The inspection of truck U-bolts must cover dimensions, material properties, mechanical performance, and other aspects. The specific standards are as follows:
1. Dimensional Accuracy Inspection
Measurement Items: Length, width, thickness, thread accuracy, etc., using calipers, micrometers, or other precision tools to ensure compliance with design requirements.
Tolerance Requirements: When checking thread fit with go/no-go gauges, the “go” gauge should screw in smoothly, while the “no-go” gauge should not exceed 2 turns.
2. Surface Quality Inspection
Visual Inspection: The surface must be smooth, free of rust, cracks, scratches, or other defects (checked by visual or tactile examination).
Coating Inspection: The galvanized coating should be uniform, with thickness meeting standards (e.g., salt spray test for corrosion resistance verification).
3. Material & Chemical Composition
Material Verification: Chemical composition analysis must confirm compliance with carbon steel (e.g., Q235) or stainless steel (e.g., 304) standards.
Grade Marking: Carbon steel bolts should have strength grade markings (e.g., 8.8), while stainless steel must indicate material codes.
4. Mechanical Performance Testing
Tensile Strength: Verified via tensile testing, ensuring fractures occur in the threaded or non-threaded shank.
Hardness Testing: Measured using a hardness tester to ensure compliance with heat treatment requirements.
Torque & Preload Testing: Verify torque coefficient to ensure reliable installation.
5. Process & Defect Detection
Cold Heading & Thread Rolling: Check for proper chamfering, burr-free edges, and no signs of mold damage.
Magnetic Particle Inspection (MPI): Used to detect internal cracks, inclusions, or other hidden defects.
6. Standards & Certification
Applicable Standards: Refer to QC/T 517-1999 (U-bolts for automobile leaf springs) or JB/ZQ 4321-97.
Packaging & Marking: Packaging must indicate national standards; bolt heads should be straight, and threads must be clean and free of contaminants.
Additional Notes:
For batch inspections, additional tests such as fatigue life and hydrogen embrittlement sensitivity may be required.
Inspection typically takes 3–5 working days, with complex cases extending to 7–10 days.
For U-bolts inquiries, please contact us via the details below
Manager：Helly Fu
E-mail: sales01@china-yongjin.com
Phone: +86 18750669913
Whatsapp: +86 18750669913
Media Contact
Company Name: FUJIAN YONGJIN MACHINERY MANUFACTURING CO., LTD.
Email: Send Email
Country: China
Website: https://www.china-yjf.com/