Getting World-Class Results using Your 3D Slicing Software

Anyone — amateur and professional alike — who has ever printed a 3D CAD model has utilised 3D slicing software. Slicing programmes are the tool that translate 3D models — everything from simple geometric shapes to complex medical and architectural models — into information that the printer can use to bring the design to life. Crucially, the right 3D slicing software will allow you to strike the perfect balance between fast printing and the quality of the printed part, so it’s important to select the right tool, and make effective use of its capabilities.

How do slicing algorithms work?

The algorithms used by 3D slicing software convert CAD models into a printable form by dividing them into thin horizontal slices, based on the slope of the model’s triangles, which the 3D printer will layer on top of each other to create the finished part. The software then calculates how much material must be extruded for each layer, and for how long, then collates all the information needed to print in a G-code file, which can be read by your 3D printer.

There are two fundamental types of algorithm used for this purpose: uniform and adaptive. Uniform slicing is simple to implement but limited in its applications, using consistent layer height for the entire model, while with the more recently developed adaptive algorithms, layer height is determined slice by slice, based on part geometry (see further down).

Modern slicing algorithms for additive manufacturing applications fall into several sub-categories:

• Trivial slicing. This is the simplest approach, and works by analysing the intersections of every triangle in the mesh. While it is effective, it can be quite slow compared to other methods.

• Sweep plane slicing. This approach involves ‘sweeping’ the 3D model from the bottom up with a simulated plane, which triggers an event every time it passes a vertex or Z coordinate, using this to generate information that can be read by the printer.

• Triangle grouping. This creates slices by grouping triangles according to their Z coordinates.

• Incremental slicing. This algorithm makes use of an internal mesh rather than a triangle-based one, for additional speed and precision.

How to get the most out of your 3D slicing software

There are a wide range of slicing tools available at the time of writing, all of which offer slightly different settings and tools. Regardless of which one you are using, here are a few tips to help you get the most out of it:

• Consider the layer height (i.e. the thickness of each slice), as this is the key to getting a truly professional result. If the slices are too thick, they will be visible after printing and any fine detail will likely be lost. If the slices are too thin, a high level of detail will be achievable, but printing will take significantly longer. The optimal layer height varies between printers and materials, so be sure to check what is recommended for your particular equipment.

Sophisticated adaptive slicing algorithms like AutoDesk’s VariSlice are able to analyse the geometry of a CAD model and automatically calculate an optimal combination of layer heights in order to balance printing speed against quality. For example, thicker slices can be used for low-detail parts of the model, while thinner ones can be used strategically to ensure fine details are all visible in the finished part. While this can be accomplished manually, it will likely be too time consuming to be practical for most day-to-day jobs, which makes a powerful case for automating the process.

• Consider whether you would be better served by a standalone slicing tool, or having it integrated as part of a wider software solution. There are a number of well-regarded 3D slicing software tools, a number of which are available in open-source format, while certain 3D modelling packages incorporate slicing tools as part of their standard features package. Whichever options you choose, make sure they will integrate properly with your other software tools, as not all solutions are compatible.
• Will support materials be required? Professional slicing software will offer multiple types of support to avoid drooping during and after the printing process. Check the available options and choose the most appropriate for your design. How thick will your initial layer be? Some slicing software incorporates a dedicated setting for your initial layer. You may want to slightly increase this in order to give your printed part a little extra stability.
• Always use the check/repair function! Truly professional 3D slicing software will incorporate a tool for checking your STL files, flagging any errors and repairing them prior to printing.

Quality 3D slicing software is just as essential as a professional printer when it comes to additive manufacturing. Consider your options carefully before selecting your preferred tool, ensuring it will integrate successfully with any other platforms you are using, and the rewards will be great.