High Speed Sintering
High Speed Sintering (HSS) is a novel, layer by layer, powder based additive manufacturing (AM) process. The process retains the benefits of AM processes whilst simultaneously eliminating drawbacks such as machine cost and process speed.
The HSS Process
In common with all Additive Manufacturing techniques, the HSS manufacturing process begins with a CAD model. This model is then sliced into 2D layers typically of 0.1mm which are then transformed into black and white bitmap images, each image represents one layer within each build.
HSS employs an InkJet printer which deposits radiation absorbing material (RAM) directly on to the surface of the powder which is followed by irradiation of the entire build surface by an IR lamp. The build volume is maintained at a temperature just below the melting point of the powder, the areas printed with RAM absorb IR significantly more than areas without, this absorption of energy is sufficient to elevate the temperature of the underlying powder to its melting point and allow sintering to occur. High Speed Sintering is a self-supporting manufacturing technique with the unsintered powder acting as a support structure.
The process of powder deposition, RAM printing and sintering is then repeated until the build is complete. The powder cake is then removed and any unsintered powder is removed to reveal the completed part(s). A key advantage of HSS is build speed, by using an InkJet printhead and an IR lamp, a large cross sectional area may be sintered in one swathe with the potential for large beds to increase production rates significantly over existing technologies. This also dictates that time per layer remains constant, regardless of the size and shape of the 2D cross section in each layer., which can help with process repeatability.
Laser Sintering is a layer by layer powder based Additive Manufacturing process. A computer model is generated and then digitally transformed into a series of 2D slices, from which the part is built layer by layer. A high powered laser is used to melt the cross sectional area of the layer and impart enough energy to causes adjacent particles to sinter (coalesce) only where the laser has scanned, leaving other areas as powder. A fresh layer of powder is deposited directly on top of the previous and the laser scans once again to sinter the top layer into the layer below. This process repeats until the part is complete leaving the sintered part surrounded by unmelted powder which is removed using compressed air to reveal the part(s). Laser Sintering is a self-supporitng manufacturing technique with the unsintered powder acting as a support structure.