Liquid Silicone Injection Overmolding | Aobo Silicone -- Custom Precision Overmolding Solutions

Aobo Silicone, a professional manufacturer based in China, specializes in liquid silicone injection overmolding. This advanced process integrates platinum‑cured liquid silicone rubber with plastic or metal substrates via precision injection molding, creating a strong molecular bond between soft and hard materials. The products deliver excellent waterproof sealing, skin‑friendly touch, wide temperature resistance and electrical insulation properties, and are widely applicable to consumer electronics, mother & baby products, automotive parts and medical devices. We provide full‑chain custom services from structural design, mold development and sampling to mass production, with flexible solutions to meet procurement and delivery demands of different order volumes.

1. What is Liquid Silicone Overmolding?

Liquid silicone injection overmolding is an advanced forming process in which high‑flow liquid silicone rubber (LSR) is injected through precision equipment to coat pre‑molded rigid substrates (engineering plastics such as PC, ABS and PA, as well as metals such as stainless steel and aluminum alloy), forming an integrated composite structure after high‑temperature curing.

This process solves common industry pain points of traditional assembled silicone sleeves, such as easy detachment, poor sealing performance and high assembly costs. It retains both the structural rigidity of the substrate and the elastic properties of silicone, enabling one‑stop realization of waterproof sealing, anti‑slip grip, shock absorption, electrical insulation and tactile upgrade. It helps customers reduce assembly procedures, lower overall procurement costs, and improve the quality and market competitiveness of end products.

2. Core Advantages of Liquid Silicone Overmolding

① Molecular‑Level Bonding, Zero Delamination Risk
Using self‑adhesive liquid silicone raw materials, combined with substrate surface plasma activation and primer pretreatment, we achieve chemical molecular‑level bonding between silicone and substrates, with a peel strength of ≥18 N/cm. It maintains seamless adhesion even under frequent bending, extreme temperature differences and long‑term immersion, completely eliminating quality risks such as delamination, debonding and water leakage.

② Micron‑Level Molding Precision for Complex Structures
Liquid silicone features excellent fluidity and can fill micro cavities as small as 0.1mm. Combined with high‑precision molds and cold runner injection systems, the molding tolerance can be controlled within ±0.05mm. It supports thin‑wall overmolding (minimum 0.2mm), complex curved surfaces, and integrated molding of multiple colors and hardness levels, perfectly matching the design requirements of high‑precision products such as precision electronics and medical devices.

③ Wide Temperature Range Weather Resistance, Ultra‑Long Service Life
Adopting food‑grade/medical‑grade platinum‑cured liquid silicone with a stable siloxane main chain structure, it maintains long‑term elasticity and sealing performance in a wide temperature range from ‑50℃ to 200℃. It has excellent aging resistance, UV resistance, acid and alkali resistance, and yellowing resistance. Its service life can reach more than 5 years under outdoor working conditions, far exceeding ordinary solid silicone and TPE overmolded products.

④ Automated Mass Production, Better Overall Cost Efficiency
Fully automated injection molding production lines enable 24‑hour continuous production, with a single‑mold molding cycle as short as 30‑‑60 seconds. The mass production efficiency is 3‑‑5 times that of traditional compression molding processes. Integrated molding eliminates subsequent assembly procedures, with a stable yield rate of over 98%. Large‑scale orders can significantly reduce customers' unit procurement costs and labor assembly costs.

