Quality Control

Quality Control

China Loong Door Co., Ltd applies a structured quality control process to support consistent manufacturing across residential, commercial, and specialized door products. Our inspection procedures cover aluminum alloy doors, solid wood and composite doors, glass doors, entrance doors, fire-resistant doors, airtight sealed doors, rolling and garage doors, courtyard gates, smart doors, and custom non-standard solutions. Inspection criteria are established according to approved drawings, order specifications, intended applications, and industry-aligned practices.

1. Incoming Material Inspection

Raw materials and purchased components are checked before they are released for production. The scope of inspection is adapted to the product type and may include aluminum profiles, steel sheets, wood-based materials, glass, seals, coatings, hardware, locks, hinges, rollers, tracks, motors, and electronic accessories.

• Material verification: Material type, dimensions, thickness, finish, color, and quantity are compared with purchase and production requirements.
• Surface inspection: Profiles, panels, glass, and decorative components are examined for visible scratches, dents, cracks, deformation, color variation, and other unacceptable defects.
• Hardware and accessory checks: Locks, handles, hinges, rollers, tracks, seals, fasteners, and electrical components are reviewed for specification compatibility and condition.
• Supplier quality feedback: Nonconforming incoming materials are identified, separated, and communicated to the relevant supplier for review and corrective action.

2. In-Process Quality Control

Quality checks are performed at appropriate production stages to identify deviations before final assembly. Production personnel follow approved technical documents, while inspection records and reference samples may be used to maintain consistency throughout an order.

• Dimensional control: Cutting dimensions, frame geometry, panel size, opening direction, hole positions, and assembly tolerances are checked against approved drawings.
• Fabrication quality: Welding, corner joining, edge treatment, bonding, machining, and fastening are examined according to the construction of each door.
• Surface finishing: Painted, powder-coated, varnished, wood-grain, plated, and other decorative surfaces are reviewed for color consistency, coverage, cleanliness, and visible workmanship.
• Glass and sealing assembly: Glass placement, gaskets, seal strips, and joint conditions are checked where applicable, especially for glass doors, airtight doors, bathroom doors, and broken-bridge aluminum systems.
• Functional component installation: Hinges, locks, rollers, tracks, closers, motors, sensors, and smart access components are inspected during assembly to reduce fit and operating issues.

3. Finished Product Inspection

Completed products undergo final inspection based on the order specification and product design. The applicable checks vary by door type, configuration, and intended use. Custom dimensions, finishes, hardware selections, and opening arrangements are verified against the approved production information.

• Appearance: Visible surfaces are checked for cleanliness, finish consistency, scratches, dents, chips, cracks, exposed joints, and other workmanship concerns.
• Dimensions and configuration: Overall size, frame and leaf dimensions, opening direction, leaf arrangement, hardware position, and specified accessories are confirmed.
• Operation: Swinging, sliding, folding, rolling, tilting, or retractable movement is tested as applicable for smooth operation, alignment, and appropriate clearance.
• Hardware function: Locks, handles, hinges, rollers, tracks, latches, closers, and related accessories are checked for secure installation and normal use.
• Product-specific checks: Sealing contact, glass stability, door-leaf alignment, motorized operation, or other relevant characteristics are examined according to internal inspection standards and agreed product specifications.

For specialized products such as fire-proof, radiation-proof, airtight, security, and electrically operated doors, inspection requirements are determined by the confirmed design, supplied components, project documentation, and applicable customer requirements. Any requested testing or documentation should be agreed upon before production.

4. Packaging and Pre-Shipment Check

Packaging is selected according to the door structure, surface finish, dimensions, transportation method, and customer requirements. Protective materials are applied to help reduce the risk of abrasion, impact, moisture exposure, or component movement during handling and transit.

• Packaging inspection: Door leaves, frames, glass sections, hardware, and accessories are checked for suitable separation, cushioning, edge protection, and secure packing.
• Quantity verification: Packed products and accessory sets are compared with the packing list and order details.
• Marking and identification: Package labels, product references, opening directions, and handling marks are reviewed where required.
• Pre-shipment review: The shipping team checks package condition, loading considerations, and available order documentation before dispatch.

5. Nonconformity Management and Continuous Improvement

When a quality issue is identified, the affected material or product is marked and controlled to prevent unintended use or shipment. The responsible team reviews the issue, determines an appropriate disposition, and records corrective actions where necessary. Depending on the situation, actions may include rework, replacement, process adjustment, supplier communication, or additional inspection.

China Loong Door Co., Ltd also reviews feedback from production, final inspection, logistics, and customers to improve manufacturing instructions and inspection methods. Clear order information is essential to this process, so our team confirms key requirements such as dimensions, materials, finishes, hardware, opening direction, performance expectations, packaging, and documentation before production. This practical approach helps us provide international B2B customers with door products that are consistent with confirmed specifications and suitable for their intended projects.