Laser cladding processes can be broadly categorized into two types based on the method of material supply: pre-placed laser cladding and synchronous laser cladding.
Pre-placed laser cladding involves placing the cladding material on the substrate surface at the designated cladding area beforehand, followed by laser beam irradiation and melting. The cladding material is added in powder or filament form, with powder being the most common.
Synchronous laser cladding involves simultaneously feeding powdered or filamentous cladding material into the molten pool through a nozzle during the cladding process. The cladding material is again added in powder or filament form, with powder being the most common.
Filament-fed laser cladding offers advantages such as high deposition rate, excellent material utilization, high metallurgical bonding strength, low dilution rate, and small heat-affected zone, but it involves complex thermo-physical-metallurgical multi-field coupling mechanisms.
The main process flow for pre-placed laser cladding is: substrate surface pretreatment – pre-placement of cladding material – preheating – laser cladding – post-heat treatment.
The main process flow of synchronous laser cladding is: substrate surface pretreatment – preheating – synchronous laser cladding – post-heat treatment.
According to the process flow, the main processes related to laser cladding are the substrate surface pretreatment method, the cladding material feeding method, preheating, and post-heat treatment.
Ultra-high-speed laser cladding (EHLA) is a novel surface treatment technology that has attracted attention due to its high cladding efficiency and rapid cooling rate. It can maintain a good metallurgical bond between the coating and the substrate with low heat input, and promotes the refinement of microstructure and uniform distribution of composition.
Laser working principle: Laser cladding equipment consists of: laser, cooling unit, powder feeding mechanism, processing table, etc.
In recent years, for specific application scenarios, new equipment designs have emerged that optimize material feeding uniformity and cooling effect. Related patented equipment, such as columnar material surface repair systems and slow cooling devices, have been developed.
Laser Selection: Most mainstream laser types support laser cladding processes, such as CO2 lasers, solid-state lasers, fiber lasers, and semiconductor lasers.
Regarding process innovation, dual-spot technology, by using one laser beam for preheating and another for cladding, can reduce thermal cracking and deformation of the brake disc, and improve the coating cladding quality, uniformity, and bonding strength.