Post-processing is part of the design decision, not only a final cosmetic step. The right finish depends on how the part will look, feel, fit and perform in use.
For polymer powder bed fusion parts, four common options cover many engineering requirements: the standard matte surface, vapor smoothing, dyeing and shot peening. Each changes the part in a different way. Some combinations are also possible, depending on the material and the required result.
Matte finish for functional prototypes and technical parts
Straight out of the machine, the standard surface is a fine matte finish. It is often the most direct choice for functional prototypes, internal components, housings and parts where appearance is not the main requirement.
A matte finish preserves the basic character of the printed surface. It does not add a separate colour treatment or create a glossy skin. This can be useful when the part must be inspected, assembled or tested quickly.
The main point to check is handling. Fine surface texture can affect how a part feels in the hand, how dirt is retained and how easily labels or markings can be applied. For a part that will be handled frequently, a smoother surface may be easier to clean and more suitable for presentation.
Vapor smoothing for sealed surfaces and product appearance
Vapor smoothing with an AMT SF50 seals the surface and produces a finish comparable to injection molding. This makes it relevant for visible housings, handheld products, covers and other parts where surface appearance and handling are important.
The process can reduce the visual impact of the original powder bed surface and create a more uniform feel. It is also useful when the part needs a less porous surface character than the standard matte finish.
Vapor smoothing should be considered during design review. Edges, interfaces, small details and clearances may need validation after processing. If a component contains moving features or must fit with another part, the finished assembly should be tested rather than evaluated from the printed geometry alone.
Dyeing when colour is part of the specification
Dyeing is suitable when colour is needed across the part rather than only as a surface marking. Norra uses a DyeMansion DM60 for dyeing polymer parts.
A dyed finish can support product differentiation, visual grouping of components and parts intended for demonstrations or end use. It can also be considered when the standard material colour does not match the product requirement.
Colour selection should be agreed before production. The result depends on the material, the selected colour and the geometry of the part. If colour matching is critical, request an agreed sample or approval process before producing the full batch. Dyeing is a finish choice, not a substitute for a material specification or a surface treatment intended to improve mechanical performance.
Shot peening for a more consistent tactile surface
Norra uses DyeMansion PowerShot C and PowerShot S equipment for cleaning and shot peening. Shot peening can be selected when the loose powder has been removed and a more consistent surface feel is required.
This option is relevant for parts that will be handled, assembled or used in applications where surface texture matters. It can also be combined with other post-processing steps when the required appearance or handling characteristics cannot be achieved with cleaning alone.
As with any finish, inspect functional areas separately from cosmetic areas. Interfaces, sealing surfaces, holes and moving features should be checked against the final processed part, not only the nominal CAD model.
Choose the process from the use case
Start with the requirement rather than the finish name:
- Choose matte for direct, functional production without additional surface treatment.
- Choose vapor smoothing for a sealed surface, improved handling and an appearance comparable to injection molding.
- Choose dyeing when colour is part of the product or identification requirement.
- Choose shot peening when surface feel and consistency are important after cleaning.
Post-processing cannot solve every design problem. Powder bed fusion parts need openings for powder removal, and fully enclosed voids cannot be produced. Tight interfaces may also require process-specific tolerances and clearance planning. Norra’s MJF dimensional tolerance is plus or minus 0.3 percent of the nominal dimension, with a lower limit of plus or minus 0.2 mm. SLS has the same percentage tolerance, with a lower limit of plus or minus 0.3 mm.
Additive manufacturing is not automatically the right choice for every production part. There are no tooling or mould costs, but unit cost does not fall with volume in the same way as injection moulding. For recurring high-volume production, compare the total cost and required surface finish with moulding. For low-volume, customised or tooling-free production, post-processing can help make printed parts suitable for both evaluation and use.