The automotive and aerospace industries often need to design lightweight materials in order to save costs. Lightweight materials often require different types of materials to be combined, which greatly increases manufacturing costs. Recent work has shown that the use of laser technology will increase the mix of metal and plastic materials. Bond strength, The engineer bonded the plastic to the aluminum by pretreating the aluminum plate with an infrared laser. They elaborated on their work in the Journal of Laser Applications. The above are two scanned images, (a) the aluminum chip at the edge of the CW laser structure, and (b) the molded after the tensile shear test. The remaining aluminum in the groove of the polymer surface.
As developers in the automotive and aerospace industries continue to push for more efficient vehicles, people are currently working on designing rugged, lightweight machines. However, Designing lightweight materials requires combining different types of materials, such as metals and polymers, and these additional steps increase manufacturing costs. Recent work has shown that the use of laser technology increases the bond strength of metal and plastic hybrid materials.
A German research team engineer recently invented a technique for bonding plastic to aluminum by pretreating an aluminum plate with an infrared laser. Their results were published in the 'Journal of Laser Applications' magazine. The researchers found that roughening the aluminum surface with a continuous laser beam produces a mechanical interlock with the thermoplastic polyamide, resulting in significant adhesion. .
One of the authors, Jana Gebauer, said: 'In other joining methods, we usually need a plastic part we want to work with metal parts. In the injection molding process, we create plastic parts directly on the top of the metal parts in the machine cavity. Due to the specific thermal conditions, this is very difficult compared to hot pressing or other joining techniques.'
In order to solve these problems, Gebauer and her colleagues used continuous laser and one pulse for 20 picoseconds on the surface of the aluminum plate. This makes the surface of the aluminum sheet more viscous in order to mold the polyamide layer thereon. Then, they put the sheet into an injection mold and overmolded with thermoplastic polyamide, which is a nylon-related polymerization. Often used for mechanical parts such as power tool housings, mechanical screws and gears.
Gebauer said: 'After we analyzed the surface morphology of the aluminum plate and mechanically tested the bonding behavior to find out which parameters can achieve the maximum bond strength.
Test results using an optical three-dimensional confocal microscope and a scanning electron microscope have shown that a smoother line pattern is formed in the groove of the aluminum plate treated by the pulsed laser compared to the morphology in the groove of the continuous laser-pretreated aluminum plate. Aluminum sheets treated with infrared lasers also exhibit greater adhesion, but as the moisture content increases, these properties decrease.
Despite the team's success, Gebauer believes that to understand how to optimize the metal surface pretreatment to make the manufacturing process more economical, there is still a lot of work to be done. Now, she and her colleagues are studying the molding of thermoplastics in cooling. How to shrink when.
Gebauer said: 'The heat shrinkage causes mechanical stress to be generated, which separates the two parts. The current challenge is to find a structure to compensate for the stress generated during the shrinkage process, while requiring that this structure does not cause softening of aluminum due to laser processing. At present, we hope to produce reliable bonding when using ultrashort pulse lasers to reduce thermal damage of metal parts.