High-Speed Thermography in Additive Manufacturing

Additive manufacturing – also known as 3D printing – is becoming increasingly popular in the industry. It refers to manufacturing processes in which material is applied layer by layer to create three-dimensional objects. Thereby chemical and physical hardening and melting processes take place, in which temperature plays a decisive role. Infrared cameras support the systematic monitoring of the entire manufacturing and machining process and record temperature developments and deviations in real time, for temperature is one of the factors on which the quality of the final product depends.

Numerous of these manufacturing processes are based on laser technologies such as laser melting, sintering or build-up welding. Other processes, such as binder jetting, are completed by a sintering pass to fully cure the material. In order to localise and detail thermal conspicuities in these processes, InfraTec infrared cameras support the determination and subsequent adherence to thermal process parameters by in-line monitoring. Infrared cameras can be integrated directly into the process control system to enable a non-contact and non-invasive temperature measurement. Here, the detection of the temperature distribution of the powder bed surface and the measurement of melting temperatures are relevant in most cases. Both can be realised for temperature ranges higher than 2,000 °C and while the laser is working (insitu measurement).

Close monitoring of machines, processing plants, materials and temperatures during the production and processing of additive parts is of fundamental importance both in industry and in research. The mapping of heat flows in components is necessary for a complete understanding of the process and allows precise control of the temperature development in the parts and materials to be processed as well as exact thermal control of the process. An early detection of errors in production is therefore possible, rejects are actively avoided and returns are minimised. 

Furthermore, process and cycle times can be significantly optimised and correlations between process parameters and (melting) temperatures can be derived.

Due to the characteristics of lasers in additive manufacturing, the infrared cameras used must meet specific requirements. This applies, for example, with regard to the temporal resolution.

Working with a laser is typically characterised by short laser action times, where heat input takes place within fractions of a second. This requires measurements with high image frequencies in full and partial images. Particularly in micro material processing with pulsed laser light, the demands on thermography systems are very high. Suitable for this application is, for example, the ImageIR® 8300 hs, as it can image high-speed processes with an image format of (640 × 512) IR pixels and the high image frequency of 1,004 Hz.

The thermal and geometric resolution of infrared cameras is equally important. Depending on the process and material, lasers can be used to create very large or very small temperature differences, which must be monitored continuously and very precisely. Here InfraTec offers different camera functions, such as HighSense mode, HDR function, binning mode and geometric resolutions in the HD range.