Post-processing in 3D metal printing
- Dust removal,
- Heat treatment,
- machining,
- Surface finishing
- and much more
- In-House SLM Manufacturing
- Personalized consultation
- One-Stop Post-Production Services
- Certified Processes
Why Post-Processing Is Crucial in Metal 3D Printing
A metal component produced using the SLM process is rarely ready for installation right away. Powder residue—especially in channels—the connection to the build plate, residual stresses in the material, and the surface finish typical of the process are all addressed during post-processing.
Typical post-processing goals for metal components:
- Dimensional Stability and Fit Accuracy on Functional Surfaces
- Surface designed for functionality, sealing, or appearance
- Relieve Internal Stresses and Prevent Warping
- Cutting Threads, Creating Fits, and Forming Seats
The post-printing process chain
These steps may occur between the end of printing and delivery. Not every part requires all of them—however, removing excess powder and separating the part from the build plate are steps that apply to every SLM part.
1
Dust Removal & Heat Treatment
Unfused metal powder is completely removed from the component. Stress-relief annealing reduces residual stresses,
2
Cutting Away from the Building Panel
Sawing or wire EDM, followed by machining the cut surface to make it flat.
3
Remove support structures
Mechanical removal and finishing of the joints on the affected surfaces.
5
Machining Finishing
CNC machining for fits, holes, threads, seal seats, and bearing seats according to technical drawings.
6
Surface Finishing
Blasting, vibratory finishing, or polishing—depending on the function and desired appearance.
7
Testing and Documentation
Dimension inspection and, upon request, a test report or measurement report for the component.
Not sure what kind of finishing your part needs?
Please send us your CAD data and requirements. We will review the material, geometry, tolerances, and any necessary post-processing together, taking all factors into account.
3D Printing Request
Describe your project—we’ll prepare a personalized quote for you as soon as possible.
Online 3D Printing Service
Instant pricing for standard geometries – no waiting.
Upload your CAD file directly and get an instant automated quote—no waiting. Ideal for standard parts with clear specifications.
- Instant pricing for STL, STEP, and 3MF
- Direct ordering available
- Various materials and processes
For complex or custom projects, please use the inquiry form.
Here's How a Request Works
From a model to a metal component ready for installation
Upload 3D Data
Model in STEP, STL, or 3MF format; if tolerances are specified, please also include the drawing as a PDF.
Select Material and Surface
Price list for available materials and surface finishes.
Have a component inspected
Rapidobject checks orientation, support structures, debinding feasibility, and any necessary post-processing.
Received ready for installation
Printing, post-processing, inspection, and shipping—all from a single source.
The Post-Processing Procedures in Detail
What each step accomplishes, when it is necessary, and what it means for the design.
Dust Removal and Powder Handling
After printing, unfused metal powder adheres to each component and must be completely removed. Internal channels, undercuts, and hard-to-reach cavities are particularly critical. Metal powder is harmful to health and, in the case of reactive materials such as aluminum and titanium, is also highly flammable; therefore, it must be handled in closed systems. For this reason, closed cavities without a drainage opening are not permitted in the design.
Heat Treatment and Stress-Relief Annealing
The layered construction creates residual stresses in the part, which can lead to warping or cracking. Stress-relief annealing reduces these stresses and ensures the part’s dimensional stability. It is advisable to perform this step after powder sintering and before cutting the part away from the build plate and support structures, since the part is still secured in place at that stage. For example, with titanium Ti6Al4V, heat treatment is an integral part of the process chain because it ensures the part retains its shape.
Cutting Away from the Building Panel
Each SLM component is manufactured as a single piece firmly attached to the build plate and must subsequently be separated, typically by sawing or wire EDM. The cut surface is then machined to a flat finish. If this surface serves a functional purpose, a machining allowance should be included in the design and indicated on the drawing.
Remove support structures
Overhanging areas at an angle of approximately 45 degrees to the build plate are supported during printing. These structures are mechanically removed; the attachment points remain as visible marks and are reworked as needed. The orientation of the part determines where support structures are placed—therefore, it is advisable to orient the part so that functional areas do not require support.
Beams
Blasting is the standard finish for metal parts at Rapidobject. It removes debris and powder residue and creates a uniform, matte finish across the entire part. For parts where functional performance is the top priority, this is often the appropriate finish.
Cut a thread
Threads are not printed as part of the SLM process; instead, they are cut, milled, or turned afterward. To accommodate this, the part must have the appropriate core hole and clearances in accordance with applicable standards, such as DIN 13-1 and DIN 76-1. In addition, the part must have a secure clamping mechanism and sufficient clearance for tool movement.
Machining Finishing
For parts up to 100 mm in size, the SLM process achieves a general tolerance of ±0.3 mm, and ±0.3 percent for larger parts. Tighter dimensions, defined fits, sealing and bearing seats, as well as flat mating surfaces are achieved through CNC machining: milling, turning, drilling, and reaming. This requires a technical drawing with the specified dimensions and marked functional surfaces, as well as a machining allowance of approximately 1.0 mm at the relevant locations.
Polishing, Trowalizing
Polishing produces smooth to high-gloss surfaces. It is useful where the surface plays a functional role—such as in cases involving friction, flow, or sealing—as well as for visible and design-oriented components.
In trowalizing or vibratory finishing, components are agitated in a tank containing abrasive media. This rounds off edges, smooths surfaces, and reaches areas that are difficult to access manually.
Additional surface treatments are available upon request.
Testing and Documentation
Upon request, documentation can be provided for each order, such as a test report or a measurement report detailing the required dimensions. This is particularly useful for components with tight tolerances, in series production, and in regulated applications. Rapidobject is ISO 9001 certified.
