| The
4 Primary Types of Cracks or Fractures
Seen in Returned Wire Dies
Cracks or fractures are almost always formed by a release of stress in the
part. Stress is inherent in any material structure. Compressive stress makes a
diamond microstructure stronger. However, as material is removed the microstructure
is subject to greater stress, making it more susceptible to cracking or breaking.
U-Shaped
Cracks
Description
Vertical fractures/cracks that turn downward at the entrance approach and then
turn upwards at the bearing zone.
Causes
- Excessive mechanical stress applied to one side of the die due to misalignment
in the casing.
- Voids or uneven distribution of materials in the sintered matrix.
Pitting
Description
One or several voids in the diamond table. Can be either a diamond crystal pull
out or a loss of metal binder.
Causes
- Excessive laser burn on one or more isolated regions that did not clean during
fabrication.
- Metal pool in diamond structure.
- Agglomeration of small diamond crystals that pulls out when overheated.
Wear
Rings
Description
One or more horizontal grooves or fractures in the bearing area or on the top
of the reduction area. Sometimes cracks can develop if not caught in time.
Causes
- Excessive use of die beyond the recommended re-cut time.
- Interrupted lubrication flow during the wire drawing process causing abrasion
from material fines.
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