Plastic Eyewear: Acetate V.S Injection

For most eyewear brands and wholesalers, “plastic frames” is an umbrella term that actually hides several very different materials and processes. In everyday production, the main plastics you see in frame fronts and temples are acetate (cellulose acetate), PC, TR, CP, and so on. At JaneyCheers, we use a simple but practical way to classify them, which is to divide them into two families: injection and non-injection.

Non-injection: hand-crafted (milled) acetate,

Injection: PC, TR, CP, and injection acetate, etc. 

Once you see the industry this way, it becomes much easier to understand why frames that all look “plastic” can behave so differently in design, production, and logistics. This distinction is practical for custom eyewear manufacturing, sunglasses OEM/ODM, and wholesale buyers, as each route entails a distinct approach to designing, producing, and managing risk along the supply chain.

Plastic Eyewear: Materials Differences

Injection-molded eyewear starts from plastic pellets. Common materials for custom plastic frames and custom sunglasses include PC, TR, CP, and related engineering plastics. These arrive as small granules in bags or drums, then must be dried to remove moisture before molding so that bubbles, streaks, and internal stress are kept under control. One mold can serve many SKUs: by changing pellet colors and pairing them with different paints or paper patterns, brands can quickly build an entire injection-molded eyewear collection.​

Acetate sheets

Plastic pellets

Acetate eyewear begins with solid sheets, not pellets. In custom acetate frame manufacturing, the brand selects physical slabs of cellulose acetate, featuring solid colors, transparent sheets, tortoiseshell patterns, and layered or laminated designs. The chosen sheet already defines much of the future frame’s depth, pattern, and tone before any CNC work starts. For brands that want to link “premium frame” directly to “premium raw material,” the acetate sheet is a natural fit.​

Plastic Eyewear: Manufacturing Differences

Injection-molded frames are cast inside a mold. In a typical custom injection eyewear or sunglasses project, the process involves drying the pellets, melting them, injecting them into a steel mold, cooling, and then demolding. The mold fixes the frame front and temple geometry: bridge, rims, thickness, and basic dimensions. After that, frames go through deburring, sanding, and tumbling to smooth edges and remove flash. Visual impact is then created by spray painting, hydro‑transfer printing, film wrapping, and local decoration. In this model, the mold defines the physical “skeleton,” and the finishing defines how attractive and consistent the product appears in the market.​

Acetate frames are shaped by cutting and polishing. In custom acetate eyewear manufacturing, sheets are cut into blanks and often pre-shrunken in ovens, so the material stabilizes before fine machining. CNC routers or milling machines then carve out frame fronts and temples: bridge curves, rim profiles, bevels, and decorative cuts all come from toolpaths, not from a single mold cavity. The parts then enter long cycles of barrel tumbling and hand polishing, which gradually build surface gloss, transparency, and soft touch on contact points. Here, there is very little full‑surface painting at the end; the material already carries its pattern, and the craft simply reveals it. The perceived quality of custom acetate frames, therefore, depends heavily on sheet quality, CNC detail, and polishing skill.​

Plastic Eyewear: Positioning Differences

Acetate and injection frames send different messages in terms of look and story. Because color and pattern run through the whole acetate sheet, a cross-section looks similar to the surface. This supports narratives about “honest material,” long-term color stability, and lower dependence on heavy coatings. For premium custom acetate optical frames, acetate sunglasses, and high‑end reading glasses, this alignment between what you see and what the frame is made from can be a strong branding point.​

Injection‑molded plastic frames are more like a flexible base for visual effects. The molded substrate is usually simple; strong gradients, prints, and textures come from paint and transfer films applied on top. This is ideal for fast‑fashion custom sunglasses, sports eyewear, and price‑sensitive optical collections, where quick trend response and style rotation matter more than visible raw‑material stories. The key trade‑off is that long‑term quality now depends on coating systems: adhesion, abrasion resistance, and batch‑to‑batch color control must be verified before committing to large OEM/ODM orders.​

Plastic Eyewear: What B2B buyers should prioritize

For B2B buyers, the decision is not just “acetate or plastic,” but “which technical nodes do we want to control most tightly?” In injection‑molded eyewear OEM/ODM, leverage sits mainly in mold engineering and finishing systems. Well‑designed molds anticipate shrinkage, warpage, and parting lines; poor molds lock defects into every frame produced. Robust painting and transfer processes keep repeat orders consistent after the first samples. For high‑volume custom injection sunglasses or plastic optical projects, extra rounds of mold trials and coating tests at the beginning usually cost less than handling claims later.​

In acetate projects, focus moves to material sourcing and craftsmanship. Reliable acetate sheet suppliers influence color purity, light transmission, and yellowing behavior over time. Factory capability in CNC (symmetry, thickness control, edge transitions) and polishing (gloss, smoothness at touch points, edge comfort) largely determines whether custom acetate eyewear feels truly premium rather than just “labeled acetate.” For design‑driven brands, structured sampling across multiple SKUs is often more informative than comparing quotes alone.​

Plastic Eyewear: Differences in Packaging, Storage, and Transport

Material behavior also shapes downstream logistics. Acetate has a lower softening point and is more sensitive to sustained heat and pressure. In hot warehouses or tightly stacked pallets, cartons can slowly push frames out of shape: fronts may twist, temples may flare, and asymmetry can appear after sea freight or long storage periods. Suppose a large share of your catalog uses custom acetate frames. In that case, it makes sense to formalize rules with suppliers: maximum units per carton, maximum pallet stack height, acceptable warehouse temperature ranges, and periodic QC checks on long‑stored stock. These rules directly protect the earlier investment in sheets, CNC, and polishing.​

Injection-molded plastics tolerate temperature and compression better, but their coatings are vulnerable. In high heat or poor ventilation, painted and transferred surfaces can stick, wrinkle, or print onto each other; rough or minimal inner packaging can lead to edge wear and pattern damage in long‑distance transport. For large custom injection sunglasses and plastic frame orders, it is useful to run simple high‑temperature or accelerated‑aging tests with the intended packaging, then adjust trays, pouches, and carton layouts before full‑scale shipping.​

Conclusion

In short, acetate eyewear manufacturing and injection‑molded eyewear manufacturing are not just two material choices, but two complete production and supply‑chain models. Custom acetate frames naturally support higher price points, design storytelling, and “material first” branding, while custom injection‑molded sunglasses and optical frames are built for scale, flexibility, and speed. Once you are clear about your target price band, sales channels, product life cycle, and inventory strategy, it becomes much easier to choose the right route—and to know exactly which technical details you need your manufacturing partner to get right.