Processing Technology and Quality Control of Agricultural Machinery Steel Sheets
I. Complete Processing Flow
Raw material acceptance → Plate flattening and straightening → Blanking and cutting → Stamping forming → Punching/chamfering → Heat treatment → Secondary straightening → Precision edge grinding → Surface treatment → Anti-rust treatment → Final inspection and warehousing
II. Core Processing Technology of Each Procedure
1. Raw Material Pretreatment Technology
Material selection: Mainly adopt 65Mn spring steel, boron steel and high-carbon steel; hot-rolled coiled plates and medium-thick steel plates are preferred.
Flattening: Level with special flattening machines to eliminate internal stress of coiled materials and ensure flat plate surfaces.
Rust and scale removal: Adopt sandblasting or shot blasting to remove rust and oxide scale, and improve subsequent coating adhesion.
2. Blanking and Cutting Technology
Thin steel sheets: CNC shearing by plate shears for high efficiency.
Special-shaped harrow discs and large-diameter plow sheets: Plasma cutting or laser cutting for smooth burr-free cuts.
High-precision blades: Die blanking for excellent dimensional consistency.
Control points: Reserve machining allowance during blanking to avoid cut cracks and edge chipping.
3. Stamping Forming Technology
Use dedicated forming dies to finish arc, disc, notch and bending forming.Spherical arc stamping is applied to disc harrow discs and plow sheets to meet standard soil penetration angles.Notched steel sheets are integrally stamped without secondary assembly.Key points: Conduct low-speed stamping to prevent plate thinning and edge cracking caused by stretching.
4. Hole Positioning and Finishing Processing
CNC punching: Unify spacing and diameter of mounting and positioning holes.
Edge chamfering: Remove sharp edges to avoid assembly scratches and stress concentration.
Trimming and shaping: Correct forming warpage and burrs.
5. Core Procedure: Heat Treatment Technology (Determines Service Life)
(1) Mainstream Process for 65Mn Agricultural Steel Sheets
Quenching: Fully hold at 810~850℃, then rapidly cool by water or oil quenching.
Tempering: Low-temperature tempering at 400~520℃ to eliminate quenching stress.
Standard hardness: HRC38~45, balancing wear resistance and toughness without brittleness or softness.
(2) Process for High-hardness Harvesting Blades
Quench at 830~860℃ followed by low-temperature tempering, reaching HRC50~60 for sharpness and superior wear resistance.
(3) Wear-resistant Boron Steel Sheets
Adopt isothermal quenching plus surface boronizing treatment, boosting wear resistance by over 40%.
Process TaboosForbid excessive high-temperature heating (causes coarse grains and sheet chipping) and insufficient tempering (leads to easy fracture).
6. Secondary Straightening Technology
Steel sheets are prone to deformation after heat treatment. Adopt double-sided precision straightening by hydraulic straighteners to control flatness and arc deviation.
7. Precision Edge Machining Technology
Edges must be processed for tillage and harvesting steel sheets:
Grind single-sided or double-sided edges evenly with abrasive wheels for uniform edge thickness.
Remove brittle quenched edges to ensure smooth soil penetration and cutting performance.
8. Surface Anti-corrosion Technology
Ordinary products: Electrostatic paint spraying and black paint anti-rust treatment.
High-end agricultural parts: Hot-dip galvanizing and plastic spraying.
Outdoor agricultural components: Impregnate with anti-rust oil for sealing to prevent rusting in humid field environments.
III. Full-process Quality Control System
1. Raw Material Quality Control
Inspect material quality certificates and conduct spectral analysis to verify qualified composition of 65Mn steel and boron steel.
Check plate thickness tolerance to prevent thin plates with negative tolerance from being used as standard thick plates.
Eliminate inherent defects such as interlayers, double skins, cracks and pinholes in steel plates.
2. In-process Production Quality Control
First-piece inspection: Test dimensions, arcs and hole spacing of the first workpiece per shift; mass production starts only after qualification.
Routine inspection: Sampling inspection on forming size, cut quality and stamping deformation every 2 hours.
Dimensional Tolerance Standards
Outer diameter deviation: ≤±1.5mm
Aperture deviation: ≤±0.3mm
Arc consistency deviation within the same batch: ≤2°
3. Specialized Heat Treatment Quality Control (Top Priority)
Regularly calibrate furnace temperature and strictly control heating, heat preservation and cooling duration.
Conduct Rockwell hardness sampling inspection batch by batch; rework unqualified products entirely.
Bending toughness test: Qualified steel sheets shall not fracture or form brittle white layers after bending.
Strictly limit heat treatment deformation and reject out-of-specification products directly.
4. Finished Product Performance Quality Control
Full-coverage hardness sampling inspection to avoid uneven hardness.
Wear resistance simulation test: Simulate friction and abrasion caused by field sand and soil.
Impact resistance test: No edge chipping or cracking after high-altitude drop impact.
Fatigue resistance test: No fracture after repeated bending.
5. Appearance Quality Control
Free of cracks, burrs, deformation and pinholes.
Uniform and firm paint coating without peeling; neat edges without notches.
No severe oxidation, yellowing or blackening on surfaces.
6. Pre-delivery Final Inspection
Conduct full-item re-inspection by batch sampling ratio.
Grade products into premium and qualified goods; isolate and scrap defective products.
Mark specifications, material grade, production date and hardness grade clearly.
#GRTECH #Tractor Clutch Kit
