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Formlabs Fuse 1 – Desktop SLS 3D Printing

Introduction With 3D printing these days, you can make just about anything due to the sheer amount of materials and technologies available. The scope of these prints are massive, with parts such as jigs or fixtures, to early stage 3D …

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Ross Campbell

November 25, 2020

Introduction

With 3D printing these days, you can make just about anything due to the sheer amount of materials and technologies available. The scope of these prints are massive, with parts such as jigs or fixtures, to early stage 3D printed human organs. However, the most adaptable material, Nylon, is limited when it comes to Fused Deposition Modelling (FDM). This is the result of the limited geometries the print head can produce due to its size.  

Stereolithography (SLA) also has limitations, however for entirely different reasons, those being nylon resins are very expensive and perform unreliably. It is because of these reasons that the Form 2, 3 and 3L are not compatible with any nylon resins.

In order to utilise nylon, FormLabs are using Selective Laser Sintering (SLS), in their new desktop SLS 3D printer, the Fuse 1.

Formlabs-Fuse-1-Black-Background

How SLS 3D Printing Works

In general, the SLS printing process uses a high powered laser to fuse small particles of polymer powder together.

SLS-Printing-Diagram
SLS Printing Diagram
  1. Powder is dispersed in a thin layer on top of a platform inside of the build chamber.
  2. The printer preheats the powder to a temperature just below the melting point of the raw material. As a result, it’s easier for the laser beam to raise the temperature of specific regions of the powder bed as it traces the model to solidify a part.
  3. The laser scans a cross-section of the 3D model, heating the powder to just below or right at the melting point of the material. The particles then fuse together mechanically to create one solid part. The unfused powder supports the part during printing and eliminates the need for dedicated support structures.
  4. The build platform lowers by one layer into the build chamber, typically between 50 to 200 microns, and a recoater applies a new layer of powder material on top. The laser then scans the next cross-section of the build.
  5. This process repeats for each layer until parts are complete, and the finished parts are left to cool down gradually inside the printer.
  6. Once parts have cooled, the build chamber is removed from the printer and transferred to a cleaning station, separating the printed parts and cleaning of the excess powder.

Post-Processing and Part Recovery

SLS post-processing provides consistent results for prints with multiple parts while also maintaining little time and labour. When the print is finished the parts need to be separated and the excess powder needs to be removed. Generally, the easiest way to do this is to manually use a media blaster, or compressed air.

The finish on SLS parts is normally quite rough and grainy when it’s removed from the printer.  However, there are a lot of options for post-processing Nylon, including; metal coating, bonding, powder coating, flocking, tumbling, dyeing, painting and stove enamelling.

After the part is removed the excess powder can be filtered to remove large particles, and then recycled. As the unfused powder can slightly degrade due to the high temperatures, new powder should be added before future jobs.  As a result of being able to re-use material, SLS produces very little waste compared to other manufacturing methods.

post-processing-fuse-1

Types of SLS Printers

The process above is used for all SLS printers, what usually differs is the laser type and build volume size. Temperature control, layer deposition and power dispensing are also dealt with differently depending on the printer.

When it comes to SLS the level of precision and control needs to be tightly monitored. The temperature of the incomplete parts and powder must be kept within 2°C during all stages f the process.

Industrial

Industrial SLS printers use high powered carbon dioxide lasers, however, due to having the larger build volume, the system is more complex. These printers require an inert environment so that the powder doesn’t oxidise or degrade. Therefore, using these printers requires specialized air handling equipment, as well as a lot of power and space. Even the smallest ones need 10m² of space for installation.

Workbench/Destop

A desktop SLS 3D printer like the Fuse 1, provides quality on par with industrial machines, but in a compact and practical form. They use diode or fibre lasers instead of carbon dioxide, to produce the same beam quality, but at smaller costs. The workbench printers also require less heating and as a result the powder is exposed for less time, making the need for the air handling equipment negligible. Finally, as the workbench printers require a lot less energy, there is no need for specialised power and can run off AC. 

Type-Of-Printer-Table

Specialities and Advantages

A lot of 3D printers utilise the SLS process to produce metal prints. This is where the Fuse 1 is special because it prints Nylon, while still using the high powered laser. This means that instead of ‘sintering,’ the material, it’s closer to hardening and bonding it together. Although SLS is not something new to the market, the ability to produce industrial grade results while on a desktop SLS 3D printer is, making the Fuse 1 the first of its kind.  

In addition to the flexibility in geometry, SLS has other advantages over FDM for engineering and design applications. As you don’t not need any support material on anything you can print merged parts in one print. Consequently, you do not need to split up your parts into an assembly and re-join them later. When it comes to the specific geometries not available to FDM, SLS enables you to create complicated interior components allowing engineers to replicate parts with high levels of precision. 

Nylon Materials

Nylon is the most common material used for SLS 3D printing. It’s a thermoplastic with lightweight, strong and flexible characteristics, it’s also resistant to impacts, heat, UV light, chemicals and water. For this reason, it’s perfect for both rapid prototyping and production.

