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Molded Part Cracking

 Cracking of ABS molded parts can be classified as one of the following three typical types in accordance with visual examination of the broken or cracked surface. The corresponding fracture mode constitutes important information for the purposes of cause identification and countermeasure.



Ductile Fracture

picture:ductile fracture

Characteristics
  • The fracture surface has turned white.
  • There are many undulations on a ductile fracture surface and it appears to have a fuzzy texture.
Cause

Ductile fractures occur when a part is simply subjected to a force that is larger than the material strength - in other words, when it is simply exposed to a large external force.

Countermeasures
  • Elimination of excessive external force

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Brittle Failure

picture:brittle fracture

Characteristics
  • The fracture surface has not turned white.
  • There are no undulations on the fracture surface and it takes on a smooth appearance. In certain significant cases, the fracture surface exhibits a mirrored finish.
Cause

The fracture is caused by a combination of a force or stress which is less than the material strength and some other factor (i.e., chemical agents, temperature, paint, plating, state of external force application, etc.).

Countermeasures
  • Change the chemical agents and/or material.
more details about chemical stress cracks
 

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Fatigue Failure

picture:fatigue failure

 

 
 
 
more details about fatigue failure
Characteristics

Clam-shell markings are visible on the fracture surface.

Cause

State of external forces and repetitive loading

Countermeasures

Switch to highly fatigable material

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Others

Fracture of Painted Parts

Cause

External force and inferior paint characteristics (for impact and extension)

Countermeasures

Eliminate the external force


Fracture of Plated Parts

 
more details about fracture of plated parts
Cause

External force and inferior plating characteristics (for impact and extension)

Countermeasures

Eliminate the external force


Fracture due to deterioration of material properties

Cause(1)

Mixing of different materials

Countermeasures

Eliminate the cause of mixing

Cause(2)

Deterioration as a result of weathering or light

Countermeasures

Use materials with good weather resistance

Cause(3)

Thermal degradation

Countermeasures

Use materials with good thermal properties

Cause(4)

Thermal degradation in the cylinder

Countermeasures

Ensure that conditions are suitable for molding


Fracture due to usage of materials with poor impact characteristics

Cause

External force and low-strength molded parts

Countermeasures

Switch to materials with high impact strength


Fracture at low temperatures

Cause

External force and a drop in molded part strength

Countermeasures

Switch to materials with high impact strength


Creep fracture

Cause

Application of loading over an extended period of time

Countermeasures

Reduce initial deformation and load Increase the modulus of section Reduce the stress


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!

 UMG ABS Ltd. accepts no responsibility for the quality or safety of any customer products which use our materials or which have made use of any type of data provided by this company.
 Customers are requested to independently determine the suitability of our materials for their products. We also request that sufficient attention also be paid to laws, regulations, and industrial rights.


molded part cracking
molding defects
weathering
painting defects