Plastic Laser Welding Mask for Bond Strength and Surface Protection
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Solution Overview
Problem
Current laser welding techniques for plastics face limitations in bond strength and surface damage, particularly in laser absorption welding, where reduced laser power to prevent evaporation and oxidation results in insufficient weld depth and strength.
Innovation Solution
The use of a mask with laser light blocking and passing features during welding, where the laser beam impacts the blocking feature to heat through conduction and passes through to directly heat the plastic, allowing for increased welding depth and bond strength without surface damage, applicable to both transmissive and opaque plastics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser absorption welding is performed with high laser power to increase welding depth and bond strength, then welding depth and bond strength are improved, but surface evaporation and oxidation damage increases
Solution Approach 1:
The laser beam is segmented into two paths by the mask: one path directs laser energy through the mask opening to weld the joint, while another path directs laser energy to the sacrificial absorptive layer. This segmentation allows independent control of welding zone heating and surface protection heating, resolving the contradiction between achieving deep welds and preventing surface damage.
Solution Approach 2:
The sacrificial absorptive layer acts as an intermediary between the laser beam and the plastic surface. It absorbs excess laser energy that would otherwise cause surface evaporation and oxidation, while the mask directs sufficient laser energy through the opening to achieve adequate welding depth and bond strength.
2Object-affected harmful factors
If laser transmission welding is used to avoid surface damage, then surface evaporation and oxidation are reduced, but the first plastic body must be transmissive to the laser beam which limits material selection
Solution Approach 1:
The mask structure provides universal applicability to both transmissive and opaque plastics. By directing laser energy through the sacrificial absorptive layer rather than requiring the plastic itself to be transmissive, the method works with any plastic material, eliminating the material selection limitation of traditional laser transmission welding.
3Adaptability or versatility
If laser absorption welding is performed on exposed surfaces, then transmissive plastic is not required, but excessive evaporation and oxidation of the plastic occurs
Solution Approach 1:
The mask with its sacrificial absorptive layer serves as an intermediary that modifies the laser-plastic interaction. It allows laser absorption welding of opaque plastics while preventing excessive surface evaporation and oxidation by controlling the distribution of laser energy between the weld zone and the surface.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances weld strength and reduces surface damage by increasing welding depth, enabling the use of opaque plastics and eliminating the need for transmissive plastics, while maintaining high bonding strength even under significant separation forces.
Implementation Method 1
a first portion of the laser beam impacts and is absorbed by the blocking feature. This heats the blocking feature
Implementation Method 2
The heat in the blocking feature spreads by conduction to body in contact with the blocking feature
Implementation Method 3
a second portion of the laser beam passes through the passing feature and impacts and directly heats the underlying body. This melts the plastic and results in a portion of the two plastic bodies melting
Implementation Method 4
The mask is made to include at least one laser light blocking feature and at least one laser light passing feature
Data Source
AI summary
The embodiments described herein provide improved techniques for laser welding. These techniques can provide improved weld strength while reducing the potential for damage at the welding surface. In general, the techniques use a mask to selectively block a portion of the laser beam during welding. Specifically, the mask is made to include at least one laser light blocking feature and at least one laser light passing feature. The mask is positioned to be in contact with the plastic bodies that are to be welded together, with the laser light blocking feature and laser light passing feature proximate to the area that is to be welded. Then during welding the laser beam is operated to simultaneously impact the laser light blocking feature and pass through the laser light passing feature.