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Painting Defects : Sinking
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Solvent in the paint penetrates the component near
the gates, at areas of varying thickness, or near welds; consequently,
luster becomes uneven and fine cracks develop.
We
recommend our special painting grades for use in painted products.
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Normal surface |
Sinking |
Example: Metallic acrylic paint
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| Cause : |
 This
problem often occurs at areas close to gates with molding defects
such as gate flash, flow marks, or jetting; furthermore, these factors
are difficult to eliminate even by annealing. |
Countermeasures:
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- Selection of a less aggressive thinner
- Slight increase of the paint's viscosity
- Raising of the cylinder temperature and die temperature.
- Lowering of the injection pressure and raising of the injection
speed
- Modification of the gate type (i.e., switching to the use of tab
gates) |
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