Integrated Structures from Dissimilar Materials: The Future Belongs to Aluminum–Polymer Joints

Abstract

The spread of integrated structural elements and parts made from low‐density materials (for example aluminum and polymers) created a need for joining technologies with which these can be joined. Herein, the most important surface preparation methods and joining processes, with which the surface structure of aluminum can be modified and aluminum and polymer structures can be joined, are reviewed. For both topics, a new classification method is introduced: surface preparation methods are grouped based on the method of creating surface structures, whereas joining technologies are grouped according to heat input and structural changes in the polymer material. Herein, “hot” joining technologies (in which so much heat is formed that the polymer material is melted) are reviewed. This grouping category includes techniques based on friction and induction, ultrasonic and laser welding, and some in situ joining technologies. With these, materials with highly different chemical structures and melting temperatures are joined in fast cycles, in a reliable manner. In the coming years, more integrated structures containing aluminum–polymer joints manufactured with fast, automatable joining techniques (such as ultrasonic and laser welding, in compliance with the requirements of Industry 4.0) will be used throughout the industry.

Advances in joining technologies for the innovation of 21st century lightweight aluminium-CFRP hybrid structures

“…In the meantime, the ultrasonic welding machine vibrates the joining area, which homogenizes the melted polymer, so that better strength can be achieved. 20,[79][80][81] However, the application of this novel technique to join aluminium and CFRP has not yet been reported. Although joining metal and CFRP with laser welding is feasible, laser welding has some limitations, including high initial cost and material degradation due to higher heat input, limiting usage.…”

“…Based on the microstructural changes during the joining of metal and CFRP, the joining technologies are classified into two categories, i.e., cold technologies and hot (thermal) technologies (Figure 1). 20 The cold technologies to join metals and CFRP are bolted joining, riveted joining, and adhesive joining. However, there are some inherent issues with cold joining methods.…”

“…As a result of this comprehensive analysis, researchers can address future challenges associated with joining dissimilar metals and CFRP. Table 1 20 lists the studies concerning thermal joining and additive manufacturing technologies to fabricate metal-CFRP hybrid structures.…”

The Effect of Processing Parameters and Calcium-stearate on the Ejection Process of Injection Molded Poly(Lactic Acid) Products

“…Asperity and ploughing are related to dynamic friction, while adhesion is related to static friction. If the surfaces are theoretically perfectly smooth (R a surface roughness is considered as zero) only adhesion remains, which could develop even between the steel or aluminum of the mold and the polymer product during solidification, if some chemical affinity is present [25,26]. This adhesion has to be overcome during the ejection of the polymer part by the force transmitted by the ejector pins.…”

High Pressure–Amplitude Ratio Ultrasonic Spot Welding of Thermoplastic Carbon Fiber‐Reinforced Epoxy

“…Application of lightweight materials, such as lightweight alloys, carbon fiber-reinforced polymers (CFRPs), has positive implications for reducing energy consumption and greenhouse gas emissions [1][2][3][4] Carbon fiber-reinforced epoxy (CF/epoxy) was utilized among CFRPs in aerospace, vehicle, and medical equipment industries, due to its weight saving, cost effectiveness, and process accessibility [5][6][7] Thermoplastic CF/epoxy largely relies on bisphenol-type monomers, which are cured by no-toxic curing agents. They provide high performance to the materials and have little effect on human health.…”