HP Multi Jet Fusion Mini Design Guide

This mini design guide will help you get the most out of Xometry’s newest additive manufacturing capability, HP Multi Jet Fusion, which is a unique 3D printing process capable of creating high-quality parts up to 10X faster than other printing processes.

By William Krueger · December 12, 2018

Xometry’s newest additive manufacturing capability, HP Multi Jet Fusion, is a unique 3D printing process that is vastly different from the others on offer. However, it is no less precise, capable of creating high-quality parts up to 10X faster than competing 3D printing processes, allowing you to get to market faster.

Like all powder-based 3D printing processes, HP Multi Jet Fusion builds parts layer by layer, using a fusing agent and heat to set each layer before moving onto the next. In the more traditional 3d printing processes — such as Selective Laser Sintering (SLS), Stereolithography (SLA), or Direct Metal Laser Sintering (DMLS) — each part is imaged, layer by layer, with a single laser beam. HP’s Multi Jet Fusion works a bit more like a traditional ink-jet printer with a printhead that deposits the material, and then a fusing agent, across the entire build plate in one pass, allowing for improved economies of scale when printing in bulk.

HP Multi Jet Fusion is an extremely exciting, robust and flexible addition to Xometry’s manufacturing capabilities. It’s excellent for prototyping, small-batch production runs or as a bridge process to injection molding, allowing you to get a feel for how your parts will perform with minimal upfront costs.

The benefits of HP’s Multi Jet Fusion 3D Printing Process

While there are many benefits to HP Multi Jet Fusion, a few truly stand out. For starters, the standard build parameters are optimized for best density. The result is that MJF parts are watertight.  

If you like SLS but want to produce higher quantities for small-batch production runs, Multi Jet Fusion is the way to go. The ability to print multiple parts simultaneously across the entire build volume means you can print parts at rates up to 10X faster than SLS or other 3D printing processes. Also, Multi Jet Fusion delivers more balanced mechanical properties across the X, Y, and Z axes compared to SLS.


If you’re interested in injection molding for your project, it’s always a good idea to get a 3D printed “test” part before making the investment in metal molds. While SLA is a great 3D printing process for extremely detailed and high-resolution prints, the UV cured resins are not as tough as traditional thermoplastics. Prints begin to degrade UV light and moisture. Multi Jet Fusion, on the other hand, can produce extremely accurate prints while also maintaining the structural durability of traditional thermoplastics. This makes it a great process for testing fit and functionality before taking your project to injection molding.

Limitations to Consider With HP Multi Jet Fusion

Like all 3D printing processes, there are some limitations to consider before selecting HP Multi Jet Fusion as your additive manufacturing process of choice. If you’re printing just a single, one-off part, Multi Jet Fusion might not be the most cost-effective option. The cost-savings for Multi Jet Fusion truly come into play when printing in higher quantities that can fully utilize the available build space.

HP MJF prints in a natural gray color with a slightly textured finish similar to SLS. The natural gray color may be somewhat inconsistent across a single part. We recommend a dyed black finish for best consistency and overall cosmetic appeal.

Teeny-tiny parts and large parts that take up nearly the entire build volume may experience issues. Parts with thicker geometries, flat or broad parts, and parts with uneven wall thicknesses may be prone to significant deviations or warp due to variable thermal shrinkage and stress.  Though Multi Jet Fusion is an accurate process — the standard layer thickness is 80 microns with a minimum recommended feature size of 0.5 mm — tiny features or small parts under 0.5 mm can be lost or won’t print correctly. Something to keep in mind when designing for Multi Jet Fusion.

HP Multi Jet Fusion Design Guidelines and Best Practices

There are some very important design specifications to bear in mind to avoid issues in the printing process and to achieve the highest part quality possible.

The minimum printable features in the X, Y, and Z planes:

Minimum hole diameter at 1 mm thickness:0.5 mm
Minimum shaft diameter at 1 mm height:0.5 mm
Minimum printable font size for embossed or debossed letters or numbers:6 pt
Minimum clearance at 1 mm thickness:0.5 mm
Minimum slit between walls:0.5 mm


The minimum gap between parts that will be assembled after printing should be at least 0.4 mm (± 0.2 mm of tolerance for each part) in order to ensure correct assembly. If you’re looking to do print-in-place assemblies such as a ball joint or hinge, we recommend a minimum clearance of 0.7 mm between the parts. Parts with very thick walls above 50 mm should have an even great gap to ensure proper performance.

When designing parts, we recommend you hollow out the part as much as possible. This will save on fusing agent and powder, reduce sink marks, and reduce print time, saving you money. If your part is hollow and also a closed geometry, drain holes need to be added to the design to aid in the removal of the material. The minimum recommended diameter for the drain holes is 2 mm and we recommend including at least two holes.

Technical Specifications

The chart below is a great reference to keep on hand when designing for HP’s Multi Jet Fusion 3D printing process.

Material Options
  • Nylon 12
  • Glass-Filled Nylon 12
Standard Accuracy
  • ± 0.012” or ± 0.003”/inch, whichever is greater
  • ± 0.4mm ≤ 100mm, ± 0.4% >100mm (± 0.016” ≤ 3.900”, ± 0.4% > 3.900”)
Standard Layer Thickness
  • 80 microns (0.0031")
Build Volume
  • 380 x 284 x 380 mm or 15” x 11” x 15”
  • 14” x 11” x 13” is recommended useable area
Minimum Printable Features
  • 0.5 mm / 0.020" in X, Y, and Z planes
Finishes
  • Natural Gray
  • Dyed Black (recommended)

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