adjust the distance between the tool and the workpiece through controlling the robot height position, thus increasing stability of the laser metal wire deposition process.