Design MJF parts around wall span, cleaning access and assembly fit. Choose the powder and finish, then qualify the features that matter for a repeat order.
MJF is a powder-bed process, but its layer mechanism differs from laser scanning. An inkjet array places fusing and detailing agents before an energy pass, so agent/material compatibility and the thermal cycle belong in the process definition.
Prepare
Build software packs parts in three dimensions and the system conditions the powder bed for the selected material.
Recoat
A thin, even layer of polymer powder is applied across the build area.
Pattern
The print array places agents where material should fuse and where edge fusion should be controlled.
Fuse
Area-wide energy fuses the patterned region. Layers repeat before controlled cooling, powder recovery, cleaning and finishing.
The mechanism follows HP’s official MJF description. Printer series, material, agents, print mode and cooling workflow can change the result; the process name alone is not a property specification.
HP’s design examples show what small features can resolve. Spans, cleaning and service loads usually set a more demanding requirement.
A short feature and a tall free-standing wall can need different design allowances. Check height, span and access for cleaning.
Ribs, a return edge and shorter unsupported spans can improve stiffness. Leave room to remove powder or supports.
Schematic illustrations; not to scale. Confirm the design for the chosen material, process and final use.
| Feature | Published example | Design implication |
|---|---|---|
| Short walls | 0.3 mm XY; 0.5 mm Z | Orientation-specific minima; long or loaded walls need a separate stiffness and handling assessment. |
| Hollow shells | 2 mm starting wall | A shell has different requirements from a tiny test feature; application loads may require more. |
| Separately printed mating parts | 0.4 mm interface gap | The handbook example allows ±0.2 mm on each part. This is a fit example, not a blanket tolerance. |
| Printed-in-place moving parts | 0.7 mm gap starting point | Tighter gaps need geometry-specific trials; powder must leave the full contact region. |
| Small hole | 0.5 mm through 1 mm thickness | A short test hole does not establish a cleanable long channel or an accurate bearing seat. |
| Long thin shapes | Review aspect ratios above 10:1 | Length-to-width ratio and section changes indicate warp risk, not a guaranteed pass/fail limit. |
Source: HP MJF Handbook, design chapters. Confirm applicability to the chosen material, geometry and finishing route; order tolerances must be agreed separately.
An economical batch still has to fit, look and behave like the approved sample. Capture the important conditions before increasing quantity.
Use representative geometry, material and finishing to verify the properties that matter before repeating the order.
Record material product, build settings, orientation, finishing and inspection criteria. Confirm changes before the next batch.
Schematic illustrations; not to scale. Confirm the design for the chosen material, process and final use.
Geometry
A compact shell uses less fused material than a solid block. Check stiffness and cleaning before hollowing; the bounding box alone does not determine the quote.
Sample
Measure after the specified blasting, dyeing or smoothing. Keep the approved colour and texture sample if appearance matters.
Repeat
Name the grade and finishing route. Record critical dimensions, inspection method and any orientation necessary for performance.
Brand product, printer compatibility, print mode and conditioning define the data you should compare.
| Material | Consider it for | Question before selection |
|---|---|---|
| PA12 | General housings, brackets and ducts | Which product and colour? Compare strength, elongation and dimensional data under the same conditions. |
| PA11 | Flexible clips and impact-sensitive geometry | Does the required deflection survive the actual cycle count? Ductility alone is not fatigue qualification. |
| PA12 GB | Stiffer enclosures and fixtures | HP’s product contains 40% glass beads. Check elongation and impact before using thin flexures. |
| TPU / TPA | Grips, cushions and compliant geometry | Name the grade and target hardness. Geometry and lattices also determine apparent softness. |
| PP | Lightweight parts and chemical-exposure candidates | Confirm the fluid, temperature, exposure time and sealing requirements. |
| White or flame-retardant PA12 | Colour-led or specified fire-performance applications | Compatibility differs by product. A powder rating does not certify an entire assembly. |
HP’s portfolio spans multiple printer series. A family listed here is not a promise that every grade is available for every order.
