The purpose of this thesis is to assess the thermal cycle and the application of thermocouples in WAAM (Wire Arc Additive Manufacturing) with CMT (Cold Metal Transfer). CMT is an arc welding method that uses regular off the shelf welding equipment. The process has been implemented in AM (Additive Manufacturing) through providing the movement to be controlled by a robot. CMT is one of many methods used to manufacture metal parts by AM but belongs to the section that has the highest deposition rates which decreases the production time. An important thermal cycle seen to production speed is the cooling time between peak temperature and the chosen interlayer temperature. This has vital part in the effectiveness of the WAAM process. Another important cooling time that is usually analyzed for structural steel is the 800 to 500°C time because it influences the materials microstructure.

Two tests were performed to give the information around the objectives, which was to assess the thermal cycle, evaluate different thermocouples attachment methods and find out how ground connection of the thermocouples affect the measurements. To be able to measure the thermal cycles, thermocouples was attached to the substrate which is the base for the thin wall. The first test used three attachment methods to fix the thermocouples in place, where one used cement, another used epoxy mixed with metal shavings and the last one used a spot welded sheet metal. Seven layers were deposited, and every layer was inspected to assess the welding quality. The test showed that the sheet metal method contributed to themost stable weld pool and the finest welding quality. The second test was mainly conducted to test ground connection, which proved to increase the noise in the measurements and make them less trustworthy. Noise of different degrees did emerge in all measurements. The underlying cause of the noise is evaluated and can arise from several factors.

The temperature measurements were saved as numerical data to allow evaluation of the thermal cycle. The first test had a chosen interlayer temperature of 50°C and proved to need a cooling time of 17 minutes to ensure that the workpiece is below 50°C before the next layer is deposited. The average cooling time between 800 and 500°C was calculated with three measurements in test two because there were no more reliable peak temperatures thatwas recorded over 800°C. This resulted in an average cooling time of 5,9 seconds.