A cleaner production method for laser transmission welding of two transparent PMMA parts using multi-core copper wire

Transparent plastic products are very common in food packaging, medical packaging and other fields. Absorber is key factor during laser transmission welding of two transparent parts. There exist some problems of low strength, powder pollution and false welding when metal powder and wire are used as absorber. Regarding this issue, the goal of this paper is to propose a high-strength and cleaner production method for laser transmission welding of two transparent PMMA (polymethyl methacrylate) parts using multi-core copper wire. A three-dimensional thermal model is developed to predict the laser energy utilization coefficient of copper wire and the geometric size of the welding joint. Compared to one-core copper wire, multi-core copper wire can increase the laser energy utilization coefficient because of reducing laser reflection, and can obtain the lager welding joint size under the same welding parameters. Experimental data show that the melted PMMA plastic can enter into the multi-core copper wire so as to increase the van der Waals force between copper and PMMA. In addition, the shear strength of weld joint by multi-core copper wire is obviously higher than that by one-core copper wire. The maximum shear force can be up to 1100 N. Moreover, the phenomenon of PMMA substrate fracture occurs under appropriate welding parameters when multi-core copper wire is used. Furthermore, the concept of laser energy per unit of area (Qs, unit: J/mm(2)) is presented to analyze the relationship between welding parameters and the shear strength of welding joint and to obtain the optimal welding parameters. The optimal laser energy per unit of area (Qs) for high shear strength is 0.59 J/mm(2) when multi-core copper wire is used. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

This paper proposes a high-strength and cleaner production method for laser transmission welding of two transparent PMMA parts using multi-core copper wire, which can address the issues of low strength, powder pollution, and false welding in transparent plastic products welding. Experimental data shows that the shear strength of weld joint by multi-core copper wire is obviously higher than that by one-core copper wire, with the maximum shear force can be up to 1100 N.