Top 3 Common Die Casting Mold Failures and Their Causes

The Common Failure Types and Causes of Die Casting Tooling

During the operation of die casting molds, various types of damage and failure can occur, which severely affect the mold’s performance and lifespan. 

Below are the most common failure modes experienced during die casting production: fracture failure, corrosion failure, and thermal fatigue crack failure. 

Each type is explained in detail:

1. Fracture Failure

Fracture failure typically originates under high injection pressure, especially in areas of the mold that are structurally weak. These weak points often include:

• Surfaces with incomplete finishing from EDM (electrical discharge machining) or visible mold parting lines.

• Sharp corners or stress concentrators.

• Zones with brittle phases or coarse grain structures.

Once a crack begins, it can rapidly grow due to brittle fracture, eventually leading to mold breakage. To prevent this:

• All surfaces, even those within the Gating system, should be polished and free of machining marks.

• High-strength materials with excellent toughness (both impact and fracture toughness) should be used.

• Mold design should minimize stress concentration points.

2. Corrosion Failure

Die casting molds are frequently used with reactive alloys such as zinc, aluminum, magnesium, and copper. 

These metals have a high affinity for mold materials, particularly when casting pure aluminum alloys. Corrosion can occur if:

• The mold surface contains soft spots.

• Inadequate surface hardness or protective coatings are present.

To enhance corrosion resistance:

• Ensure high surface hardness.

• Apply surface treatments or coatings where appropriate.

• Avoid inconsistent hardness on the molding surfaces.

3. Thermal Fatigue Crack Damage

Thermal fatigue is one of the most common and critical failure modes in die casting molds. It results from repeated cycles of rapid heating and cooling, which induce thermal stress and lead to:

• Micro-crack formation due to repeated expansion and contraction.

• Structural degradation and loss of elasticity.

• Crack propagation, worsened by fluid stagnation and mechanical stress.

To mitigate thermal fatigue:

• Preheat the mold thoroughly before production.

• Maintain a consistent operating temperature during casting.

• Use materials with good thermal fatigue resistance and design for uniform heat distribution.

Summary

Understanding and addressing these common die casting mold failure types—fracture, corrosion, and thermal fatigue—can significantly improve mold performance and longevity. Proper material selection, surface treatment, and temperature control are key to preventing premature tooling failure.