Analysis of Interlayer Idle Time as a Temperature Control Technique in Additive Manufacturing of Thick Walls by Means of CMT and CMT Pulse Welding Processes

Abstract

Inserted in the scenario of innovations and technological trends of Industry 4.0, this work aims to obtain detailed knowledge on the influence of idle time between layers as thermal control technique for the Wire Arc Additive Manufacturing (WAAM) with two GMAW process variants of high controllability (CMT and CMT Pulse). The problem focuses on the deposition of thick walls, seeking to emulate the challenges of manufacturing big parts with medium geometric complexity, such as propellers and screws, which usually have sections of this thickness. Although works in the area of additive manufacturing point out the use of idle time as a feature to stabilize the thermal gradient, detailed information about the thermal behavior ends up being omitted. Both processes variants used presented high metallic transference stability and low thermal input when compared to the conventional GMAW, being positive differentials for WAAM. In the tests, walls with eight layers were built with ER309LSi steel in which the interlayer idle time varied from 0 to 300 s. It can be concluded that both processes are WAAM compliant, and that although the CMT Pulse has a higher energy input, the temperature control by idle time was able to control the thermal accumulation in the part for both processes.

Simulações Computacionais dos Processos de Manufatura Aditiva de Metais: Um Review Introdutório

“…Para modelos térmicos, os ciclos térmicos da peça durante a fabricação podem ser registrados experimentalmente com instrumentos como termopares, pirômetros e câmeras termográficas (Schoinochoritis et al, 2017). Enquanto o termopar mede a temperatura apenas no ponto onde está instalado, câmeras termográficas (Silva et al, 2020) podem fornecer uma imagem de distribuição de temperatura, provendo informações em uma área maior. No entanto, estas exigem maiores cuidados de calibração.…”

Effect of the CMT advanced process combined with an active cooling technique on macro and microstructural aspects of aluminum WAAM

“…Thus, long dwell times in-between layers have to be programmed to allow mitigation of heat accumulation and its deleterious consequences. Based on this WAAM problematic, Da Silva et al (2020) developed a thermal management technique named near immersion active cooling (NIAC) for parts built via this manufacturing route and showed an improvement in the heat extracted from them. In such a technique, the preform is continuously kept partially immersed in a liquid (usually water) during the entire deposition time.…”

A Study on Power-Controlled Wire-Arc Additive Manufacturing using a Data-driven Surrogate Model

“…They implemented a dwell time between the beads to control the temperature in each of the beads. Silva et al [23] showed that the physical properties of the specimen are affected by the heat accumulation during the WAAM process due to different temperatures in each layer. They found that regulating the operating temperature by introducing idle time helps to minimize heat accumulation.…”