Post-Processing 3D Prints: Manual vs Automated Finishing

Not all 3D-printed parts are ready for use directly out of the printer. Virtually all 3D prints — whether prototypes or end-use components — require at least some degree of post-processing. 

Post-processing can be done manually, but cleaning and preparing prints by hand is time-consuming and labour-intensive. Automated 3D print post-processing solutions save your business precious time, improve uniformity of the surface finish and can meet high performance demands. 

But which kinds of post-processing systems are suitable for your 3D printers?  

In this article, we explore the basics of post-processing 3D prints whilst exploring the advantages along with the drawbacks of both manual and automated finishing. 

Manual vs Automated Post-Processing at a Glance

What Kind of Post-Processing 3D Prints Need?

Perhaps the one thing all 3D printing technologies have in common is that they need some level of post-processing after printing.  

Each 3D printing method requires different post-processing steps, depending on the specifics of the printing process. For example, an FFF print may require supports to be broken away or dissolved, whilst SLS prints need to be de powdered.  

That said, we can identify a basic 3D print finishing workflow. All of these steps don’t apply to each and every part, but the general finishing process includes: 

1. Cleaning

All prints require at least some cleaning. FFF and SLA prints need support removal, while SLA prints also need washing to remove uncured resin. SLS prints, as mentioned, don’t have support structures, but they require de-powdering. 

2. Repairs & Assembly

Sometimes prints may have small flaws that can be fixed without reprinting the entire part, such as filling small holes or gaps with putty. Multi-component parts may also require assembly using various adhesives, depending on the print material. 

3. Curing

SLA 3D printers cure most of the resin during printing, but these parts will require additional curing after printing to achieve the correct mechanical properties and appearance. 

4. Smoothing

Manufacturers use a variety of smoothing methods to improve their 3D-printed parts’ appearance and dimensional tolerances. These could include simply smoothing with sandpaper to chemical smoothing with various substances.

5. Coating

Finally, manufacturers may choose dye, paint or to apply coatings to enhance parts’ looks or performance. Various coatings used on 3D prints include paints, protective coatings, and electroplating. 

Manual Post-Processing 3D Prints — Slow but Accurate

Manual post-processing is exactly what it says on the tin. It involves carrying out all post-processing steps by hand using manual tools. 

There are a couple of reasons why manufacturers may choose to finish their 3D-printed parts manually. 

First, post-processing 3D prints by hand generally comes with low up-front costs. Since it requires only basic tools — such as files, paint brushes, and so forth — there is no need for significant investment in special machinery. 

The second reason is accuracy. Human hands are nimble and can reach into nooks and crannies that automated machines may struggle with. As such, a degree of manual finishing may always be a requirement for parts with extremely complex geometries. 

However, manual 3D print post-processing is often extremely slow and labour-intensive. It may take a worker hour or even days to finish cleaning, smoothing, and preparing particularly large or complex components. 

Naturally, the slow speed of manual post-processing increases lead times, which has a direct negative impact on your business’ productivity. As a result, producing 3D-printed parts becomes less cost-effective, which can reduce or even negate the cost-savings of not purchasing special equipment. 

In fact, according to Joseph Crabtree, the CEO of additive manufacturing post-processing solutions manufacturer AMT, manual post-processing can make up as much as 60% of a 3D-printed part’s costs. 

Although some high-precision tasks may always require a human touch, there is definitely a business case for automating 3D print post-processing. 

Why Automate Post-Processing 3D Prints?

As we have explained, automated finishing methods can drastically improve your business’ productivity. They are significantly faster than manual methods, which allows you to shorten lead times in part manufacturing and prototyping. 

The time savings benefit your company, whether you use 3D printing for manufacturing prototypes or end-use parts. By producing prototypes faster, you will shorten the product design phase and improve your time to market, while manufacturing end-use parts faster allows you to fulfil customer orders in record time.  

We also should not ignore the cost savings avoiding the laborious manual finishing processes can bring. 

