Prototyping Technology Spotlight: SLS

Over the years, we’ve written a lot about SLS – Selective Laser Sintering, also called Laser Sintering – as a versatile prototyping technology which opens up a lot of possibilities for product and technology design engineers.

In this short article we’re going to ‘spotlight’ some of the key benefits and discuss when and why to choose SLS, along with some of the finishing options available.

SLS technology at Prototype Projects

At Prototype Projects we recently invested in a second SLS Machine, thus doubling our capacity.

This extra capacity allows us to speed up turnaround times on certain specifications of SLS parts and in many cases to despatch parts next day. (Orders for next day despatch must be received by 5.00pm)

Both of our SLS machines are Formiga P110 LS machines, and are manufactured by EOS GmbH.

The Formiga P110 Laser Sintering machine is among the most technically advanced and versatile 3D Printing and additive manufacturing machines in the world, capable of delivering very high quality parts in a relatively short period of time.

See our finishing and dispatch options for details of the next day SLS service.

The complex part shapes that can be achieved using the SLS process make it applicable across a range of industry sectors. As well as prototype parts, SLS can also be used to manufacture production parts for use in working models and finished products.

Main advantages of SLS in a nutshell

The main advantages of SLS as a prototyping technology are:

• Speed: build time is relatively fast, depending on size and complexity of the part, meaning that in many cases the part can be built overnight and dispatched next day. By its nature, no post-curing is required, though if extra finishing is required (see below) this may extend the dispatch time.

• Part complexity: fine levels of details and accuracy are achievable (because no supports are required during the build), which may not be possible with SLA, FDM or DLP.

• Function: SLS can be used to make flexible and working parts such as clasps and fasteners can be made, as well as parts with hollow internal cavities.

• Finishing options: SLS parts can be shot blasted to smooth them and then painted, sprayed or dyed and lacquered.

• Durability: SLS parts manufactured from PA 2200 can be used for both prototyping and production manufacturing due to the stability and resilience of this material.

Key aspects of SLS technology

Like all the 3D printing and other forms of prototyping work we do, the benefit of the technology is part process, part material, part finishing.

As the word ‘sintering’ in the name suggests, the SLS process consists of successive layers of powder material deposited onto a base plate, with each successive layer being fused or ‘sintered’ together by the heat of a highly accurate laser. The ‘laser sintering’ hardens the material, layer after layer, until the part takes shape and is complete.

In term of the build dimensions and detail, SLS parts layer thickness (layer definition) and build volume dimensions offered by Prototype Projects are as follows:

• Build layer available in 0.1 mm (NR)
• Effective build volume – 200mm x 250mm x 330mm (Z)

Uses of SLS

SLS is an ideal technology for both prototyping and additive manufacturing. Due to the fact that the SLS process obviates the need for supports during the production process, more geometrically complex parts (for instance with internal cavities) can be produced than is possible with other 3D printing processes.

It therefore lends itself well to prototyping for both presentation and functional purposes, and additive manufacturing of small quantities of production parts.

SLS Material

At Prototype Projects we make SLS prototype parts using PA 2200 (based on a polyamide 12) material. The property profile of this material is well balanced, allowing us to produce simple or complex SLS parts for a range of different applications.

Laser-sintered parts made from PA 2200 possess the following material properties:

• Strength and rigidity
• Mechanical functions, ideal as a substitute for injection moulding plastics in parts such as clips and brackets
• Abrasion resistance, ideal in parts with movable components
• Long-term stability
• Detail resolution
• Biocompatibility for EN ISO 10993-1 and USP/level VI/121 °C, ideal for medical applications
• Food contact compliance to EU plastics directive 2002/72/EC (exception: foodstuffs with high alcohol content)
• Chemical resistance
• Ecological valuation – US Pharmacopeia Class VI Approved

SLS Part Finishing

Parts straight of the SLS machine may be naturally textured or rough to the touch, so smoothing is a popular finishing option.

Once smoothed using a blasting process to the required level, the part can be coloured using a dyeing, hand painting or spray painting process in a variety of colours.

See our article on the dyeing options available with SLS parts.

Having been coloured using whatever method the part can be lacquered – or lacquer can be applied to the natural white material after it has been smoothed.

Quotes and ordering

As outlined at the beginning of this article, we can manufacture many SLS orders overnight for dispatch next day, depending on the exact part specification.

Click here to request a quote or contact us on 01763 249760.