Donghong Ding

Fabricating superior NiAl bronze components through wire arc additive manufacturing

Cast nickel aluminum bronze (NAB) alloy is widely used for large engineering components in marine applications due to its excellent mechanical properties and corrosion resistance. Casting porosity, as well as coarse microstructure, however, are accompanied by a decrease in mechanical properties of cast NAB components. Although heat treatment, friction stir processing, and fusion welding were implemented to eliminate porosity, improve mechanical properties, and refine the microstructure of as-cast metal, their applications are limited to either surface modification or component repair. Instead of traditional casting techniques, this study focuses on developing NAB components using recently expanded wire arc additive manufacturing (WAAM). Consumable welding wire is melted and deposited layer-by-layer on substrates producing near-net shaped NAB components. Additively-manufactured NAB components without post-processing are fully dense, and exhibit fine microstructure, as well as comparable mechanical properties, to as-cast NAB alloy. The effects of heat input from the welding process and post-weld-heat-treatment (PWHT) are shown to give uniform NAB alloys with superior mechanical properties revealing potential marine applications of the WAAM technique in NAB production.

Process Planning Strategy for Wire and Arc Additive Manufacturing

Additive manufacturing has gained worldwide popularity in the last 20 years as many different methods and technologies for adding materials have been developed. Among them, wire and arc additive manufacturing (WAAM) is a promising alternative for fabricating high quality aerospace metal components economically. This study introduces a process planning strategy for WAAM that produces the path and parameters for the deposition process from CAD and process models. After introducing the framework for process planning, two important steps, tool-path generation and optimization of welding parameters, will be presented in detail. Based on the general requirements for a good quality AM tool-path, including high geometrical accuracy and a minimal number of tool-path passes and elements, two novel tool-path patterns suitable for various geometries are introduced. Using the proposed weld bead model and the overlapping model, appropriate welding parameters, such as the travel speed, wire-feed rate, and layer thickness, can be determined. The performance of the proposed process planning strategy is verified through building a sample impeller.

Arc Welding Processes for Additive Manufacturing: A Review

Arc-welding based additive manufacturing techniques are attracting interest from the manufacturing industry because of their potential to fabricate large metal components with low cost and short production lead time. This paper introduces wire arc additive manufacturing (WAAM) techniques, reviews mechanical properties of additively manufactured metallic components, summarises the development in process planning, sensing and control of WAAM, and finally provides recommendations for future work. Research indicates that the mechanical properties of additively manufactured materials, such as titanium alloy, are comparable to cast or wrought material. It has also been found that twin-wire WAAM has the capability to fabricate intermetallic alloys and functional graded materials. The paper concludes that WAAM is a promising alternative to traditional subtractive manufacturing for fabricating large expensive metal components. On the basis of current trends, the future outlook will include automated process planning, monitoring, and control for WAAM process.

Process planning for robotic wire and arc additive manufacturing

This study presents a process planning system, which directly generates manufacturing code from CAD models for robotic wire and arc additive manufacturing (WAAM). A variety of modules are developed for this system with special considerations on slicing and path planning. Multi-direction slicing methodology is developed to allow the WAAM system to deposit material along multiple directions and eliminate the need for supporting structure. MAT-based path planning method is proposed for void-free deposition of layers with any complex geometry. The proposed automatic process planning system is an important tool for the development of mature WAAM technology.