Papers by Author: Nathan Larkin

Abstract: In order to achieve higher productivity and flexibility, manufacturing industry is turning increasingly to robotics based lean automation systems. This lean approach presents a series of new challenges for the control, operation and programming of robotic hardware implemented to carry out a range of manufacturing processes. This paper reviews relevant path planning methodologies alongside a specific set of requirements for a manipulator operating in a lean automation workcell. Then, new challenges to path planning for a lean automation system are presented. Finally, a framework for a new path planner is developed and its performance is compared to existing methods.

Abstract: The objective of this study is to determine an optimal welding procedure that can be implemented to repair damaged Nickel Aluminium Bronze (NAB) components. NAB is commonly used in marine applications where components are subject to a constant corrosive environment and high stresses. Research into ideal NAB microstructure for a marine application, was performed in order to gain a baseline for experimental analysis of potential welding procedures. The results indicated that the welding repair can be performed with a wide range of heat input. The effect of post-weld heat treatment (PWHT) on the microstructure and mechanical properties in the heat affected zone (HAZ) and weld metal was also investigated in this research. The dominant microstructure in weld metal at as-welded condition is coarse Widmanstatten type structure with high hardness; post-weld heat treatment resulted in significant grain refinement and hardness reduction in weld metal.

Abstract: In this paper we developed a novel and cost effective automated system for use in the Australian shipbuilding industry. We began by investigating current shipbuilding processes and determining the most feasible area where automation could be further developed. Then we designed an automation concept with the objective of developing a highly flexible system. A prototype of the integrated tool was developed for preliminary testing in a simulated industry assembly process, the results of which were benchmarked against a manually fabricated assembly. The outcomes from the benchmarking showed the feasibility of such a system and allowed us to determine the future direction for further development of the integrated tool.

Abstract: The feasibility of using Tandem Gas Metal Arc Welding (T-GMAW) to produce full penetration butt welds in 5mm ship panel steel plates has been assessed and compared to the current Submerged Arc Welding (SAW) process. Experiments conducted show that the T-GMAW process is feasible and demonstrated a significant improvement over the SAW process in several areas including higher travel speed, a reduction in filler material, significantly lower post weld distortion, and a smaller Heat Affected Zone (HAZ), while maintaining similar microstructure and mechanical properties in the weld metal and HAZ.