Failure analysis of a medical device

A medical device company's angioplasty device was failing several months after manufacturing. The device actually developed cracks that would result in the loss of system pressure. The company called in many consultants to evaluate the situation. Most identified low processing temperatures as the source of the problem. The manufacture increased the temperatures and found that this did not change the rate of failure so the manufacture went back to the faster processing at lower temperature and increased its inspection program. 

MCS became involved with the project and found that the failure had many contributing factors, as is most often the case.

MCS simulated the assembly of the system which included the crushing of the system's 'O'-rings using nonlinear finite element structural analysis. MCS also performed flow simulation and identified the in cavity melt conditions during molding in order to evaluate molded in residual stress levels. MCS also noticed that some inserts retained significant gate vestige. Simulation of insertion with the 'O'-Ring and gate vestige resulted in local stress levels that were well below the strength of the material. However, the use of silicone lubricate changed  the material's strength under stress. 

The device was redesigned to avoid excessive stress levels caused by assembly and the molding of the insert modified to eliminate gate vestige and the injection molding conditions for the device were optimized. The modifications resulted in product success. 

As with most cases of product failure, there is often many contributing factors. MCS has the experience and expertise to evaluate the whole situation, considering manufacturing, user action and material behavior when solving the toughest of engineering problems.

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