VisiJet M2 ENT (Elastomeric Natural Translucent) is a UV-curable elastomeric photopolymer supplied for the 3D Systems ProJet MJP 2500 and ProJet MJP 2500 Plus material jetting platforms. The resin is deposited from sealed cartridges through a multi-jet printhead array, and each layer is cured by an integrated ultraviolet source. The standard high-definition build mode operates at a layer thickness of 32 µm and an in-plane resolution of 1200 x 1200 dpi. The cured material is a low-durometer elastomer with manufacturer-published typical properties of 27 Shore A hardness, 0.8 MPa ultimate tensile strength, 650% elongation at break, and 7.0 kN/m tear strength. The natural translucent color differentiates it from black elastomeric grades and permits visual inspection of internal voids, wall-thickness transitions, and crack initiation in translucent or transparent prototype geometries. The support material used in the same build is a melt-away wax, typically designated VisiJet M2 SUW, which is removed after printing in a heated melt-away station. M2 ENT is not represented as an implantable or food-contact material. Uncured resin should be handled with nitrile gloves and eye protection; biocompatibility, migration, and long-term aging must be verified for the final post-processed part under the intended use.

At the network level, the M2 ENT elastomer has high segmental mobility and low crosslink density. This gives large recoverable elongation but low tensile strength and reduced resistance to solvent swelling compared with high-crosslink rigid photopolymers. Layer-by-layer UV cure can produce slight through-thickness conversion gradients, and mechanical properties may continue to drift during the first hours after printing as residual species diffuse and the part equilibrates with ambient moisture and temperature. Conditioning at 23 °C and 50% RH according to ASTM D618 is therefore advisable before comparative mechanical testing.

Build orientation has a measurable effect on M2 ENT mechanical behavior. Tensile specimens printed with their long axis in the XY build plane usually show the highest elongation at break, while Z-oriented specimens can show reduced elongation because interlayer bond strength becomes the limiting factor. Support-material removal is the most demanding post-processing step. The melt-away wax support is solid at room temperature and is removed by heating the build tray. Enclosed internal channels, blind pockets, and fine lattice structures can trap molten wax; drain holes or venting paths are required. Small drain diameters can be insufficient because the wax has limited flow rate at the removal temperature, and the low-modulus elastomer can deform if the wax is forced through restricted passages. After wax removal, short-duration isopropanol cleaning is used to remove residual wax film, but extended solvent contact should be avoided because solvent absorption can swell the low-crosslink-density network and temporarily depress the Shore A reading. Parts should be cooled in a fixtured state to minimize warpage after support-material removal.

Support removal for the MJP 2500 series is typically performed in a controlled wax-removal oven or bath integrated into the workflow. The operating temperature must be high enough to reduce the support wax viscosity but below the temperature at which M2 ENT exhibits rapid creep. Agitation or ultrasonic energy may accelerate wax removal, but thin elastomeric sections can be damaged by high-frequency mechanical energy if the part is not fixtured. Residual wax remaining on the surface can be removed with a compatible solvent wipe; however, the wipe procedure should be validated because low-durometer photopolymers can retain solvent and exhibit delayed hardness loss. Drying after cleaning should be conducted at ambient temperature or within the printer manufacturer’s recommended post-processing envelope. The exact oven temperature for M2 ENT support removal is not listed in all public technical data sheets, so the current VisiJet M2 SUW processing guide should be followed.

Design rules for M2 ENT differ from rigid photopolymers. Because tensile modulus is below 1 MPa, bosses and snap-fit arms do not generate high clamping force. Threaded inserts and press-fit pins should be installed in a rigid carrier or embedded during post-processing rather than screwed directly into elastomer walls. Thin membranes can flex but may collapse during support removal if unsupported. Ribbing, gussets, and thickened sections improve dimensional stability during wax drainage. Sub-millimetre feature resolution is process-limited; published data for this specific configuration is limited. Sharp internal corners should be replaced with fillets to reduce notch-initiated tearing. The natural translucency is useful for visual crack tracking during prototype flex testing.

What Mechanical Test Data Define the Soft-Elastomer Response?

Manufacturer-published properties for M2 ENT are generated using ASTM methods. Tensile stress-strain response follows ASTM D412; the reported ultimate tensile strength is 0.8 MPa, and elongation at break is 650%. Hardness is 27 Shore A under ASTM D2240. Tear strength is reported as 7.0 kN/m under ASTM D624, typically with a Die C geometry. Specific gravity is approximately 0.94 under ASTM D792. These values describe a tensile modulus below 1 MPa, roughly three orders of magnitude lower than typical rigid MJP resins. The high elongation value is a single-stroke tensile property, not a fatigue limit. The low hardness means indentation and creep under compressive load should be evaluated for gasket or seal functions. Hardness measurements are time-dependent in elastomers; readings taken before full relaxation after support removal or solvent cleaning can produce misleading values. Conditioning according to ASTM D618 stabilizes the specimen before data collection.

Anisotropy is a critical qualification parameter. Material jetting builds parts layer by layer, and layer interfaces are lower-strength planes. Test bars should therefore be printed in both XY and Z orientations because published datasheet values generally represent a single orientation. A three-axis validation build on the specific ProJet MJP 2500 or 2500 Plus serial number is recommended to quantify orientation-dependent tensile, elongation, and tear differences. The manufacturer does not publish complete data for long-term humidity, ultraviolet aging, or dynamic cycling effects on M2 ENT. For critical applications, ASTM D412 or ASTM D638 tensile testing should be supplemented by application-specific dynamic mechanical analysis and fluid compatibility testing.

Table values are manufacturer-published typical data, not guaranteed specifications. The current revision of the 3D Systems technical data sheet should be referenced before serial production.

