Three main manufacturing processes exist; formative, subtractive and additive processes. These manufacturing processes can be divided by the type of action or actions required to produce the final part. Formative processes form the material into the desired shape, either by using dies or moulds. Examples of formative processes are stamping, forging, drawing, rolling or extruding. Subtractive processes on the other hand remove layers of material to form the final part. Turning, milling, grinding, electro chemical machining (ECM), electric discharge machining (EDM), etc. are all examples of subtractive processes. Additive processes, which is the most recent manufacturing process, produces parts by building the part up in a layer-by-layer manner.
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Optical fibres or mirrors are used to convey the laser beam to a lens which focuses it to an optimal spot size. Different types of lasers can be used in the LMD process such as Nd:YAG laser, CO2 laser and excimer laser. [8] However, the most commonly used laser for LMD is the Nd: YAG laser. Nd:YAG lasers are solid-state lasers. The lasing material in a Nd:YAG laser is neodymium ions doped in YAG (yttrium aluminium garnet –Y3Al5O12) rod. At 1.06μm the wavelength of Nd:YAG lasers is close to that of infrared. The lasers beam in a Nd:YAG laser can be transmitted and delivered through optical fibres which is one of its greatest advantages. This allows processing of 3D components to be carried out much easier when industrial robots is used. The shorter wavelength of Nd:YAG lasers in comparison to CO2 lasers enables better beam absorption by metallic materials. However, Nd:YAG lasers are more expensive and costs more to run compared to CO2 lasers. The lasers that are used in the LMD process either be used in continuous wave (CW) or pulsed wave (PW) …show more content…
The lower heat produced in PW lasers are also beneficial in the case where features are built on thinner metal components as it means the component is less likely to distort when the LMD process is happening. CW lasers have the advantage of being to penetrate deeper into the substrate which allows better fusion between clad and substrate.
Powder feeding system
Powder feeders in the LMD system are what feed the powder to the substrate. Powder feeders basically control the amount of powder that is being deposited which is important as the powder flow rate is a key factor in deposition rates. The powder used in the LMD processes are a collection of small solid particles which have the ability to move relative to each other quite easily. However, inter-particle friction forces do occur between these small solid particles. In order to overcome these inter-particle forces and allow powder to flow easily into the powder feeder, the hoppers have high-wall angles which produce gravitational forces that exceed inter-particle forces. Powder feeder mechanisms are the systems that deliver the powder from the hopper to the carrier gas where the powder exits a nozzle. They can be categorized
Optical fibres or mirrors are used to convey the laser beam to a lens which focuses it to an optimal spot size. Different types of lasers can be used in the LMD process such as Nd:YAG laser, CO2 laser and excimer laser. [8] However, the most commonly used laser for LMD is the Nd: YAG laser. Nd:YAG lasers are solid-state lasers. The lasing material in a Nd:YAG laser is neodymium ions doped in YAG (yttrium aluminium garnet –Y3Al5O12) rod. At 1.06μm the wavelength of Nd:YAG lasers is close to that of infrared. The lasers beam in a Nd:YAG laser can be transmitted and delivered through optical fibres which is one of its greatest advantages. This allows processing of 3D components to be carried out much easier when industrial robots is used. The shorter wavelength of Nd:YAG lasers in comparison to CO2 lasers enables better beam absorption by metallic materials. However, Nd:YAG lasers are more expensive and costs more to run compared to CO2 lasers. The lasers that are used in the LMD process either be used in continuous wave (CW) or pulsed wave (PW) …show more content…
The lower heat produced in PW lasers are also beneficial in the case where features are built on thinner metal components as it means the component is less likely to distort when the LMD process is happening. CW lasers have the advantage of being to penetrate deeper into the substrate which allows better fusion between clad and substrate.
Powder feeding system
Powder feeders in the LMD system are what feed the powder to the substrate. Powder feeders basically control the amount of powder that is being deposited which is important as the powder flow rate is a key factor in deposition rates. The powder used in the LMD processes are a collection of small solid particles which have the ability to move relative to each other quite easily. However, inter-particle friction forces do occur between these small solid particles. In order to overcome these inter-particle forces and allow powder to flow easily into the powder feeder, the hoppers have high-wall angles which produce gravitational forces that exceed inter-particle forces. Powder feeder mechanisms are the systems that deliver the powder from the hopper to the carrier gas where the powder exits a nozzle. They can be categorized