Mechanical Failures

A Mechanical Failure is the inability of a device or component to withstand the physical forces and conditions it is designed for, often resulting in structural weaknesses, broken parts, or a breakdown in intended function.

In regulatory terms, this often translates to a Malfunction, which is defined as the failure of a device to meet its performance specifications or otherwise perform as intended

Mechanical failures represent a broad range of product defects that can undermine product safety and effectiveness, making them a primary focus in device manufacturing and quality management.

Scope and Causes of Mechanical Failures

Mechanical failures encompass a wide array of issues that can lead to catastrophic results.

Causes:

Mechanical failures may arise from engineering oversights, manufacturing irregularities, or material defects. They can also result from improper or inadequate design, manufacture, or user error.

Manifestation:

Examples include structural weaknesses, component malfunctions, or material fractures.

Vulnerability:

Components subjected to stress, such as implantable devices or surgical instruments, are particularly susceptible to mechanical issues over time.

Real-World Example:

In the medical device industry, leaky connectors and seals are a pervasive threat that can lead to serious consequences like contamination, device interruption (e.g., triggering alarms on infusion pumps), or potential infections in patients.

Regulatory Importance and Reporting

For medical devices, addressing mechanical failures is foundational to maintaining regulatory compliance, such as with the FDA’s Quality System Regulation (QSR) (21 CFR Part 820) and device reporting requirements (21 CFR Part 803).

Serious Adverse Events:

The most frequent causes for recalls are related to Design, Software, and Non-Conforming Materials/Components. If a device failure or malfunction causes or may have caused or contributed to a death or serious injury, it is an event that must be reported to the FDA by manufacturers and importers.

Malfunction Reporting:

Manufacturers or importers must report to the FDA when a device has malfunctioned and that device or a similar device marketed by them would be likely to cause or contribute to a death or serious injury if the malfunction were to recur.

Corrective and Preventive Action (CAPA):

Mechanical failures often trigger the CAPA process. CAPA is a systematic approach to identify, investigate, resolve, and prevent issues such as manufacturing process failures. This investigation must determine the root cause of product and process failures, leading to corrective actions (CA) and preventive actions (PA).

Assessing and Preventing Mechanical Failures (Non-Clinical Testing)

To ensure mechanical integrity, manufacturers must conduct rigorous testing during the design phase (Design Control) and throughout production. Many regulatory guidelines specify non-clinical performance testing requirements focusing on mechanical properties:

Integrity and Strength

Demonstrate that the device will withstand forces encountered during use. This includes mechanical integrity testing, tensile testing of joints and materials, and component strength testing.

Durability and Fatigue

Demonstrate that the device performs as intended over its expected life. This includes use-life testing, fatigue testing, and reliability testing.

Resistance to Damage

Testing focused on specific failure modes, such as kink resistance, corrosion testing, impact testing (e.g., for lenses, where the lens must not fracture), and bite testing (for ingestible capsules).

Sealing and Leakage

Required to ensure containment and barrier function. This involves testing for leaks, ruptures, and loss of pressure/vacuum capability. Watertight barrier failure (a leak) is a defined defect for medical gloves.

Modern Detection and Root Cause Analysis

Historically, traditional inspection methods like visual inspection or 2D X-ray sometimes fail to capture subtle defects, leading to mechanical failures later.

To address this, techniques such as Industrial CT scanning offer a non-destructive method to inspect complex assemblies in situ and obtain high-resolution 3D images of internal structures. This technology allows engineers to pinpoint the causes of failures (such as misalignments, material defects, or porosity). By detecting these issues early, manufacturers can identify root causes and implement proactive corrective actions to prevent recurrence.

As a metaphor, assessing mechanical integrity is like having a home inspector review the hidden framework of a building (the non-clinical testing and internal scanning). It's not enough to check the paint (visual inspection) or confirm the lights turn on (functional performance); the true measure of longevity comes from checking the foundation for hairline fractures (fatigue testing) and ensuring the plumbing connections won't leak under pressure (leakage testing) before the customer ever moves in.

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