Our Cold Runner Injection Molding Services
Looking for high-precision, cost-effective plastic manufacturing solutions? Cold Runner Injection Molding delivers exceptional efficiency, minimal material waste, and consistent part quality—ideal for industries from automotive to medical. At Yigu Technology, our expertise in this technology ensures your projects meet tight tolerances, use optimal materials, and benefit from tailored surface treatments. Discover why businesses trust our cold runner capabilities to turn ideas into reliable, high-performance products.
What is Cold Runner Injection Molding?
Cold Runner Injection Molding is a widely used plastic manufacturing process where the molten plastic (resin) flows through a cooled channel system (the “cold runner”) to reach the mold cavity. Unlike hot runner systems, the cold runner does not retain heat—instead, it uses cooling channels to keep the runner material solid, which is later removed and recycled.
This process revolves around a few core principles:
- The cold runner system separates the molten resin from the mold cavity, preventing material from curing in the channels.
- Recyclable runner material reduces waste, making the process more sustainable and cost-effective.
- Precise temperature control in the runner ensures consistent flow to the cavity, improving part uniformity.
Below is a quick overview of key terms to understand the basic concept:
| Term | Explanation |
| Cold Runner | Cooled channel system that guides molten resin to the mold cavity; remains solid after molding. |
| Mold Cavity | The hollow space in the mold where plastic cools and takes the shape of the final part. |
| Molten Resin | Thermoplastic material heated to a liquid state for injection into the mold. |
| Recycling | The process of reprocessing solid cold runner material into new resin for future use. |
Yigu Technology’s Cold Runner Injection Molding Capabilities
At Yigu Technology, our Cold Runner Injection Molding Capabilities are built on decades of technical expertise and state-of-the-art equipment. We specialize in delivering solutions that meet the unique needs of diverse industries, combining precision with flexibility.
Our key strengths include:
- Technical Strength: Team of engineers trained in advanced mold design and cold runner system optimization.
- Capability Range: Production of parts from 0.1g to 5kg, suitable for small components (electronics) and large parts (automotive housings).
- Services Offered: End-to-end support, from material selection and prototyping to mass production and surface treatment.
- Proficiency: Experience with tight-tolerance projects (±0.005mm) and complex geometries.
See how our capabilities compare to industry standards:
| Capability | Yigu Technology | Industry Average |
| Part Weight Range | 0.1g – 5kg | 0.5g – 3kg |
| Tolerance Precision | ±0.005mm | ±0.01mm |
| Lead Time for Prototyping | 3–5 days | 7–10 days |
| Material Compatibility | 50+ thermoplastics | 30+ thermoplastics |
How Does Cold Runner Injection Molding Work? (Step-by-Step Process)
The Cold Runner Injection Molding Process follows a clear, repeatable workflow to ensure consistent part quality. Each step is optimized to minimize waste and maximize efficiency.
Step 1: Material Preparation
First, thermoplastic resin (in pellet form) is dried to remove moisture (critical for avoiding defects like bubbles). The dried resin is then fed into an extruder.
Step 2: Melting & Injection
The extruder heats the resin to its melting point (180–300°C, depending on the material). A screw pushes the molten resin through the cold runner system—cooled by water channels—to the mold cavity.
Step 3: Cooling & Solidification
Once the mold cavity is filled, cooling channels in the mold and cold runner system lower the temperature. The plastic solidifies in the cavity (taking the part shape) and the cold runner (remaining solid).
Step 4: Demolding & Runner Removal
The mold opens, and the part (attached to the cold runner) is ejected. The runner is then cut off and sent for recycling.
Step 5: Quality Inspection
The final part undergoes inspection for dimensional accuracy, surface quality, and defects—ensuring it meets tolerance limits.
