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Quality in SLS prints- is it absolute or relative? The machine perspective


Image source: Shining3D


Everyone wants high quality prints, but does everyone need high quality parts? What is high quality and how can one assure he gets what’s needed?


Part quality is measured relatively to the part demands. Some would demand high dimensional accuracy and tight tolerances while others can compromise to achieve higher production rates or just prototyping. Like in every part or system design, the first step would be defining the part Requirements. To my perception, the part is considered as high quality if it can meet the requirements. Requirements can be thermal resistance, mechanical properties, surface roughness, part movement, aesthetics, geometry, size, quantity, pricing and more. If SLS was chosen as the suitable technology, then printer and materials should be considered.


Materials were discussed in the previous article and have a major effect on part quality. Unfortunately, not all printers can print all materials.

SLS 3D printing. Image source: XYZprinting


Let’s have a look at the printers’ main parameters, both desktop and industrial, to figure out opportunities and limitations.


Build chamber. Desktop printers are roughly 100X100X100(mm) or a bit larger but clearly are limited with part size. Industrial printers are much larger with size of roughly 400X400X400(mm) that enable larger parts or production of several parts simultaneously.

Laser type. The most common laser is CO2 laser with wavelengths of 10.2-10.6µm which is absorbed by polymers that heat up. Some desktop printers use IR laser diode at wavelength of 808nm (or a bit higher) that limits printing to carbon filled polymers, which means mainly black parts.

Laser power. Industrial printers would have higher laser power ranging from 30-100W while desktop printers can have much lower power (5-14W). higher laser power enables faster printing.


Scanning speed. Directly related to laser power. The higher the power the faster print. Industrial printers can print Fill at 10-12.7 m/sec.

Layer thickness. With better layer thickness control, more detailed parts are possible. Desktop printers have a layer thickness of roughly 100µ, while industrial printers have a wider range from 60-180µ.


Chamber maximal temperature. The chamber must be heated to avoid large temperature gradients and enable better sintering. Both industrial and desktop printers have a T max of 170-200°C. If high performance materials like PAEK’s are required, then a temperature of

260°C is needed (available for few industrial machines).

Nitrogen supply. Nitrogen supply is required from safety reasons and have an impact on part surface quality. Industrial printers have external or integrated nitrogen supply system with better control than desktop printers.

Price. Entry-level printers are available at 5-12K$ while industrial printers can reach 60-300K$ depends on size and specifications.

Industrial SLS 3D printer. Image source: Shining3D


Can we have similar quality for industrial and desktop printers?

It is possible but not always. The best answer would be – it depends. Since quality is not absolute but relative, it would be better to say that you can have high quality prints with desktop printers as well.


Before purchasing a printer-


Do’s:

- Get a long-term vision of your products or services

- Get a budget for the printers but don’t forget materials cost and other expenses

- Read the design manuals of the leading vendors

- Compare printers’ specs

- Reach out to the vendors

- Contact current users

- Ask as many questions as you can

- Make your benchmark samples

Don’t:

- Don’t skip the Do’s

Enjoy your high quality parts 😉


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