How to Choose Equipment for Mold Repair: Cold Welding Machine, TIG Welding, and Laser Welding Machine
- 邵萱 黃
- Aug 19
- 3 min read
Importance and Challenges of Mold Repair
In modern mold manufacturing and mold development, molds are not only the fundamental tools of industrial production but also the core of components such as automotive parts, electronic devices, medical products, household appliance housings, and even automotive headlamp injection molds.
However, after long-term use, molds inevitably suffer from cracks, chipping, pitting, and wear. Replacing molds directly is not only extremely costly but also causes production delays. Therefore, mold repair has become a crucial process to ensure production stability.
Common Causes of Mold Damage
Thermal Fatigue – Cyclic heating and cooling lead to cracks.
Wear – Continuous injection molding or stamping gradually consumes the mold cavity surface.
Mechanical Impact – Dropped objects causing dents on mold surfaces.
Human Factors –
Improper disassembly leading to chipping.
Incorrect cleaning methods causing surface pitting.
Misalignment during assembly resulting in edge damage.
👉 Especially in automotive headlamp injection molds or high-precision transparent plastic molds, even the slightest damage may lead to optical defects or surface blemishes on finished products.
Three Main Mold Repair Equipment
1. Cold Welding Machine (Micro-Arc Discharge Welding)
Principle: Utilizes low-heat micro-discharge welding, creating metallurgical bonding between filler and base material.
Feature: Extremely low heat input, preventing mold deformation.
Application: Commonly used in plastic injection molds for repairing minor chipping, shallow pits, and fine cracks.
Headlamp Mold Application: Prevents localized hardening, avoiding light distortion in transparent plastic components.
2. TIG Welding (Tungsten Inert Gas Welding)
Principle: Utilizes an inert argon shielding gas to protect the arc, fusing filler rod with base metal.
Feature: High bonding strength with faster repair speed.
Application: Suitable for repairing major cracks, deep cavities, or structural damages in mold manufacturing.
3. Laser Welding Machine
Principle: Employs high-energy-density laser beams to locally melt filler wire and base metal.
Feature: Extremely fine weld seams with minimal heat-affected zone.
Application: Particularly suitable for high-precision optical molds, headlamp molds, and medical device molds.
Usage Scenarios and Pros & Cons
Cold Welding Machine
Usage: Small cracks, chipping, shallow pits, surface pitting.
Advantages:
Minimal heat input, no deformation.
Fine repair seams, directly polishable.
Ideal for transparent molds, prevents optical defects.
Disadvantages:
Limited strength, unsuitable for deep cracks.
Welding electrode must be very close to the workpiece, prone to sticking, requiring skilled operation.
TIG Welding
Usage: Large cracks, deep pits, structural repairs.
Advantages:
High strength and fastest repair efficiency.
Applicable to a wide range of mold steels.
Disadvantages:
High heat input may cause annealing or hardening.
Not suitable for transparent plastic molds, may induce light distortion or stress marks.
Laser Welding
Usage: Precision molds, micro-cracks, aesthetic surface repairs.
Advantages:
Extremely small heat-affected zone, preserving base metal properties.
Excellent for automotive headlamp molds and optical molds, ensuring flawless surface quality.
Disadvantages:
High equipment cost and slower efficiency.
Limited welding angles due to fixed optics; mold must be repositioned during repair.
Repair Efficiency Comparison
Fastest → TIG Welding (ideal for large-scale repairs).
Moderate → Cold Welding (faster than laser but slower than TIG).
Slowest → Laser Welding (highest precision, lowest efficiency).
Filler Wire Diameter and Application Range
Laser Welding: ≤ 0.8 mm, suitable for ultra-precise welding.
Cold Welding: 0.8 – 1.2 mm, suitable for small to medium repairs.
TIG Welding: ~1.6 mm, suitable for large cracks and major repairs.
👉 Since each process has specific filler diameter and current limitations, they cannot completely replace one another. In practice, the choice must be made according to the extent and severity of mold damage.
Comparative Summary of the Three Repair Methods
Equipment | Usage Scenarios | Advantages | Disadvantages | Speed | Filler Range |
Cold Welding Machine | Small cracks, chipping, shallow pits | Low heat input, no deformation, suitable for transparent molds | Limited strength, electrode may stick | Moderate | 0.8 – 1.2 mm |
TIG Welding | Large cracks, deep pits, structural repairs | Strong welds, fastest efficiency | High heat input, unsuitable for transparent molds | Fastest | ~1.6 mm |
Laser Welding | Precision molds, micro-cracks, aesthetic parts | High precision, minimal heat, ideal for optical molds | High cost, slow, limited angles | Slowest | ≤ 0.8 mm |
Conclusion
In the field of mold repair, Cold Welding Machines, TIG Welding, and Laser Welding Machines each have their unique roles and are complementary rather than interchangeable:
Cold Welding → Small to medium-sized quick repairs, particularly suitable for transparent plastic molds.
TIG Welding → Large-area structural repairs, offering the fastest repair speed.
Laser Welding → High-precision surface repairs, ensuring optical quality in headlamp molds and optical molds.
👉 Choosing the appropriate repair method during mold development and mold manufacturing not only extends mold lifespan but also guarantees the consistent quality of automotive headlamp injection molds and other high-precision molded products.
