Quality Control

Quality Control

China Loong Metal Window Co., Ltd. applies structured quality control throughout material receiving, fabrication, assembly, finishing, inspection, packaging, and shipment. Our procedures are designed to support consistent quality across aluminum, carbon steel, galvanized steel, stainless steel, and copper window products for residential, commercial, and industrial applications.

Inspection requirements are defined according to product specifications, approved drawings, order details, intended applications, and industry-aligned practices. Special attention is given to dimensions, structural integrity, opening performance, glazing, sealing, surface finish, hardware installation, and overall workmanship.

1. Incoming Material Inspection

Raw materials and purchased components are checked before they are released for production. The inspection scope is adjusted to the window type and project requirements, including thermal-break aluminum systems, steel window profiles, glazing units, seals, fasteners, hinges, locks, rollers, and other functional components.

• Metal profiles and sheets: Material type, dimensions, surface condition, straightness, and visible damage are checked against purchasing and production requirements.
• Glass and glazing materials: Glass configuration, dimensions, edge condition, visible defects, and compatibility with the specified window system are reviewed.
• Hardware: Hinges, handles, locking points, rollers, stays, and fasteners are checked for correct type, quantity, finish, and basic operation.
• Sealing components: Gaskets, weather strips, sealants, and related materials are reviewed for their specified size, condition, and intended use.
• Surface-treatment materials: Coating colors and relevant finishing requirements are confirmed according to approved order information or samples where applicable.

2. In-Process Quality Control

Production personnel follow approved drawings, process instructions, and internal inspection standards. Checks are carried out at appropriate stages to identify dimensional or assembly issues before they affect subsequent operations.

• Cutting and machining: Profile lengths, angles, hole positions, drainage paths, and hardware preparation are verified against fabrication requirements.
• Frame and sash assembly: Squareness, corner joints, weld quality where applicable, alignment, and connection strength are examined during assembly.
• Surface preparation and finishing: Components are checked for cleanliness, uniform appearance, color consistency, exposed defects, and handling damage.
• Glazing and sealing: Glass positioning, setting blocks, gasket installation, sealant application, and contact surfaces are inspected for proper assembly.
• Hardware installation: Hardware position, fastening, alignment, and operating clearance are checked to support smooth and reliable use.

For products with specialized requirements, such as fire-resistant, blast-resistant, explosion-resistant, airtight, sound-insulating, thermally insulated, moisture-resistant, or anti-theft windows, the control plan is established according to the confirmed product configuration and project specifications. Relevant materials and critical assembly details are reviewed with added attention.

3. Finished Product Inspection

Completed windows are inspected before packaging. The inspection may be performed on individual products or by an appropriate sampling method, depending on order requirements, product characteristics, and the agreed quality plan.

• Dimensions and configuration: Overall size, sash arrangement, opening direction, profile combination, glass type, and hardware configuration are compared with approved documents.
• Appearance: Frames, sashes, glass, coatings, weld areas, joints, and visible surfaces are checked for scratches, dents, contamination, uneven finishing, or other unacceptable defects.
• Operation: Casement, awning, hopper, sliding, tilt-and-turn, louver, and other operable systems are opened, closed, locked, and unlocked to confirm proper movement.
• Fit and alignment: Sash-to-frame clearance, meeting points, locking engagement, roller movement, and visible alignment are examined.
• Glazing and sealing: Glass installation, gasket continuity, sealant condition, drainage provisions, and weather-sealing details are reviewed.
• Accessories and completeness: Required screens, handles, fasteners, connectors, installation accessories, and supporting documents are checked against the order where applicable.

Any performance testing required for a particular project is determined by the product specification and agreed inspection criteria. Test methods, sample selection, and acceptance requirements are confirmed before testing rather than applied as unsupported general claims.

4. Packaging and Pre-Shipment Check

Packaging methods are selected according to window dimensions, weight, surface finish, glass configuration, transportation method, and destination requirements. Protective measures are intended to reduce the risk of scratching, impact, moisture exposure, component movement, and handling damage during transit.

• Frames, corners, finished surfaces, glass, and projecting hardware are protected as appropriate for the product.
• Movable sashes and accessories are secured to help prevent unintended movement during handling and transportation.
• Package labels, product references, quantities, and accessory lists are checked against the shipping documents.
• The loading arrangement is reviewed with consideration for weight distribution, package stability, and practical unloading at the destination.
• A final pre-shipment review confirms product completeness, packaging condition, identification, and order consistency.

5. Issue Management and Continuous Improvement

China Loong Metal Window Co., Ltd. records and reviews quality issues identified during production, final inspection, shipment preparation, or customer feedback. When a nonconformity is found, the affected product is identified and evaluated before an appropriate action is taken, which may include correction, rework, replacement of a component, or further verification.

Recurring issues are reviewed to determine possible causes related to materials, equipment, fabrication methods, assembly, handling, packaging, or documentation. Corrective actions may include updating work instructions, refining inspection points, improving tooling or fixtures, providing additional operator guidance, and strengthening supplier communication. This practical feedback process helps us maintain consistent manufacturing control and respond clearly to the quality expectations of international B2B customers.