Designing for DMLS Prototyping: 7 Mistakes That Waste Your Build Volume

Direct Metal Laser Sintering (DMLS) can be a great option for making metal prototypes because it can allow you to realize designs with intricate geometries and fine details that may be too difficult or costly to achieve with conventional manufacturing. However, DMLS prototyping has specific design rules you must follow to avoid problems. Even the smallest mistakes in wall thickness or support placement can waste valuable build volume and lead to complete part failure. Let’s discuss the seven most common mistakes to watch out for when designing prototypes for DMLS.

Mistake	What Can Go Wrong	What to Do Instead
1. Poor wall thickness	Thin walls may break, warp, or create stress points	Keep walls ≥ 0.8 mm (≥ 1 mm for supported walls) and avoid sudden thickness changes
2. Misusing supports	Excess material use, longer post-processing, instability	Design with 45° angles, fillets, and support only where needed
3. Improper hole design	Distortion, rough surfaces, or fused features	Use tear drop/diamond shapes and keep unsupported holes ≤ 8 mm and ≥ 1 mm diameter
4. Unsupported overhangs	Surface defects or build failure	Support overhangs > 0.5 mm or angles > 45°
5. Thin pins and details	Breakage or instability	Use pins ≥ 1 mm diameter and avoid unsupported features < 0.8 mm
6. No escape holes	Powder entrapment, unusable parts	Add 2–5 mm holes and place them at edges or opposite sides
7. Parts too close together	Fusion, trapped powder, failed movement	Keep 0.5 mm spacing between features and 0.6 mm clearance for moving parts

 

1. Poor wall thicknesses

While wall thickness is one of the most critical factors in metal 3D printing, it depends on the material and resolution. If it’s too thin, the part can break or distort. For general designs, maintain a minimum thickness of 0.8mm to avoid failure. 1mm should be enough for supported walls, particularly those joined on two or more sides.

It’s also important to maintain consistency in wall thickness when designing for DMLS prototyping, as sudden changes in wall dimensions can create stress points.

2. Overusing or misusing support structures

Overhangs and surfaces angled beyond 30° typically need added supports to prevent warping and keep the part secure during printing. While necessary, supports increase material consumption and require extra post-processing.

A smarter approach is to design features that reduce the need for support in DMLS prototyping. You can:

• Use angles of 45° or more to create self-supporting features.
• Add fillets to sharp corners and use angles under 30° to reduce stress.
• Provide adequate support only where needed, such as on horizontal surfaces and extended overhangs, to prevent part movement and potential machine errors.

3. Improperly shaped holes

One of the biggest advantages of DMLS is the ability to create internal channels and holes with complex geometries, such as conformal cooling channels. These reduce weight and enable designs not possible with traditional manufacturing.

To avoid distortion and achieve smoother surfaces:

• Keep channel diameters at 8 mm or smaller.
• Use a tear drop or a diamond shape instead of circles for unsupported holes.
• Design holes with at least 1 mm in diameter to prevent fusion.
• Tear-drop shapes reduce the need for supports for holes not aligned with the build direction.

4. Using oversized overhangs without support

When overhangs extend beyond 0.5 mm, they usually need added support. Pushing these limits often results in rough surface finishes or even complete build failure during DMLS prototyping. Adding support for overhangs longer than 0.5mm can prevent deformation and result in a smoother finish. The same goes for angles greater than 45 degrees.

5. Small details and narrow pins

Pins and other thin vertical features are particularly vulnerable during DMLS printing, even during prototyping. Use a minimum diameter of 1 mm for reliable strength to keep them stable. Unless you plan to reinforce them during post-processing, avoid features smaller than 0.8 mm.

6. Forgetting to put escape holes in your design

Hollow parts need escape holes to eliminate unsintered powders. Otherwise, they can trap the powder and make the part heavier and unusable. To make effective escape holes, keep their diameters between 2 mm and 5 mm. Additionally, make sure they’re placed strategically near the edges or the opposite sides of the part instead of clustering them in one place.

7. The parts too close together

The printer’s laser creates a melt pool that’s a bit bigger than its own diameter. If you place the features too close to each other, they may fuse together or trap powder in unintended areas. To avoid these issues in DMLS prototyping:

• Maintain at least 5 mm of space between features.
• Make sure there’s a 6 mm clearance for printed linkages to prevent sticking and enable smooth movement.

Avoid the guesswork from DMLS prototyping

You don’t have to worry about these common mistakes when you leave your DMLS prototyping to us. Prototypes. At HLH Prototypes, we offer design tips to optimize your part and ensure successful prototyping. Reach out today — chat with us online or email FreeQuote@HLHPrototypes.com for a free project review.