Erosion is the continuous material loss due to the abrasive wear of die-cast surfaces. It’s a defect mostly observed in aluminum alloys. Many involved factors directly or indirectly contribute to its formation.
Erosion also includes cavitation which primarily happens during casting. Bubbles in the flow burst upon entering the low-pressure region. It initiates an aggravated erosion to wipe out some of the mold steel.
This article sheds light on comprehensive details of sources, causes, effects, and prevention of erosion.
Causes of Erosion
Erosion in aluminum alloys features a complicated action with many factors involved. Some of the leading reasons to trigger this defect include –
- Excessive/high velocity than required at the gate.
- Distorted temperature at impingement points.
- Compromised condition of the aluminum die-cast.
- Improper inclusion of contributing matrix alloy.
- Chemical reaction of aluminum with mold steels.
The cavitation in aluminum die casting is more of a combined defectassociated with corrosion.
Erosion in Aluminum Die Cast Effects
The successive surface material loss exerts a direct negative effect on certain casting requirements, like –
- Damaged Aesthetics –The most obvious issue concerns the severely damaged surface finishing. The abrasive wear slowly but surely takes out the exterior. Cast parts requiring a good look become almost impossible to obtain.
- Reduced Strength –Material loss from critical points is sure to hamper the overall structural integrity. The cavitation affected section suffers from scattered bearing or tolerance, often making the entire part vulnerable.
- Additional Defects –Since the exterior cover is getting wiped out, the interior parts have no protection from the surroundings. And the negligible defects continue to grow as the negligible cracks, bubbles, and impurities get exposed.
Preventing Die Casting Erosion
The problem tends to accelerate at higher temperatures, similar to corrosion. As die-casting corrosion also contributes to erosion, it’s a must to take corrective actions. Preventive measures to eliminate the chances of abrasive surface wear are –
- Upper Gate Velocity– Setting the upper limit for gate velocity is the first preventive step. The common limiting range lies between 1000 ips to 1600 ips (25 m/s up to 40 m/s) for aluminum. An exact value will require die configurations and quality requirements.
- Check of Temperature– It’s possible to terminate erosion completely through low temperatures. Keeping the temp low but over 350°F/177°C around the gate can help. Either spraying or spot cooling along with additional water lines can lower the gate temperature.
- Included Alloy Content– Presence of oxides-silicates within the alloy composition is also important. The impurities carried to aluminum are sure to exhibit some negative effects. Cleaning, de-gassing, and filtering should be implemented properly to minimize inclusions.
- Careful Flow Design– All the operating parameters, including the flow pattern should minimize erosion. It concerns maintaining a short filling time while keeping the velocity at lower limits. Proper calculation of design parameters based on requirements is the key.
Sunrise Metal is a well-experienced die casting manufacturer with experts in designing perfection. It maintains the highest standard from the initial design based on the required configuration. Contact us to let our professionals help you with your project.