Mechanical Engineering Design Process for Combination Products

The previous post in this series explored key design and development considerations for novel combination products. In this installment, we take a deeper look at the mechanical engineering phase, highlighting how the West team applies a data-driven, risk-based approach to ensure each device is not only safe and functional, but also engineered to meet the demands of global-scale manufacturing.

1. Requirements Engineering & Mechanical Specifications

The first step in the process is to take a detailed and technical approach to gathering requirements and establishing mechanical specifications.

• Design Input Translation: Converting qualitative user needs into measurable mechanical specifications (torque, force, tolerances).
• Mechanical Risk Management: Conducting DFMEA (Design Failure Mode and Effects Analysis) to mitigate mechanical risks at the component level.
• Environmental & Material Tolerance Setting: Defining operational limits for temperature, chemical exposure, and structural load.

2. Architectural Concept & Biocompatible Design

Next, the focus shifts to definition of high-level system structure of the combination product and specifying/selecting materials that are in direct or indirect contact with the drug or patient are safe for use.

• Mechanism Development: Engineering internal architectures, including complex gear trains, linkages, and fluidic pathways.
• Medical-Grade Material Selection: Specifying materials that meet ISO 10993 (biocompatibility) and specific sterilization requirements (Autoclave, Gamma, EtO).

3. Detailed CAD Modelling & Virtual Simulation

Detailed CAD modelling and virtual simulation translate the architectural concept into a validated digital product definition.

• Precision 3D CAD & GD&T: Developing detailed digital assemblies and 2D manufacturing drawings with strict Geometric Dimensioning and Tolerancing.
• Finite Element Analysis (FEA): Simulating stress, strain, and fatigue to predict mechanical failure points.
• Computational Fluid Dynamics (CFD): Modelling liquid or gas flow for drug delivery or respiratory devices.

4. Functional Prototyping & Iterative Testing

Functional prototyping and iterative testing transform the validated CAD design into physical builds to evaluate real-world performance.

• Alpha Prototype Fabrication: Rapidly producing low-fidelity models (3D printing/SLA) for form, fit, and ergonomic assessment.
• Functional Beta Prototyping: Building high-fidelity, representative versions for mechanical bench testing and user feedback.

5. Rigorous Mechanical Verification & Validation

Mechanical Verification & Validation (V&V) ensures that the final product meets defined design inputs and fulfils intended use and user needs.

• Design Verification Testing (DVT): Executing bench tests to prove the physical device meets all engineering specifications (e.g., pull-force or cycle testing).
• Summative Usability Validation: Supporting clinical simulations to ensure the mechanical interface meets the needs of practitioners and patients.

6. Design for Manufacture (DFM) & Industrialisation

Design for Manufacture and Industrialisation ensures that a mechanically sound design can be produced at scale, manufactured consistently, assembled reliably, and can be delivered cost-effectively.

• DFM/DFA Optimization: Refining part geometries to reduce cost and complexity for injection moulding, CNC machining, or 3D printing.
• Design Transfer Management: Compiling the Design History File (DHF) and Device Master Record (DMR) for regulatory compliance.
• Manufacturing Process Validation: Developing and executing IQ/OQ/PQ protocols for custom production equipment and tooling.

The next blog post in this series will walk through design controls, which is a formal, structured framework used to ensure that the final combination product is safe, effective, and fully aligned with the needs of its intended users.