Laser Network News: Welds and bonds in powertrain assemblies must meet stringent quality standards. For best-in-class performance, the joints must be thoroughly cleaned. The laser is an efficient cleaning tool that removes all traces of residual grease.
The components may be contaminated with drawing or cooling lubricants and anti-rust oils used in the manufacturing process. These residues are usually not visible, but they can seriously reduce the quality of subsequent high-energy bonding or bonding processes. Especially in the automotive industry and its highly automated manufacturing environment, standards for the quality and reliability of components have been increasing, and surface contamination detection has become an indispensable part of the production process.
Traditional cleaning methods are time consuming, impossible to automate, and often have harmful effects on the environment. At the same time, there is no reliable method for measuring the cleaning effect. In accordance with standards such as VDA19 and corresponding ISO guidelines, a program for the uniform inspection of particulate contamination of automotive functional components was established. Recently, more attention to liquid contamination has made laser cleaning the protagonist. The pulsed laser can quickly evaporate the residual liquid in the target area, the effect can be measured, can be repeated, the process is environmentally friendly and can be automated.
● Cleanliness improves reliability
In the production of large gear assemblies, laser welding has become a popular choice due to the low energy required to reduce distortion. A large number of components in automotive powertrains must meet stringent quality standards. They are made of different materials and alloys, and it is difficult or impossible to use conventional welding techniques for welding.
● Powerful laser, shorter cycle
Automotive manufacturers need a fast, automated way to thoroughly clean the surface residues for powerful, void-free and micro-crack welding and bonding. Laser cleaning systems, especially laser cleaning systems using pulsed solid-state lasers, can meet all of these requirements. The main factors that determine the choice of laser are the degree of cleanliness required and the cycle time of the cleaning components.
● Fast and efficient arrival at designated locations
Time is critical in highly automated, high volume production processes. Unlike conventional cleaning methods where the entire assembly needs to be immersed in a solvent, or using abrasives or thermal shock techniques, laser cleaning can be performed on specific functional surfaces such as welds and bonds, typically no more than a few square millimeters in size.
The time required for cleaning depends on the time required for laser welding, typically between 4 and 10 seconds. Another advantage of selective cleaning is that it eliminates the intermediate steps of transporting components from cleanliness to the production line. The cleaning laser is integrated in the production line just upstream of the welding.
● Corner cleaning
To clean a specific surface, the scanner optics move the laser beam back and forth quickly on the workpiece. Different scanning patterns and speeds can be used depending on the desired cleaning effect. The linear scanning motion can be used to clean light contamination; if deeper cleansing is required, overlapping circular scanning motions (similar to those of electric toothbrushes) can be used. In this case, the pulse of the laser light passes through the same spot many times, thereby enhancing the cleaning action.
Typical laser cleaning applications: Quickly remove residue adhering to the surface of transmission components.
The laser can also "clean the rounded corners" without repositioning the workpiece. Place the mirror and direct the laser beam while cleaning the top and bottom surfaces of the tubular or contour assembly.
● Clean only places that need cleaning
The laser can clean extremely sensitive surfaces such as aluminum, carbon fiber composites or coated parts without damaging the underlying material. Alternatively, by choosing different parameter sets, the same laser can also roughen the surface and increase the bond strength. The flexibility of laser tools allows them to be applied to the various tasks required. According to the principle of “do not exceed the necessary limit, minimize as much as possible”, the laser power and pulse frequency suitable for various applications are determined. This method can bring benefits to customers because the cost of laser cleaning is about five times lower than the wet chemical cleaning process.
● Is it clean enough?
The criteria and guidelines for particulate pollution inspection procedures have been established and it is expected that these standards and guidelines will cover liquid pollution sooner or later.
Using scanning optics can achieve different cleaning effects by changing the scanning method. If a part of the beam is reflected by the mirror, it is even possible to clean the upper and lower surfaces of the assembly at the same time without repositioning the workpiece.
● Another cleaning option
"Clean" means not only that the effect of laser processing is very clean, but also that the process itself is a green process. Unlike wet chemical processes, it does not use toxic solvents and avoids the noise generated by the use of abrasive methods. In addition, the laser cleaning is gentle and the process speed is obviously faster than other methods. These advantages have been recognized by the automotive industry, and other industries are currently following up, because lasers are a versatile cleaning tool.
Pulsed lasers can be used to selectively clean bonded surfaces or small objects (such as ancient coins), while UV lasers are ideal for cleaning large components. They can be used to remove liquid residues from CFRP components or by setting other parameters to help remove stubborn paint or rust. As a high-tech cleaning tool, lasers have great potential.