How to Determine if a Slitting Blade Needs Replacement?
Determining whether a slitting blade needs replacement requires an assessment of factors such as visual wear, cutting quality, usage time, and noise/vibration. The following are specific assessment methods and operational suggestions:
- Visual Wear Inspection
—Dulling of the Blade Edge
Symptoms: The blade edge becomes rounded, loses sharpness, and produces burrs or tears during cutting.
Assessment Method: Observe the blade edge with a magnifying glass. If the edge is rounded rather than straight, or if irregular tears appear on the cutting surface, the blade edge is dull.
Treatment: Mild dulling can be attempted with resharpening (such as sanding or using professional resharpening equipment), but the number of resharpening attempts is limited (usually 3-5 times). If sharpness cannot be restored after resharpening, the blade needs to be replaced.
—Chipping or Wadding
Symptoms: The blade edge has chips, cracks, or chipped off.
Assessment Method: Visually inspect the blade edge. If obvious chips or cracks are found, or abnormal vibrations occur during cutting, the blade edge is damaged.
Handling: If the chipped or nicked edge is irreparable, the insert must be replaced immediately to prevent further damage to the workpiece or equipment.
—Corrosion or Rust
Symptoms: Rust spots, oxide layers, or discoloration appear on the insert surface.
Judgment Method: Visually inspect the insert surface. If rust or corrosion is found, the insert material is damaged.
Handling: Light rust can be removed with sandpaper. However, if the rust penetrates deep into the material, the insert must be replaced to prevent further rust spread and breakage.
- Cutting Quality Assessment
—Deterioration in Cutting Surface Quality
Visual Inspection: Observe whether the cutting surface is smooth and free of burrs.
Measuring Tools: Use calipers, micrometers, or a roughness tester to measure the dimensions and roughness of the cutting surface. If it exceeds process requirements (e.g., roughness Ra > 0.8 μm), the insert is worn.
Symptoms: Burrs, wavy lines, dimensional deviations, or excessive surface roughness appear on the cutting surface.
Judgment Method:
Handling: If the cutting quality deteriorates and cannot be improved after re-sharpening, the insert must be replaced.
—Abnormal Cutting Force
Assessment by feel: The operator feels increased cutting effort, or the equipment current or power is abnormally high.
Data monitoring: Monitor the cutting force through the equipment’s sensors. If it exceeds the normal range (e.g., cutting force increases by more than 20%), it indicates that the cutting tool is worn.
Symptoms: Increased resistance during cutting, requiring increased feed pressure or cutting speed, leading to increased equipment load.
Troubleshooting method:
Solution: Abnormal cutting force accelerates equipment wear; the cutting tool must be replaced promptly.
- Usage Duration and Frequency
—Cumulative Usage Time
Troubleshooting method: Record the cumulative usage time of the cutting tool (e.g., hours or cutting length). If it exceeds the manufacturer’s recommended lifespan (e.g., 500-1000 hours for carbide cutting tools), it must be replaced.
Solution: Even if there is no obvious external wear, micro-cracks may develop inside the cutting tool after long-term use, requiring periodic replacement.
—Cutting Material Type
Judgment Method: When cutting hard materials (such as stainless steel and titanium alloys), the cutting tool wears faster, requiring a shorter replacement cycle; when cutting soft materials (such as paper and rubber), the service life can be appropriately extended.
Solution: Adjust the replacement frequency according to the material hardness to avoid premature tool failure due to material differences.
- Sound and Vibration Monitoring
—Abnormal Noise
Audio Judgment: Abnormal noise is heard when the operator approaches the equipment.
Acoustic Monitoring: Use a sound level meter to monitor the noise level. If it exceeds the normal range (e.g., >85dB), it indicates that the cutting tool is worn or damaged.
Manifestations: A harsh sound, metallic friction sound, or irregular vibration sound is produced during cutting.
Judgment Method:
Solution: Abnormal noise may be a signal of tool chipping or nicking; the machine should be stopped immediately for inspection and tool replacement.
—Equipment Vibration
Tactile Judgment: The operator feels obvious equipment vibration.
Vibration Sensor: A vibration sensor monitors the equipment’s vibration frequency and amplitude. If these exceed the normal range (e.g., amplitude > 0.1mm), it indicates the cutting tool is unbalanced or damaged.
Symptoms: Increased equipment vibration during cutting leads to chatter marks or dimensional deviations on the workpiece surface.
Diagnosis Method:
Handling: Abnormal vibration accelerates equipment wear; timely replacement of cutting tools and checking of equipment dynamic balance are necessary.
- Regular Maintenance and Records
—Establish Replacement Standards
Method: Based on the cutting tool material, cutting parameters, and process requirements, establish clear replacement standards (e.g., cumulative usage time, cutting length, or cutting surface quality threshold).
Example: Replace carbide cutting tools every 500 kilometers or when noticeable burrs appear; replace high-speed steel cutting tools every 300 kilometers or when cutting force increases by 15%.
—Record Usage Data
Method: Record the time of each cutting tool replacement, cutting material, cutting parameters, and reason for replacement, creating a database.
Purpose: Optimize replacement cycles through data analysis, avoiding premature or delayed replacement.
- Professional Inspection and Evaluation
—Non-destructive Testing
Methods: Use ultrasonic testing, magnetic particle testing, or X-ray inspection to check for internal cracks or defects in the cutting tool.
Applicable Scenarios: Regular inspection of high-value cutting tools or critical processes to identify potential problems early.
—Cutting Test
Methods: Cut on a sample and observe the cut surface quality, cutting force, and noise, comparing it with a new cutting tool.
Judgment Criteria: If the cutting test results are significantly worse than those of a new cutting tool, replacement is required.