HP’s portfolio includes materials developed with polymer suppliers as well as HP-branded grades. Product naming matters because compatibility, colour, powder reuse and test data differ across systems.
| Material family | Product examples | Selection direction | Performance evidence to compare |
|---|---|---|---|
| PA12 | HP 3D HR PA 12 HP 3D HR PA 12 S enabled by Arkema | General functional housings, ducts and production candidates. | Match product to printer and print mode; compare conditioned tensile/impact data, dimensional guidance, colour and reuse protocol. |
| PA11 | HP 3D HR PA 11 | Ductile clips, impact-led parts and flexible thin geometry. | Use the named product’s elongation and impact data, then qualify the actual deflection, orientation and cycle count. |
| Glass-bead PA12 | HP 3D HR PA 12 GB | Stiff housings, fixtures and dimensionally stable candidates. | The filler is glass bead, not generic glass fibre. Compare modulus together with elongation and impact before using a flexure. |
| Elastomers | Forward AM Ultrasint TPU01 ESTANE 3D TPU M95A | Grips, seals, compliant ducts and lattice candidates. | Specify product, hardness, section and loading; compare tear, compression and recovery rather than treating every TPU as interchangeable. |
| PP / TPA / special PA12 | HP 3D HR PP enabled by Forward AM HP 3D HR TPA enabled by Evonik | Chemical-exposure, lightweight or application-specific parts. | Confirm product/system compatibility and test the actual fluid, temperature, duration, sealing and finish requirements. |
These are examples from HP’s official material portfolio, not a FabDigit availability list. Confirm the named powder, printer series, colour, finish and traceability for the order.
Use the live library to connect polymer grades with manufacturer powders and original sources. These pages support comparison; a quote confirms the available printer, material and finishing route.
4 material grades 12 manufacturer products
Explore the indexed grade and product pages here. A quote confirms the material, machine, finish and sourcing available for a specific order.
Accuracy, repeatability, roughness and colour are separate specifications. A single tolerance cannot describe the whole part.
Required
Recovered powder is separated before residual surface powder is removed. Blasting establishes the baseline grain and can damage unsupported detail.
Confirm: unpacking method, blast medium, protected features, cavity access and internal cleanliness.
Colour
Dyeing changes near-surface colour without adding a paint-like film. Uptake and attainable colours depend on powder and pretreatment.
Confirm: substrate/base colour, approved sample, penetration limits, scratch exposure and final dimensional inspection.
Surface
Vapour or chemical smoothing modifies roughness and gloss and can soften edges. A smoother surface does not itself prove sealing or cleanability.
Confirm: material compatibility, text/edge retention, mating gaps, leakage test and any cleanliness requirement.
Functional
Secondary machining can create a bearing seat or datum; a coating adds thickness and may change flexibility.
Confirm: machining stock, workholding, masking, coating build and measurements after every heat/moisture step.
| Concern | Specify | Avoid assuming |
|---|---|---|
| Fit | Final dimensions, datums and inspection condition | That layer height or printhead resolution equals part tolerance. |
| Batch consistency | Acceptance limits and sampling requirements | That every part repeats within ±0.1 mm regardless of geometry, build and finish. |
| Warp | Free-state flatness and functional mounting condition | That ribs automatically prevent distortion; added mass can change cooling. |
| Powder removal | Clean access to channels and mating gaps | That an entrance proves every internal branch can be cleared. |
| Dye | Base colour and approved appearance sample | That the entire cross-section becomes black or every substrate takes the same bright colour. |
| Vapor smoothing | Final fits, legible text and any leakage test | That smoothing guarantees watertightness or preserves every edge. |
| Strength | Grade, orientation and environment | That similar XY and Z tensile strengths establish identical impact or fatigue properties. |
HP’s handbook gives 0.3 mm for short XY walls and 0.5 mm for short Z walls. These small-feature examples do not establish a working shell thickness: span, cleaning and service loads also matter.
Not universally. Compare the actual systems, materials, geometry and finished state. Printhead resolution, layer height and inspection tolerance describe different things.
Yes, with clearance that prevents fusion and allows powder removal. HP gives 0.7 mm as a general starting gap for printed assemblies; test the exact joint, especially long contact faces.
Some properties can be similar between directions, but elongation, impact and fatigue may differ. Use the orientation-specific data for the exact powder and validate the load case.
Dyeing does not build a paint-like coating, but heat, moisture and other finishing steps can affect final dimensions. Check critical fits after finishing. Dye penetrates a surface region rather than the whole wall.
Compare actual total costs for the final design: tooling, parts, finishing, inspection, delivery and expected revisions. Quantity alone cannot establish a universal crossover.
Upload the model with material or functional requirements, quantity, finish and critical dimensions. Your quote confirms the available route and delivery.
