Material Jetting Printer Product

Overview

Material jetting (also known as PolyJet, a proprietary term) is a high-speed additive manufacturing process that deposits small droplets of liquid photopolymer resin and support material onto a moving build platform, immediately curing them with UV light. Unlike stereolithography, which scans a laser beam across a large pool of resin, material jetting jets precise microdroplets (3–5 pL) from 96–128 independently controlled nozzles, curing each layer in <1 second.

This process excels at speed (20–60 mm/h build height), high resolution (50 µm XY, 16 µm Z-layer), and multi-material capability. Applications include prototype molds with conformal cooling channels, multi-color figurines, flexible seals embedded in rigid housings, and dental prosthetics.

How it works

Liquid photopolymer resin is stored in the Dual Resin Supply System, maintained at 40–50 °C for optimal viscosity (5–15 mPa·s). Piezo-driven Micro-Pump (Piezo-Driven) units feed the nozzle arrays on-demand. The Piezoelectric Jetting Array contain two separate arrays:

1. Build resin array (96 channels): deposits the primary material (rigid acrylic or rubber-like elastomer).
2. Support resin array (128 channels): deposits water-soluble or thermally dissolvable support material.

As the XY Gantry & Z-Lift moves the platform beneath the nozzles in a raster scan, the PLC & Jetting Controller fires individual nozzles at 10–30 kHz, placing droplets at 50–100 µm spacing. Droplets land on the platform and immediately cure when struck by the UV Curing Lamps (365–405 nm LED, 1–5 mW/cm²).

The curing is nearly instantaneous: the photoinitiators in the resin absorb UV photons and trigger free-radical polymerization within 0.5–2 seconds. By the time the raster scan completes (10–50 seconds per layer, depending on area), the layer is fully cured and ready for the next.

After one layer is complete, the XY Gantry & Z-Lift descends 16–30 µm (the programmed Z-layer thickness), and a fresh raster is scanned. The extreme Z-resolution (16 µm vs. 50–100 µm for FDM or SLA) is possible because each droplet lands in place without needing to melt or blend with adjacent material—surface tension and viscosity hold each droplet in place before polymerization.

Multi-Material & Grayscale Capability

The dual nozzle arrays enable true multi-material printing. Rigid and elastomer resins can be jetted simultaneously on the same part, creating a single print with both stiff and flexible regions. The PLC & Jetting Controller routes the CAM toolpath to whichever array is needed at each location.

Some systems offer grayscale curing, modulating the UV Curing Lamps intensity per pixel. Underexposed regions (less UV) are partially cured, creating a soft, rubbery intermediate texture. This enables parts with continuously variable shore hardness (0 to 60A durometer).

Support Material & Post-Processing

Support material is essential for overhangs, thin walls, and undercuts. Two strategies exist:

Water-soluble support (e.g., polyethylene glycol or polypropylene glycol-based): After printing, the part is dunked in the Support Dissolution Chamber wash bath (40–60 °C) for 2–8 hours. Support dissolves, leaving no scarring. This is ideal for complex internal channels (heat-exchanger cores, microfluidic devices).

Thermally dissolvable support (e.g., thermoplastic polyurethane): Requires heating to 80–100 °C and mechanical removal (brushing, ultrasonic agitation). Leaves some surface roughness but is faster and cheaper than water-dissolution.

Z-Resolution & Layer Quality

Z-layer thickness is 16–30 µm, yielding ultra-smooth surfaces (<10 µm Ra) and excellent dimensional accuracy (±0.3 mm). In contrast, FDM with 0.2 mm layers or SLA with 0.05 mm layers produce rougher z-steps when surface normals are vertical.

The fine Z-resolution is only achievable because droplets land and cure in place, without spreading or sagging. In SLA or FDM, layer height is limited by material flow (resin wicking, filament extrusion rate); in material jetting, layer height is set purely by nozzle-to-platform distance and phototool resolution.

Resin Chemistry & Cure Depth

Build resin and support resin are typically acrylate-based oligomers with photoinitiators (α-hydroxy ketones or acylphosphine oxides). When UV strikes, radicals form and cross-link the oligomer chains, raising viscosity until the resin is solid (<1 second).

Unlike SLA, where cure depth is 0.1–0.5 mm and poses a resolution risk, material jetting cures only the droplets themselves (a few nanoliters). Excess UV from the lamp does not over-expose adjacent areas because each droplet is small and isolated.

Mechanical Properties & Post-Cure

Jetted parts are partially crosslinked after printing. A post-cure step (oven at 60–80 °C for 30 minutes, or UV oven for 1–2 hours) completes polymerization, raising tensile strength and elongation to design values.

Mechanical properties depend on material selection. Rigid acrylic resins achieve tensile strength ~50 MPa; rubber-like elastomers achieve elongation >100%. The ability to blend materials on a per-layer or per-pixel basis enables unprecedented control over mechanical response.

Speed & Throughput

Build speed is 20–60 mm/h (part height). For a 100 mm tall part, 2–5 hours of print time is typical. This is much faster than SLA (10–30 mm/h) and faster than most FDM (5–20 mm/h for precision parts). The parallelism of 96–128 nozzles firing simultaneously is key to the speed advantage.

Accuracy & Surface Finish

Dimensional tolerance is ±0.3 mm, excellent for prototyping. Surface finish is 10–20 µm Ra, smoother than FDM or laser sintering. For cosmetic or tribological surfaces, minimal post-processing is required.

However, fine features (<0.5 mm) may be difficult to reproduce consistently due to the discrete nature of 50 µm droplets. A 0.3 mm feature is only ~6 droplets wide, and edge rounding from droplet coalescence is unavoidable.

Environmental & Safety Considerations

Uncrosslinked resin is a skin irritant and sensitizer. Proper gloves and ventilation are critical. The Ventilation & Fume Extraction system captures volatile monomers (acrylate vapors) and removes them via activated-charcoal filtration or exhausts them to outdoors.

Post-cure ovens must be well-ventilated; cross-linking releases volatile organic compounds (VOCs), principally acetaldehyde and other aldehydes.

Hazardous waste from support-material baths and uncrosslinked resin residues must be disposed according to local regulations.