1. Reliability design system
Failure mode analysis (FMEA)：
Conduct FMEA analysis of key components (engine, gearbox, hydraulic system), identify potential failure points (such as gear broken teeth, oil cylinder leakage), and formulate preventive measures (such as increasing gear modulus and optimizing sealing structure).
Example: In the steering system FMEA, when the risk priority (RPN) of ”steering shaft fracture" is set to ≥100, the shaft diameter size needs to be improved and flaw detection needs to be increased.
Simulation verification：
Use CAE software to simulate the load distribution of the whole machine (such as chassis stress analysis during deep plowing) to ensure that the safety factor of key structures (frame, suspension) is ≥3.0.
Engine combustion simulation optimizes the fuel injection timing and reduces nitrogen oxide emissions to the national IV standard (NOx≤3.5g/kWh).
2. Material and process verification
Material selection criteria：
The steel used for the frame must meet the tensile strength≥550MPa and the yield strength≥355MPa (such as Q355ND low temperature steel, -20℃ impact work≥34J).
The tires are made of puncture-resistant rubber (Shore hardness 65±5A), and the tread pattern depth is ≥18mm to adapt to muddy conditions.
Process test：
The evaluation of the welding process (such as butt welding of the frame stringer) needs to pass X-ray flaw detection (defect level≤Level II), and stress relief annealing is carried out after welding (temperature 550±20℃, keep warm for 2 hours).
2. Supply chain and parts quality control
1. Supplier management
Access mechanism：
Suppliers of core components (such as engines and transmissions) need to pass ISO/TS 16949 certification and conduct on-site audits (quality system, production equipment, and testing capabilities) every year.
Key indicators: The supplier's delivery pass rate is ≥99.5%, and the batch defect rate is ≤0.1%.
Hierarchical control：
Detection frequency of parts grade control measures
Class A (safety parts) 100% flaw detection (such as steering knuckle magnetic powder detection) full inspection of each batch
Class B (functional parts) sampling inspection (such as hydraulic pump withstand pressure test) 5% sampling per batch
Class C (general parts) appearance and size inspection 2% sampling per batch
2. Incoming inspection standards
Mechanical performance testing：
The gear shaft needs to detect the depth of the carburizing layer (0.8-1.2mm), surface hardness (HRC58-62), and heart hardness (HRC30-35).
Sealing test：
The oil pipe joint is tested for air pressure leakage (at a pressure of 0.8MPa, the pressure drop within 30 seconds is ≤0.05MPa).
3. Quality control of manufacturing process
1. Key process control points
Assembly torque management：
The engine cylinder head bolts are tightened 4 times in sequence (initial tightening 50N-m→middle tightening 100N・m→final tightening 150N-m →angle tightening 90°), and the data is recorded using an intelligent torque wrench (error ≤±3%).
Welding quality monitoring：
Robot welding (such as chassis stringer welds) is used to monitor current and voltage fluctuations in real time (deviation ≤±5%), and destructive tests are carried out for every 50 pieces (tear strength≥80% of the base material).
2. Process inspection process
Three inspection system：
Self-inspection: The operator performs 100% visual inspection of the assembly process (such as the direction of the wiring harness and the fixing of the pipeline).
Mutual inspection: The next process checks the previous process (for example, after the gearbox is assembled, the inspector checks the gear meshing gap of 0.15-0.3mm).
Special inspection: The quality control department samples key stations (such as engine assembly) (5 units per hour) to test performance parameters.
4. Factory inspection of the whole machine
1. Performance test items
Dynamic test：
The maximum power deviation of the bench test is ≤±5% (for models with a calibrated power of 100kW, the actual measurement is ≥95kW), and the maximum torque point speed deviation is ≤±3%.
Reliability test：
The whole machine conducts 100 hours of intensive road tests (including 20% climbing, muddy roads, and cobblestone roads), and the time between failures (MTBF) is ≥500 hours.
Emission detection：
The exhaust gas detection needs to meet the national IV standard (particulate matter PM≤0.02g/kWh, smoke ≤1.0FSN), and real-time monitoring with an opaque smoke meter is used.
2. Functional inspection
Hydraulic system test：
When lifting the maximum load (such as a 3-ton suspension device), the pressure fluctuation of the hydraulic system is ≤±0.5MPa, and the sedimentation amount is ≤5mm/10 minutes.
Safety device inspection：
The response time of the emergency stop button is ≤0.5 seconds, the volume of the reversing buzzer is ≥85dB, and the lighting distance is ≥30 meters.
5. After-sales quality feedback and improvement
1. Fault data management
After-sales database：
Establish a CRM system to record fault information (such as the frequency of occurrence of ”engine pull cylinder" and user usage scenarios), and generate monthly quality analysis reports (TOP5 fault rankings).
Example: A certain type of tractor accounts for 15% of high-temperature boiler failures in summer, and the temperature control threshold of the radiator fan coupler needs to be optimized (the original 75℃ start, adjusted to 70℃).
User return visit mechanism：
Return visits 3 months, 6 months, and 1 year after the delivery of the new machine to collect feedback on use (such as operating comfort and maintenance convenience), and projects with a score of less than 80 points are included in the improvement plan.
2. Quality traceability system
Traceability of parts：
Key components (engine, frame) are implanted with RFID chips to record the production date, batch, and assembly station, and support the rapid traceability of faulty parts (such as abnormal noise caused by a certain batch of bearings, the scope of influence will be located within 24 hours).
6. Industry standards and certifications
1. Domestic standard
Mandatory standard：
GB 18447.1-2015 "Safety of Agricultural Machinery Part 1: Tractors": The braking distance is required to be ≤5.4m (30km/h speed), and the strength of the safety protection device is ≥1000N.
GB 20891-2014 "Emission Limits of Exhaust Pollutants from Diesel Engines for Off-road Mobile Machinery": The SCR system needs to be installed in the national IV stage (urea injection error ≤±5%).
2. International certification
EU CE certification：
It is necessary to pass the EMC electromagnetic compatibility test (radiation harassment ≤40dBµV/m, 30-1000MHz frequency band), and the noise limit is ≤96dB (driver position).
7. Application of intelligent quality control technology
IOT monitoring：
Install sensors on the production line to monitor key parameters (such as assembly torque and hydraulic system pressure) in real time, and automatically alarm when the data exceeds the standard (such as when the torque wrench does not reach the set value, the equipment cannot start the next process).
Big data analysis：
Collect historical fault data of similar products and establish predictive models (such as predicting gearbox wear through vibration sensors, and warning of remaining life).
Visual inspection：
The AI vision system is used to detect appearance defects (such as coating leakage, weld pores), and the recognition accuracy rate is ≥99%, which replaces manual visual inspection.
Eight, quality and cost control
Prevention costs: accounting for about 30% (such as FMEA analysis, supplier training).
Identification cost: accounting for about 25% (such as investment in testing equipment and factory testing).
Failure cost: target ≤15% (reduce after-sales maintenance costs to less than 3% of sales through quality control).
Through the above-mentioned full-process quality control system, the MTBF (average failure interval) of the tractor machine can be increased to more than 800 hours, and the user satisfaction can reach more than 90 points.It is recommended that enterprises combine intelligent manufacturing technology to move the quality control node forward to the design and supply chain links to achieve a quality management model of "prevention as the main and inspection as the supplement".