Material Jetting (PolyJet)
Material jetting sprays droplets of photopolymer and cures them layer by layer, allowing several materials and colors in one build.
- Part
- Forming
- Revised
- 2026-08-11
At a glance
- Family
- Additive Manufacturing
- Typical tolerances
- About ±0.004 in (±0.1 mm) on parts up to 4 in (100 mm), and roughly ±0.008 in (±0.2 mm) or ±0.1% of nominal on larger geometry.
- Surface finish
- Ra 20–40 µin (0.5–1 µm) on up-facing glossy surfaces — the smoothest available from an additive process. Surfaces built against support gel are matte and noticeably rougher.
- Typical volumes
- 1–50 parts
- Lead time
- 1–3 business days. Printing is typically 4–12 hours, with support removal adding anywhere from minutes to several hours depending on internal geometry.
- Materials
- Plastic
What it is
Material jetting sprays droplets of liquid photopolymer from a piezo inkjet head and cures each layer with a UV lamp on the same carriage, at layer heights of 0.0006–0.0013 in (14–32 µm) — the finest of any additive process. Because the print head can lay down several resins in the same pass, one build can combine rigid and rubber-like materials, transparent and opaque regions, and full-color texture maps in a single part.
That capability, not raw accuracy, is why the process exists. A PolyJet anatomical model can carry compliant vessels inside a clear rigid shell; an overmolded handle can be prototyped with the grip already in place at Shore A 30–95; a color-mapped concept model needs no painting.
Accuracy is around ±0.004 in (±0.1 mm) on parts under 4 in (100 mm), and as-built surfaces reach Ra 20–40 µin (0.5–1 µm) in glossy mode. Support is a separate gel resin removed by waterjet or caustic bath. The materials are brittle photopolymers with poor UV stability, so material jetting is a communication and validation process rather than a production one.
How it works
- Slice and assign materials. Layers are sliced at 0.0006–0.0013 in (14–32 µm) and each voxel is assigned a resin. Multi-material systems blend base resins on the fly to produce intermediate stiffnesses and colors, so a gradient between rigid and elastomeric can be printed rather than assembled.
- Jet. The carriage traverses the build tray, and hundreds of piezo nozzles jet picoliter droplets of model and support resin simultaneously. Support is a soft gel-like photopolymer placed wherever the geometry overhangs and, unavoidably, on every down-facing surface.
- Level. A roller passes over the freshly jetted layer to bring it to exact thickness and remove excess; that excess is scavenged to waste.
- Cure. UV lamps mounted on the carriage cure the layer immediately behind the jetting heads, so each layer is fully solid before the next is deposited. No separate post-cure is required.
- Repeat. The tray indexes down one layer. Build time scales with tray area covered and total height, not with part count in a given layer.
- Remove support. The gel is stripped with a waterjet for accessible geometry, or dissolved in a heated caustic solution for internal channels and lattices. This is the process's main labor step, and delicate features are frequently damaged during it.
Design guidelines
Wall thickness
0.024 in (0.6 mm) minimum in rigid resin and 0.035 in (0.9 mm) in rubber-like grades. The limit is not the printer — layers are extremely fine — but the waterjet used to strip support, which will destroy anything thinner.
Support removal access
Every down-facing surface is printed on support gel, and every internal cavity fills with it. Design access for either waterjet or solution: openings of 0.12 in (3 mm) or larger for waterjet, and remember that soluble support in a long narrow channel takes hours and may never fully clear.
Multi-material design
Assign materials by body in the CAD assembly rather than trying to patch them at the slicer. Rigid-to-elastomer transitions bond chemically during printing and are far stronger than a mechanical joint, but a sharp stiffness discontinuity still concentrates strain — blend the transition over 0.04–0.08 in (1–2 mm) where the part will flex.
Glossy versus matte
Up-facing surfaces printed without support come out glossy at Ra 20–40 µin (0.5–1 µm). Any surface that touches support prints matte and slightly rougher. If appearance matters, orient the show face upward.
