Polyamide 6-Aluminum Assembly Enhanced by Laser Microstructuring.

Karol Bula,Bartosz Korzeniewski

doi:10.3390/polym14020288

Abstract

The presented work’s aim is the application of low-power laser treatment for the enhancement of interfacial micromechanical adhesion between polyamide 6 (filled with glass fiber) and aluminum. A fiber laser beam was used to prepare micro-patterns on aluminum sheets. The micro-structuring was conducted in the regime of 50, 100, 200 and 300 mm/s laser beam speeds, for both sides. The joining process was realized in an injection molding process. Metallic inserts were surface engraved and overmolded in one-side and two-side configurations. A lap shear test was used to examine the strength of the joints. Engraved metallic surfaces and adequate imprints on polyamide side were checked by optical microscope with motorized stages, and roughness parameters were also determined. Microscopic observations made it possible to describe the grooves’ shape and to conclude that a huge recast melt was formed when the lowest laser beam speed was applied; thus, the roughness parameter Ra reached the highest value of 16.8 μm (compared to 3.5 μm obtained for the fastest laser speed). The maximum shear force was detected for a sample prepared with the lowest scanning speed (one-sides joints), and it was 883 N, while for two-sided joints, the ultimate force was 1410 N (for a scanning speed of 200 mm/s).

Highlights

IntroductionIn the emerging field of lightweight construction, a lot of new attempts have been made in which stiff metal parts are joined with engineering thermoplastic materials, without the use of a third, adhesive-like component
Polyamide 6-aluminum hybrid joints were made by means of an overmolding process conducted using the ENGEL ES 80/25 HLS (Engel Austria GmbH, Schwertberg, Austria) type injection molding machine, in which the mold had rectangular shaped cavities with thicknesses of 2 mm and 3 mm
It is likely that the intensity of the heat beam allowed for the melting of a huge amount of aluminum in that precise location and, after that, the melted aluminum was frozen by the surrounding cold bulk material

Summary

Introduction

In the emerging field of lightweight construction, a lot of new attempts have been made in which stiff metal parts are joined with engineering thermoplastic materials, without the use of a third, adhesive-like component. Various methods have been utilized to gain mechanical interlocking between polymeric parts and metal surface. These methods are majorly connected with mechanical coupling where molten polymer forms rivet joints in the through-holes of the metallic part [1–3]. Among the novel versions of rivet-like connections are those that are based on friction spot welding (FSW) [4–6] and the friction filling staking joining technique (FFSJ) [7]. Mechanical fastening and the production of rivet-like connections have potential disadvantages. Most of them are focused on additional operations with a third machining stage, such as, for example, clinching [8,9], ultrasonic and hot air stacking [10] and the fused deposition modeling (FDM) method [11]

Methods

Results

Conclusion