How to Design for HP Multi Jet Fusion

Design rules, minimums, and best practices to improve print success, dimensional accuracy, and post-processing outcomes.

Minimum feature sizes for walls, wires, and fine detail

Clearances for assemblies, hinges, and moving parts

Escape holes and powder-removal design considerations

MJF Quick Specs

Typical accuracy: ±0.3% (minimum ±0.3 mm)
Max build (one piece): 284 × 380 × 380 mm
Min wall: 0.4 mm supported / 0.5 mm unsupported
Min clearance: 0.6 mm
Escape holes: 4.0 mm recommended, 2.0 min

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MJF enables complex, production-grade nylon parts — but proper design can eliminate preventable issues during printing and cleaning. Use this guide to validate key thresholds and submit designs that print reliably.

Design Essentials

Tolerances

Expect a dimensional accuracy of +/- 0.3% (with a lower limit of +/- 0.3%)

Bounding Box

This represents the largest model we can manufacture in one piece. As with injection molding, a larger part can be digitally cut and printed in smaller parts, which can be re-connected after printing.

Maximum

284 x 380 x 380 mm

Minimum

x + y + z greater than 9 mm

Wall Thickness

Walls that do not meet the minimum measurements risk damage in the cleaning and printing process. They are also prone to warping during printing.

Min. supported wall thickness

0.4 mm

Min. unsupported wall thickness

0.5 mm

Wires

"Wires" are sections that are long and narrow. Supported wires are connected at 2 ends. Unsupported wires are connected at only one end.

Min. supported wires

0.4 mm

Min. unsupported wires

0.9 mm

Surface Detail

Min. embossed detail

0.2 mm high & wide

for readable text - 0.5 mm wide, 0.3 mm high

Min. debossed detail

0.2 mm high & wide

for readable text - 0.4 mm high & wide

Escape Holes

Because Multi Jet Fusion uses layers of powder to build parts, excess powder can be trapped in hollow models. The powder can be left in the hollow piece, or "escape holes" can be added so pressurized air can be used to blast out excess powder.

Diameter of single escape hole

4.0 mm

Diameter of 2+ escape holes

2.0 mm

Clearance

Clearance is the space between parts that are built in place, such as in a ball-and-socket joint or hinge.

Minimum clearance

0.6 mm

Sprues

Sprues are wires that join multiple parts. To minimize the risk of breaking during the cleaning process they should be thicker than the minimum wire thickness.

Sprue minimum thickness

2.0 mm