Color and texture
Full-color systems accept texture-mapped models. Color is printed as a thin shell over a white core, so engraved detail can cut through the color layer — keep engraving shallower than the shell or design the color into the geometry.
Do not design for load
Material jetting resins are brittle, creep under sustained load, and yellow under UV within weeks of sun exposure. Use the process for fit, appearance, and communication; move functional testing to SLS or a molded thermoplastic.
| Feature | Recommended | Limit | Why |
|---|---|---|---|
| Wall, rigid | 0.040 in (1.0 mm) | 0.024 in (0.6 mm) | Waterjet support removal |
| Wall, elastomeric | 0.060 in (1.5 mm) | 0.035 in (0.9 mm) | Soft material tears during cleaning |
| Support access opening | 0.20 in (5 mm) | 0.12 in (3 mm) | Waterjet needs line of sight |
| Detail size | 0.016 in (0.4 mm) | 0.008 in (0.2 mm) | Survivable through cleaning |
| Layer height | 0.0011 in (28 µm) | 0.0006 in (14 µm) | Finer layers roughly double time |
| Clearance, moving | 0.016 in (0.4 mm) | 0.008 in (0.2 mm) | Support gel must be removed from the gap |
Cost drivers
Material jetting has the highest material cost per part of the common additive processes, for two reasons. The resins themselves are expensive, and support gel is consumed in large quantity — a part with substantial overhang can consume as much support resin as model resin, and all of it is thrown away. Roller scavenging adds further waste on every layer.
Machine time scales with the area of the tray covered and the total build height, so nesting several parts across the tray is efficient in a way that stacking them vertically is not.
Support removal labor is the third cost and the one that varies most. A simple exterior shell cleans in minutes; a lattice or a closed internal channel can take hours of soaking and picking.
Volume breakpoints: material jetting is a 1–50 part process. It has no volume story at all — nothing about it gets cheaper with quantity beyond tray packing — and any functional or production requirement should move to another process.
- Orient so cosmetic faces point up and support lands on hidden geometry.
- Reduce overhang volume; you pay full price for support resin.
- Print only the region that needs multi-material or color, and machine or print the rest elsewhere.
- Use a single material and standard finish for pure fit checks — multi-material builds cost substantially more.
- Spread parts across the tray rather than stacking them tall.
Questions
6 questionsWhat layer height does PolyJet print at?
0.0006–0.0013 in (14–32 µm), the finest of any commercial additive process. High-quality mode is typically 16 µm and high-speed mode around 28–32 µm. Layer height affects build time roughly proportionally.
Can material jetting print rigid and flexible material in one part?
Yes — that is its main reason for existing. Rigid resins and rubber-like grades from about Shore A 30 to 95 can be jetted in the same pass and bond chemically at the interface, so overmolds, gaskets, and living hinges can be prototyped as a single printed assembly.
How accurate is PolyJet?
Roughly ±0.004 in (±0.1 mm) on parts up to 4 in (100 mm), and ±0.008 in (±0.2 mm) or about ±0.1% of nominal on larger ones. Accuracy is good but the material properties, not the dimensions, are what limit the process.
How is PolyJet support removed?
A gel-like support photopolymer is jetted alongside the model material and stripped afterward with a waterjet, or dissolved in a heated caustic solution for internal geometry. Waterjet cleaning is what sets the 0.024 in (0.6 mm) minimum wall thickness — thinner walls do not survive it.
Are PolyJet parts usable as functional parts?
Rarely. The resins are brittle, creep under sustained load, and yellow and embrittle under UV within weeks of sun exposure. Use material jetting for appearance, fit, and communication models, and move functional testing to sintered nylon or molded thermoplastic.
Why is material jetting expensive?
Model resin is costly, support gel is consumed in comparable quantity and discarded, and the roller scavenges excess material from every layer. On top of that, support removal is a manual operation that can take hours on parts with internal geometry.