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Adaptive Weld Control for Resistance Spot Welding

Compared to conventional CCC welding control (Constant Current Control), adaptive weld control offers significant advantages. Above all, this includes the property of regulating disturbance variables / influences such as shunts or sheet thickness changes (due to manufacturing tolerances). As a result, these processes deliver a reliably high production quality, especially in an industrial environment. The processes developed and used by the Matuschek company for the first time in the 1990s have been continuously developed and are still the reference worldwide today.


MASTER is an adaptive welding control method developed for the steel welding section and based on the principle of reference welding. During reference welding, the welding current is constantly controlled to the set CCC value. A good weld joint is achieved without disturbing influences with the optimum selection of welding time, welding current and electrode force. The data of welding current and electrode voltage measured during this welding are stored. After switching to the control mode, all subsequent welds are controlled according to the stored MASTER reference data of the good weld.

These control processes necessarily require fast welding power sources. Medium frequency inverters with a reaction time of 1 millisecond - at 1 000 Hz inverter frequency - fulfil this requirement. Thyristor controllers with a reaction time of 10 or 20 milliseconds are too slow for adaptive MASTER control.

The adaptive MASTER control compensates for:

The MASTER control method compensates for the various influences by increasing (or decreasing) the current intensity and extending (or shorten) the welding time. The welding time extension can be limited. The monitoring of weld spatter is carried out by issuing a corresponding status message.

Due to the optimal adaptation to each individual welding spot, the required strength of the welded joint is guaranteed in wide areas.


AluMASTER is an adaptive welding control method for the aluminium welding section that compensates for the following process disturbances and variations:


The AutonomousMASTER represents a new dimension as an adaptive welding control method for steel welding section. With this method, no parameterization or presettings for the welding spot are necessary. That means:


The MicroMASTER is an adaptive welding control method for small part welding.

The following problem is known in many small part welding applications:
The components to be welded, often only millimeters thick, may only sink into a very narrow tolerance band during fusion, otherwise they will not hold, because they have not been sufficiently or too strongly welded (through-welded). Once parameters for an optimal weld have been found, they are often only valid for the following welds for a short time due to various influences such as component tolerances, electrode cooling temperature variations, positioning inaccuracies or dirty electrodes. Quality problems and their costly consequences are the result.

The MicroMASTER solves this problem by welding to the target position with micrometer accuracy using a welding trajectory. The principle is easy to operate and works as follows:

Predestined for this control process are the linear precision welding heads of the LSK series with their integrated high-resolution position measuring system.


Adaptive Weld Control MicroMASTER
Weld: Constant current with ramps
Red: current
Blue: actual penetration
White: reference penetration
Difference: 112 µm
micro master control
Weld: MicroMASTER, adaptive controlled
Red: current
Blue: actual penetration
White: reference penetration
Difference: 3 µm

NUGGETIndex - Non-destructive monitoring

For each weld, the SPATZ+ weld timer records the curves for all electrical and mechanical signals. This data is analysed and summarised to one single value, the NUGGETIndex. This quality parameter provides the correlation to the spot diameter of each weld spot!

During MASTER setups, the NUGGETIndex limits are automatically calculated. The NUGGETIndex, as a 100 % inline NDT system in production, therefore does not require any statistical data. This helps to drastically reduce cost-intensive destructive testing.

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