The Fuse 1 was designed to best accommodate Nylon from the start, so much so that it solely prints Nylon. Consequently, the Nylon powder is made to the highest possible specification by Formlabs, so the best quality parts can be produced. They have called their material Nylon 12.

Nylon 12 is seriously strong, with a 50-52 MPa tensile strength rating and a 12% fracture strain. Their other material Nylon 11 has a 48 MPa tensile strength with a 35% fracture strain.

Material-Table

With the Fuse 1 you can print with maximum of 50% recycled powder in the machine.  The Fuse 1 can print single component powders (Nylon 11 and 12) however it can also use two component powders. For example, Nylon composites with aluminide, carbon or glass which can be used to optimise specific mechanical properties of parts. Again it’s worth mentioning that the Form 2,3 and 3L cannot print Nylon, so if you want to use nylon, the Fuse 1 is for you!

Nylon-material-products

Why Chose SLS?

Engineers usually use SLS due to its, high productivity, design freedom and low cost per part.

High productivity and throughput

SLS 3D printing is the quickest additive manufacturing method to produce durable, functional prototypes and end use parts. The lasers used to fuse the material are both faster and more accurate than the layer deposition used by FDM.

stacking-parts-together-fuse-1

To maximise the build space in the printer you can arrange multiple parts so that they are very close together. You can also use specific software to optimise productivity by leaving only the minimum clearance between part. Also parts can be added while the print is already in progress, allowing last minute design changes.

Design Freedom

Additive manufacturing method, such as Stereolithography (SLA) and FDM, need to use support material in order to make parts with features that overhang.

The reason it doesn’t require support structure is due to the power that’s encases the part while printing. With SLS printing, you produce parts which couldn’t be made previously, such as interlocking or moving parts, parts with interior channels and components as well as other complex designs. 

SLS printers are becoming a suitable rapid manufacturing method for more and more end use applications. Due to it being able to print complex designs without the need for separating the parts. Consequently, this helps cut down on both assembly time as well as weak joints/areas.

complex-sls-design

Low Cost Per Part

You can split the cost of a part into 3 sections, material, labour costs and equipment owner ship;

Material: Nylon is a common thermoplastic produced in massive quantities for industry, it is one of the cheapest materials available. This makes it cheaper than other 3D printing methods. Other cost reducers are lack of support material and waste produced by the SLS process.

Labour: The post processing required after traditional 3D printing can require a lot of time and labour, which can have a substantial impact on cost. SLS requires less labour due to the simple post processing method, therefore, reducing costs.

Equipment Ownership: As a machine produces more parts, the attributable cost of each unique part decrease. Meaning, that the more productive a machine is, the lower the cost per part. Due to the fast speed of the laser, the simple post processing, and ability to nest parts SLS printing offers the best productivity – cost per part of all additive manufacturing techniques.

sls-drill-casing

Printer Specifications

The Fuse 1 comes with a build volume of 165 x 165 x 320 mm, a print speed of 10mm/hr and an impressive 100 µm layer resolution. The printer’s body is 677 x 668 x 1059 mm, so even compared to other workbench/desktop printers it’s rather compact. However, it does weight 88kg which makes it very heavy, but that’s just a sign of quality craftsmanship and performance. The Fuse 1 uses the existing PreForm software and can print both STL. and OBJ. Files.

Desktop-SLS-3D-Printer-Formlabs-Fuse-1
The Fuse 1 desktop SLS 3D Printer

Fuse 1 Applications

As said previously SLS printing can create precise, lightweight and robust parts with complex geometries that would otherwise be unavailable. It’s also extremely repeatable due to the reusable powder in addition to the consistent technology and print results. With all these benefits it’s hard to see why you wouldn’t choose the Fuse 1 over any other printer. However, the Fuse 1 is a product designed for industrial/engineering purposes, not your average office prints.

Fuse-1-bike-seat

The uses for the Fuse 1 are limited by the material it uses, nylon. Nylon is incredibly strong and is heat, abrasion and chemically resistant, it’s friction coefficient is also very low. When you add these properties to SLSs complex geometries, the uses drastically increase. Let’s go through the features of the Fuse 1, one more time:

– High throughput
– Excellent productivity
– High uptime
– Top quality results
– Repeatability
– Low cost of ownership

The Fuse 1 can produce a massive range of high performance machine parts, from jigs and living hinges to housings and electronic components to gears and sprockets. You can also print super detailed models, for example the bike seat above, printed on the Fuse 1 at 100µm.

Conclusion

With the affordability, low maintenance and large uptime of the Fuse 1, it seems perfectly suited for designers and engineers. Compared to the Industrial SLS 3D printers, it’s far more compact and workbench friendly, all while maintaining industrial-grade performance. The only concerns are the smaller build volume and slower build time. However, when you take into account that the Fuse 1 is ten times cheaper, you can’t complain. There’s a reason it’s the first desktop SLS 3D printer to market!

Solid Print3D is here to help you with the right decisions when it comes to 3D printing. For more information, please call Solid Print3D at 01926 333 777 or email us at info@solidprint3d.co.uk

Sources: Formlabs SLS guide (click here), Formlabs Fuse 1 (click here).

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