MJF Design Guidelines

If your parts require specific tolerances, please include an engineering drawing along with the part. Parts designed with large flat planes will likely warp, so this should be avoided if tight tolerances are required.

CriticalParts with large flat surfaces are prone to warping and should be avoided for applications requiring tight tolerances.

If your parts require specific tolerances, please include an engineering drawing along with the part. Parts designed with large flat planes will likely warp, so this should be avoided if tight tolerances are required.

NoteAlways provide engineering drawings for parts requiring specific dimensional tolerances. Tolerances differ for Polypropylene: ±1.75% (min ±0.7 mm).

The layer height is the overall Z resolution of the part; we avoid stepping artifacts on important features of your models by orienting the part(s) along the Z plane or at a 20 degree angle on all sides.

TipOptimal part orientation minimizes visible layer lines on critical surfaces.

Parts are bead blasted and have a uniform grainy matte texture, similar to ultra-fine sandpaper.

NoteThe matte finish provides excellent grip and professional appearance for functional parts.

Supported walls are connected to two or more sides and are thick enough to support the model.

CriticalThinner walls may warp or distort during the sintering process due to thermal stresses.

Unsupported walls are connected on only one side or edge.

CriticalUnsupported walls thinner than 1.5mm may sag or curl during printing, especially with larger layer heights.

The minimum pin size depends on a combination of parameters such as; part orientation, nozzle diameter, and length of the pin.

Debossed details are recessed features on your model. These features should be no shallower than 0.5mm (0.019").

TipAdd draft angles to debossed features for better definition and easier support removal.

Embossed details are raised features on your model. These usually resolve better than engraved details. Extruded text should have a wall thickness of at least 1.5mm (0.059") when printed flat, and 2mm (0.079") when printed vertically.

Minimum suggested text size on the top or bottom build plane of a MJF model is 16 point boldface. Minimum suggested text size on vertical walls is 10 point bold.

Clearance is the distance between two moving parts on hinges, joints, mating parts, etc.

CriticalInsufficient clearance can cause parts to fuse together during the printing process.

For a tight press fit, add a small offset, and chamfer the leading edge to ease entry. Always print an initial test part to dial in dimensions.

This defines the minimum allowed gap between a bush and a bolt, to avoid bonding of the hinge parts.

TipMJF excels at printing functional assemblies, but larger clearances may be needed compared to powder-based processes.

Depending on orientation, circular holes can resolve as ovals – if higher accuracy is required, printing the hole smaller and then drilling it out is recommended.

NoteVertical holes print more accurately than horizontal ones due to layer stacking.

Gaps or slots can fuse if made too narrow, and support material may be difficult to remove. If possible, orient gaps along the xy-plane for highest accuracy.

Hollow features may be filled with soluble support material, and must be designed with drain holes so that the support can be dissolved and removed during cleaning. Larger parts or parts with complex internal features may require larger holes to allow support material to fully dissolve.

TipSoluble supports make complex internal geometries possible with proper drain hole design.

Fillets can be used to reduce stress concentrations and increase the strength of your part. When designing fillet features across inside and outside corners, it is best to have them share a common center point in order to maintain a consistent wall thickness.

Bosses and ribs are an effective way to add strength and stiffness to a part while keeping material consumption to a minimum, this can also reduce build time and use less support material.

Parts do not require physical support structures. Parts are supported by the surrounding powder in the build chamber. This powder material is removed using compressed air glass beads leaving no defects or residual powder on the final part.

TipSelf-supporting nature allows for complex geometries without support removal marks.

Parts are always produced with solid walls. Infills are not applicable for MJF.

NoteSolid construction ensures consistent mechanical properties throughout the part.

We recommend M6 thread sizes or larger, and use thread profiles designed for plastics. The rough surface produced from MJF printing will result in increased friction with connecting thread parts. We recommend using an offset of 0.5mm to compensate for thermal shrinkage.

Design parts with holes sized for tapping, or center marks for drilling a pre-tapped hole. Tapping removes material, puts pressure on the surrounding geometry, and fastener locations are often points of stress, so make sure there is enough material surrounding the tapped hole.

CriticalEnsure adequate wall thickness around tapped holes to prevent cracking under stress.

Inserts are not required for MJF parts.

NoteMJF parts can be directly threaded or machined for fastening without inserts.

Parts too big to fit on the print tray can be split in CAD and printed in multiple parts, then glued or press fit. Use joinery features, such as tongue and groove, to ensure the sections are aligned and bond tightly.

Parts can be machined to tighter tolerances using traditional or CNC subtractive manufacturing equipment.

TipMJF parts machine similarly to conventionally manufactured metals.

Parts can be treated with standard metal coatings (anodization, powder coating etc).

Not applicable for MJF.

NoteMJF parts achieve excellent surface finish through bead blasting and other mechanical processes.