What Is Vacuum Casting? Process, Pros & Cons, and Materials

Vacuum casting (also called urethane casting) is a manufacturing process that pours liquid resin into a silicone mold under vacuum, producing dozens of parts from a single mold — without the cost of injection mold tooling. It delivers near-production-quality plastic parts quickly and affordably, which makes it a go-to choice for design validation before injection molding and for low-volume production.

Compared with printing parts directly in small quantities, vacuum casting is often faster and more cost-effective for medium-to-large parts and flexible materials — so mechanical engineers frequently reach for it during product development.

진공주형 과정을 보여주는 이미지 — Plastic parts being produced with the vacuum casting process

How Vacuum Casting Works: 5 Steps

Vacuum casting is a relatively simple process, but managing each step is what determines final quality.

Master pattern — Create the master model with SLA 3D printing or CNC machining.
Silicone mold — Encase the master in liquid silicone, let it cure, then cut it open and remove the pattern.
Vacuum pour — Pour liquid resin into the mold under vacuum so it fills completely without trapped air bubbles.
Cure & demold — Allow the resin to cure, then remove the part from the mold.
Finishing — Trim the gate, then apply surface finishing, painting, and other secondary operations.

A single silicone mold typically yields about 20 parts (roughly 10–20 pours). When you need more, additional molds are made.

Advantages of Vacuum Casting

Fast, low-cost tooling — Dramatically cheaper and quicker than cutting steel injection mold tooling.
Built for low volumes — Reliably reproduces dozens of parts from a single mold.
Near-production quality — Resins similar to production plastics give consistent parts that can be hard to tell apart from molded ones.
Wide material range — From ABS-like, PC-like, and PP-like resins to rubber-like (TPU) and transparent materials. Multi-material (two-shot-style) parts are also possible.
Flexible finishing — A full range of colors, painting, and printing makes it well suited to final validation.

플라스틱 제품 소량 제작 진공주형 방식을 보여주는 이미지 — Example of parts made by vacuum casting

Limitations to Know

Thermoset resins only — Materials are limited to polyurethane-based thermosets (urethane, epoxy, and silicone families).
Property differences vs. injection materials — Cast resins approximate, but don't exactly match, production thermoplastics. Be clear about what you're validating (design, fit, function, feel).
Volume ceiling — Beyond a few hundred parts, mold wear makes the process inefficient; at that point, consider injection molding.

OG 이미지 — Parts cast in multiple materials from a single silicone mold for material property testing, supported by Creallo

Available Materials

Creallo supports a broad range — ABS-like, PC-like, PP-like, rubber-like (TPU/PU), and transparent resins. Rubber-like materials in particular replace rubber and silicone to produce flexible yet durable parts. See Creallo's vacuum casting materials for the full list.

When Vacuum Casting Makes Sense

Vacuum casting is the right call when you need a small but consistent batch of prototypes, or fast, cost-efficient validation before committing to injection mold tooling.

Situation	Why it fits	Vacuum casting advantage
Batch of prototypes (10–100)	Need a set quantity for testing, marketing, or display	Reliable repeatability from one silicone mold
Pre-injection validation	Confirm design and function before cutting tooling	Catch design errors early, save tooling cost
Tight budget or lead time	High upfront tooling cost and lead time are a concern	Low upfront cost, parts in ~1–2 weeks
Flexible-material samples (TPU, etc.)	Hard to achieve with CNC or 3D printing	Produces flexible, elastic parts

For a full comparison of when to choose 3D printing, CNC, or vacuum casting → Prototyping process comparison: 3D printing vs. CNC vs. vacuum casting.

Applications

Vacuum casting shines for flexible-material samples and limited test runs across industries.

Here are some examples of applying vacuum casting for production:

Wearable bands: 50 TPU samples for fit and wear testing

사람, 시계, 패션 액세서리, 손목이(가) 표시된 사진

AI 생성 콘텐츠는 정확하지 않을 수 있습니다. — Vacuum casting used to make wearable band test samples for a smartphone

Appliance button: durability and feel validation before injection tooling

가전용품, 주방가전, 세탁기, 의류 건조기이(가) 표시된 사진

AI 생성 콘텐츠는 정확하지 않을 수 있습니다. — Vacuum casting used to make and test buttons where durability and feel matter, before injection mold tooling

Medical device housings: 30 sets for trade-show demos, on a short timeline

실내, 원격, 제어, 리모컨이(가) 표시된 사진

AI 생성 콘텐츠는 정확하지 않을 수 있습니다. — Vacuum casting applied to a medical device housing for trade-show demonstration

Delivery-robot housings: 10 sets of large body covers, delivered fast

바퀴, 차량, 교통, 건물이(가) 표시된 사진

AI 생성 콘텐츠는 정확하지 않을 수 있습니다. — A large delivery-robot outer housing produced by vacuum casting

You can see real vacuum casting projects from Creallo in our 3D printing, CNC & vacuum casting portfolio | Creallo.

FAQ

How many parts can one mold produce? Typically around 20, depending on geometry; additional molds are made for higher volumes.
What's the minimum quantity? As few as one, but vacuum casting is most economical in the 10–100 range.
What tolerances are achievable? Typically ±0.5% of the nominal dimension, with a minimum of ±0.5 mm.
What's the lead time? Usually about 1–2 weeks.
How does quality compare to injection-molded parts? Very close, though materials are limited to thermosets, so some property differences exist.

Vacuum Casting with Creallo

Vacuum casting is a practical answer when you need speed, cost, and quality together — for pre-production validation or low-volume runs. Not sure whether to build your master with 3D printing or CNC, or at what quantity vacuum casting becomes the economical choice? Creallo's engineering team reviews your part, quantity, and cost targets and recommends the right process.

Get an instant online quote — just upload your 3D file to see pricing and lead time.