The manufacture of medical device components via injection moulding requires stringent verification and validation activities to ensure precision, reliability, and regulatory compliance. A key stage in this process is the Factory Acceptance Test (FAT), a structured assessment carried out before mould delivery to confirm tool compliance, mechanical function, and process capability. At Micro Systems, FAT is fully integrated into the manufacturing workflow, utilising advanced metrology techniques (including Cp/Cpk capability studies, CT scanning, and dimensional verification) to establish baseline data for subsequent Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ) processes. This approach ensures every mould meets the highest performance standards before entering production.

Objectives of FAT

The FAT provides formal confirmation that:

• Mould construction is consistent with the User Requirement Specification (URS) and approved design.
• Tooling aligns and operates correctly under both ambient and operating conditions.
• Initial process settings can be defined, documented, and transferred.
• The mould demonstrates adequate robustness to support validation and production activities.
• Metrology data (dimensional, statistical, and imaging) confirms compliance with defined acceptance thresholds.

Medical device manufacturing operates under strict regulatory oversight; hence, documented FAT results provide essential evidence for regulatory submission, supporting claims of reproducibility and quality for critical features. FAT contributes to:

• ISO 13485 compliance: ensuring design verification and process validation documentation
• FDA 21 CFR Part 11: traceable electronic records for process parameters and part inspection
• MDR/ISO 14644: controlled environments and validated tooling for critical components

In-house metrology and validation capabilities provide Medical Device mould manufacturers with distinct advantages in executing even the most complex projects (photo: Micro Systems)

Role of Metrology in FAT

Metrology is integral to FAT, providing objective evidence of part conformity and process capability.

Capability Analysis (Cp/Cpk):

Statistical analysis is used to demonstrate that the mould can repeatedly produce conforming parts. Thresholds vary depending on stage and feature criticality:

CT Scanning:

• Enables non-destructive validation of external and internal geometry.
• Critical for complex features (e.g., undercuts, thin walls, or embedded channels).
• Provides complete 3D datasets for comparison against CAD.

Dimensional Inspection Strategy:

• Combination of CMM, optical metrology, and CT scanning.
• Ensures comprehensive part qualification and verification of dimensional stability.

FAT and Validation relationship

The FAT forms the foundation of mould validation and is directly aligned with subsequent qualification stages:

• IQ (Installation Qualification): Confirms installation integrity and compliance with design/construction requirements.
• OQ (Operational Qualification): Defines and validates the moulding process window (low/nominal/high). Demonstrates robustness to variation and identifies optimisation opportunities.
• PQ (Performance Qualification): Confirms mould performance in the production cell, including automation and quality sampling under real manufacturing conditions.

Standard FAT protocol

A medical device mould FAT typically follows a structured sequence:

Construction Verification

• Comparison against the URS and construction checklist.
• Dry cycling at ambient and operating temperatures.

Process Establishment

• Application of scientific moulding methodology.
• Documentation of nominal settings for transfer.

Wear and Durability Assessment

• Short runs executed at nominal settings.
• Tool disassembly and inspection for abnormal wear.
• Photographic and dimensional documentation supplied.

Extended Assessment (optional/customer-specific)

• Short-term process capability studies (IPC).
• First Article Inspection (FAI)-dimensional and functional.
• Visual quality evaluations.

Example data output from FAT: This dataset illustrates how FAT identifies which features are already production-ready and which require optimisation before OQ/PQ.

Significance of FAT in Medical Device Manufacturing

The FAT provides:

• Early detection of design or manufacturing deviations.
• Reduction of rework risk during validation.
• Generation of traceable metrology and process data.
• Establishment of baseline conditions for lifecycle monitoring.
• Assurance of readiness for regulated, high-volume manufacturing.

Challenges of achieving a successful FAT for Medical Device moulds

One primary difficulty lies in establishing and controlling tight process windows for critical features, particularly when tolerances are in the micrometre range. Variations in material properties, environmental conditions, or machine performance can result in deviations that compromise part compliance. Integrating robust metrology, including Cp/Cpk capability studies and non-destructive CT scanning, adds complexity but is essential to objectively demonstrate conformity.

Furthermore, complex mould designs, such as multi-cavity tools, thin walls, or intricate internal geometries, pose mechanical and thermal challenges that can affect alignment, filling, and cooling uniformity. Short production runs during FAT may not fully capture wear patterns or long-term stability, requiring careful simulation and inspection planning.

Finally, coordinating cross-functional teams, tooling engineers, process engineers, and quality/validation specialists, while maintaining traceable documentation for regulatory compliance, adds a procedural layer that can be difficult to execute flawlessly. That’s why it is significantly meaningful if Medical Device mould manufacturers could provide in-house FAT services or full support for their customers in this critical process.

In order to overcome these challenges, some risk mitigation strategies include conducting pre-FAT simulation for thermal and mechanical performance, implementing robust metrology to detect deviations early, documenting all findings in traceable FAT reports, optimising cycle parameters prior to OQ to maximise Cp/Cpk, and scheduling iterative inspection and maintenance for multi-cavity moulds.

Conclusion

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