How Sunglasses Are Made: A Complete OEM Manufacturing Process Guide
Most OEM buyers interact with the sunglass production process at two points: sample approval and final shipment. Everything in between — the tooling, the coating lines, the assembly process, and the quality gates — is invisible unless something goes wrong. Understanding how production actually works makes it easier to specify correctly, manage timelines, and catch problems before they become expensive.
This guide covers the complete sunglass manufacturing process, with particular attention to three areas that most affect OEM program outcomes: the design and specification confirmation stage, the three-round sample approval sequence, and the quality inspection checkpoints embedded at every stage of production.
- The Production Process at a Glance
- Stage 1 — Design and Specification Confirmation
- The Three Sample Rounds
- Stage 2 — Tooling and Frame Production
- Stage 3 — Lens Production
- Stage 4 — Lens Coating
- Stage 5 — Assembly
- Stage 6 — Printing and Branding
- Stage 7 — Final QC Inspection
- Stage 8 — Packaging
- Stage 9 — Shipment
- Timeline Summary
- FAQ
Most OEM buyers interact with the sunglass production process at two points: sample approval and final shipment. Everything in between — the tooling, the coating lines, the assembly process, and the quality gates — is invisible unless something goes wrong. Understanding how production actually works makes it easier to specify correctly, manage timelines, and catch problems before they become expensive.
This guide covers the complete sunglass manufacturing process, with particular attention to three areas that most affect OEM program outcomes: the design and specification confirmation stage, the three-round sample approval sequence, and the quality inspection checkpoints embedded at every stage of production.
The Production Process at a Glance
Stage 1 — Design and Specification Confirmation
Every production program begins with a complete specification confirmation. This is not a brief conversation — it is a documented sign-off on every variable that will determine what arrives in the final shipment. Changes made after this stage add cost, delay, or both.
The specification confirmation covers:
• Frame: Style reference or design file, frame material (PC, TR90, acetate, metal), color, temple length, bridge width, hinge type (standard, spring, or flex).
• Lens: Substrate (CR-39, PC, TAC, nylon), tint color, VLT category (0–4 per EN ISO 12312-1), polarization (yes/no), photochromic (yes/no), base curve, prescription range if applicable.
• Coating stack: Hard coat grade, AR coating, mirror specification (color, density), hydrophobic topcoat, UV400 compliance.
• Branding: Logo artwork (vector file), placement position on frame and/or lens, process (laser engraving, silk screen, pad print), color standard.
• Packaging: Case type, cleaning cloth, retail box dimensions and print specification, barcode format, compliance labeling content.
• Compliance: Target market (EU / US / AU / other), required certifications (CE, ANSI Z80.3, AS/NZS 1067.1), documentation set for shipment.
• Commercial terms: MOQ per SKU, unit price, packaging quantity, lead time, payment terms, incoterms.
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Karuson provides a pre-production confirmation checklist covering all specification points above. Signing off this document is the formal trigger for tooling and sample production. No production work is initiated on an incomplete specification. |
The Three Sample Rounds
Karuson uses a three-round sample sequence before mass production is released. Each round has a specific confirmation scope — approving a round means confirming the items within its scope, not all remaining open points. This structure prevents the most common sampling failure: approving a sample that looks roughly right, then discovering at bulk delivery that the details were never confirmed.
