Adhesively bonded joints in components manufactured via selective laser melting

Abstract

Additive manufacturing has gained increasing attention in recent years in numerous industrial sectors due to its inherent characteristics, e.g. tool-free production and unprecedented freedom of design. However, in some applications such as heat exchangers the design has to follow certain restrictions, e.g. to allow for the removal of unfused powder, which can be enclosed in cavities. Moreover, in case multi-material parts are considered, the use of different powders during processing is often uneconomical since powder recycling is highly challenging. Therefore, the production of complex structures being characterized by limited accessibility and components made of different materials often require a subsequent joining process. Based on an analysis of state-of-the-art joining technologies employed for additively manufactured metal components, research gaps related to adhesive bonding are deduced. In light of the prevailing gaps, the influence of selective laser melting process parameters like laser power and build direction on the surface topography and, thus, on the bondability of the substrates are investigated. The mechanical tests reveal a high bond strength for the vertically oriented samples and the samples manufactured with a laser power of 400 W. Furthermore, a laser post-treatment of the SLM samples lead to an improvement of lap shear strength. Finally, results reporting on the ageing behaviour of these joints and an outlook on further research activities are given.

Additive Manufacturing of Titanium with Different Surface Structures for Adhesive Bonding and Thermal Direct Joining with Fiber-Reinforced Polyether-Ether-Ketone (PEEK) for Lightweight Design Applications

“…With the progressive application of additive manufacturing processes, the joining of additively manufactured components is also becoming more and more relevant [34]. The results obtained in this study indicate that the inherent surface roughness of additively manufactured parts has a beneficial effect on the bond strength of metal-CFRP hybrid joints in comparison to flat, unstructured surfaces.…”

Effect of interlayer rescanning on surface roughness and overhang sinking distance of AlSi10Mg alloy via selective laser melting

“…Maamoun et al 16 formed AlSi10Mg alloy under different SLM process parameters and investigated the effects of laser process parameters on relative density, porosity, surface roughness, and dimensional accuracy, and they developed the optimized range of SLM process parameters for each characteristic to ensure the quality of printed samples. Koch et al 17 used different laser process parameters to fabricate AlSi10Mg samples via SLM. They analyzed the effects of laser power and building direction on surface topography and found that surface properties significantly influence the adhesion properties between samples and substrates.…”

Overmoulding of Additively Manufactured Titanium Inserts Using Polyoxymethylene (POM)—Evaluation of Bond Quality as a Function of Process Parameters

“…In all of these sectors, abrasive behaviour is non-desirable and can result in damage with serious consequences. Therefore, many studies [11][12][13] have focused on improving the surface quality of additive manufactured parts, since additive manufactured structures without any subsequent treatment are not to be considered ideal friction partners, due to their porous surface. In most studies, the high surface roughness is decreased by subtractive methods as turning and polishing [14][15][16] in order to enhance the mechanical and tribological behaviour.…”