Post-processing by Material
The standard finish for all materials is sandblasted. Differences arise in the heat treatment: For titanium Ti6Al4V, it is an integral part of the production process because it produces the specified material properties. For aluminum AlSi10Mg, stainless steel 1.4404, bronze CuSn10, and copper, the heat treatment is determined by the component and its application. The quality of the surface finish depends on the component’s orientation within the assembly and the specific material.
| Material | Standard Version | Heat Treatment | Typical Finishing Processes |
|---|---|---|---|
| Aluminum AlSi10Mg | blasted | depending on the application | Trowalizing, CNC Finishing |
| Titanium Ti6Al4V | blasted | an integral part | CNC Finishing, Polishing |
| Stainless steel 1.4404 | blasted | depending on the application | Trowalizing, Polishing, CNC Finishing |
| Tool steel 1.2709 | blasted | an integral part | CNC finishing after hardening |
| Inconel 718 | blasted | an integral part | CNC Finish |
| Bronze CuSn10 | blasted | depending on the application | Polishing to a High Gloss, Trowalizing |
| Copper | blasted | depending on the application | Polishing, CNC Finishing |
Which surface finish is right for your component?
For metal components, functional performance is the top priority: dimensional stability, load-bearing capacity, and precise fit. The surface finish depends on the function the surface will serve once the component is installed. We’d be happy to advise you on the best post-processing options for your component.
Documents on Tolerances, Data, and Installation Spaces
FAQ
Frequently Asked Questions About Post-Processing in Metal 3D Printing
Does a 3D-printed metal part always need to be post-processed?
Yes. Depowdering and separation from the build plate are necessary for every SLM component. Whether additional heat treatment, machining, or surface finishing is required depends on the material, geometry, tolerance requirements, and intended use.
What post-processing services does Rapidobject offer for metal parts?
Rapidobject processes SLM metal parts through depowdering, heat treatment, separation from the build plate, removal of support structures, machining (including threading), blasting, vibratory finishing, polishing, deburring, marking, as well as inspection and documentation. Additional coatings are available upon request.
How is metal powder removed from channels and cavities?
After printing, the unfused powder is removed from the part; in the case of internal channels, this is done through openings designed for that purpose. These openings should be at least 3.0 mm in size, and correspondingly larger for long or branched channels. Closed cavities without a drainage opening are not permitted, as the powder cannot be reliably removed from them.
Why might heat treatment be necessary for SLM components?
The laser melting process generates residual stresses in the part. Certain geometries—such as large surfaces and areas with highly variable wall thicknesses—may warp or crack without heat treatment. Stress-relief annealing should ideally be performed before separating the part from the build plate and support structures.
How are support structures removed, and what remains visible?
Support structures are removed mechanically. Traces remain on the surface at the attachment points, which can be reworked if necessary. The location of these areas is determined by the part’s orientation—therefore, whenever possible, support structures should be placed on surfaces that are not critical to the part’s function.
What types of surfaces are possible in metal 3D printing?
Rapidobject’s standard finish is a sandblasted, uniformly matte surface. In addition, vibratory finishing is available for rounded edges and a uniform appearance, as well as high-gloss polishing and CNC finishing for specific functional surfaces. These and other post-processing options are available upon request.
What tolerances does a metal component achieve after finishing?
Directly from the SLM process, a general tolerance of ±0.3 mm applies for parts up to 100 mm in size, and ±0.3 percent for larger parts. Tighter dimensions are achieved through targeted CNC machining of the relevant functional surfaces. A technical drawing with the required dimensions is required; the achievable values are listed in the "Manufacturing Tolerances" data sheet.
Can threads be cut later?
Yes, and that is typically the case with the SLM process: Threads are not printed, but rather cut, milled, or turned. The component must be designed with the appropriate center hole and clearances in accordance with standards, such as DIN 13-1 and DIN 76-1. The threading is ordered separately.
How much extra material should be factored in for finishing work?
For surfaces that will be machined, an allowance of approximately 1.0 mm should be included in the CAD model. This applies to mating holes, threaded areas, bearing and seal seats, and flat surfaces. These areas must be marked as functional surfaces in the technical drawing.
Does post-processing affect dimensional accuracy?
Yes. Blasting and vibratory finishing alter the surface and round off edges; heat treatment can cause slight dimensional changes. For this reason, tight tolerances on functional surfaces are achieved through machining after heat treatment, not before.
What drives post-processing costs?
Four factors in particular: the number and location of support structures, the number of functional areas with tight tolerances, accessibility to internal areas for powder removal, and the required surface finish. All four can be influenced during the design process.
Is there any documentation on post-processing?
Upon request, Rapidobject provides a test report or measurement report detailing the required dimensions. This is particularly useful for tight tolerances, mass production, and regulated applications. Rapidobject is ISO 9001 certified.
What is the difference between the post-processing of metal and plastic components?
For metal components, functional performance is the top priority: dimensional stability, load-bearing capacity, and fit accuracy. In addition, there are steps not required in plastic manufacturing processes, such as separating the part from the build plate and stress-relief annealing. The page provides an overview of all processes and materials 3D Printing Post-Processing.
Your Contact Person
What kind of post-processing does your component require?
Send us your 3D model along with your requirements for surface finish, tolerances, and operating conditions. Rapidobject will determine which post-processing steps are necessary.
- Recommendation Regarding Surface Finish and Scope of Post-Processing
- Evaluation of Critical Geometries and Support Structures
- Design of Dimensions and Functional Areas
- Quote for a prototype, small-batch production, or replacement part
Markus Prokscha
, SLM Expert in Metal 3D Printing at Rapidobject
+49 341 231 837 32
metall@rapidobject.com