Solving the Problem of Broken Screw Tails with Imported Taps: A Practical Maintenance Guid

Problem Phenomenon: Excessive rake angle of the tap leads to noticeable screw tail breakage.

1. Select Appropriate Tools: Use a professional diamond file, which has high hardness and is less likely to damage the tap surface.
2. Adjust Rake Angle Height: Gently file along the direction of the tap's rake angle to reduce the height to an appropriate range.
3. Enhance Anti-Slip Function: Roll non-slip teeth into the adjusted area to increase friction and prevent recurring breakage.
4. Verify Repair Effect: Conduct a trial pressing after each adjustment. Observe if the breakage improves, and repeat adjustments if necessary.

Problem Phenomenon: Slight tail breakage requiring investigation into potential root causes.

1. Insufficient Thread Groove Opening
   • Solution: Use a triangular diamond file to slightly widen the thread groove along its direction, ensuring the screw tail passes through smoothly.
2. Mismatched Rake Angle Height
   • Solution: Precisely adjust the rake angle using a diamond file to achieve a perfect match with the screw tail.
3. Weakened Non-Slip Teeth Function
   • Solution: Grind a punch into a flat "-" shape on a grinding wheel and use it to deepen the non-slip teeth, enhancing grip.

Problem Phenomenon: Breakage unrelated to the tap itself, caused by external factors.

1. Excessively Hard Wire Material
   • Switch to softer wire material, or perform annealing treatment on the existing wire to reduce its hardness.
2. Improper Screw Dimensions
   • Adjust the photoelectric marking length to avoid excessive screw tail length that causes stress concentration.
3. Mismatched Process Parameters
   • Thoroughly check thread rolling speed, pressure, and other parameters to ensure they are compatible with the tap characteristics.

When performing repairs, pay special attention to the following points:

• Protect Tap Structure: Always avoid the tap's cutting edge area during maintenance to prevent structural damage that could scrap the tap.
• Maintain Length Consistency: After adjustment, ensure the lengths of the long and short sections of the tap are equal to prevent screw forming deviations.
• Follow the Slope Direction: Perform adjustments along the direction of the tap's tail slope, maintaining a smooth surface to reduce stress concentration points.
• Apply Gradual Adjustments: Adhere to the principle of "small amounts, multiple times." Conduct a trial pressing after each adjustment to avoid over-correction.

When repair costs approach or exceed the price of a new tap, consider the following alternatives:

1. Localized Precision Repair
   • Use an oilstone to lightly polish the broken tail area, rounding its edges to reduce the risk of breakage (suitable for minor breakage).
2. Custom Professional Taps
   • Commission new, high-precision taps to ensure long-term stability and production efficiency.
3. Optimize Production Process
   • Adjust thread rolling machine parameters, such as optimizing the feed chamfer and grinder feed ratio, to reduce stress on the tap.

• Priority Repair Scenarios: When breakage is caused by tap rake angle, thread groove, or non-slip teeth issues, professional filing adjustments can usually resolve it effectively.
• Comprehensive Investigation of External Factors: If the breakage is related to wire material characteristics or process parameters, adjust the materials or production process accordingly.
• Structural Protection Principle: Always protect the core structure of the tap during maintenance, maintain component consistency, and avoid over-adjustment.
• Cost-Benefit Assessment: When repair costs reach 50%-70% of the price of a new tap, consider ordering a new tap to ensure production quality and long-term stability.