One of the most accurate additive manufacturing processes is Laser Sintering (LS), and the experts at Ogle have worked with this technology since 2000. LS or SLS as it is also known is a well-developed additive manufacturing process that can be successfully used for both prototyping and small batch production applications.
The process uses an Argon laser, which traces the required shape direct from a 3D CAD model via an .stl file across a compacted powder bed of material. As the laser interacts with the first layer of powder it is fused – or sintered – to form the prerequisite shape, and as each layer is completed the powder bed drops down fractionally so the next layer of powder is introduced to the laser and can be sintered and bonded to the previous layer. The powder bed provides any necessary support for the parts that are being built, negating the requirement for any additional supports to be built into the design – a favourable difference from stereolithography. Once the part is complete, it is raised out of the powder bed and any excess powder can simply be removed by brushing it away.
A distinct advantage of the LS process is that because it is fully self-supporting, it allows for parts to be built within other parts – with highly complex geometry that simply could not be constructed any other way. Another key advantage of this technique is the durability and strength of the materials and in addition LS produces a product that requires no post-curing.
Like any manufacturing technique however, it is not perfect. One of the disadvantages of the LS process is that it can result in parts that are porous, and for certain applications, this may necessitate the part being infiltrated to improve certain properties of the material. However, it should be stated here, that with Ogle’s EOS machines only the surface of LS parts are porous and therefore, there is no requirement for infiltration. Also, the surface finish and accuracy of LS are not of as high a standard as with Stereolithography (SL). However Ogle has now installed vibro equipment that allows the sintered parts to be tumbled in a ceramic medium allowing for the surface layering to be removed.
A specific application that illustrates this point extremely well comes in the form of a brief given to Ogle to produce a series of liquid containers – Ogle built the containers using the LS process and they all performed perfectly, with no extra post process required. The team at Ogle is fully experienced with the LS process for plastic materials and can offer comprehensive advice to clients to enable them to realize the process’ full potential – both for prototyping applications and manufacturing/production applications.
In-house LS machines at Ogle: