Not everything can be corrected with the laser. How do product design and clamping affect weld quality? (part II)

When a laser welding process does not deliver repeatable results, the natural reaction is often to look for the cause in the laser settings.

Higher or lower power. A different speed. A change in focal position. A different path shape. Yet the source of the problem may lie outside the laser system itself.

Process stability is also directly affected by joint geometry, product tolerances, gaps between components, the locating method, and the design and position of the clamping system.

Therefore, some of the most important decisions affecting the future welding process are made before the laser is even selected.

The product should be designed with the process in mind

When designing a component intended for laser welding, it is necessary to take into account not only its final function, but also the conditions under which the joint will be produced.

Relevant factors include:

• joint geometry,
• the relative arrangement of the materials,
• beam access,
• space for clamping elements,
• permissible tolerances,
• the ability to achieve repeatable positioning.

If the product design does not provide the appropriate conditions, increasing the power or modifying the process parameters at a later stage may not be sufficient. A good example is aluminium-copper joints used in battery modules.

These materials have different thermal properties. They differ, among other things, in melting point, thermal expansion, and the way they absorb laser beam energy. Excessive mixing of the materials can lead to the formation of hard and brittle structures. Insufficient penetration depth, in turn, may fail to provide the required contact area and the appropriate electrical and mechanical properties.

Therefore, even a seemingly minor design change can significantly alter process behaviour.

The gap may matter more than another parameter adjustment

In one of the projects carried out by Nextomation, one of the main challenges was the gap between the terminals.

Adjusting the laser alone did not solve the problem. The product and tooling had to be designed so that the components could be properly supported and clamped exactly in the welding area.

Involving the technology team as early as the product design stage made it possible to modify the product concept, carry out trials, and develop a dedicated clamping system. This illustrates an important principle: not every process instability can be eliminated by changing the laser settings.

If the part does not provide repeatable positioning, adequate support, or beam access, the stable parameter range will be very limited.

Clamping is not just a mechanical element

Tooling is sometimes treated as a separate element of the production station, designed only after the technology has been developed.

In laser welding, this approach can lead to problems. Even a small gap between components affects heat flow and the way the joint is formed. It can cause variations in weld depth, local collapse, spatter, or an insufficient joint area.

Thin components are particularly demanding, as the gap may occur only locally. At first glance, the part may appear to be clamped correctly. In reality, material contact exactly at the point where the beam acts remains insufficient.

Therefore, when designing the clamping system, it is necessary to analyse not only the clamping force, but also where it is applied, the stiffness of the part, the distance from the weld path, the ability to dissipate heat, and beam access.

Subsequent operation also matters. A clamping element may become contaminated, wear out, or change position. In each of these cases, the welding result may change even though the laser parameters remain identical.

Clamping is part of the process.

Technology, product, and machine should be developed in parallel

The greatest opportunities for optimisation exist before the product and production station designs are finally approved.

At this stage, it is still possible to modify the joint geometry, improve beam access, provide space for clamping, or plan the quality control method. If the welding technology is introduced into the project only after the product design has already been frozen, the available options become significantly more limited. Therefore, when developing a serial laser welding process, three areas should be treated as one project: product + technology + production station.

The most reliable solutions are created when all three are developed in parallel.

Is your product design ready for serial laser welding?

Process stability depends on more than the selection of laser parameters. Joint geometry, tolerances, beam access, gaps, and the positioning and clamping method can determine whether the technology can be scaled repeatably.

During a free consultation, Nextomation experts will help analyse the application from the perspective of serial production, identify potential design and technological risks, and determine the scope of trials required before the production station concept is prepared.

Consult us on scaling your laser welding process

Read also

Laser welding in serial production – how to move from process trials to a stable process? (part I)

See which stages separate a successful laboratory trial result from a technology that is ready to operate under real production conditions.

Process window in laser welding – how to ensure repeatability and effective quality control? (part III)

Find out how to verify process robustness against natural deviations between successive parts.

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