Below is a visual of the process flow:
| Sequence | Operation | Key Action |
| 1 | Material Prep | Dry resin pellets; feed to extruder. |
| 2 | Melting | Heat resin to melting point; mix uniformly. |
| 3 | Injection | Push molten resin through cold runner to mold cavity. |
| 4 | Cooling | Cool mold and runner; solidify plastic. |
| 5 | Demolding | Eject part + runner; separate runner for recycling. |
| 6 | Inspection | Check part dimensions, surface quality, and defects. |
Materials for Cold Runner Injection Molding
Choosing the right Cold Runner Injection Molding Materials is critical for part performance, durability, and cost. Yigu Technology works with a wide range of thermoplastics, each selected based on the application’s requirements (e.g., heat resistance, flexibility).
Common Materials & Their Properties
| Material Type | Examples | Key Properties | Suitable Applications |
| Polypropylene (PP) | Homopolymer PP, Copolymer PP | Lightweight, chemical-resistant, flexible | Packaging, consumer goods, automotive parts |
| Polyethylene (PE) | LDPE, HDPE | Impact-resistant, low friction | Toys, containers, pipes |
| Polyamide (PA/Nylon) | PA6, PA66 | High strength, heat-resistant | Automotive components, electrical parts |
| Polycarbonate (PC) | General-purpose PC | Transparent, shatter-resistant | Electronics housings, medical devices |
| Acrylonitrile Butadiene Styrene (ABS) | General-purpose ABS | Rigid, impact-resistant | Toys, automotive interiors, electronics |
Material Selection Criteria
When choosing materials, we consider:
- Material Requirements: Heat resistance, chemical resistance, and mechanical strength.
- Cost: Balancing performance with budget (e.g., PP is more affordable than PC).
- Process Compatibility: Ensuring the material flows well through the cold runner system.
Surface Treatment for Cold Runner Molded Parts
Cold Runner Injection Molding Surface Treatment enhances both the aesthetic appeal and functional performance of parts. Yigu Technology offers a range of surface finishing options to meet industry-specific needs.
Common Surface Treatment Methods
| Treatment Type | Process | Benefits | Applications |
| Polishing | Buffing the part surface to a smooth, glossy finish | Improves aesthetics; reduces friction | Consumer goods, medical devices |
| Texturing | Creating a patterned surface (e.g., matte, ribbed) via mold design | Enhances grip; hides minor defects | Automotive interiors, tool handles |
| Painting | Applying a protective or decorative coating | Custom colors; UV resistance | Toys, electronics, automotive parts |
| Plating | Depositing a metal layer (e.g., chrome, nickel) on the surface | Improves conductivity; corrosion resistance | Electrical components, decorative parts |
Surface Quality Standards
We adhere to strict surface quality guidelines, including:
- No visible scratches, bubbles, or unevenness.
- Consistent color and texture across all parts in a batch.
- Compliance with industry standards (e.g., ISO 8256 for plastic surface finish).
Tolerances & Precision in Cold Runner Injection Molding
Cold Runner Injection Molding Tolerances refer to the allowable variation in part dimensions—critical for ensuring parts fit and function as intended. Yigu Technology prioritizes high precision and uses advanced measurement tools to maintain tight tolerances.
Tolerance Ranges by Part Type
| Part Category | Dimensional Tolerance | Measurement Tool | Quality Control Check |
| Small Electronics (e.g., connectors) | ±0.005mm – ±0.01mm | Optical Comparator | 100% inspection of critical dimensions |
| Automotive Components (e.g., sensors) | ±0.01mm – ±0.02mm | Coordinate Measuring Machine (CMM) | Sampling (10% of batch) + full inspection for critical parts |
| Consumer Goods (e.g., bottle caps) | ±0.05mm – ±0.1mm | Calipers, Micrometers | Sampling (5% of batch) |
How We Ensure Accuracy
- Mold Design: Precision machining of mold cavities and cold runner systems.
- Process Control: Real-time monitoring of temperature, pressure, and injection speed.
- Inspection: Post-production checks using CMMs, optical comparators, and laser scanners.
