Injection molding is one of the most widely used core processes in plastic product manufacturing. Its essence is to inject molten plastic raw materials into a preset mold cavity under pressure, and then get products that meet design standards after cooling and solidification. With the advantages of high efficiency, precision and mass production, this process has become the mainstream way to process plastic parts in the eyeglass industry. injection molding depends on special injection equipment and strictly follows industry-specific standards, balancing the functionality, comfort and aesthetics of products. Compared with injection molding for ordinary plastic products, it has higher demands on precision control, material selection and mold design.
The core equipment for eyeglass injection molding is a special injection machine adapted to the characteristics of eyeglass production. It needs to meet the requirements of miniaturization, high precision and stable pressure to fit the small size and fine structure of eyeglass parts. The biggest difference from ordinary injection molding processes is that eyeglass frame injection molding requires the supporting use of metal eye core molds, which are special core parts for eyeglass frame injection molding. The metal eye core mold is embedded into the mold cavity through precise positioning. During injection molding, the molten plastic wraps the eye core mold to form a shape. When the product is taken out after cooling, the metal eye core mold will leave a regular lens groove inside the frame, ensuring the fit and stability of subsequent lens assembly. This design directly determines the assembly precision and wearing comfort of the eyeglass frame. Besides eyeglass frames, most plastic accessories like temple arms, temple tips, nose pads and decorative parts are processed by injection molding. Somelenses (such as PC material lenses) can also be mass-produced through injection molding.
Material selection directly affects the quality and performance of eyeglass products. The industry mainly uses two types of granular raw materials: nylon and rubber, and strictly selects materials that meet environmental protection, weather resistance and ergonomic requirements. Among them, nylon is the preferred material for eyeglass frames because of its high strength, wear resistance, good toughness and non-deformation features. It is especially suitable for making fashionable casual and sports eyeglass frames, which can balance wearing comfort and structural stability. Rubber materials (mostly TPE/TPR elastomers) are mainly used for temple tips, nose pads and some decorative parts due to their soft, anti-slip and skin-friendly advantages. They can effectively reduce the pressure on the skin from long-term wearing and improve the wearing experience. Some high-end eyeglasses also adopt carbon fiber composite injection materials or transparent PC materials to meet special needs such as light weight and high transparency.
The mold is a key factor that determines the quality of injection-molded eyeglasses. The premise of a high-quality injection-molded eyeglass product is a reasonably designed and exquisitely made mold. The mold needs to accurately design the cavity, runner and cooling system according to the structure and shape of eyeglass components, so as to ensure uniform filling of molten plastic and consistent cooling speed, and avoid defects such as shrinkage marks and bubbles. Precision mold processing can make the surface of injection-molded products achieve a smooth and delicate mirror effect, with very inconspicuous parting lines and flash (burrs), which can enter subsequent processes without additional extensive polishing. On the contrary, insufficient mold precision will lead to product size deviation and rough surface, which not only affects the appearance, but also may cause assembly difficulties, wearing discomfort and other problems, increasing the cost of subsequent rework.
with a large order quantity for a single model. Due to the high initial investment required for mold development and debugging, if the batch is too small, the unit product cost will rise sharply, resulting in the loss of market competitiveness. At the same time, the advantage of the injection molding process lies in its ability to realize complex structure and shape design. It can easily create integrated, hollowed-out, curved and other personalized structures, satisfying the diverse and fashionable design needs of the current eyeglass industry and providing designers with sufficient creative space.
To endow injection-molded eyeglasses with rich appearance texture and fashion features, a series of surface treatment and spraying processes are needed after injection molding. Common processes include painting, coating, screen printing, gold stamping, frosting and so on. These processes can not only improve the scratch resistance and wear resistance of products, but also create various effects such as matte, high gloss, gradient and color contrast, catering to the aesthetic needs of different consumer groups. Some high-end products will also undergo UV curing treatment to further enhance surface hardness and oxidation resistance, extending the service life of eyeglasses. On the whole, eyeglass injection molding is a systematic project that integrates equipment, materials, molds and post-processing. Only by precise control of each link can we finally produce eyeglass products with both quality and appearance.
