Mould Maintenance Guide: Sharpening and Demagnetizing Curbstone Mould Edges
The edge condition of curbstone moulds directly determines product quality and production efficiency. Many production interruptions and rising scrap rates trace back to neglecting two critical maintenance procedures: edge sharpening and demagnetization .
Why Edges Dull and Magnetize
During prolonged use, mould edges gradually wear due to continuous friction with abrasive concrete mixtures containing sand, gravel, and aggregates. Dull edges increase forming resistance, causing defects-burrs, chipping, missing corners-on produced concrete products. Regular sharpening is essential to restore performance .
However, the sharpening process itself introduces a "side effect"-magnetism. Friction between the grinding wheel and steel generates heat and creates a magnetic field, leaving residual magnetism on the sharpened edge. This magnetism attracts fine iron particles or dry mix from the concrete slurry, causing poor material flow or clogging. Production must stop for cleaning .
The Correct Procedure: "Sharpen First, Then Demagnetize"
1. Edge Sharpening Guidelines
Sharpening aims to sharpen the tool, not excessively consume the mould :
Timing Judgment: Sharpening is required when product edge quality declines or forming resistance increases noticeably.
Precision Control: Sharpening must be performed by trained personnel using appropriate grinding machines and wheels. The feed rate per pass must be minimal to prevent localized softening of the edge from overheating. According to industry technical data, the single-pass grinding depth should not exceed 0.013mm, and adequate coolant must be applied .
Know When to Stop: Mould edges have a limited grinding allowance. Once the wear limit is reached, the mould must be scrapped. Excessive grinding leads directly to mould failure .
2. Critical Step: Thorough Demagnetization
Demagnetization is as important as the sharpening itself. Immediately after sharpening and thorough cleaning, a professional demagnetizer must be used to completely demagnetize the cutting edge area. The goal is to ensure the edge surface is fully demagnetized-the core principle of "demagnetize after every sharpening" .
Building a Comprehensive Maintenance System
Beyond edge maintenance, a sound system includes regular inspection and replacement of wear parts such as springs, punches, and punch sleeves, as well as checking for air leaks in the pneumatic ejection system :
| Maintenance Item | Key Operation | Primary Purpose |
|---|---|---|
| Daily Cleaning | Clean immediately after each shift with low-pressure water and soft brushes; avoid metal tools. | Prevent hardened concrete residue, avoid abrasion, and prevent sticking. |
| Proper Release Agent Application | Apply professional release agent evenly before each cycle. | Reduce friction, ensure smooth demolding, and protect the mould surface. |
| Inspection & Tightening | Regularly inspect and tighten all bolts; check for cracks and wear. | Prevent deformation and loosening from vibration; maintain equipment precision. |
| Component Replacement | When replacing springs, verify that colour, outer diameter, and length are identical to the original. | Restore elastic function; prevent malfunctions due to spring fatigue. |
| Professional Storage | Store moulds in a dry, covered environment. | Prevent rust and corrosion from moisture. |
Maintenance Records
It is highly recommended to create detailed maintenance files for each mould set, recording the dates and specific actions of every sharpening, demagnetization, and parts replacement. This helps track mould service life, allows proactive spare parts planning, and avoids sudden production halts from unexpected failures .
Conclusion
"Demagnetize after every sharpening" is the core rule for curbstone mould maintenance. Correctly executing both operations, combined with a comprehensive upkeep system, extends mould service life and ensures efficient, stable production line operations .
