Finishing: How to Take 3D Printed Parts to the Next Level

At ProtoFab we offer a wide range of post-processing options that give vastly differing finishes. Some options are primarily about improving the mechanical properties of the part, while others are purely for aesthetics. Let's take a detailed look at the options available.

We offer a variety of spectacular finishing options

Electroplating

Overview

Although 3D printing materials are quite versatile, finished parts are still somewhat lacking in certain mechanical properties and aren't suitable for all applications. In many cases, the solution to this is electroplating, which significantly improves the properties of the part and gives it a finish that resembles solid metal. Electroplated plated parts have a much wider range of applications than regular 3D printed parts and look absolutely stunning.

Electroplating gives the benefits of metal without the drawbacks of traditional manufacturing

Technique

Electroplating works by depositing a thin layer of metal ions on the surface of the part through the application of electrical current. A variety of metals can be used and different effects can be achieved through variation of the thickness of the coating and different types of sanding and polishing.

Benefits

Electroplated parts feel much more substantive and when held in the hand many people swear it feels like solid metal. Needless to say, this significantly improves the aesthetics of the part and makes it much more suitable for consumer use.

In terms of mechanical properties, the improvement is even greater. Broadly speaking, there are three areas where improvement is most noticeable: strength, thermal performance and chemical resistance.

The specific improvement in strength depends on the metal used, but generally tensile strength will somewhere around 10 times greater and flexural strength will be more than 20 times greater. These improvements completely transform the part and give it a whole new range of applications.

The improvement in thermal performance is easy to understand as electroplating places a physical barrier between the photosensitive resin and the wider environment. It’s the same story for chemical resistance – the electroplating prevents potentially corrosive substances from coming into context with the 3D printed material. The same is also true for UV light, which will gradually degrade and discolor SLA 3D printed parts over time.

Colored electroplating

Standard electroplating gives an impressive finish, but if you want to take aesthetic enhancement to the next level you can consider colored electroplating. This involves the same process as the regular electroplating described above, but afterwards the metallic surface is then sprayed with special paint. The final effect is stunningly high-end and completely transforms the part.

Adding color to electroplating creates a truly stunning finish

Vacuum plating

Overview

Vacuum plating is similar to electroplating but with a much thinner metallic coating. Although electroplated parts feel solid and substantive, in some cases the added weight may not be desirable. Vacuum plating keeps the weight down while still giving an attractive metallic finish and improving mechanical properties.

Vacuum plating produces an attractive, lightweight metallic coating

Technique

First of all, the part is sprayed with a primer and is placed inside a vacuum chamber. Metal material is then added into the chamber where it is evaporated. Due to the vacuum, the metal atoms condense onto the part, and when the process is complete the part will have an even covering of the material.

Benefits

Aside from keeping the weight down, vacuum plating also allows for plating that works on highly detailed and intricate parts. Using electroplating on ultra-detailed parts may cause a loss in definition, or in some cases may simply not be feasible.

As with electroplating, mechanical properties are significantly improved in all areas, although the improvement in strength is likely to be some way behind that offered by electroplating. However, the thin plating still provides very effective resistance against UV light and corrosive substances. The main downside of vacuum plating is that due to its thinness it is prone to scratching and may not withstand a prolonged period of wear and tear.

Hydrographic printing

Overview

This is a relatively recent technique that has come forward in leaps and bounds in recent years. It is a great method of achieving detailed, vivid designs in a short period of time.

Hydrographic printing is perfect for complex patterns

Technique

The technique works by submerging a part in water with a pre-designed film floating on the surface. As the part goes into the liquid, the pattern transfers from the floating membrane onto the part. The part has to be sprayed with primer in advance and an activator substance is applied to the membrane prior to submerging. This technique was first pioneered in the 1980s but it lacked precision, and only repetitive patterns were possible. Nowadays, it's possible for software to produce precise designs that can be transferred with a high degree of accuracy.

Benefits

Hydrographic printing can produce stunningly vivid colors that take the finish of any part to the next level. It also allows for a level of design complexity that is difficult to achieve using other methods. Hand-painting very intricate designs is extremely time-consuming, not to mention difficult. With hydrographic printing no design is too complex, and it can be applied very quickly. The part is only immersed in the water for a few moments and the entire process from beginning to end takes just a few hours, including the preparation and drying time.

Painting

Overview

Spray painting may seem low-tech compared to some of the other finishes available, but the benefits of painting 3D printed parts should not be underestimated. Painting is cost-effective and provides significant improvements without any major drawbacks. Of course, painting is often done purely for aesthetic reasons, but it provides physical benefits too. There are also different types of paint finishes to choose from, each of which have their own unique characteristics and applications.

Example of a two-tone paint finish

Technique

Painting SLA 3D printed parts is a complex and skill-intensive process. It's not a case of just applying the paint, there are usually several coats required and multiple rounds of sanding. The part is first gently sanded to prepare it for the undercoat. The undercoat is then sprayed on under laboratory conditions, with great care taken to make sure the covering is smooth and even. There is then another round of sanding before the top coat is applied. If a part needs to be painted in multiple colors then masking tape must by carefully applied and each of the colors done in turn. Once the paint has dried the surface is polished to achieve the required finish.

Benefits

Aside from looking stunning, painting parts has similar effect to plating them in that it protects the surface from UV light. Discoloration and degradation over time are some of the main downsides of printing using photosensitive resin, and painting solves this to a large extent. It also helps protect against other types of corrosion, for example exposure to chemical substances.

Painting also helps mask any joins or imperfections that may have resulted from the printing process. For example, some parts need to have drainage holes that are later filled in during post-processing, and certain designs need to be printed in sections and glued together. Painting is a great way making such parts appear perfectly smooth and seamless.

Different paint finishes

At ProtoFab we offer three main style of paint finish: glossy, matte and leather-effect. Let's take a look at each in turn.

Glossy paint has an attractive shine that accentuates the lines and curves of a design. A coat of glossy paint and a period of skilled polishing can make even a very plain part look eye-catching.

Glossy paint produces an eye-catching shine

A matte finish adds textural depth and can bring a sense of quality and solidity to a part. Although not as shiny as a glossy finish, when done well it can be equally eye-catching.

A matte finish makes parts look high-quality and substantive

We also offer more complex finishing styles such as leather-effect painting. This gives the part a highly detailed textured look and feel. Not all parts suit this style, but when used appropriately it can turn a basic part into something that looks and feels high-end. Different paint finishes have a major effect on the final look of the part so it's important to consider the different options and work out which look best suits your part.

Leather-effect painting totally transforms the look and feel of the part