Waterproof overmolding components are a key technology in modern outdoor consumer products (such as waterproof backpack accessories, camping lantern housings, trekking pole grips, fishing reel handles, drone protective cases, etc.) to achieve IP67/IP68-level waterproofing, dustproofing, and weather resistance.
The main manufacturing process for waterproof overmolding (Overmolding / secondary overmolding injection) is as follows:
- First, mold the rigid substrate Use engineering plastics such as PC, ABS, nylon PA66, PBT, etc., to injection mold the structural body (e.g., housings, button skeletons, handle frames).
- Surface treatment of the substrate Plasma treatment, flame treatment, or primer coating to enhance adhesion—especially essential for difficult-to-bond materials like PP/PE.
- Secondary overmolding with soft material
- Common materials: TPU, TPE, silicone (LSR), TPV
- Typical hardness: Shore A 40–80 Most popular combinations: PC/ABS + TPU, PA + silicone, PP + TPV Using insert molding or two-shot/multi-shot rotary molding machines for secondary injection, the soft material tightly encapsulates critical areas of the substrate, forming a seamless waterproof sealing layer.
- Key process control points
- Precise mold temperature matching (to avoid material degradation or poor mold release)
- Optimized injection pressure and holding time to ensure complete filling of the soft material without flash
- Material compatibility testing (peel strength ≥1.5–3 N/mm as the qualification benchmark)
- Controlled cooling time to prevent delamination due to shrinkage stress
Compared to traditional methods like bonding O-rings or ultrasonic welding, this process offers seamless construction, better aesthetics, higher production efficiency, and superior waterproof reliability. It has become the preferred solution for outdoor brands to enhance product durability and user experience.
Need high-level waterproof overmolded components for your outdoor waterproof backpacks, camping gear, or sports electronics? Professional overmolding factories can provide one-stop services from material matching, mold design to finished IPX testing—welcome to inquire about mass production solutions!
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