A Case Study:
Molded Part Defect Identification

The Case

Polymer Solutions Incorporated received a molded silicone medical part that contained a small discoloration on the tip. It was of interest to identify the composition of this defect region in order to discover its origin. Testing showed that the defect was composed of an alloy of cobalt, chromium, and molybdenum, embedded in a silicone matrix. This alloy was present in another process in the same manufacturing facility and contaminated the silicone part.

Full Study> DefectIdentification.pdf (1.3 MB)

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The Approach

In order to arrive at this conclusion, Polymer Solutions Incorporated used two main analytical techniques to examine the defect region:

• Optical microscopy
• Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS)

Initially, the defect was viewed and documented using an optical microscope. A white dashed oval in the 32x image above encompasses the location of the contaminants.

In order to characterize the defect region, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) was utilized. This analytical technique is ideal for determining the presence of inorganic species, especially in very small spot sizes.

Many small particles were embedded in the surface of the silicone as seen in the above 500x and 2,000x SEM images. EDS analysis of a wide area of the defect region indicated the presence of silicon, oxygen, aluminum, cobalt, chromium, and molybdenum.

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