3. Detailed Technical Specifications

4. Full Application Scenarios

Consumer Electronics Industry
● Smart Wearables: Smart watch straps, band housings, TWS earphone ear tips and charging case seals, providing skin‑friendly wearing feel and IP68 waterproof protection
● 3C Digital Products: Button overmolding for phone/tablet protective cases, data cable connector seals, camera module waterproof rings, improving product grip and sealing reliability
● Smart Home: Electric toothbrush handles, humidifier seals, remote control anti‑slip buttons, achieving dustproof and waterproof performance with comfortable pressing experience

Mother & Baby Products Industry
● Feeding Products: Anti‑slip overmolding for PPSU baby bottles, spoon tip overmolding for complementary food spoons, water cup seals, compliant with food contact safety standards, soft for gum protection, anti‑drop and anti‑slip
● Teething Toys: Hard skeleton coated with liquid silicone, combining structural strength and oral safety, bite‑resistant and easy to clean

Automotive Parts Industry
● Interior Electronics: Automotive buttons, steering wheel multifunctional buttons, center console knob overmolding, wear‑resistant, anti‑slip and non‑yellowing after long‑term use
● Functional Seals: Headlight waterproof seals, sensor protective sleeves, charging interface seals, resistant to engine compartment high temperatures and complex outdoor environments, ensuring electrical safety

Medical Device Industry
● Surgical Instruments: Handle overmolding for scalpels and hemostatic forceps, providing anti‑slip grip and biocompatibility, suitable for high‑temperature steam sterilization
● Respiratory Equipment: Mask sealing edges, oxygen valve seals, skin‑friendly and non‑irritating, high comfort for long‑term wear

Industrial Equipment Industry
● Power Tools: Handle overmolding for electric drills and wrenches, shock‑absorbing and anti‑slip, improving operation comfort and safety
● Instruments & Meters: Connector seals, sensor protective sleeves, insulating and waterproof, suitable for harsh industrial working conditions

5. Certifications & Quality Control

Authoritative Certification System

Raw materials and finished products have passed multiple international mainstream certifications, meeting market access requirements worldwide:

● Food Contact Safety: FDA 21 CFR 177.2600 (USA), LFGB (Germany/EU)
● Environmental Compliance: RoHS 2.0, REACH (EU)
● Flame Retardant Safety: UL94 V0 (for industrial grade products)
● Medical Biocompatibility: ISO 10993 (selected items, for medical grade products)

Full‑Process Quality Control

1. Incoming Raw Material Inspection: Each batch of liquid silicone raw materials comes with the original material certificate. Upon arrival, we conduct random inspections on hardness, curing performance and environmental indicators. Unqualified raw materials are rejected directly.
2. In‑Process Patrol Inspection: Size, appearance and bonding strength are inspected every 2 hours during production. The MES system monitors key parameters such as mold temperature, injection pressure and curing time in real time, with temperature error controlled within ±1℃.
3. Finished Product Full Inspection Before Delivery: 100% visual inspection of finished product appearance; key dimensions are inspected by AQL sampling. Waterproof products undergo 100% air tightness testing to ensure sealing performance meets standards.
4. Delivery Sample Retention & Traceability: Production samples and inspection records are retained for each batch, supporting full‑chain quality traceability.

6. Differentiated Competitive Advantages – Why Choose Aobo Silicone

Product‑Side Advantages

● Stronger Bonding Stability: Our independently developed substrate surface treatment process and bonding formula reduce the delamination defect rate after high and low temperature cycle tests by 80% compared with the industry average.
● Higher Molding Precision: Mold processing accuracy reaches ±0.005mm. Combined with imported liquid silicone injection molding machines, the molding yield of complex thin‑wall parts is 5‑‑8 percentage points higher than the industry average.
● Wider Material Selection: We stock multiple grades of liquid silicone raw materials with 30‑‑80 Shore A hardness, covering food grade, medical grade, flame retardant grade, high transparency grade and other types, to quickly match different performance requirements.

Factory‑Side Advantages

● Shorter Delivery Cycle: With multiple liquid silicone injection molding machines and automated production lines on standby, the delivery cycle for regular bulk orders is 7‑‑15 days, 3‑‑5 days faster than the industry average.
● Flexible MOQ: We support seamless transition from small‑batch trial production to large‑scale mass production. The minimum order quantity for customized products can be as low as 500 pieces, suitable for trial orders of cross‑border sellers and startup brands.
● Comprehensive Custom Support: With an in‑house mold workshop and structural engineering team, we provide one‑stop services from product structure optimization, mold design, 3D sampling to mass production, reducing customers' multi‑party communication costs.

