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+86 133 9281 9446
+86 133 9281 9446
Apr. 09, 2025
Vacuum casting is an extremely valuable manufacturing process for producing high-quality plastic prototypes and short-run production parts.
It works because liquid plastic materials are injected into a silicone mold, and vacuum pressure is applied. Parts produced using vacuum pressure can be highly detailed with accurate dimensions and smooth surface finishes. Selecting the right material for vacuum casting is one of the most critical aspects. The choice of material affects the finished components' quality, usability, and cost-effectiveness.
We’ll talk about how materials affect vacuum-cast parts.
Quality, functionality, and cost are three factors that are impacted significantly by the choice of materials used in vacuum casting.
Critical features of the final product are greatly affected by the inherent properties of the plastic used in the vacuum casting process. Materials respond differently in mechanical properties such as tensile strength, elasticity, hardness, and heat tolerance until decomposition. For instance, ABS-like resins are particularly suitable for vacuum casting due to their toughness and shape stability. This makes them a widely used option for automotive vacuum-cast prototyping and housings.
On the other hand, materials such as PMMA/acrylic resins tend toward very high optical clarity, making them good candidates for use cases like clear lenses or transparent housings. When the properties of the selected material do not match the application's requirements, the final vacuum-cast parts can exhibit defects such as distortion under stress, becoming brittle over time, or simply failing by the time of service.
Environmental factors determining the conditions in which the vacuum-cast plastic components are eventually used are crucial. Medical devices should also be constructed from unique biocompatible silicones that do not contact with sensitive tissues and fluids. Resins with high thermal resistance, capable of sustaining 130 °C without degradation, are used for aerospace components that must endure intense engine heat.
In addition to temperature resistance, the material needs to withstand other environmental contributors, such as ultraviolet radiation, exposure to specific chemicals or solvents, and moisture absorption, depending on the use conditions.
The price of the plastic raw material can be one of the highest costs associated with a vacuum casting project, particularly when large production runs are planned. Therefore, the pricing of the resins themselves needs to be factored in. For specific cases, such as the production of a low-cost batch of simple snap-fit plastic components, a fairly inexpensive yet elastic and fatigue-resistant polypropylene-like resin would offer the best compromise between economic planning and quality assurance.
When evaluating very short prototype runs, costs are kept low by selecting low-cost rapid-turnaround materials such as PU8150, whose mechanical properties are not severely compromised. However, some resin formulations, such as PX100, feature improved viscosity profiles that prolong the liquid pot life before solidification occurs, vastly increasing the working time for manufacturers and reducing the volume of material wasted due to potential casting errors.
To choose among the vast array of plastic and elastomer options applicable to vacuum casting, below are the most pivotal considerations to take into account when making selections:
If the application will lead to the casted plastic products being utilized in more demanding and inhospitable operating surroundings, their material composition must be resilient enough. High engine heat conditions in automotive under-hood components need infusion resins with high heat deflection thresholds before losing structural integrity, typically 120°C or more.
Applications with frequent exposure to oils, solvents, or combustion byproducts require enhanced flame-retardant properties for safety; thus, materials like PU8263, formulated to minimize flammability risks, are prudent.
The anticipated mechanical demands that the vacuum-formed parts experience over their usable lifespans is possibly the most significant determinant for material selection. Will the application require high structural strength and durability under strain? Specific advanced ABS-like resin formulations offer imposing strength-to-weight values and impact resistance ideal for consumer electronics housings designed for ruggedness.
Does the component need more inherent flexibility or pliability? Thermoplastic polyurethane (TPU) bridges the gap between hard yet brittle plastics and soft but weak rubbers, giving it prominence in seals, gaskets, flexible tubing, and medical goods that need elasticity combined with toughness.
If planning a high production run of tens or hundreds of thousands of units, vacuum casting is likely the wrong process compared to alternatives like plastic injection molding from metal molds. Within the ideal scope of vacuum casting, silicone mold tooling intrinsically allows for approximately 20 to 50 sample parts before material degradation, depending on the material and mold intricacy.
For low-to-moderate production lots, relatively affordable basic resin formulations minimize overall expenses. PU8150 offers proven, well-balanced properties for general functional prototyping without sacrificing quality and provides excellent value for money.
Meeting strict biocompatibility standards and regulations is mandatory for vacuum-casting parts and products destined for critical industries, health applications, or public consumption. Any components expected to contact food or beverages absolutely require resin materials having FDA safety ratings suitable for food contact or USP Class VI certification, ensuring negligible contamination risk and toxicity if ingested. For medical implements like surgical tools or prosthetics, specialized biocompatible silicone materials approved for bodily implantation often represent the sole material option.
Below covers the most prevalent category of materials utilized for vacuum casting applications and their relative general characteristics:
● ABS-Like Resins —These Acrylonitrile Butadiene Styrene formulations produce vacuum cast parts mimicking properties of engineering-grade ABS plastics with high tensile strength, excellent dimensional stability even with some flexibility, and capability to chemically bond with ABS glues or be easily painted for enhanced aesthetics.
● PC-Like Resins—Resins in the polycarbonate plastic family offer an enticing balance of transparency nearing that of acrylic, heightened impact and scratch resistance, and improved heat resistance, reaching 120°C for hot components.
● PMMA/Acrylic Resins—Acrylic plastic resins derived from polymethyl methacrylate are unmatched for unparalleled optical clarity, with light transmission exceeding 92 percent and a sleek, glass-like surface finish.
● PP-Like Resins—Polypropylene-mimicking plastic resin variants provide tactile softness and flexibility. They are similar to ABS resins in vacuum casting processability yet have enhanced chemical inertness even when contacted with acids or solvents.
● Silicone Rubber—With a reputation for biocompatibility and bio-inertness, silicones built from silicone polymer chains impress for wide functional temperature range stability, sealing abilities, and resistance to moisture and aging yellowing.
● TPU Plastic—Thermoplastic polyurethane marries rubber elasticity with hardy resin tensile strength into versatile co-block polymer thermoplastics. These thermoplastics lend themselves to applications needing flexibility and deformation tolerance without compromising abrasion protection.
Selecting the optimal resin or plastic material aligns technical specifications, environmental needs, and budget for vacuum-cast part success. As this guide covered, properties like strength, heat resistance, FDA compliance, and cost efficiency determine quality, functionality, and manufacturability.
Partnering with experts like Kaierwo Vacuum Casting service lends material science and precision manufacturing expertise cultivated from years of industrial prototyping. Their specialized knowledge of advanced resins and certified medical-grade silicones helps identify high-performance, compliant solutions tailored to unique application criteria. Kaierwo’s vacuum casting achieves accuracies within 0.1mm using state-of-the-art equipment and verifies tolerances through stringent optical QA testing.
From aerospace and automotive prototypes to biocompatible medical implements, the material science foundations empower design innovation. For your next vacuum casting materials project, connect with Kaierwo to request custom-formulated, precision vacuum cast parts that excel from concept to production.
We attach great importance to customers' needs for product quality and rapid production.
We always insist that meeting customers' needs is to realize our value!