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Sample round 1 — Style confirmation • Frame shape and silhouette — confirmed against the reference design or 3D file • Overall dimensions — frame width, bridge, temple length, lens size • Fit and wearability — checked on a head form or physical fit model • Hinge type and temple operation — confirmed for the intended use category • This round uses standard lens color and finish — specific tint, coating, and branding are NOT evaluated at this stage • Outcome: buyer approves frame shape, or provides revision comments for a new round |
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Sample round 2 — Design confirmation • Tint color — matched against the buyer's color standard or Pantone reference • Mirror and coating effects — color, density, and uniformity confirmed • Logo and branding — placement, size, process, and color confirmed against approved artwork • Special finishes — matte / gloss / rubberized surface, two-tone frame color, temple pattern • Packaging prototype — retail box print, case, and cleaning cloth confirmed • Outcome: buyer approves all visual and design elements, or provides revision comments |
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Sample round 3 — Pre-production sample (PPS) — final confirmation • Produced to full mass-production standard using production molds, production-grade materials, and the full coating stack • All specifications from rounds 1 and 2 are integrated into one complete sample • Optical performance measured: VLT, UV400, polarization efficiency (if applicable) • Coating adhesion tested per ASTM D3359 before sample is shipped to buyer • PPS is the legal and commercial reference standard for mass production — if bulk goods do not match PPS, they are subject to rejection • Outcome: buyer signs off PPS → mass production is released |
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⚠ PPS sign-off is the point of no return. Once mass production is released against an approved PPS, changes to specification require either a production hold (with associated delay and cost) or acceptance of the original specification. Ensure all details are confirmed before signing off the PPS — do not approve a PPS under time pressure if there are outstanding open points. |
| Material | Suitable positioning | Main advantages | Key limitations | Tooling implication |
|---|---|---|---|---|
| PC | Promotional / mass market | Lightweight, economical | Lower premium feel | Injection mold required |
| TR90 | Sports / outdoor | Flexible, lightweight | Color and surface control needed | Injection mold required |
| Acetate | Premium fashion | Rich patterns, premium finish | Longer production time | CNC and hand-finishing |
| Stainless steel | Fashion / optical | Slim, durable | Plating and soldering control | Metal tooling required |
| Titanium | Premium / lightweight | Corrosion resistant, lightweight | Higher cost and process requirements | Specialized fabrication |
Stage 2 — Tooling and Frame Production
Frame production runs after PPS approval. For injection-molded frames (PC and TR90), the production mold is the same mold used to produce the PPS — no further tooling changes are permitted after PPS sign-off without a new sample round.
• PC / TR90 injection molding: Plastic pellets are heated and injected into the production mold under high pressure. Cycle time is 25–45 seconds per frame. Frames are ejected and cooled before dimensional inspection.
• Acetate cutting: Cellulose acetate sheets are CNC-milled to shape. Used for premium fashion frames where layered color patterns are required.
• Metal fabrication: Stainless steel or titanium frames use stamping, bending, soldering, and electroplating. Hinge quality and screw torque specification are confirmed at this stage.
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✓ QC checkpoint — Frame production • Dimensional check: frame width, bridge, temple length, hinge position against approved PPS dimensions • Visual inspection: short shots, sink marks, weld lines, warpage, surface finish consistency • Color match: frame color compared against approved color standard under D65 lighting • Hinge torque and operation: confirmed against specification before frames advance to assembly |
Stage 3 — Lens Production
Lens production runs in parallel with frame production — the two processes use separate equipment and are independent until assembly.
• CR-39 casting: Liquid monomer mixed with catalyst and cured in a glass mold for 8–16 hours. In-mass tinting is achieved by adding dye to the monomer before casting.
• PC injection: Polycarbonate resin injected into lens molds. Cycle time 30–60 seconds per pair. UV400 blocking is inherent in the PC material — no additive required.
• TAC laminate cutting: Pre-manufactured TAC polarized sheet cut to lens blank shape. The PVA polarizing film is laminated into the sheet structure, not applied to the surface.
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✓ QC checkpoint — Lens production • Optical clarity: blanks inspected for bubbles, haze, inclusions, and surface defects before coating • Power check (prescription programs): vertex power confirmed against specification • Tint uniformity: color measured spectrophotometrically against approved color standard • TAC polarization: PVA film inspected for streaks, voids, or tension bands before coating |
Stage 4 — Lens Coating
Coating is the most process-sensitive stage. Each layer must be applied in the correct sequence to the correct substrate — coating sequence failure is the primary cause of field delamination. Karuson applies the following standard stack for sport and outdoor lenses:
• Hard coat (4–6 μm): Scratch-resistant silicon-organic layer, UV-cured. Mandatory on PC and nylon — without it, uncoated PC fails under normal outdoor use within weeks.
• AR coating: Multi-layer vacuum-deposited anti-reflective stack. Applied after hard coat; never directly to bare substrate.
• Mirror coating (where specified): Vacuum-deposited metallic layer. Reduces VLT by 15–25% — final VLT is measured on the finished lens, not the base lens.
• Hydrophobic topcoat: Fluoropolymer layer reducing water and oil adhesion. Contact angle ≥ 100° is the standard acceptance criterion.
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✓ QC checkpoint — Lens coating • Adhesion test: cross-hatch per ASTM D3359 on every coating batch before release to assembly • VLT measurement: spectrophotometric measurement per EN ISO 12312-1, D65 illuminant • UV400 transmittance: confirmed <1% at 380 nm per batch • Polarization efficiency: measured per ANSI Z80.3 for polarized programs (≥99% required) • Mirror color and density: compared against approved PPS sample under standard lighting |
Stage 5 — Assembly
Assembly combines the finished frame and lenses. Dimensional match between the lens edge and frame groove is critical — misfit is the primary cause of lens pop-out in field use.
