GULLET CRACKING

Bandsaw Gullet Cracking

Cause: The gullet area (the space between the teeth) can crack due to a variety of factors. Common causes include issues with guides, tension, feed rate, coolant, speed, bearings, and welding.

Key Factors & Solutions:

  • Guides Too Tight
    • Issue: Excessive side pressure from tight guides restricts blade movement, causing the blade to stretch.
    • Effect: The tension creates stress on the gullet, which leads to cracks.
    • Solution: Adjust guides to ensure minimal side pressure, allowing the blade to run smoothly.
  • Tension Too High
    • Issue: Excessive tension on the blade causes the flexible backing to stretch, while the rigid teeth resist.
    • Effect: This results in uneven stress on the gullet and cracking.
    • Solution: Reduce the blade tension to ensure the blade maintains flexibility and reduces over-stretching.
  • Feed Rate Too Heavy
    • Issue: A high feed rate pushes material too quickly into the blade.
    • Effect: The gullet area fills too quickly, preventing the teeth from exiting the material properly, leading to pressure and damage.
    • Solution: Reduce the feed rate to allow the teeth to clear the material more effectively.
  • Coolant Flow Too Low
    • Issue: Insufficient coolant causes rough cutting due to a lack of cooling.
    • Effect: The blade temperature rises, which can cause heat-related damage, especially to HSS teeth.
    • Solution: Ensure adequate coolant flow to maintain proper cooling during operation.
  • Improper Coolant Mixture
    • Issue: An improper coolant concentration reduces cooling efficiency.
    • Effect: Insufficient coolant leads to heat build-up, increasing blade wear.
    • Solution: Use the correct coolant dilution (e.g., 1:20 for steel, 1:10 for stainless steel) based on the material being cut.
  • No Need for Coolant (for Certain Materials)
    • Issue: Materials like SpK alloy steel and cast iron have low friction and don’t require coolant.
    • Effect: Coolant may cause the blade to slip, leading to damage.
    • Solution: Avoid using coolant for such materials, and instead, reduce the blade speed to manage heat.
  • Speed Too Fast
    • Issue: Cutting too fast with hard materials (like stainless steel) increases blade wear.
    • Effect: Excessive speed leads to blade damage, gullet cracking, and premature wear.
    • Solution: Slow down the cutting speed to minimize wear, especially for harder materials.
  • Broken Guide Bearings
    • Issue: Vertical guide bearings help keep the blade aligned. If damaged, the blade can wobble.
    • Effect: Wobbling leads to erratic cutting and increases the risk of blade breakage.
    • Solution: Inspect and replace any worn or damaged guide bearings to ensure proper blade alignment.
  • Jumping or Shaking Machine Head
    • Issue: Shaking or jumping can be caused by:
      • Damaged guide bearings
      • Misaligned blade welding
      • Hydraulic system defects
    • Effect: These vibrations cause stress on the blade, leading to cracks and other failures.
    • Solution: Replace damaged bearings, re-align the blade during welding, and inspect the hydraulic system for leaks or failures.
  • Gullet Welding (for Certain Materials)
    • Issue: Materials like aluminum can stick to the gullet.
    • Effect: This buildup reduces the blade’s effectiveness and increases wear.
    • Solution: Use a brush or increase coolant flow to clean the gullet and prevent material buildup.