Comprehensive Analysis of Vacuum Casting Process: The Secret to Delivering 100 Sets of Small-Batch Plastic Parts in 5 Days
When product development enters the trial production phase, and dozens to hundreds of parts are needed for market testing, exhibition displays, or small-scale trials, the cost and cycle time of injection molds are high, while the cost per unit for 3D printing or CNC machining is also too high. Vacuum casting is the ideal process for solving this "intermediate" demand. This article will comprehensively explain the principles, processes, and application scenarios of vacuum casting.
What is vacuum casting?
Vacuum casting is a small-batch production method based on silicone molds. Its core steps include:
- Master model making: A master model is made using CNC machining or high-precision 3D printing to ensure surface quality and dimensional accuracy.
- Silicone mold making: The master model is suspended in a casting box, and liquid silicone is poured in. After vacuum degassing, it is cured into shape.
- Removing the master model: The silicone mold is cut along the parting line, the master model is removed, and a silicone mold with a cavity is obtained.
- Vacuum casting: The mixed two-component PU resin is poured into the silicone mold under vacuum conditions.
- Curing and demolding: After being placed in an oven for curing, the mold is opened, and the replica is taken out. The gate and flash are trimmed.
The entire process from master model making to the delivery of the first batch of finished products usually takes 5-7 days.
Core advantages of vacuum casting
- Very low cost: The material and manufacturing cost of a silicone mold is only one-tenth to one-fifth of that of a formal steel mold.
- Very fast delivery: Standard delivery time is 5-7 days, and urgent orders can be shortened to 3-4 days.
- Rich materials: PU resin can simulate various plastic properties such as ABS, PC, PP, POM, soft rubber (similar to rubber), transparent materials, heat-resistant materials, and flame-retardant materials.
- Flexible surface treatment: The cast parts can be painted (matte, glossy, rubber paint), screen printed with logos, electroplated, or water transferred, with appearance quality almost identical to injection-molded parts.
- High dimensional consistency: The dimensional deviation of parts produced by the same mold is small, making them suitable for products requiring assembly.
Key points of the vacuum casting process
- Master model precision determines everything: The surface quality and dimensional accuracy of the master model directly affect each replica. Yiruida Technology uses CNC machining to make the master model, ensuring a tolerance of ±0.05mm.
- Silicone mold design: The position of the parting surface, gate design, and vent groove settings require rich experience. Poor design may lead to bubbles, insufficient material, or noticeable parting lines.
- Vacuum casting: Casting under vacuum conditions can completely eliminate bubbles, ensuring dense internal structure and no pinholes on the surface of the parts.
- Post-processing: After demolding, the gate and flash need to be trimmed, and grinding, painting, or screen printing may be necessary if required.
Which products are suitable for vacuum casting?
- Medical device housings (10-100 sets for clinical testing)
- Consumer electronics housings (20-50 sets for crowdfunding photography)
- Automotive interior modification parts (30-100 sets for small-batch supply)
- Robot housings (10-50 sets for exhibition demonstrations)
- Any small-batch plastic parts that require quick access to a "near-injection molding" appearance
It is worth noting that vacuum casting is not suitable for products requiring extremely high strength (such as structural parts) or very large quantities. For demands over 100 pieces, it is recommended to evaluate a simple injection mold solution.
Choosing the right supplier is also critical. Experienced teams can optimize mold design according to product features, reduce post-processing workload, and improve yield rates. If you have a small-batch plastic parts demand of 10-200 pieces, consider sending your drawings to a professional supplier to get a free process evaluation.