Establishment of a Rotary Print Head to Effect Residual Stresses and Interlayer Bonding in an FLM-Process

• Main Authors: Philipp Bengfort, Dennis Stracke, Bernd Künne
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Journal of Manufacturing and Materials Processing
• Subjects: FLM; FDM; pre-deposition heating; laser; rotary print head; polypropylene
• Online Access: https://www.mdpi.com/2504-4494/5/3/82

In fused layer modeling (FLM) manufacturing technology, there is an increased demand for semi-crystalline materials due to their favorable mechanical properties, such as high strength and toughness. The reasons for their limited use are process-related residual stresses and reduced interlayer bonding, resulting in component distortion, warping and poor strength. Addressing these problems, this paper presents the development and implementation of a rotary print head that enables local laser pre-deposition heating and forced air cooling in the 2.5-dimensional FLM process. Samples of polypropylene are fabricated to investigate the effects of the modified process on residual stresses and interlayer bonding. The investigations show that local laser pre-deposition heating can positively influence the interlayer bonding. In combination with a reduction of the extrusion temperature and additional cooling, it is possible to considerably reduce the residual stresses. The results of this research show that pre-deposition heating and forced air cooling significantly improve the processability of semi-crystalline thermoplastics in the FLM process.