3D Printing Slicer

A 3D slicer defines how a model is built and instructs the 3D printer how it’s printed.
Learn all about this essential software in 3D printing.

Table of Contents

What is a 3D Printing Slicer?

A 3D printing slicer is a program that converts digital 3D models into printing instructions for a given 3D printer to build an object. In addition to the model itself, the instructions contain user-entered 3D printing parameters, such as layer height, speed, and support structure settings.

Every 3D printing technology creates 3D objects by adding material layer by layer. Slicer software is therefore appropriately named because it virtually “cuts” 3D models into many horizontal 2D layers that will later be printed, one at a time.

In this article, we’ll discuss the role of slicers in 3D printing, detail how 3D slicing works for FDM and resin, and finally finish up with slicing in other 3D printing technologies. 

How does a slicer work?

With a 3D model in a format that a slicer can understand, the next step is to provide printing details, like layer height, speed, part positioning, and several other manufacturing-related settings. These user-entered values are defined prior to printing.

The 3D model can also be partially modified during this step. You can change dimensions through scaling features, and parts can be partially or entirely hollowed, filled with infill patterns, and provided wall-thickness values. This step also includes enabling support structures, which is one of the most practical features of a 3D slicer.

The 3D printing parameters will differ depending on the type of technology (FDM or resin-based) as well as on the type of material (different kinds of filaments for FDM require different settings, for example), the object to be printed, and its intended use. So let’s see what comes into play for each.

The video below shows a visual demonstration of using a slicer.

Credit: Advanced engineering technologies

Slicer Interface: Graphic Area Elements

Slicers offer a 3D graphics area where you can visualize how the model transforms into a layered representation. Every slicer has its unique interface style, but there are common elements to consider:

Sliced Model

Printing bed plane: It represents the shape and dimensions of the real bed. Here you can visualize a comparison between the object and the space provided by the printer. With this, you have a graphical representation for:

  • Coordinate systems.
  • Model orientation, scale and position relative to the bed.
  • How the model adheres to the bed.
  • If you are printing multiple objects, you can check how they’ll arrange.


Visualization and camera control:
Through icon bars and mouse/keyboard controls.
Model positioning controls: Same as the previous point.
Layer preview: Once the parameters are ready, the interface lets you scroll through each layer. It allows you to check how the material would be distributed within. The following are the main types of distributions:
Shell: The external lines that define the shape of the object.
Outer wall: The material line that defines the surface of the shape.
Inner walls: The material lines that define the shell thickness.
Infill: Fixes density percentage inside the object. There are many possible patterns to distribute the material within the hollow space.
Supports: Structures made for overhangs. We need them to avoid layers collapsing during the printing process if their overhang. You can generate them automatically or manage manually for better control over the result.

The graphic below shows that if we tilt the cover up a little then the slicer will suggest and create supports between the model and the bed.

Supports between bed and model

Adhesion layers: Sometimes an object has poor contact area with the bed, considering it needs to stick well during the printing process. There are many more factors that could affect adhesion, like part height, bed surface rugosity, type of material and printing speed. Regardless of the case, slicers offer the following structures as a solution for this.
Raft: A thick plate between the part and the printing bed.
Skirt: A single line around the part. It allows testing material flow and bed leveling before starting with the part itself.

Raft

Skirt

Slicing Settings Panel

This is where you really control what the printer will do, through specific settings and commands. This marks the difference between the beginner and an experienced user. Depending on which slicer you use, this could either be an easy task with suggested default settings, basic and approachable settings or a highly complex set of manual options. Every software has its own criteria, but the following are key concepts:

Layer Height 

Layer height: The most important setting. Defines how thick each layer is and whether the object will be strong or weak, print faster or slower. This is also fundamental for resolution quality. It should be clear that almost all other settings will depend on layer height.
Line width: It refers to the horizontal thickness of each extruded line.
Shell thickness: Higher thickness allows a stronger and better surface finish at the expense of using more material.
Top and Bottom thickness: Quantity of solid layers for the top and bottom sides of your model.

The visual below shows where these settings are:

Layer Height and Layer Thickness

Infill

Infill settings: Defines the inner material density percentage and how is patterned. Each pattern is a strategy for adding material depending on design intent like material saving, weight, stiffness and printing efficiency.

Infill Settings: (eg: Wiggle)

Wiggle infill

Temperatures

Extruder temperature: Defines how the plastic flowing through the nozzle will behave. Depending on which material you use, there will be a temperature range to work with. Conveniently, the product you bought should have a technical sheet for thermic properties. You can see the datasheets for both PLA and PETG here.

Bed Temperature: Depending on the type of plastic you use, it may be worth checking on the manufacturers website, but having a heated bed is a must when using PLA or PETG as these tend to warp or shrink upon cooling. TPU plastic doesnt require a heated bed.

Extruder and Bed Temperatures

Speed

Print speed: How fast the model will print. Yes, you get a quicker result, but you’ll lose quality and the process will be more prone to error.

Printer Speeds

Cooling

Cooling settings: Affects how the cooling fan will work during the process. Setting decisions are based mainly on material properties.

Printer Cooling

Supports

Support settings: Criteria vary from software to software. Regardless, all slicers will generate automatic supports where needed. Major manual settings are minimum overhang angle and some other settings for specifying areas you want to protect from scaring.

Adhesion structure settings: Here you define how you want to apply rafts, brims and skirts.