Advantages of Cold Runner Injection Molding
Cold Runner Injection Molding Advantages make it a top choice for businesses seeking efficiency, sustainability, and cost savings. Compared to hot runner systems, it offers unique benefits:
| Advantage | Description | Value to Customers |
| Reduced Material Waste | Cold runner material is 100% recyclable (no cured waste), cutting material costs by 15–30%. | Lower production costs; more sustainable operations. |
| Lower Initial Investment | Cold runner molds are simpler and less expensive than hot runner molds (30–50% lower cost). | Ideal for small to medium production runs; lower upfront costs. |
| Easy Maintenance | No complex heating elements or controllers (common in hot runners), reducing maintenance time and costs. | Fewer production delays; longer mold lifespan. |
| Versatility | Compatible with a wide range of thermoplastics (including low-temperature resins). | Flexibility to produce diverse part types. |
| Consistent Part Quality | Uniform cooling in the runner ensures stable resin flow, reducing defects like warping or sink marks. | Higher yield rates; fewer rejected parts. |
Applications & Industries for Cold Runner Injection Molding
Cold Runner Injection Molding Applications span across industries, thanks to its versatility and precision. Yigu Technology serves key sectors with tailored solutions:
| Industry | Specific Applications | Material Used | Key Requirements Met |
| Automotive | Sensors, connectors, interior trim, battery housings | PA, ABS, PC | High precision, heat resistance, durability |
| Electronics | Connector pins, switch housings, LED brackets | PP, PC, ABS | Tight tolerances, electrical insulation |
| Medical | Syringe barrels, diagnostic device components, surgical tools | PP, PC, PE | Biocompatibility, sterility, precision |
| Consumer Goods | Bottle caps, toy parts, kitchenware | PP, PE, ABS | Cost-effectiveness, durability, aesthetic finish |
| Packaging | Food containers, lids, packaging inserts | PP, PE | Chemical resistance, food safety |
Manufacturing Techniques & Tooling for Cold Runner Injection Molding
Cold Runner Injection Molding Manufacturing Techniques rely on advanced tooling and process optimization to deliver high-quality parts. Yigu Technology’s expertise in mold design and production ensures optimal performance.
Key Manufacturing Techniques
- Mold Making: Precision machining of mold cavities (using CNC mills and EDM machines) to match part specifications.
- Cold Runner Design: Customization of runner size, shape, and cooling channels to ensure uniform resin flow.
- Injection Parameter Tuning: Adjusting temperature, pressure, and speed to match the material and part design.
Tooling Highlights
- Mold Material: H13 steel (high wear resistance) for long mold life (up to 1 million cycles).
- Cooling System: Optimized water channels in the mold and runner to ensure fast, uniform cooling.
Ejection System: Customized ejector pins or plates to prevent part damage during demolding.
Case Studies: Yigu Technology’s Cold Runner Success Stories
Our Cold Runner Injection Molding Case Studies demonstrate how we solve complex challenges for clients. Below are two real-world examples:
Case Study 1: Automotive Sensor Housing for a Global OEM
- Challenge: The client needed 100,000 sensor housings with tight tolerances (±0.01mm) and heat resistance (up to 120°C).
- Solution: Used PA66 (heat-resistant material) and a precision cold runner mold. Implemented real-time process monitoring to maintain tolerances.
- Results: 99.8% yield rate; material waste reduced by 25%; on-time delivery (30-day production run).
Case Study 2: Medical Syringe Barrels for a Pharmaceutical Client
- Challenge: Required biocompatible, sterile syringe barrels with a smooth inner surface (to prevent drug adhesion).
- Solution: Used medical-grade PP; added a polishing step to the mold cavity; implemented 100% inspection via CMM.
Results: Complied with ISO 13485 (medical device standards); zero defects in 50,000-unit batch; client renewed contract for 3 more years.
Why Choose Yigu Technology for Cold Runner Injection Molding?
When you partner with Yigu Technology, you benefit from our unique selling points and commitment to customer success:
- Expertise: 15+ years of experience in cold runner injection molding; team of 50+ certified engineers.
- Quality Assurance: ISO 9001 and ISO 13485 certifications; strict inspection protocols (100% for critical parts).
- Cost Savings: Recyclable runner material + efficient process design = 15–30% lower production costs.
- Customer Service: Dedicated project managers; 24/7 support for urgent requests; transparent communication (regular progress updates).
- Flexibility: Custom mold design for complex parts; quick turnaround (3–5 days for prototyping, 2–4 weeks for mass production).