Non-Contact Temperature Measurement Improves Industrial Metal Coating Processes

Early Identification of Process Deviations in Metal Coating

Thermal metal coating plays an important role in industrial manufacturing processes by improving the wear resistance, durability, and service life of metal components. Thermal spraying processes are particularly common for tool components, machine parts, and rotationally symmetrical workpieces, where a special alloy is applied to the surface as an additional material layer. During this process, the component to be coated is clamped into a machine and continuously moved or rotated. At the same time, a spray nozzle moves along the workpiece surface, applying the coating material in the form of a high-velocity spray jet. The combination of rotation and linear nozzle movement produces a coating that is as uniform as possible across the entire surface.

A key challenge is reliably monitoring both movement sequences and the continuous material feed. If the workpiece stops rotating, material deposition becomes concentrated on a limited surface area. If the spray nozzle stops moving, a localized, ring-shaped coating forms. Both malfunctions can result in uneven coating thicknesses, thermal stress, and damage to the workpiece. Interruptions in the powder or wire feed also alter the temperature distribution and negatively affect coating quality.

The temperature of the substrate is particularly critical. Although the spray jet reaches significantly higher temperatures, the workpiece in the described application must not exceed a maximum temperature of 130 °C. The relevant process temperatures range approximately from 80 to 200 °C. Reliable temperature monitoring is therefore essential to prevent overheating and undesirable changes in material properties.

Conventional contact-based measurement methods have limited applicability due to the rotating components, moving spray nozzle, and enclosed coating chamber. Single-point measurements using a pyrometer also cover only a limited surface area. In contrast, an infrared camera enables non-contact temperature measurement across the entire surface, making localized temperature deviations visible throughout the coating process. This allows critical process conditions to be identified early and targeted quality assurance measures to be implemented.

Infrared Temperature Measurement Reduces Scrap and Protects Sensitive Workpieces

The use of Optris thermal imaging cameras improves the transparency and controllability of thermal metal coating processes. Even during test measurements, infrared thermal imaging reveals how the temperature develops across the workpiece surface and how quickly localized temperature increases occur when process deviations arise. The full-area visualization makes it possible to simultaneously assess the movement of the spray jet and the thermal load on the rotating component. As a result, interruptions in workpiece rotation, spray nozzle standstills, or irregularities in material feed can be identified through characteristic temperature changes.

A major advantage is the early identification of critical process conditions. If the workpiece temperature exceeds a defined limit, operating personnel can intervene, or an appropriately integrated machine controller can respond. This reduces the risk of thermal damage, uneven coatings, and resulting scrap. At the same time, the temperature data provides a basis for adjusting the rotation speed and spray nozzle movement to different substrates and coating materials. Infrared temperature measurement therefore supports consistent product quality and more economical material usage.
Optris offers a range of thermal imaging cameras that can be adapted to specific applications in terms of resolution, thermal sensitivity, and frame rate. The compact design of the PI series facilitates integration into enclosed coating systems. Interchangeable lenses, the license-free PIX Connect analysis software, and industrial process interfaces enable both flexible process analysis and continuous temperature monitoring.

Additional system components can be integrated for further optimization. An industrial process interface enables alarm signals to be transmitted to higher-level control systems. A USB Server Gigabit 2.0 supports network-based connectivity for the infrared camera, while a PI NetBox enables standalone data evaluation without a permanently connected standard PC. In environments with elevated ambient temperatures or increased particle exposure, suitable protective housings, air purge systems, and temperature-resistant connection cables can further improve operational reliability. Optris thus provides a scalable solution for long-term quality assurance in industrial coating processes.