Laser Welding of Dissimilar materials

Many manufacturing industries merge two or more materials to boost productivity and save cost. Laser welding of dissimilar material is a process that uses a concentrated laser beam to join different materials under specific conditions. Dissimilar material welding allows you to get more out of each metal’s special characteristics. With the right laser radiation parameters, even the most difficult metal component can be welded seamlessly.

However, different engineering metals have unique physical and chemical properties. Hence, it is important to consider some key factors before welding them. This article explains some factors to consider when welding different metal parts and their use in various applications across manufacturing industries.

Factors Affecting Laser Welding of Plastics and Metals

The use of suitable metals and plastics determines the overall success of the welding process. It is important to consider the following before joining different material types using a laser beam.

· Melting Point

The difference in melting point of plastic materials plays a key role in the quality of the resulting weld. A significant variation in melting point may lead to weld failure. The plastic with a lower melting point heats up and liquefies faster than the other one. This can result in overheating, charring and evaporation of the alloy elements.

However, pre heating the material with a higher melting point and using filler materials will ensure that the plastics melt and fuse together simultaneously.

· Linear Expansion Coefficients

The rate at which different plastic types expand and contracts in response to a change in temperature differs. Plastics with larger coefficient of linear expansion have a higher shrinkage rate when cooling. Defects including cracking and distortion of the heat affected zone may be produced. Hence, it is important to use materials with similar linear expansion coefficients when manufacturing structural components.

· Thermal Conductivity

The ability to conduct thermal energy differs among metals. This property may affect the quality and quantity of heat transfer during the laser welding process. If the use of metals with difference in thermal conductivity is unavoidable, it is important to control the laser parameters. Regulating these parameters helps to prevent mechanical distortion for parts with complex shapes.

· Electromagnetic Properties

To successfully carry out laser plastic welding, one must consider their electromagnetic properties of the different polymer type. The difference in the level of absorption of the laser energy of materials may cause changes at the weld joint interface. Plastics with lower absorption properties heats up more slowly and require a relatively higher power density.

· Electrochemical Characteristics

A large difference in the electrochemical properties of metals may result in intermetallic compound formation. These intermetallic compounds may be brittle which makes weld seams prone to cracks and fractures.

Additionally, galvanic corrosion may occur when these metals are in close contact with moisture. Galvanic corrosion can lead to aesthetic damage and may affect the functionality of the part.

· Automotive Industry

Welding of dissimilar plastic materials using a laser light is becoming a norm in the automotive industry. With this technology, auto part manufacturers can integrate lightweight materials including aluminum and steel into a vehicle component.

Furthermore, laser welding of different materials eliminates the use of fasteners in the production interior components and chassis system. These mechanical fasteners add to the total weight of a car. Overall, welding different materials improves fuel efficiency while meeting tight tolerances.

· Aerospace Industry

The process of welding various materials in the aerospace industry is nothing new. This laser welding contour process is used when bonding a metal component to composite materials. Hybridization of titanium with carbon fiber reinforced plastic is particularly useful in the production of aircraft structural components. The mixture of the two materials gives a product that has a light weight even for very large parts.

· Medical Device Industry

The laser plastic welding process plays a key role when manufacturing medical tools and devices. Because of the highly concentrated laser beam used, it merges materials with a high degree of accuracy and precision. This is especially important in medical industry where a slight mistake may impair the functionality of a part. However, before using any transmission welding method, it is important to confirm their level of biocompatibility of the material with body fluid.