If you’re a product engineer or procurement specialist looking for a cost-effective way to make small-batch, high-precision prototypes, the gel injection mold processing prototype process is exactly what you need. This method blends the advantages of vacuum casting and silicone rubber molds, making it perfect for creating detailed prototypes without breaking the bank. Let’s dive into how it works, real-world examples, and key tips to get the best results.
What Is the Gel Injection Mold Processing Prototype Process?
The gel injection mold processing prototype process is a manufacturing technique that uses silicone rubber molds and vacuum casting equipment to produce prototypes. Unlike traditional injection molding (which needs expensive metal molds), this process relies on flexible silicone molds—great for low-volume runs (usually 10-50 pieces) and complex designs. It’s widely used in industries like consumer electronics, medical devices, and toy manufacturing.
For instance, a startup making a new wireless earbud needed 20 prototypes to test fit and design. Using this process, they got the prototypes in 7 days at 60% of the cost of metal mold injection molding. Each earbud had precise details (like tiny button grooves) that matched the original design perfectly.
Step-by-Step Guide to the Gel Injection Mold Processing Prototype Process
The process has 8 core steps. We’ll use a case study of a medical device company (prototyping a plastic inhaler component) to show how each step works.
1. Create the Original Prototype
First, you need an original model (called a “master prototype”). This can be made via 3D printing, hand-carving, or CNC machining. The quality of this master directly affects the final prototypes—so it must be accurate and smooth.
- Case Example: The medical company used SLA 3D printing to make the inhaler master prototype. The 3D printer had a layer height of 0.05 mm, ensuring the inhaler’s 2 mm-wide air channel was perfectly shaped.
- Key Tip: If you’re 3D printing the master, use a high-resolution setting (0.05-0.1 mm layer height) to avoid visible layer lines.
2. Make the Silicone Rubber Mold
Next, you build a mold frame around the master prototype and pour liquid silicone rubber into it. Once the silicone cures, you split the mold to remove the master—leaving a cavity that matches the prototype’s shape.
| Component | Choice for the Inhaler Case | Reason |
| Silicone Rubber Type | Two-part addition-cure silicone | Cures without releasing toxic fumes; has good flexibility |
| Mold Frame Material | Acrylic (5 mm thick) | Easy to cut; lets you check the silicone pouring process |
| Curing Time | 4 hours (at 25°C) | Ensures full curing without warping the mold cavity |
3. Prepare Vacuum Casting Equipment
Vacuum casting equipment is a must—it uses negative pressure to pull the liquid pouring material into the silicone mold. This eliminates air bubbles, which can ruin prototype details.
For the inhaler case, the company used a vacuum casting machine with a 50-liter chamber. The machine pulled a vacuum of -0.095 MPa, ensuring the liquid material filled every part of the mold (including the tiny air channel).
4. Select the Right Pouring Material
Choose a pouring material (like resin or plastic) that matches the final product’s properties. For example, if your prototype needs to be flexible, use a soft resin; if it needs to be strong, use a rigid plastic.
- Case Example: The inhaler prototype needed to be lightweight and impact-resistant. The company chose a polycarbonate (PC) resin with a tensile strength of 65 MPa—matching the material they planned to use for mass production.
- Common Pouring Materials:
- ABS resin (good for rigid, heat-resistant prototypes)
- Silicone resin (ideal for flexible parts like gaskets)
- Polyurethane (PU) resin (works for parts needing high impact resistance)
5. Pouring & Vacuum Defoaming
You pour the liquid material into the silicone mold, then put the mold into the vacuum casting machine. The machine removes air bubbles from the material—critical for prototypes with small details.
In the inhaler case, the team poured 15 ml of PC resin into each mold cavity. The vacuum machine ran for 3 minutes, removing bubbles that would have blocked the 2 mm air channel. Without this step, 40% of the prototypes would have had defective channels.
6. Curing the Material
After defoaming, you let the material cure. Curing time depends on the material type and temperature—higher temperatures speed up curing, but don’t overheat (it can warp the prototype).
- Case Example: The PC resin cured in 2 hours at 60°C. The team used an oven with temperature control (±2°C) to ensure even curing.
- Warning: If you’re using a heat-curable material, never exceed the recommended temperature. For example, PU resin can warp if cured above 80°C.
7. Demold the Prototype
Once the material is fully cured, you split the silicone mold to remove the prototype. Silicone’s flexibility makes this easy—you won’t damage the prototype’s fine details.
In the inhaler case, the team split the silicone mold by hand (no tools needed). The mold was flexible enough to stretch slightly, letting them pull out the prototype without bending the 2 mm air channel.
8. Post-Processing & Quality Checks
Finally, you do post-processing (like removing burrs or coloring) and check the prototype’s quality.
- Post-Processing Steps for the Inhaler:
- Used a small file to remove tiny burrs around the air channel.
- Sanded the prototype’s surface with 400-grit sandpaper to make it smooth.
- Sprayed a clear coat to protect the surface from scratches.
- Quality Checks:
- Measured the air channel width with a digital caliper (target: 2 mm ±0.05 mm).
- Checked for air bubbles using a magnifying glass (10x magnification).
- Tested the prototype’s fit with the inhaler’s other parts (ensured no gaps).
Common Challenges & How to Solve Them
Even with careful planning, issues can happen. Here are 3 common problems and their solutions—using data from the inhaler case.
| Challenge | Impact | Solution |
| Air Bubbles in Prototype | Ruined 30% of early inhaler prototypes | Increased vacuum time from 2 to 3 minutes; preheated the resin to 40°C |
| Mold Cracking | Silicone mold broke after 15 uses | Switched to a thicker silicone rubber (from 20 Shore A to 30 Shore A) |
| Prototype Warping | 15% of prototypes had bent air channels | Reduced curing temperature from 70°C to 60°C; added a cooling step |
Yigu Technology’s View on Gel Injection Mold Processing Prototype Process
At Yigu Technology, we’ve helped over 300 clients use the gel injection mold processing prototype process to speed up product development. We think this method is a game-changer for small-batch prototypes—it cuts costs by 40-60% compared to metal mold injection molding and shortens lead times to 5-10 days. Our team focuses on choosing the right silicone and pouring materials for each project, and we use advanced vacuum casting machines to ensure 98% of prototypes meet quality standards. For procurement teams, this means lower upfront costs and faster testing cycles.
FAQ
- Q: How many prototypes can one silicone mold make?
A: It depends on the mold material and prototype complexity. A high-quality silicone mold (30 Shore A) can make 20-50 prototypes. For simple parts (like a small button), it can make up to 100; for complex parts (like the inhaler), it’s usually 20-30.
- Q: How long does the entire gel injection mold processing prototype process take?
A: From master prototype to finished prototypes, it takes 5-10 days. For example, the inhaler project took 7 days: 1 day for 3D printing the master, 1 day for silicone mold making, 2 days for casting/curing, and 3 days for post-processing/quality checks.
- Q: Can this process make prototypes with overmolded parts (e.g., a hard plastic body with a soft rubber grip)?
A: Yes! You can use a two-step casting process: first cast the hard part, then place it back into the mold and cast the soft part around it. We’ve used this method to make prototypes for toothbrushes (hard handle + soft grip) and remote controls.