7. Custom Services & Production Process

Customization Scope

● Structural Dimensions: Custom shapes and specifications based on customer 3D drawings or samples
● Material Hardness: Adjustable from 30 to 80 Shore A, supporting integrated molding of multiple hardness levels in one product
● Color & Appearance: Customizable by Pantone color codes, supporting transparent, translucent, solid color, matte/glossy finishes
● Marking Processing: Supporting in‑mold logo, laser engraving, silk screen printing and other surface treatments
● Substrate Selection: Specified plastic/metal substrate materials and brands are acceptable; we also provide overmolding processing with customer‑supplied substrates

Full Cooperation Process & Timeline

1. Requirement Communication & Solution Evaluation: 1‑‑2 working days to confirm product requirements, provide estimated quotation and delivery time
2. 3D Drawing Confirmation & Mold Design: 3‑‑5 working days to output mold plan and DFM (Design for Manufacturability) analysis
3. Mold Manufacturing & Sampling: 10‑‑15 working days to complete mold processing and send initial samples for confirmation
4. Trial Production Adjustment: 3‑‑5 working days to optimize process parameters based on customer feedback
5. Mass Production: 7‑‑15 days for regular orders, subject to order volume and process complexity

8. Real Customer Application Feedback

"We had worked with three suppliers before for our smart watch waterproof seals, and all had the problem of debonding after high temperature exposure. After cooperating with Aobo, they optimized the surface treatment process for PC substrates. After 100 cycles of ‑40℃ to 85℃ thermal shock testing, there was no delamination or water leakage at all, and all IP68 waterproof tests passed. Their mass delivery is also very stable, and we have not had any batch quality issues for over a year."
— Procurement Manager, Cross‑Border Smart Wearable Brand

"We have very high food‑grade safety requirements for PPSU baby bottle overmolding. Aobo's raw materials all have complete FDA and LFGB certifications, the finished products have no odor, and all sensory tests meet standards. Moreover, their overmolding layer has uniform thickness, smooth corner transitions, and no flash or burrs, which has improved our subsequent assembly yield a lot. They also accept small‑batch trial orders, which is very friendly for new product development."
— Sourcing Director, Mother & Baby Products Brand

"Automotive buttons require high and low temperature resistance, UV resistance, and guaranteed wear resistance after 100,000 presses. After aging testing, Aobo's liquid silicone injection overmolding products show no obvious changes in appearance and feel, and the pressing feel is highly consistent. Their delivery is always on time. We place stable orders every month, and they have never delayed our production schedule."
— Purchasing Engineer, Automotive Electronic Accessories Supplier

9. Sample & Testing Support

Sample Policy

● Stock Samples: If we have similar standard mold products, we can provide 2‑‑3 pieces for free, with the customer only bearing the shipping cost
● Custom Sampling: Mold and sampling fees will be charged for custom sampling based on customer drawings. The mold fee can be refunded when the bulk order reaches the agreed quantity. Sampling lead time: 10‑‑15 working days
● Sample Quantity: Usually 3‑‑5 pieces for initial samples, which can meet basic testing and assembly verification requirements

Testing Report Support

● Material certificates and environmental test reports of corresponding batches can be provided with the shipment
● Testing by customer‑specified third‑party institutions (such as SGS, TÜV, etc.) is supported, with fees subject to specific items
● Special certification report copies can be provided for food‑grade and medical‑grade products

10. Packaging Solutions & Logistics Delivery

Standard Packaging

● Inner layer: Food‑grade PE bag sealed packaging to prevent dust and moisture contamination
● Middle layer: EPE foam or bubble bag for buffer protection to avoid scratches and collisions during transportation
● Outer layer: Reinforced 5‑layer corrugated carton, marked with product model, quantity, batch number and other information
● Custom blister trays and anti‑static packaging are available for special precision products

