Laser Cladding

Introduction

Recently, we had the exciting opportunity to test our WLDR process monitoring system in cooperation with one of the industry’s leading laser manufacturers, Laserline GmbH, at their site in Mülheim-Kärlich, Germany. Our focus was on two main objectives: 1) to demonstrate Weldmetrix’s performance in defect detection in the laser cladding process and 2) to verify the full compatibility of our hardware with Laserline’s optical units.

In our particular case, the task was to coat wear parts such as brake discs with a higher-quality material. Why? Using a harder material significantly reduces the amount of particulate matter released in the form of brake abrasion during braking – a crucial factor in meeting European standards.

Laser Cladding

Laser cladding is an innovative surface technology that is becoming increasingly important in various industries. A laser beam is used to apply a coating material to a base material. This creates a wear and corrosion resistant surface that significantly extends the life of machine components.

Applications range from aerospace and automotive to medical technology. In the oil and gas industry, for example, drilling pipes and pump shafts are laser clad to extend their life and reduce operating costs. The process also offers significant benefits in heavy industry, for example in the manufacture of rolls for steel mills.

Despite its versatility, laser cladding is a complex process that is influenced by many factors, including the choice of cladding material, laser parameters and cladding speed. This area must therefore be carefully controlled through special process optimisation and monitoring to achieve optimum results.

Influencing factors

The quality and efficiency of laser cladding depends on a number of factors that must be carefully monitored and controlled. One of the most important factors is the laser parameters, in particular the laser power and beam guidance. Too much or too little power can result in defects such as cracks, pores, or uneven material distribution.

The application speed is also important; too high or too low a speed can affect the adhesion of the material to the base material. The temperature of the base material and the ambient conditions, such as the inert gas atmosphere, are also important.

Test summary

Monitoring the laser cladding process is a complex undertaking with many parameters to consider. Weldmetrix has carried out a series of tests to better understand the influencing factors. Analysis of the measurement data shows that factors such as laser power, the direction of rotation of the workpiece and the amount of shielding gas supplied are critical. For example, the wrong direction of rotation or too much laser power led to suboptimal results (NIO).

Another critical point is the powder supply. Experiments have shown that changing the amount of powder or pulsing the powder can affect the signal and therefore the final result. The condition of the component before the process, such as rust, can also have an influence, but this was not significant in the Weldmetrix trials.

Real-time analysis of the measurement data is therefore an important tool for monitoring the process. By comparing the current data with an IO (In O.K.) reference, deviations can be detected and corrected at an early stage. This enables continuous process optimisation and ensures that the quality of the treated components meets the requirements.

Weldmetrix uses state-of-the-art sensor technology and software algorithms to provide this real-time monitoring. As a result, even short-term changes, such as the closing of an injector or changes in gas flow, can be detected and corrected immediately.

Process monitoring

weldmetrix uses a combination of advanced sensor technology and software algorithms to monitor the laser cladding process in real time. The continuous acquisition and evaluation of measurement data allows early detection of deviations in the process. This enables immediate corrections to be made to the laser power, the direction of rotation of the workpiece or the powder and gas supply.

For example, the Weldmetrix test series showed that changes in the amount of powder or gas flow can affect the final result. With real-time monitoring, such parameters can be adjusted immediately to achieve optimal results.

Functional principle – the comparative system

A central element of the Weldmetrix monitoring strategy is the so-called „comparison system“. In this context, this means that the current process data is compared with a specified ideal model or an OK reference.

This comparison allows even more precise control of the laser cladding process. If the current data deviates from the reference, this is used as a signal for a necessary adjustment of the process parameters. The comparison system is therefore a powerful tool for quality control and process optimisation, as it allows continuous adjustment and improvement.

In process monitoring and optimisation, a comparison system offers decisive advantages over a pure measurement system. Whereas a measurement system merely records and displays data, a comparison system allows direct comparison of current process data with a given reference or ideal model. This allows deviations to be detected immediately and the process to be adjusted in real time.

This not only improves the quality of the end products, but also increases the efficiency of the entire process. In addition, the benchmarking system enables continuous improvement by constantly updating the reference data based on the latest results. This results in greater flexibility and adaptability to changing production conditions or materials.

Conclusion

The results of our tests were very promising and represent an important step on our way. It is important to emphasise that, to our knowledge, we are the first to monitor this process using a photodiode system.

With a sampling rate of 1,000,000 measurements per second, the WLDR sensor is the most powerful on the market. According to Laserline, photodiode-based systems deliver superior results, confirming our confidence in our approach. Our test report shows the initial setup, IO references, and identified and even deliberate errors.

We are happy to share these results with the public to contribute to common understanding and progress in this exciting field. Innovation is a journey and we look forward to paving the way for the development of efficient photodiode-based monitoring systems for laser cladding.