Quality Control Process: Precision Tube Bending Machines
Company: ZHANGJIAGANG CEDAR TECHNOLOGY CO., LTD.
Document Type: Manufacturing & Quality Assurance Workflow
1. Overview
At ZHANGJIAGANG CEDAR TECHNOLOGY CO., LTD. , we understand that in tube bending, precision is not just a metric—it is a guarantee of structural integrity and performance. Our Quality Control (QC) process is designed to ensure that every machine leaving our facility meets stringent international standards for accuracy, durability, and safety.
2. Incoming Material & Component Inspection (IQC)
Quality begins at the source. All raw materials (steel plates, hydraulic components, electrical systems) undergo a 100% inspection upon arrival.
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Material Certification: Verification of mill certificates against order specifications.
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Dimensional Check: Critical dimensions of castings and machined parts are measured using Coordinate Measuring Machines (CMM) and precision calipers.
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Third-Party Branding: All core components (PLC, servo motors, hydraulic pumps) are verified for authenticity against approved vendor lists (e.g., Siemens, Bosch Rexroth, FANUC).
3. In-Process Quality Control (IPQC)
We employ a "Stop-Line" authority for our QC engineers. If a deviation is detected during assembly, production halts immediately until a corrective action plan is approved.
A. Structural Fabrication
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Welding Inspection: All structural welds undergo visual and non-destructive testing (NDT) to ensure zero porosity or cracks.
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Stress Relieving: Critical frames are subjected to vibration aging or heat treatment to eliminate residual stress, ensuring long-term machine rigidity.
B. Machining & Fitting
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Geometric Accuracy: Key mounting surfaces for the bending die and mandrel are inspected for flatness and parallelism. Tolerances are maintained within ±0.01mm where applicable.
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Hydraulic System: All hydraulic pipelines are flushed and pressure-tested at 1.5x the working pressure to ensure zero leakage.
C. Assembly
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Torque Control: Every bolted connection is tightened using torque wrenches with traceable records.
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Alignment: The bending axis (Y, B, C) alignment is calibrated using laser interferometers to ensure perfect synchronization between the bend arm, carriage, and collet.
4. Final Assembly & Performance Testing (FAT)
Before any machine is disassembled for shipment or prepared for customer sign-off, it undergoes a rigorous Factory Acceptance Test (FAT) . We simulate real-world production conditions.
| Test Category | Parameters Checked | Acceptance Criteria |
|---|---|---|
| Bending Accuracy | Repeatability, Angle precision (D/B value), Springback compensation | Bending angle tolerance: ±0.1° ; No visible wrinkling or flattening of the tube OD. |
| Hydraulic System | Temperature rise, Pressure stability, Cycle time | Max temperature rise < 35°C; No pressure drop under sustained load. |
| Electrical Safety | Grounding continuity, Insulation resistance, Emergency stop response | Emergency stop reaction time < 0.1 seconds; Meets CE/UL standards. |
| Functionality | CNC interface responsiveness, Mandrel retraction logic, Program storage | 72-hour continuous run test with mixed production batches. |
5. Calibration & Traceability
All measuring instruments used in our QC process (including vernier calipers, protractors, and pressure gauges) are externally calibrated annually by accredited laboratories.
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Traceability: Each machine is assigned a unique serial number. A complete "Birth Certificate" is filed, including:
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Hydraulic pump test reports
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Electrical wiring checklist
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Final laser alignment report
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CNC parameter backup
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6. Pre-Shipment & Packaging
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Final Audit: A final visual inspection is conducted to ensure paint finish meets RAL standards and that all safety labels are correctly affixed.
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Anti-Rust Treatment: Exposed machined surfaces (guide rails, bending dies) are coated with anti-rust oil and wrapped in VCI (Volatile Corrosion Inhibitor) paper.
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Shockproof Packaging: Machines are fixed to reinforced steel skids with shock sensors (tilt/impact indicators) attached to the crate to monitor handling during transit.
7. Continuous Improvement
We utilize a Closed-Loop Feedback System. Data collected from our QC checkpoints is fed back to the design and procurement teams.
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Non-Conformance Reports (NCR): Any defect found is logged into our database. Root cause analysis (8D Report) is conducted within 48 hours to prevent recurrence.
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Customer Feedback: Post-installation service reports are integrated into our QC cycle to improve future product iterations.
Why Choose Us?
By combining German/Japanese precision standards with robust manufacturing processes, we minimize downtime, reduce scrap rates for our clients, and ensure that our bending machines operate with consistent accuracy for over a decade.
