Nylon SLS Design Guide


Below is a list of guidelines and tips that you should note when designing parts for Nylon SLS.

Production Time


Minimum 2-3 Working Days

Our fastest production time for Nylon is 2-3 Working Days. This depends upon the size, quantity, quality of 3D data, and the production space available at the time of your request. We operate on a first come first served basis and have a cut off point at 3pm each day to begin collating and sending the data to the printers.

Maximum Build Size


300 X 300 X 600mm

If your project exceeds this size, then you may wish to reduce the scale of the object, or separate it into parts so it can be reassembled afterwards.

We would often recommend adding tapered location pins and corresponding holes with a clearance to accurately locate and connect parts afterwards.

Remember that when working with a digital design file, you have the opportunity to create joints that follow the contours of your object. You do not necessarily have to resort to traditional straight cuts. Think about where the joints will be best concealed on the finished object.

Pricing


The cost of Nylon is primarily based on the overall height of the parts once they have been positioned to fit as low as possible within our maximum build chamber, with a small charge per any additional parts within that height. For multiple parts the cheapest and most efficient way is to use our Nylon Container System. For an estimate on a single part you can use our Nylon Estimator.

Accuracy


±0.3mm

Generally our machines will print with a higher accuracy, they are calibrated up to ±0.15% on the X and Y axis and build with 0.1mm layers on the Z axis.

We find that some shapes and forms can be more forgiving than others, depending on the overall size, form, density, and orientation. If you are working within these tolerances we recommend you contact us first to discuss your project. It is often advised that you try printing a small number of tests or prototypes before printing parts fit for functional purposes or low level production.

Minimum wall thickness


0.5mm

This thickness will produce enough strength for most requirements.

It is defined by its ability to withstand pressure from the blow gun and bead blaster to remove the unsintered powder. There are many variants when it comes to providing a minimum thickness, as it can vary depending on the amount of structural support, shape, orientation, weight load, and generally how you need the object to perform. So smaller structures could be possible dependant on these factors. Purchasing our thickness swatch may be useful which to help you gauge the appropriate thickness.

Minimum Surface Details


0.4mm

This measurement is given for details that are extruded or embossed on a surface, meaning they are fully supported. Any less than this and these details may not appear clear and consistent on all axes.

Shell Thickness


0.7 - 3mm

The outer shell thickness all depends on how you need to object to perform and function. Parts under 3mm may contain a degree of flexibility dependant on the shape support and structure. Anything above 3mm generally provides enough strength for all forms and sizes to remain rigid.

Clearance between parts


0.4mm

This is used to determine how close 2 objects or surfaces can be printed next to each other. If they are much closer than this, then the surfaces can begin to fuse together, distort or it may become impossible to remove the unsintered powder between the separate parts.

Clearance for Interlocking Parts


0.5mm

This is determined by how close 2 objects or surfaces can be printed next to each other. If they are much closer than this, surfaces or objects can begin to fuse together.  For best results we recommend you contact us or design some small tests first.

Escape holes


It is important to remember that Nylon SLS is a powder based technology, meaning that powder can become trapped inside hollow parts if there is no hole to remove the powder from. Depending on the amount of trapped powder, we may ask to edit the part to allow for this. The larger the hole is, the more unsintered powder we are able to remove.

Trapped Powder


Deep holes or recess’s can often create problems when removing the unsintered powder. We have techniques to avoid this before printing, so let us know if this is a concern and we can discuss it further with you.

Texture


The texture of Nylon has been accurately compared to a Extra Strong Mint, or a 320 grit sand paper.

This texture is a result of the outer grains of nylon powder adhering to the outer surface of the sintered Nylon. All parts will have a grain of 0.1mm layers in the Z axis, which is often invisible to the eye and only becomes more visible on gradual curves. Sometimes you can choose a more favourable orientation to avoid this. If the orientation of the grain is important to you, please let us know and we can advise.

Flexibility


When parts are thin, they can bend and flex with pressure. You can use this to your advantage when designing functional parts for your product. Nylon SLS also has a material memory so that when thin parts bend under pressure, they then return to their as built position when the pressure is relieved.  This is demonstrated in our Nylon SLS Thickness Swatch.

D2W Nylon Design Sample


D2W has produced a set of files, including an .igs, a .3dm and a .STL file of its Nylon SLS sample that you can download here. It shows minimal clearances, living hinges, threads and the minimal detail achievable when printing in Nylon SLS.

Post Processing Options

Vibro Finishing / Polishing


£30+VAT - £50+VAT per batch

This process can be used to smooth the surface texture of objects printed in Nylon SLS. It works by placing your object in a tumbler with small ceramic stones that vibrate against the object and gradually wear away the outer texture down to a polished finish.

General Vibro Finishing  This is performed in our large Vibro Finisher and is the quicker of our processes.  1 hour within this machine improves the surface texture of Nylon prints significantly, where the outer layer of semi sintered powder is removed.  Beyond 1 hour, the ceramic chips start to eat in to the fully sintered material and therefore starts to alter the shape of your part.  The times we offer beyond 1 hour are 2, 4, 8 and 24 hours.  You can purchase a Vibro Finishing Sample to see the relative surface finishes and corresponding loss of detail.  This is quite a rough process and there are limitations on the size of parts that can so delicate or large objects may not be suitable for this.

The General Vibro Finishing services costs £30+VAT per batch, regardless of the duration that you choose.

Delicate Vibro Finishing This is performed in a smaller vibro finisher with lighter ceramic chips.  Therefore this allows you to polish small parts that would be too delicate for the General Vibro Finishing process.  Because it is a more gentle process, it takes longer to smooth the parts.  Delicate parts take 48 hours to produce nice smooth prints.  The size of the machine is smaller and therefore can only accommodate small parts.

The Delicate Vibro Finishing service costs £50+VAT per batch.

Not all parts are suitable for either of these processes.  We will advise on which would be most appropriate once we receive your CAD files.

Dyeing


+ 50% on top of the Printing Cost

We have successfully developed our own process for dying parts a single colour however complex the geometry of the part. Our extensive research allows us to produce a consistent colour which penetrates the surface of the part to a depth of 0.25mm.  This doesn’t add any thickness to the part and means that if the part is subject to wear, it will take a long time before the white core of the part is exposed.

The process adds a day to the production time.

Currently available in black. More colours will become available soon, and can also be developed upon request.

Metals


Contact Us First

We have developed a close relationship with a Hatton Garden based casting company to successfully investment cast using our Nylon SLS. Nylon does not offer as high resolution when compared to our Wax prints. If you require highly detailed prints for producing metal objects, then Wax remains your better option.  However if your level or detail is not so demanding or you parts are large, then Nylon SLS offers an exciting new alternative.

Nylon is great for studying parts before they are cast so that you can get a good idea of form and scale before casting and printing in more expensive materials. We also recommend Vibro Finishing Nylon parts to provide a smoother finish before casting.

Spraying


Nylon parts can be spray painted, but they will require Vibro Finishing and priming before applying a final spray coat. We do not offer this as a service but we can provide advice on how to do this.