The essence of the process is a reaction injection molding technology that replicates the prototype through a silicone mold. The core uses two-component polyurethane resin (such as Smoothed Cast 300 series), which is injected into the silicone mold for curing and shaping after vacuum degassing. The typical process includes: prototype 3D printing (cost: 15-80), silicone mold making (curing time: 6-8 hours), resin injection (pressure: 0.3-0.5 MPa), and post-treatment (application of mold release agent). Compared with CNC machining, urethanecasting can save 89,227 yuan and reduce it to $24.
The economic inflection point for small-batch production is at the level of 50 to 500 pieces. When the demand exceeds the 3D printing capacity (usually less than 20 pieces) but does not reach the injection mold threshold (more than 5,000 pieces), this process achieves the optimal ROI. Data from Protolabs in the United States shows that for manufacturing medical catheter handles (made of ABS material), the total cost for a 500-piece order is 5,200 (including 1,800 mold fees), with an average cost of 10.4 per piece. If injection molding is adopted, the mold cost is 15,000 + $3.2 per piece, and the break-even point requires 1,734 pieces.
The material performance covers 80% of the mechanical indicators of engineering plastics. By adjusting the ratio of isocyanate to polyol (typical ratio 1:1), the material properties ranging from soft TPU (Shore hardness 60A) to rigid PC (flexural strength 98MPa) can be simulated. The Bayer Desmopan series achieves an elongation at break of 450% (close to injection-grade TPU), with a heat deflection temperature of up to 120 ° C (±2 ° C deviation). Automotive OEM cases show that the fatigue life of the heat-resistant bracket under the hood exceeds 200,000 times (ISO 527 standard), which is 12 times longer than that of 3D printed parts.
The surface treatment quality meets the optical grade standard of Ra 0.8μm. Vacuum injection (vacuum degree <1mbar) enables the replication accuracy of parts to be ±0.15mm/mm. Apple supply chain enterprises use this process to manufacture earphone prototypes, achieving a 18° gloss (GU) surface and a dimensional tolerance of ±0.05mm. The 2024 Leica camera housing trial production project verification: The polyurethane housing with metal deposition coating (film thickness 30μm) has a wear resistance reaching the EN ISO 4649 Ma grade.
Industry application decision trees focus on three major scenarios:
Medical verification devices: Surgical guides are manufactured using biocompatible resin (ISO 10993-1 certified), with a single mold capable of producing 250 pieces (unit price 32), saving 120 yuan per piece compared to machining, and meeting the FDA 510(k) requirement of anatomical precision error <0.3mm
Automotive function testing: The development of BMW’s aerodynamic kit adopted urethane casting, completing 50 sets of spoilers (made of PP material) in 7 days, reducing the cost of wind tunnel testing by 67%
Consumer electronics iteration: Small-scale production of GoPro action camera housings (300 pieces), mold cost 650 (injection mold 28,000), achieving a 11-week advance in product launch time