Custom Packaging Services

● Support customer‑specified packaging methods, shipping marks, neutral packaging, etc., with customer brand labels applicable
● Special packing arrangements such as separate packing and mixed packing can be made according to customer requirements

Logistics Delivery

● Production Lead Time: 7‑‑15 days for regular bulk orders; rush orders can be negotiated for expedited processing
● Loading Ports: Yantian Port (Shenzhen), Guangzhou Port; domestic designated warehouse delivery is also available
● Shipping Methods: Support sea freight, air freight, international express (DHL/FedEx/UPS) and other methods; we can cooperate with customer‑specified forwarders
● Trade Terms: Support EXW, FOB, CIF and other trade terms

11. After‑Sales Guarantee & Service Commitments

Warranty Commitment

● The product warranty period is 12 months after delivery
● Within the warranty period, if quality problems (such as debonding, cracking, dimensional deviation, etc.) are caused by raw materials or production processes, we offer free returns and exchanges after confirmation, and bear the corresponding shipping costs

Quality Problem Handling Process

1. Customer feedback with photos/videos and defect quantity
2. We respond within 24 hours and provide preliminary analysis and solutions within 48 hours
3. If on‑site confirmation is required, technical personnel will be arranged for communication or defective products can be sent back for inspection
4. After confirming it is our responsibility, we will complete replenishment or refund processing within 7 working days

Supporting Services

● Each customer is assigned a dedicated business contact to follow up on order progress and after‑sales issues throughout the process
● Free technical consultation is provided, assisting customers with product structure optimization and material selection
● We can cooperate with customers for joint new product development, providing process feasibility assessment and cost optimization suggestions

Product Specifications

12. Frequently Asked Questions (FAQ)

Material Safety

Q: Are liquid silicone injection overmolding products compliant with food contact standards?
A: Our food‑grade liquid silicone raw materials are all certified by FDA 21 CFR 177.2600 and EU LFGB. The platinum curing process leaves no harmful residues, making them safe for contact with food and drinking water, suitable for mother & baby and kitchenware products.

Q: Do the products have environmental certifications? Are they compliant for export to Europe?
A: Regular products comply with RoHS 2.0 and REACH regulations. Corresponding test reports can be provided, and they are fully compliant for export to major markets such as the EU and the US.

Customization & Delivery

Q: How long does it take to develop a custom mold if there is no ready mold?
A: The mold development cycle for conventional structural products is 10‑‑15 working days, and 15‑‑20 working days for complex structures, subject to product complexity. Sampling and mass production can be arranged immediately after the mold is completed.

Q: What is the delivery cycle for bulk orders?
A: With ready molds, orders within 50,000 pieces can be delivered in 7‑‑10 days; large orders over 100,000 pieces can be delivered in 10‑‑15 days. We have multiple automated production lines and can flexibly allocate production capacity according to order volume.

Minimum Order Quantity

Q: What is the minimum order quantity? Can I place a small‑batch trial order?
A: The minimum order quantity for customized products is 500 pieces, supporting small‑batch trial production. Standard products with public molds can have even lower MOQ. We understand the demand for new product trial sales and have set flexible MOQ tiers to help customers reduce trial and error costs.

Sample Policy

Q: Can I get samples for testing first? Are samples free?
A: If we have similar stock samples, we can provide 2‑‑3 pieces for free with freight collect. Custom mold samples require mold and sampling fees, which can be fully refunded when the subsequent bulk order reaches the agreed amount.

After‑Sales Rules

Q: What should I do if I find quality problems after receiving the goods?
A: Please inspect the goods promptly after receipt. If defective products are found, please keep the evidence and contact our dedicated contact person. After confirming it is our production responsibility, we offer free returns and exchanges within the warranty period and bear the round‑trip shipping costs. For special cases, we can negotiate expedited replenishment to avoid delaying your production schedule.

For detailed quotations, custom solutions or sample applications, please feel free to contact our business team. Aobo Silicone will provide you with professional one‑stop solutions for liquid silicone injection overmolding.