• Lens fitting: Lens checked against frame for fit before insertion. Rimless frames require drilling at this stage.
• Hinge and temple: Hinges checked for smooth operation and screw torque set to specification. Both temples checked for symmetry.
• Nose pad fitting: Adjustable pads fitted and aligned. Fixed integral pads checked for shape consistency against PPS.
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✓ QC checkpoint — Assembly • Lens retention: each assembled pair checked for firm lens seat — no movement or clicking • Temple symmetry: confirmed on flat surface — both temples at equal angle • Hinge torque: spring force and self-closing function confirmed on spring hinge programs • Visual inspection under magnification: assembly scratches, misalignment, debris |
Stage 6 — Printing and Branding
Brand marking is applied to the fully assembled frame. Process selection depends on frame material and detail requirement.
• Laser engraving: Most durable process. Produces a permanent mark on lens surface or metal components. Default for lens branding at Karuson.
• Silk screen printing: Standard for temple branding on plastic frames. Validated by rub test (100 double rubs with isopropyl alcohol per EN 1895).
• Pad printing: Used for curved surfaces, recessed areas, and nose bridge logos.
• Compliance labeling: CE mark, UV400 symbol, tint category, and driving restriction (for Category 4) applied per target market requirements.
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✓ QC checkpoint — Printing & branding • Logo position and alignment: compared against approved PPS and confirmed artwork file • Ink adhesion (silk screen / pad print): rub test per EN 1895 on each production batch • Laser depth and clarity: engraving depth and legibility checked against approved standard • Compliance label content and placement: verified against target market requirements |
Stage 7 — Final QC Inspection
Final QC is a 100% cosmetic inspection combined with batch-level functional and optical testing. Units that fail are separated and root-caused before the batch advances to packaging.
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✓ QC checkpoint — Final QC — full inspection scope • Optical: VLT and UV400 per batch (spectrophotometric); polarization efficiency per ANSI Z80.3 for polarized programs • Cosmetic (100%): surface scratches, coating defects, bubbles, color consistency against PPS under D65 lighting • Functional: hinge torque, lens retention, spring hinge operation, temple symmetry, nose pad alignment • Dimensional: frame width, bridge, temple length against PPS specification • Impact (where specified): ANSI Z87.1 per batch for PC and nylon programs — test report included in shipment documents • Units failing cosmetic or functional inspection are reworked where possible; optical and structural failures are rejected and replaced |
Stage 8 — Packaging
Packaging runs in parallel with production where possible to maintain consolidated lead times. Branded packaging components (cases, retail boxes, cleaning cloths) are confirmed at the Sample Round 2 stage.
• Primary packaging: Individual case (hard or soft), cleaning cloth, hang tag or product card.
• Retail box: Branded outer box with product imagery, compliance information, and barcode. Print proof confirmed before production.
• Master carton: Corrugated outer carton sized to optimize freight. Gross weight, dimensions, and stacking strength reviewed before freight booking.
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✓ QC checkpoint — Packaging • Unit count per inner box and master carton verified against packing list • Retail box print quality: color match and barcode scan confirmed • Case and cleaning cloth: correct SKU matched to correct packaging • Compliance leaflet content: instruction leaflet included and market-appropriate |
Stage 9 — Shipment
After packaging QC, the order undergoes a pre-shipment carton inspection before freight booking. Standard documentation included with every Karuson OEM shipment:
• Commercial invoice and packing list
• QC test reports: VLT, UV400, polarization efficiency (where applicable), impact test (where applicable)
• CE documentation (EU-bound shipments)
• ANSI Z80.3 documentation (US-bound programs, where applicable)
• Certificate of origin
• Additional documents (REACH, fumigation, country-of-origin declaration) available on request — specify at order placement
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✓ QC checkpoint — Pre-shipment • Carton count and labeling verified against packing list • Random unit pull from packed cartons — final visual and optical spot check • Documentation completeness verified before freight booking |
Timeline Summary
|
Stage |
Activity |
Typical duration |
|
Samples |
Sample round 1 (style) |
5–7 working days |
|
Samples |
Sample round 2 (design) |
5–7 working days |
|
Samples |
Sample round 3 — PPS |
7–10 working days |
|
1 |
Tooling (new mold) |
15–20 working days |
|
1 |
Tooling (existing mold / logo only) |
5–7 working days |
|
2 |
Frame production (PC / TR90) |
8–12 working days |
|
2 |
Frame production (acetate) |
12–18 working days |
|
3 |
Lens production |
5–8 working days |
|
4 |
Lens coating |
3–5 working days |
|
5 |
Assembly |
3–5 working days |
|
6 |
Printing & branding |
2–3 working days |
|
7 |
Final QC |
2–4 working days |
|
8–9 |
Packaging & shipment |
3–5 working days |
|
— |
Total mass production (existing mold) |
15–20 working days |
|
— |
Total mass production (new mold) |
30–45 working days |
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⚠ Stages 2 (frame) and 3–4 (lens + coating) run in parallel — the total production timeline is driven by the longest parallel path, not the sum of all stages. Confirm your factory's parallel-processing capacity before accepting a lead time quote. |
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Start Your OEM Sunglass Program Request samples · Confirm production specifications · Get a lead time and MOQ quote �� nicole@karusonco.com | �� WhatsApp: +86 158 1710 2455 Karuson | Dongguan & Guangzhou | MOQ 300 units | EN ISO 12312-1 | ANSI Z80.3 |
FAQ
Why are there three sample rounds — can we reduce this to save time?
