The appearance of yellow discoloration when cutting white paper with a base paper cutting machine can result from multiple technical and operational factors. Below is a detailed analysis of the causes and recommended solutions:

1. Blade-Related Issues of Yellow Discoloration

• Dull or Worn Blades$Q = \mu F v$, where $\mu$ is friction coefficient) that can thermally degrade paper fibers, leading to yellowing.
• Incorrect Blade Material: Low-quality blades may oxidize or deform during cutting, exacerbating heat buildup.
• Solution: Use high-carbon steel or tungsten carbide blades, maintain sharpness (recommended edge angle: 25°–30°), and replace blades after processing 50–70 tons of paper.

2. Cutting Pressure Problems

• Excessive Pressure: Pressure exceeding 3.5 MPa compresses paper fibers excessively, causing structural damage and discoloration.
• Inconsistent Pressure: Uneven pressure distribution (e.g., due to misaligned rollers) creates uneven cutting lines and localized yellowing.
• Solution: Calibrate hydraulic/pneumatic systems to maintain 2.5–3.0 MPa pressure and ensure even roller alignment.

3. Paper Quality Defects of Yellow Discoloration

• High Moisture Content (>6%): Wet paper fibers are more prone to thermal degradation during cutting.
• Chemical Contaminants: Residual bleaching agents (e.g., chlorine) or lignin can react under heat, causing yellowing.
• Solution: Store paper in controlled humidity (45–55% RH) and test paper batches for pH (target: 6.5–7.5) and chemical stability.

4. Mechanical Failures

• Bearing Wear: Worn bearings increase rotational resistance, raising operational temperatures by 15–20°C.
• Insufficient Lubrication: Poor lubrication in guide rails or drive chains elevates friction heat.
• Solution: Implement predictive maintenance (vibration analysis every 500 operating hours) and use high-temperature grease (e.g., lithium-complex types).

5. Preventive Measures of Yellow Discoloration

• Regular Maintenance: Clean blades and lubricate moving parts weekly.
• Process Monitoring$\Delta T > 5°C$ triggers alarms).
• Professional Servicing: Schedule bi-annual inspections by certified technicians to assess motor alignment and blade integrity.

For persistent issues, consult manufacturers for advanced diagnostics, such as thermal imaging or vibration spectrum analysis.

: Blade wear and thermal effects research
: Mechanical failure detection methods