An investigation into using laser micro channelling to assist fibre integration via Ultrasonic Consolidation

Ultrasonic Consolidation (UC) is a layer-by-layer metal-based additive manufacturing process. Bonding between two layers is accomplished by energy transmission in form of ultrasonic oscillations inducing localised plastic deformation. The benefit of localised plastic deformation and bonding below melting temperatures has been effectively used for fibre integration. Thus, UC presents a feasible alternative to other metal-manufacturing processes as well as an attractive method for novel engineering materials production such as smart structures.Yet, high volume fibre embedding has been shown to result in delamination of foils and greater porosity at the bonding interfaces due to insufficient plastic flow around the fibres. Furthermore, post-functionality of delicate fibre types was limited. In this study a novel hybrid approach aiming to reduce the necessary plastic flow around fibres and high fibre volume embedding is presented. [Continues.

Exploring the mechanical strength of additively manufactured metal structures with embedded electrical materials

Ultrasonic Additive Manufacturing (UAM) enables the integration of a wide variety of components into solid metal matrices due to the process induced high degree of metal matrix plastic flow at low bulk temperatures. Exploitation of this phenomenon allows the fabrication of previously unobtainable novel engineered metal matrix components. The feasibility of directly embedding electrical materials within UAM metal matrices was investigated in this work. Three different dielectric materials were embedded into UAM fabricated aluminium metal-matrices with, research derived, optimal processing parameters. The effect of the dielectric material hardness on the final metal matrix mechanical strength after UAM processing was investigated systematically via mechanical peel testing and microscopy. It was found that when the Knoop hardness of the dielectric film was increased from 12.1 HK/0.01 kg to 27.3 HK/0.01 kg, the mechanical peel testing and linear weld density of the bond interface were enhanced by 15% and 16%, respectively, at UAM parameters of 1600 N weld force, 25 µm sonotrode amplitude, and 20 mm/s welding speed. This work uniquely identified that the mechanical strength of dielectric containing UAM metal matrices improved with increasing dielectric material hardness. It was therefore concluded that any UAM metal matrix mechanical strength degradation due to dielectric embedding could be restricted by employing a dielectric material with a suitable hardness (larger than 20 HK/0.01 kg). This result is of great interest and a vital step for realising electronic containing multifunctional smart metal composites for future industrial applications

Enabling dissimilar fibre embedding and explicit fibre layout in ultrasonic consolidation

Ultrasonic Consolidation (UC) is a manufacturing technique based on the ultrasonic metal welding of a sequence of metal foils which are bonded to one another in a layer by layer manner. It combines the ability of additive and subtractive manufacturing techniques to create complex three-dimensional shapes. Due to moderate applied pressures and the relatively low temperatures experienced by a sample during manufacture, UC operates as a solid-state process. UC could potentially enable the fabrication of smart structures via integration of sensor, actuator and reinforcement fibres within a single metal matrix. Previous issues with the optimal placement of fibres directly between foils during UC have been identified. Also, different types of integrated fibres require different UC process conditions and thus present complications when integrating them in combination. To truly exploit the full potential of UC for smart structure capabilities it is envisioned that a high volume fraction of dissimilar fibres are required to be integrated together within a single metal matrix structure. Research on a new method to consolidate fibres securely and more accurately during UC is presented. Channels created prior to UC within metal matrix composites are investigated as a method to aid the embedding of high volume fractions of different fibres in unison without damage. Initial research using a 200 W fibre laser as an enabling tool to create channels of specific geometry onto a previously UC processed surface is detailed. The research verifies that controlled channelling on a UC surface is possible and that channel geometry is dependent on: laser traverse speed, laser beam power, and shroud gas flow rate. © (2010) by the International Conference on Adaptive Structures and Technologies (ICAST)

Use of a Holistic Design and Manufacturing Approach to Implement Optimized Additively Manufactured Mould Inserts for the Production of Injection-Moulded Thermoplastics

Injection moulding is one the most familiar processes for manufacturing of plastic parts by injecting molten thermoplastic polymers into a metallic mould. The cycle time of this process consists of the phases of injection, packing, cooling, and ejection of the final product. Shortening of cycle time is a key consideration to increase productivity. Therefore, in this manuscript the adoption of additively manufactured mould inserts with conformal cooling channels by means of selective laser melting (SLM) with the aim to reduce process cycles is presented. The design and manufacture of a mould insert with conformal cooling channels for producing pressure fitting thermoplastic parts is described. Numerical analysis of the injection process and simulation of shape distortions after SLM were conducted providing useful results for the design and manufacture of the mould insert. The results of the numerical analyses are compared with experimental 3D geometrical data of the additively manufactured mould insert. Temperature measurements during the real injection moulding process demonstrating promising findings. The adoption of the introduced method for the series production of injection moulded thermoplastics proves a shortening of cycle times of up to 32% and a final product shape quality improvement of up to 77% when using mould inserts with conformal cooling channels over the conventional mould inserts

Fiber laser induced surface modification/manipulation of an ultrasonically consolidated metal matrix

Ultrasonic Consolidation (UC) is a manufacturing technique based on the ultrasonic joining of a sequence of metal foils. It has been shown to be a suitable method for fiber embedment into metal matrices. However, integration of high volume fractions of fibers requires a method for accurate positioning and secure placement to maintain fiber layouts within the matrices. This paper investigates the use of a fiber laser for microchannel creation in UC samples to allow such fiber layout patterns. A secondary goal, to possibly reduce plastic flow requirements in future embedding processes, is addressed by manipulating the melt generated by the laser to form a shoulder on either side of the channel. The authors studied the influence of laser power, traverse speed and assist gas pressure on the channel formation in aluminium alloy UC samples. It was found that multiple laser passes allowed accurate melt distribution and channel geometry in the micrometre range. An assist gas aided the manipulation of the melted material

New concept to aid efficient fibre integration into metal matrices during ultrasonic consolidation

Ultrasonic consolidation has been shown to be a viable metal-matrix-based smart composite additive layer manufacturing process. Yet, high quantity fibre integration has presented the requirement for a method of accurate positioning and fibre protection to maintain the fibre layout during ultrasonic consolidation. This study presents a novel approach for fibre integration during ultrasonic consolidation: channels are manufactured by laser processing on an ultrasonically consolidated sample. At the same time, controlled melt ejection is applied to aid accurate fibre placement and simultaneously reducing fibre damage occurrences. Microscopic, scanning electron microscopic and energy dispersive X-ray spectroscopic analyses are used for samples containing up to 10.5% fibres, one of the highest volumes in an ultrasonically consolidated composite so far. Up to 98% of the fibres remain in the channels after consolidation and fibre damage is reduced to less than 2% per sample. This study furthers the knowledge of high volume fibre embedment via ultrasonic consolidation for future smart material manufacturing