3D-printed objects, whether metal or plastic, may also undergo one of several types of heat treatment as part of the finishing process. Like shot peening, heat treatments improve the material by reducing the stress strain. It compensates for the high and low stress areas of the item, helping to avoid failure. You may also use heat treatment to increase density or help shape the item to the final desired shape.
Following more normal heat treatments, which reduce tension and increase energy, some artifacts may undergo hot isostatic pressing. Also called HIP, this heat treatment eliminates pores and repairs any defects before the part reaches 100% theoretical density. This step is critical if the part is exposed to some harsh conditions or if fatigue failure is likely to have serious consequences. This applies to components which will be used in sectors such as:
- • Aerospace
- • Marines
- • Medical
- • Generation of pow'er
Initial heat treatment normally takes place in a vacuum furnace, while HIP generally occurs in a pressure vessel. However, some equipment can perform both functions and use rapid cooling.
Vibration systems can be used to process and polish multiple 3D-printed objects at once. To use this process, position the items to be polished in a unit that contains a ground-up material that is smoother than the 3D-printed component. This material is often ceramic, plastic, corn cob, or synthetic medium. The vibratory unit is usually tubular or bowl-shaped and may come in a variety of sizes. The unit pulsates until the medium polishes the components repeatedly.
This technique is most commonly used for metal components because the polishing medium must be softer than the component, but it can also be used to polish different types of heavy plastics. The biggest benefit is that you can finish several items at once with minimum manual effort.
One downside is that this method can damage uneven edges and corners of the piece. Because of this, it is mostly applied to round products or those with rounded edges. This method is not as reliable as some others, because it finishes the whole surface at once.