Laser Welding Plastic Parts Using Absorber Mat
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Solution Overview
Problem
Existing laser welding methods for connecting plastic parts, particularly filter membranes to housing parts, require undesirable laser-absorbing additives that increase costs, are not approved in pharmaceutical and medical sectors, and result in incomplete or weak connections due to incompatibility of materials.
Innovation Solution
A method where a thin filter membrane with a fusible reinforcing fleece is laser-welded to a housing part using a non-fusible, reusable mat that absorbs laser light, eliminating the need for additives and allowing use of commercially available diode lasers with wavelengths between 800 nm and 1000 nm, and a high-melting fleece is inserted between incompatible plastic parts to ensure a solid connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser-absorbing additives are used in the plastic housing, then laser welding can be performed, but manufacturing costs increase and the additives are not approved in pharmaceutical and medical sectors
Solution Approach 1:
The solution separates the laser absorption function from the housing material itself by using a dedicated absorber mat as a separate component. This allows the housing to remain free of additives while the mat provides the necessary laser absorption capability, resolving the contradiction between welding reliability and manufacturing cost/approval status
Solution Approach 2:
An absorber mat is introduced as an intermediary component between the laser source and the plastic housing. This mat absorbs the laser light and transfers the energy to the housing material, enabling welding without requiring the housing material itself to contain laser-absorbing additives, thus avoiding cost increases and approval issues
2Reliability
If laser-absorbing additives are used in the plastic housing, then laser welding can be performed, but the laser power requirement increases which is harsher on sensitive membranes
Solution Approach 1:
The absorber mat acts as an energy-efficient intermediary that directly absorbs laser light and converts it to heat at the welding interface. This eliminates the need for high laser power that would be required if additives were dispersed throughout the housing material, thereby protecting sensitive membranes from excessive thermal exposure while maintaining reliable welding
3Reliability
If laser-absorbing additives are used in the plastic housing, then laser welding can be performed, but the components and end products become more expensive and extractables increase
Solution Approach 1:
By separating the absorber function into a distinct mat component, the housing material remains free of potentially harmful additives. This eliminates the source of extractables in the final product while still enabling reliable laser welding through the intermediary mat, thus resolving the contradiction between welding reliability and product safety
Solution Approach 2:
The absorber mat serves as a mediator that enables welding without requiring additives in the housing material. This intermediary approach allows the housing and end products to remain free of harmful substances that would otherwise be necessary to enable laser welding, thereby reducing extractables while maintaining connection reliability
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 approach eliminates the need for costly additives, ensures a tight and safe connection, and allows for the use of affordable diode lasers, while the high-melting fleece ensures a strong bond between incompatible plastics, enhancing the reliability and cost-effectiveness of the welding process.
Implementation Method 1
a mat absorbing the laser light and not meltable by the laser light is placed in front of the second plastic part
Implementation Method 2
both plastic parts being transparent to the laser light
Implementation Method 3
tightly connected to one another by laser welding with a laser light
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a method for connecting a first plastic part (2, 2') to a second plastic part (4) by laser welding, wherein the two plastic parts (2, 2', 4) are positioned on one another, pressed together in a clamping device by a transparent holding-down element (11) and bonded to one another by laser welding with a laser light (7). The invention is distinguished by the fact that the two plastic parts (2, 2', 4) are made transparent to laser light (7), that at least the second plastic part (4) is made thin, that, for the welding, the second plastic part (4) has placed in front of it, on the outer side (16) that is facing away from the first plastic part (2), a mat (8) that absorbs the laser light (7), cannot be melted by the laser light (7) and does not become connected to the second plastic part (4) in contact with it, and that the laser light (7) is fed to the second plastic part (4) via the first plastic part (2).