Additionally, automated post-processing methods offer higher repeatability than finishing 3D prints manually. Manual processes are always vulnerable to human error, while a well-automated and closely monitored process results in more uniform results in terms of part quality and dimensional tolerances. 

Automating 3D print post-processing can also improve safety in the workplace. Some 3D printing materials (like SLA resins and some SLS powders) and the chemicals used in the finishing processes can be dangerous to handle. Self-contained, well-sealed post-processing machines reduce health and safety risks. 

Choose the Right Post-Processing Solution for Your 3D Prints

Automating 3D print finishing brings businesses significant benefits. However, since 3D printing technologies differ significantly from each other, there is no single post-processing solution that works for all of them. 

You must choose your 3D print finishing solutions based on the needs of the additive manufacturing technology you use.  

FFF

Most components produced with an FFF 3D printer will require at least support removal. This can be made easier by using water soluble support materials like BVOH or PVA. Parts can then be dropped into an Ultrasonic bath or into the Ultimaker PVA Removal Station for automated removal. 

Sanding FFF parts is a common practice as users look to smooth the layer lines associated with process. The AM Solutions M1 Basic can be used in some circumstances to automate this process. However, infill percentage, material choice and the layer height of the FFF printer used can make or break the success of using a vibratory finishing machine on FFF parts. Parts with low infill percentage can de laminate and allow water into cracks. 

The M1 works great on high strength composite parts with high infill percentage and exceptionally for metal FFF parts that often have a very rough surface finish to begin with. 

The machine’s PLC allows you to experiment with different variables and then save programs for future use. 

The M1 Basic system is also a good fit for smoothing the texture of SLS-printed components. 

SLA

SLA 3D printing requires two key post-processing steps — washing and curing. Although both can be done by hand, it is slow and could expose workers to resin and harmful IPA. A better solution is to use dedicated automated wash and cure stations, such as Formlabs Wash and Formlabs Cure. 

Formlabs Wash is a fully automated, simple solution for cleaning SLA prints of residual resin. All you have to do is place your part into the IPA-filled wash chamber and the machine cleans it quickly, gently, and thoroughly. After the process is done, it lifts the part out of the IPA to prevent damage from overexposure. 

Formlabs Cure uses 450nm light sources to cure washed SLA components quickly and reliably. It is compatible with any SLA resin and helps improve the parts’ physical quality and appearance. 

SLS

Although SLS parts are self-supported by the un-sintered powder below and around them within the build chamber you still need to remove that powder cake from around the parts once the print is completed.  

The Formlabs Fuse Sift extracts parts from the build chamber before removing un-sintered powder with its negative air pressure extraction. Once the un-sintered powder is reclaimed it can be re used for future prints making it incredibly economical. 

For many applications, a final bead blasting after sifting is required. This is often done using a manual hand blast cabinet, which can be labour intensive. The AM Efficiency CCP-2 3 in 1, Automated batch post processing solution completes the final stringent de powdering process whilst also smoothing and dying multiple parts at a time in a single system! 

Also, discover AMT’s advanced post-processing solutions. It is our new partner that can elevate the quality and efficiency of your 3D-printed components with AMT’s large scale, fully automated post processing technology.

Improve your Productivity with Automated 3D Print Finishing

It simply makes sense for additive manufacturing businesses to automate their post-processing steps as much as possible. Doing so helps them shorten lead times, introduce cost savings, and produce parts with more consistent high quality. 

But not every automation solution works for every 3D printing technology. Post processing can be highly personalised depending on the parts and application so it’s always a promising idea to speak to an expert who can work with you to discuss your technological and business needs when evaluating how you can best automate 3D print finishing. 

Even the best automation solution may not always produce perfect parts. Particularly complex 3D prints may require a final human touch for ideal results. For this reason, you can prove out your process ahead of time by requesting a free sample.  

Thanks to the automated post-processing steps, you will have time to give those few challenging components the attention they need — while your machines work on finishing other parts. 

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