Short answer: A horizontal channel may be feasible, but the useful question is whether the chosen supplier can manufacture, clean and verify it to your requirements.
A designer asks if a hole needs supports. The full decision also includes its shape, manufacturing orientation, fluid duty and inspection access.
There is no diameter in this article that guarantees success across alloys, machines and parameter sets.
Change the cross-section only if the function allows it
Protolabs presents a DMLS example in which a circular channel required inaccessible internal supports. A teardrop cross-section allowed a different build orientation without those trapped supports. [1]
That is a useful design option, not a general replacement for a round bore.
If the passage is only carrying fluid, an alternative section might be worth evaluating. If it seats a tube, seal or precision component, its required shape may be fixed. Ask the supplier to compare a redesigned channel with a route that preserves and finishes the required bore.
Renishaw’s hydraulic-manifold case also shows why the system requirements matter: the redesign considered interfaces, passage dimensions, stiffness and flow performance together. [2]
Depowdering is different from smoothing
Depowdering removes residual, unfused powder. Surface finishing changes the surface condition. One operation does not automatically achieve the other.
Solukon identifies internal geometry as a major depowdering challenge and describes controlled rotation and vibration for powder evacuation. [3] Its equipment claims do not establish that your particular channel will be clean.
Ask the supplier to explain the evacuation path and how the result will be demonstrated on representative geometry. A CAD passage connected to the outside is a starting point, not acceptance evidence.
Prepare a channel brief before asking for a quote
This is an Addithive template for discussion with the design authority and supplier. Fill in the actual requirements; do not infer them from a successful print.
| Field | What to specify |
|---|---|
| Fluid duty | Fluid, flow range, temperature and pressure requirements |
| Geometry | Section, length, turns, intersections and minimum wall regions |
| Interfaces | Ports, seals, threads and dimensions that must remain fixed |
| Internal condition | Required roughness and permitted finishing methods |
| Cleanliness | Permitted residual material and an agreed verification method |
| Functional evidence | Required flow, leakage and pressure evidence |
| Traceability | Material, process condition and manufacturing records |
| Acceptance owner | Who approves the requirements and evaluates the results |
Do not select proof pressures or test procedures from a forum comment. The responsible engineering team must define those against the application and applicable requirements.
Worked design-review scenario
Suppose a manifold has a round passage through the body and precision fittings at both ends.
Ask for three route proposals:
- Preserve the circular section and explain the build and finishing approach.
- Change only the internal flow passage while retaining the required interfaces.
- Compare a conventional drilled or assembled route.
Then compare the delivered result: geometry, cleanliness, functional evidence, total lead time and price. The AM route earns its place if the resulting benefit justifies the extra work.
The decision to make before printing
Write one sentence for each of these:
How does the passage form? How does powder leave? How are required surfaces finished? How will acceptance be demonstrated?
If one answer is missing, resolve it before treating the design as production-ready.
Continue with Addithive’s Research Hub and Engineering Tools.
Sources
[1] Protolabs, The Cost of 3D Printing: Key Factors to Consider. Specific channel redesign example; reported savings are not generalized here.
[2] Renishaw, Hydraulic Block Manifold Redesign for Additive Manufacturing. Application case, not a universal acceptance specification.
[3] Solukon, Unpacking and Depowdering of 3D Printed Metal Parts and FAQ. Manufacturer descriptions of powder removal and downstream implications.
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