The pinion shaft is the core transmission component that drives large girth gears (such as ball mills, rotary kilns, and other heavy-duty equipment). The pinion shaft design, manufacturing, and assembly quality directly affects the stability, service life, and efficiency of the entire gear transmission system.

I. Function and Importance of Pinion Shafts
Mesh with gear rings to transmit torque and power (typically driven by motors or reducers), withstand high dynamic loads (impact, bending stress, torsional loads).
 
II. Typical Applications
Mining equipment (Ball Mills, SAG Mills, AG Mills)
Cement industry (rotary kilns, roller presses)
Large transmission systems in metallurgy, power generation, and other industries
 
III. Design and Materials for Pinion Shafts
1. Material Selection
High-Strength Alloy Steel
Common grades: 42CrMo (DIN 1.7225), 34CrNiMo6 (DIN 1.6582), SAE 4340, and so on.
Properties: High fatigue resistance, excellent hardenability (core toughness + surface hardness)
2.Heat Treatment Process
Quenching & Tempering: Overall hardness HRC 28-32 (ensures core toughness)
3.Surface hardening
Tooth surface induction hardening (HRC 55-60)
Case hardening: Carburized layer depth ≥1.2mm (per ISO 6336-5 requirements)
 
IV. Inspection Methods for pinion shaft
1. Geometric Accuracy Testing
Dimensional Tolerances:
Gear ring diameter, roundness, face runout (ISO 1328, AGMA 2015)
Pinion shaft concentricity, keyway symmetry (ISO 2768)
Gear Tooth Profile Testing:
Pitch deviation (single pitch, cumulative pitch)
Tooth profile deviation (pressure angle, involute profile)
Lead deviation (helix angle error)

2. Material and Hardness Testing
Material composition: Optical emission spectroscopy (OES) to confirm alloy composition
Hardness testing: Brinell hardness (HB) or Rockwell hardness (HRC) per ISO 6506/ISO 6508
Non-destructive testing (NDT):
Ultrasonic testing (UT): Internal defects (porosity, cracks)
Magnetic particle testing (MT) or penetrant testing (PT): Surface cracks
 
3. Surface Quality and Heat Treatment
Metallographic examination:
Carburized layer depth (per DIN 50190-3), grain size (ASTM E112)
Surface roughness: Contact surfaces Ra ≤1.6μm (ISO 4287)  
V. Common Quality Grades for Pinion Shaft:
Mining/cement industry: ISO Grade 6-7 (or AGMA Class 10-11)
Critical equipment (such as SAG Mills): ISO Grade 5-6, higher precision grades as required.