Study on the thermal stability of cold forged carbon fibre-based structural member for high dynamic machinery applications

Structural components in high dynamic machines such as industrial robots are typically made from structural steel, aluminium alloys or cast iron, and play a vital part in ensuring precision, load capacity and dynamic characteristics. These machines are widely used for material handling, machining, assembly and other processes like welding, painting, etc. However, these structures are susceptible to thermal distortion, which can affect accuracy and medium – term repeatability. There is a motivation to replace moving structures made from these traditional materials to lightweight structures manufactured using more sustainable methods. In this work, a structural member prototype was manufactured with carbon fibre tubes using a cold forging-based method. This prototype was tested for thermal stability using a high-accuracy Coordinate Measuring Machine (CMM) to measure dimensional change as a response to various thermal perturbations . The Coefficient of Thermal Expansion (CTE) of the prototype was calculated to be 3.4 ± 0.1 µm/m.°C which is 71% less than the structural steel-based structure. The prototype is able to provide high thermal stability, with anticipated high dynamic stiffness without compromising strength-to-weight ratio, making it ideal for applications like robot links, where both precision and stiffness are critical.