In the development of industrial products, the choice of manufacturing process for plastic parts not only has an impact on the technical feasibility, but also on the product’s commercial strategy. Vacuum Casting and Injection Molding are among the most common methods used in the industry to manufacture plastic components with high precision. Both processes can produce high quality parts, but they are designed for different needs and development stages.
In this post we provide an in-depth technical comparison, based on real industrial production experience, to help engineers, designers and production managers make informed decisions. In addition, we share how Gestión de Compras uses these technologies in real projects for demanding industries such as automotive, electronics, medical and consumer goods.
What is Vacuum Casting and when is it used?
Vacuum Casting is a casting process that uses silicone molds generated from a master pattern (usually manufactured by 3D SLA printing or CNC machining). The process is performed inside a vacuum chamber to eliminate air bubbles and ensure a faithful reproduction of the design. Parts are obtained by pouring liquid polyurethane resins that cure inside the mold.
This method is especially useful in early stages of development or when limited production (up to about 100 units per mold) with short lead times and high aesthetic quality is required.
Technical characteristics:
- High fidelity to the original design, including complex details, thin walls and organic geometries.
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Use of technical resins that mimic the properties of plastics such as ABS, PP, TPE or PC.
- Possibility of obtaining functional parts with high quality visual and tactile finishes.
In Gestión de Compras, we apply Vacuum Casting when our customers need to validate a design before investing in an expensive injection mold, for short series production or when functional production is required for field testing, marketing or delivery of pilot batches to end customers. We control both dimensional quality and cosmetic finishes, including post-processing options such as painting, metallizing or screen printing.
What is Injection Molding?
Injection Molding is the most widely used process worldwide for the production of plastic parts in large volumes. It consists of melting thermoplastic polymer granules and injecting them at high pressure into a metal mold, where the material cools and solidifies, taking the shape of the cavity.
The mold can be made of steel or aluminum, and is specifically designed to withstand high pressures and repetitive cycles, making it possible to manufacture millions of identical parts with minimum tolerances.
Technical features:
- Large-scale production with very short cycle times (from 10 to 60 seconds per part).
- High dimensional accuracy and excellent repeatability between units.
- Wide range of thermoplastic materials available: from ABS and PA6 to technical plastics with fiberglass, flame retardants or biopolymers.
- Ability to integrate metal inserts, overmolding, multi-component parts or customized surface textures.
In Gestión de Compras, we design and manufacture customized injection molds, adapted to both medium and mass production runs. We work with customers who need advanced solutions such as hot runners, multi-cavity molds, automatic demolding systems or precise adjustment of functional tolerances, especially in sectors such as the automotive industry, where the robustness of the tooling and the optimization of cycles are key to product profitability.
In-Depth Technical Comparison
| Aspect | Vacuum Casting | Injection Molding |
|---|---|---|
| Production Volume | 1 – 100 units per silicone mold | 1,000 – millions of units per metal mold |
| Mold Cost | Low (silicone) | High (steel/aluminum, precision machining) |
| Mold Fabrication Time | 1 – 3 days | 3 – 6 weeks |
| Cycle Time | Minutes per part | Seconds per part |
| Mold Lifespan | ~20–25 casts per mold | 100,000 – 1,000,000 cycles |
| Materials | Polyurethane resins | Industrial-grade thermoplastics |
| Tolerances | +/- 0.3 mm | +/- 0.05 mm or better (depending on material/design) |
| Unit Cost | High for large volumes | Very low for high volumes |
| Post-processing | Painting, polishing, metallization | Direct texturing, chrome plating, painting, technical coatings |
| Best For | Functional prototypes, short runs, design validation | Mass production, final parts, regulated markets |
Typical industrial applications
- Vacuum Casting: electronic housings, visual parts for commercial presentations, functional prototypes, assembly tests, pilot batches for market tests.
- Injection Molding: automotive components, electrical connectors, lids, closures, light structural parts, appliance housings, consumer goods.
Our experience in Gestión de Compras
In Gestión de Compras, we have more than 20 years of experience in the manufacture of plastic parts by Vacuum Casting and Injection Molding. Our technical team works closely with customers from the design phase, advising on process selection, materials, mold design and post-processing requirements. In addition, we perform filling simulations (moldflow), parting line studies, shrinkage analysis and cost/benefit evaluations according to the required volume.
This allows us to guarantee
- Optimal lead times for both short series and high volume launches.
- Customized technical solutions for complex designs or regulated sectors.
- Cost reduction without compromising quality, taking advantage of our international manufacturing capabilities.
Conclusion
Vacuum Casting and Injection Molding are not mutually exclusive technologies, but complementary within a well-planned industrial strategy. The key is to identify at what stage of development the product is and what technical and logistical requirements are priorities.
At Gestión de Compras, we integrate both solutions within a global engineering, tooling and manufacturing service. From the first functional unit to full-scale production, we are your strategic partner for the development of high-quality plastic components.
