How can you stop your 3D prints from warping and cracking?

1 Choose the right material

The first step to avoid warping and cracking is to select a suitable material for your 3D printing project. Different materials have different thermal properties, such as melting point, glass transition temperature, and thermal expansion coefficient. These affect how much they shrink and warp when they cool down after being extruded. Generally, materials with higher melting points and lower glass transition temperatures are more prone to warping and cracking, such as ABS, nylon, and polycarbonate. On the other hand, materials with lower melting points and higher glass transition temperatures are less likely to warp and crack, such as PLA, PETG, and TPU. You should also consider the mechanical properties of the material, such as strength, flexibility, and durability, and how they match your design requirements.

2 Adjust your printer settings

To prevent warping and cracking, you should optimize your printer settings to reduce the thermal stress on the printed layers. Pay attention to bed temperature, nozzle temperature, cooling fan, and printing speed. The bed temperature should be 10°C lower than the glass transition temperature of the material; for example, PLA has a glass transition temperature of about 60°C so a bed temperature of 50°C would be suitable. The nozzle temperature should be 10°C higher than the melting point of the material; for example, PLA has a melting point of about 180°C, so a nozzle temperature of 190°C would be suitable. The cooling fan should be set to about 50% for materials that are prone to warping and cracking and to about 100% for materials that are less prone to warping and cracking. The printing speed affects how much time the printed layers have to cool down and bond with each other; a good rule of thumb is to set it to about 40-60 mm/s, or lower if you notice any signs of warping or cracking. You can adjust the printing speed for different parts of your model as well.

3 Control your printing environment

To prevent warping and cracking, the third step is to control your printing environment and minimize any external factors that may affect the cooling process of the printed layers. Ambient temperature should be stable and consistent throughout the printing process, and ideally match the bed temperature. If possible, avoid printing in a cold or drafty room, or near a window, an air conditioner, or a heater. An enclosure is also recommended as it can help to maintain a constant temperature, reduce air flow, and protect prints from dust, moisture, and other contaminants. Additionally, using a raft can provide better adhesion, distribute thermal stress, and allow for easier removal - especially for models with large footprints, small contact areas, or sharp corners.

4 Apply post-processing techniques

The final step to prevent and fix warping and cracking is applying post-processing techniques that can enhance the appearance and performance of your prints. Sanding is a method of smoothing and leveling the surface with abrasive paper or tools. This can help remove warping or cracking defects, as well as any rough edges, blobs, or strings. Start with a coarse grit and gradually move to a finer one, always sanding in the same direction as the printed layers. Filling is a method of filling and repairing any gaps, holes, or cracks by using filler material such as epoxy, putty, or glue. This can help restore the integrity and strength of your prints, as well as hide any imperfections. Apply the filler material carefully and evenly, then remove any excess with a knife or a spatula. Lastly, coating is a method of applying protective or decorative layers of material over your prints like paint, varnish, or resin. This can prevent warping or cracking from happening again, as well as enhance the color, gloss, or texture of your prints. Choose a coating material that is compatible with your printing material and apply it in thin and even coats.

5 Here’s what else to consider

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