Advantages of laser welding
Laser welding offers numerous advantages, such as deeper and narrower welds with high depth-width ratio, as well as bright and aesthetically pleasing welds. Additionally, it has a high power density, which leads to fast melting, low heat input to the workpiece, faster welding speeds, small thermal deformation, and minimal heat affected zone.
Moreover, the molten pool in laser welding is highly compact, which results in constant stirring and easy gas escape, leading to non-porous and deeply penetrated welds. The high cooling efficiency after welding enables refining of the weld structure, thereby resulting in high strength, toughness, and overall properties.
Furthermore, the use of strong weld technology, high-temperature heat source, and full absorption of non-metallic material components in laser welding produce a purification effect. This effect reduces the impurity content, alters the size of inclusions, and their distribution in the molten pool. Additionally, since welding electrodes or filler wires are not used, the melting zone suffers less damage, resulting in weld strength and toughness equivalent to or higher than the parent metal.
Laser welding is a highly precise and easy-to-operate technique. It employs a small focus spot to position the weld with precision, and the beam is easy to transmit and manipulate. The welding torch and nozzle do not require frequent changes, reducing shutdown time and increasing production efficiency. Additionally, it has no light inertia and can stop and restart quickly.
This welding technique operates in a non-contact atmospheric environment. The energy is derived from the laser, which means there is no physical contact with the workpiece, and no force is applied to it. Magnetic fields have no impact on laser welding, and due to the low average heat input and high machining accuracy, reprocessing costs can be reduced. Moreover, the operating cost of laser welding is low, which further reduces the cost of the workpiece.
Laser welding is easy to automate, and it enables the manipulation of beam intensity and precise positioning.
Different ways of laser welding
According to the working mode of laser welding, it can be divided into:
Galvanometer welding utilizes the rapid scanning function of a galvanometer to pre-set the welding path, manipulate laser energy, and adjust other parameters on a computer.
This method offers faster welding speeds, high precision, and a good beam mode, making it a preferred choice for fine welding applications.
Lap welding/splice welding
This is a welding technique used to join two plates together, regardless of whether they have the same thickness or material composition. It finds widespread use in manufacturing automobiles, container shells, metal frames, and filing cabinets.
This process utilizes a high-energy laser pulse generated by the laser to instantly heat the metal, forming a short molten pool. The molten pool then solidifies before the next pulse is applied. This technique offers several advantages, including faster speed, high efficiency, large height, small deformation, and a smaller heat-affected zone. It is commonly used for jewelry making, welding advertising words, and other similar applications.
There are two methods of penetration welding:
The first is heat conduction welding, in which the heat is transferred from the upper material to the lower contact surface, effectively welding the two materials together.
The second method involves using a laser to heat the lower material by passing it through an upper, transparent material such as plastic. This process joins the upper and lower materials together.
This welding technique is also known as oscillation welding.
During the welding process, the laser beam is moved back and forth along the weld track to enhance the weld’s tolerance requirements and reduce the impact of pores.
In laser welding, precise control of the laser power is crucial for the weld’s quality, especially at the start and end of the welding process.
Metal’s absorptivity and reflectivity to the laser vary significantly at different stages of melting.
Experimental results indicate that excellent welding quality can be achieved by using segmented power control at the beginning and end of the welding process.
However, laser welding without segmented control can lead to noticeable start and end effects.