Standardising File Formats – An Ongoing Challenge For AM Service Providers

With dozens of different 3D file formats used in the 3D printing industry, establishing a standardised, universal file format has been a challenge. 
 
A lack of a standard file format creates a lot of issues. For example, you, as a 3D printing service provider, have probably been in a situation where you can’t accept customer’s files because your software or hardware doesn’t support it. 
 
As the industry slowly moves to establish a single file format for AM, we explore new file format alternatives and tools to make your 3D printing services even more flexible. 
 

STL remains the industry standard 

 
To print a three-dimensional object, a 3D printer needs a digital blueprint of the object. This is just a file that stores all the relevant data about the object such as geometry, colour, texture and materials. 
 
STL files have long been the most commonly used file format for 3D printing and remain in widespread use among companies offering AM services. However, while the format has proven effective for many applications, it has yet to catch up with many of the more recent innovations in additive manufacturing.
 
The STL file format was invented in the mid-1980s to enable CAD software to transmit files to print 3D objects. Using STL, a design in CAD is exported as an STL file, which describes a three-dimensional object as a series of linked triangles (polygons).
 
Despite a lot of advancements happening in the industry, the STL format has remained largely unchanged for over 30 years. As the 3D printing industry continues to develop and evolve, the limitations of the STL format has become more readily apparent, especially when using 3D printing to design complex production parts.  
 
Here are just some of the challenges of using STL files: 
 

• Accurately defining complex or large geometric shapes and structures can be difficult and involves creating files that can become impractically large (e.g. several gigabytes). These files take a long time to send to a 3D printer and in some cases can be so large that a 3D printer won’t be able to accept the entire file. 

• The format doesn’t specify the information about colour, texture or material.

• The STL format can’t embed any other data beyond the design, including information related to copyright and file security.

• Modifying the file is difficult. The file format can’t distinguish between minor and major changes so any change means the entire workflow must start over, which can add hours to the design process.

 
These limitations, along with the growing popularity of 3D printing services over the past 30 years, have led to several efforts to establish a new standard file format for AM, with varying degrees of success.
 

Modern STL contenders 

 
To accelerate the industrialisation of the technology, the AM industry needs to develop an enhanced 3D data format, which can maintain the fidelity of the original CAD. 
 
The American Society for Testing and Materials (ASTM) Standards initiated one of the first projects to develop a new file format for AM. They eventually came up with the AMF 3D printer file format in 2011. It’s an XML based format with native support for geometry, scale, colour, materials, lattices, duplicates and orientation. 
 
AMF file format also introduces the concept of print constellations, allowing information on multiple objects to be positioned and arranged together. For example, one of the benefits it provides is increased packing efficiency. 
 
Additionally, with the AMF 3D printer file format, you can specify the scale of the design in different units. The lack of this feature is a source of great frustration for STL users.
 

The 3MF file format

 
In the meantime, Microsoft came up with the 3MF format, designed to become an ultimate alternative to the STL file format, in 2015.
 
Unlike the ASTM, which kept the development process to a select few experts, Microsoft has set up a Consortium to govern the development and progress of the 3MF format. 
 
One advantage in the newer 3MF is the format’s inherent ability to understand and treat different segments of the geometry based on purposes, such as marking certain segments as lattice fills and others as support structures.
 
In the last two years, there have been several updates to 3MF, including four extensions for Materials and Properties, Production, Beam Lattice and Slice. More recently, the 3MF Consortium has introduced the Secure Content extension, responsible for the encryption of sensitive AM data. 
 
Furthermore, 3MF is packed with several built-in features unavailable in STL like complex shape data with low file sizes, one or multiple textures and multiple colour data. 
 
In addition to AMF and 3MF, other file formats available for 3D printing include STEP, IGES, NURBS, OBJ and VRML. STEP has also been considered as a potential replacement for STL, although its relative complexity compared to other formats mean it has yet to receive widespread acceptance.
 
Ironically, the new file formats are being rather slowly adopted within the AM industry that is so closely associated with innovation. 
 
With the industry being reluctant to switch to more efficient formats, a standardised file format for AM is still likely to be some time away. 
 

Creating an interoperable workflow 

 
That said, AM service providers must be able to adapt to the lack of a standardised file format.
 
When a customer wants to order from you, it must be a top priority for you to let them place an order in any file format suitable for 3D printing.  
 
However, offering this level of flexibility is often easier said than done, considering the number of 3D file formats that you must be able to support. 
 
On top of that, many of these file formats are tied to specific AM hardware or software, which means you may need to purchase multiple software licenses to deliver your services.
 
To avoid costly investment in multiple licences, it makes sense to integrate a specialised system that can support multiple file formats and convert customers’ files into the formats supported by your machines. 
 
Workflow automation software, developed for 3D printing, is arguably the best solution. Such software can help you set up a centralised platform, which will allow your customers to place 3D printing orders through your website, and you – to automatically price and manage incoming requests.
 
Advanced workflow software can support multiple file formats – AMFG, as an example, supports more than 40 – allowing you to increase file format compatibility and, therefore, enhance customer service. 
 
Ultimately, the case for standardisation remains strong, so companies offering AM services must be willing to explore the available options and take an objective stance on which will be most suitable for their and their customers’ requirements. 
 
The faster the industry is moving away from STL, the closer we are to the vision of a file format that can truly serve the evolving needs of the additive manufacturing sector.