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Zinc Die Casting Components


Die Cast Defects

Die casting is a process that takes a lot of skill and planning. At Brillcast, our quality engineering and process engineers work very hard to monitor our castings to ensure the highest quality products for our customers. The following are pictures of die cast defects along with descriptions to explain why they occur.

Pin Push

Definition: Pin push is caused when the part or core(s) are sticking in the die during ejection. This condition will be in the same location every time until process or spray adjustments are made.

Appearance:
The ejector pin will push the stuck part out of the die causing a bump on the cover side, opposite the ejector pin location.



Shot Over

Definition: Shot over is caused when zinc (drip, flash or stuck piece of a part) is left in the die and the next shot is made. This condition sporadically happens and can occur over many shots. Typically occurs during start up and when die temperatures are not up to operating temps.

Appearance:
Outline of stuck zinc will show on part.



Shrink

Definition: Shrink is caused during the cooling process in the part. This condition stays in the same area until process is adjusted or die reaches operating temperature. This may require tooling adjustments. Appears on the cover side of a part opposite a cast feature such as a rib or boss on the ejector side of part, due to temperature differences between die halves or components.

Appearance:
Negative on the part.



Cracks

Definition: Crack is caused during the ejection process due to excessive heat or cold, or insufficient draft or velocity. This condition will typically be in the same location every time until process is adjusted or die reaches operating temperature.

Appearance:
Fracture on the part.



Flash

Definition: Flash is caused by poor steel condition, improper lock up or improper shut off. This condition will be in the same area every time until process is adjusted, or tool is corrected.

Appearance:
Positive on part.



Blow Out

Definition: Blow out is caused when the die temperatures are too hot and the skin fractures. This condition will be in the same area until process is adjusted.

Appearance:
Positive on the part.



Parting Line Holes

Definition: Parting line holes are caused by poor die cast design or poor fill condition or plugged vacuum or excessive die spray or location of neutral thermal axis or not enough metal pressure. This condition typically tays in the same area until process or tooling corrections are made.

Appearance:
Negative holes on the part located at parting line between die halves of inserts.
Note: *Neutral Thermal Axis is the planned area for trapped gasses, typically the center of the casting.



Pull

Definition: Pull is caused by improper spray or die temperature or burnout/drag or uneven ejection or build-up on cores or shrink. This condition will be in the same area until process adjustments are made, or tooling corrections are made.

Appearance:
Deformation on the part can be caused by a lack of draft or damage incurred on die steel feature.



Mis-Punched Part

Definition: Mis-punched part is caused when trim does not cycle properly or not set up properly. This condition will occur in the same area until trim die is adjusted.

Appearance:
Positive on the parts, gate mis-located on trim die.



Trim Shear

Definition: Trim shear is caused when the part is not properly located on the trim nest or trim steel is not properly adjusted or due to method used to cool part. This condition will be in same location and may damage the trim die. If trim adjustments are not made this condition may worsen.

Appearance:
Negative on the part.



Break Out

Definition: Breakout is caused during the trim operation, where too much material is removed. This condition will be in the same area until trim steels are adjusted.

Appearance:
Negative on the part.



Slugs

Definition: Slug is caused when a part is trimmed with debris on the trim steel, trim post or part. This condition will typically stay in the same area until trim die is cleaned.

Appearance:
Negative or positive on the part.



Solder

Definition: Solder is caused when zinc builds up on the die during the run. This condition will be in the same location every time until it is polished (removed) from the die. If it is not polished and process adjustments are not made than this condition will worsen.

Appearance:
Negative on the part.



Build Up

Definition: Build up is caused when spray deposits build up on the die during the run. This condition will typically be in the same location every time until it is polished (removed) from the die. If it is not polished and spray adjustment corrections are not made this condition will worsen.

Appearance:
Build up on die usually means negative on part.



Cold

Definition: Cold is caused when zinc or die are too cold during cavity fill or spray or water drip. This condition will remain the same until the zinc or die reaches the operating temperature.

Appearance:
Overlapping/laminate flow on the part.



Heat

Definition: Heat is caused when zinc or die are too hot during cavity fill. This condition will remain the same until the zinc or die temperature are reduced.

Appearance:
Negative on the part.



Gas Blister

Definition: Gas blisters are caused by trapped gases below the surface. This condition will stay the same or worsen until the vacuum, machine or process adjustments are made.

Appearance:
Positive on the part.



Spray Blister Defects
Spray Blisters

Definition: Spray blisters are caused by trapped gases due to excessive spray. This condition will typically be in the same location every time until spray adjustments are made.

Appearance:
Positive on the part.



Burnout

Definition: Burnout is caused by cavitations of the metal during cavity fill causing die erosion. This condition will be in the same location every time until it is polished (removed) from the die. If it is not polished and processes adjustments are not made to correct this condition, this condition will worsen.

Appearance:
Positive on the part.
Note: *Cavitations – coming from gas bubbles trapped in the incoming metal stream. These bubbles implode on the die steel causing tiny pits.



Metal Flow

Definition: Metal flow is caused by excessive temperature of the die and zinc. This condition will typically be in the same general area until process or spray adjustments are made. It is caused by difference in die temperature between die halves.

Appearance:
Lines on the part or sometimes positive on the part.

The North American Die Casting AssociationThe North American Die Casting Association
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