The three rounds serve different purposes and each catches a different class of problem. Round 1 is about shape and fit — catching dimensional and ergonomic issues before any money is spent on color matching or branding. Round 2 is about visual details — confirming color, coating effects, and branding before the pre-production sample. Round 3 (PPS) is the final production-standard confirmation before mass production is committed. Skipping rounds increases the risk of a bulk delivery that does not match expectations — a problem that is expensive to resolve post-production and cannot be solved quickly. Programs with simple designs using existing molds can sometimes combine rounds 1 and 2 where the buyer has a clear reference; discuss this with the Karuson account team.
What happens if the PPS has a small issue — do we have to redo all three rounds?
No. If the PPS has a minor issue (a small logo position adjustment, a slight color correction), a targeted revision sample addressing only that specific point is produced and submitted for approval. A full three-round restart is only required if the overall design direction changes substantially — for example, switching frame style or switching lens substrate. The scope of the revision determines the scope of the new sample.
What is confirmed at the design specification stage that cannot be changed later?
Frame mold design is fixed at tooling confirmation — any dimensional change to the mold after tooling is completed requires rework or new tooling, both of which add cost and time. Lens substrate selection is fixed before lens production begins, as different substrates require different coating processes and equipment. Compliance market is fixed before production because CE labeling content, driving restriction warnings, and documentation packages are market-specific and are printed and prepared during production. These three items — mold, substrate, and target market — should be confirmed with certainty before any production work is authorized.
How does inline QC differ from a final inspection?
Inline QC catches defects at the stage where they originate, before downstream processing adds value on top of a defective component. A lens blank with a bubble is cheap to reject before coating; after coating, assembly, and branding, the same defect has accumulated 4–5 additional process steps of cost. The coating adhesion test is the clearest example: lenses that fail adhesion before assembly cost only the lens blank to replace. Lenses that delaminate in the field after delivery cost the full product value plus return logistics and reputation damage. Final QC is necessary but not sufficient — it is the last gate, not the only gate.
What documents do I need to import sunglasses into the EU?
For EU import, sunglasses must carry CE marking and comply with EN ISO 12312-1 as personal protective equipment. Required documents: CE declaration of conformity (DoC), test report from an accredited laboratory confirming EN ISO 12312-1 compliance (UV400, VLT category, optical power, prismatic effect), and user instructions in the language of the destination country including tint category and driving restriction warning for Category 4 lenses. Karuson provides EN ISO 12312-1 test reports and DoC templates as standard deliverables for EU-bound programs. If your product will be sold into multiple EU markets, confirm that the user instruction translation set covers all required languages before production.
Can we audit the QC process during production?
Yes. Karuson welcomes buyer-side QC participation at any stage of an active production program. Options include a third-party inspection agency visit during production or pre-shipment (Karuson can recommend agencies; buyer books directly), a Karuson-managed video call walkthrough of the QC process during production, or a direct factory visit. For programs where a third-party pre-shipment inspection (PSI) is a commercial requirement, confirm this at order placement so the inspection window can be built into the shipment schedule.
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OEM Photochromic Lenses: Technology, Custom Options & B2B Sourcing Guide
Prescription Myopia Sunglass Lenses: Complete Guide on Optics, Production Process & Material Selection
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