Build location has an empirical effect on mechanical properties. UV lamp irradiance may not be perfectly uniform across the entire build area; center and perimeter locations can produce measurable differences in cure conversion and tensile strength. A grid of tensile bars printed in the XY and Z orientations across the build platform provides data for process capability. For a low-durometer elastomer, small cure differences are magnified because the network is highly compliant. Print orientation and location should therefore be fixed before generating design allowables. If production parts are scattered across the platform, the design allowable should be based on the weakest validated location, not the center-line average.

First article inspection for M2 ENT should include dimensional measurement after support removal and after 24 h conditioning at 23 °C and 50% RH. The soft elastomer can exhibit springback after fixturing, so measurement fixtures should support the part without applying compressive strain. Touch-probe coordinate measuring machines can deform the surface and produce unrepeatable readings; non-contact scanning is preferred for thin-walled elastomeric parts. Tensile bars should be printed in the same orientation and at the same build-platform location as production parts to capture process variation. A documented process capability study using ASTM D412 tensile strength and elongation at break is appropriate for serial production.

Cross-Grade Differentiation and Comparable Elastomeric Systems

Within the M2 material family, M2 ENT and M2 EBK are both elastomeric grades. M2 ENT is natural translucent, while M2 EBK is black. The primary documented difference is optical density and color; pigmentation can influence cure depth, surface energy, and visual inspection. M2 ENT permits transmitted-light inspection of wall thickness and internal micro-cracks in translucent parts. M2 EBK is selected when black color is required or when light-blocking behavior is needed. Mechanical differences between the two elastomeric grades are smaller than the difference between elastomeric and rigid MJP materials, but direct substitution should be validated with control coupons.

Contrast with rigid MJP grades is pronounced. Rigid multipurpose materials have Shore D hardness, high tensile modulus, and low elongation at break. M2 ENT cannot replace rigid grades in snap-fit closures, optical mounts, or high-stiffness brackets. Conversely, rigid grades cannot tolerate the recoverable deformation of M2 ENT. The castable wax grade M2 CAST is a different product intended for burnout during investment casting and is not an engineering elastomer.

Compared with other commercial elastomeric additive manufacturing materials, M2 ENT uses material jetting with melt-away wax support. This is different from PolyJet elastomers that use a gel-like support removed by water or mechanical methods. The melt-away wax support can produce smooth internal channels but requires thermal post-processing. Vat-polymerized elastomeric resins are built in a vat with same-material supports, which can leave attachment nibs and reduce surface finish. Direct side-by-side mechanical data across platforms are rarely published under identical orientation and conditioning; qualification builds should include control coupons on each candidate material.

Compared with molded silicone or polyurethane elastomers, M2 ENT is intended for direct additive manufacture of low-volume parts and prototypes without tooling. The property profile is closer to a very soft thermoplastic elastomer or silicone than to high-durometer molded urethane. However, additive manufacture introduces anisotropy and process-dependent mechanical behavior not present in isotropic molded materials. Design engineers should not assume that a molded Shore A 27 compound and M2 ENT will behave identically under compression set, tear, or dynamic cycling.

The MJP 2500-series build chamber is maintained under controlled temperature, but the user facility should avoid high relative humidity because UV-curable resins are moisture-sensitive before cure. Cartridges should be allowed to reach room temperature before loading, and partially used cartridges should be sealed when not in the machine. Resin viscosity is managed by the printer’s heated delivery system; the manufacturer does not publish exact jetting viscosity for M2 ENT. Process validation can be performed by printing a tensile bar array at the center and perimeter of the build platform to detect lamp irradiance gradients or temperature differences. The support-material wax is selected for melt-away removal and is not used as a final surface coating.

When the M2 ENT Network Reaches Its Practical Tear Threshold

Under cyclic tensile or flexural loading, M2 ENT may accumulate permanent set before the single-stroke elongation at break is reached. The soft network can microtear at stress concentrations, especially when loading is normal to the build plane. Tear resistance of 7.0 kN/m is moderate and should not be compared with high-durometer industrial elastomers. Dynamic sealing applications should be analyzed for friction, abrasive filler contact, and extrusion gap. M2 ENT is not suitable for high-pressure seals where the elastomer can be extruded through a clearance gap under load.

Chemical compatibility is limited. Strong polar solvents, aromatic hydrocarbons, and concentrated acids or bases can swell or degrade the UV-cured network. The material should be tested in the actual service fluid at service temperature because hardness and tensile strength alone do not predict retention of sealing force. Outdoor exposure to ultraviolet radiation can continue crosslinking and may alter color and mechanical response; aging studies are required before use in exterior or sun-loaded environments. Continuous service temperature is restricted by the low-durometer network; exposure above ambient drying or support-removal temperatures can cause accelerated creep and loss of dimensional stability. The manufacturer does not publish UL94 flammability ratings for this grade in standard datasheets, so flame-contact applications are outside the documented envelope.

Production-scale qualification on a ProJet MJP 2500 series line should include batch-to-batch viscosity checks, printer calibration verification, and reference tensile bars printed at the beginning and end of each build. The MJP printheads are temperature-controlled, and material pot life is governed by cartridge handling. If the machine is left idle for extended periods, the printhead can require a purge cycle that consumes resin and may slightly alter the first few parts of the run. Maintenance records should track UV lamp irradiance and printhead nozzle condition because both influence cure conversion and mechanical consistency in low-modulus elastomers. Final parts should be inspected for residual wax, oil-free surfaces, and dimensional stability after cooling to ambient temperature. Published data for this specific configuration is limited for long-term creep, compression set, and dynamic fatigue; these properties should be experimentally determined before deployment in safety-critical applications.