Elements of Effective Device Design Transfer to a Contract Manufacturer

By: Mark McElfresh

Proper planning and adherence to the key elements of effective device design transfer can aid any medical device company in creating an effective product. For the purposes of this article, design transfer covers the process of translating the validated device design into a validated process for manufacturing. These principles are particularly important when the transfer of the design to manufacturing involves moving to a contract manufacturing organization (CMO). By evaluating design validation, verification, scale-up, and assembly activities while assessing risk early in the process, the transfer of a medical device design to manufacturing will be more effective and robust. By having the right tools in the design transfer tool box, medical device manufacturers and CMOs can clearly communicate and understand the requirements and deliverables from the start of the design transfer process. 

Building a Design Transfer Toolbox

The fundamental consideration of design transfer is clarity of documentation that verifies that the input requirements are met by the process output. The keys to a successful transfer to a CMO are clear definition, documentation, and agreement on design specifications. A successful relationship with a CMO must be based on honest, upfront discussions between both parties regarding expectations, deliverables, and capabilities. A misunderstanding of the requirements can cause significant delays and rework. There are no do-overs when it comes to the commercial pressures of cost and timing. Rework costs time and money, and creating retrospective validation documentation is harder to complete and defend when the device reaches regulatory review. Clarity in the documentation can create a design transfer process that will move the product along the manufacturing pipeline smoothly and efficiently. 

To build a design transfer tool box, the medical device company and contract manufacturer must work together to define and create the following:

?User requirements specification (URS). What must the process do?

?Sequence of events (SOE) chart. When will each assembly step occur?

?Functional requirements specification (FRS). How will the process operate? How will the functionality be tested?

?Design specification (DS). How will the configuration of the process with detailed drawings and databases be defined?

?Trace matrix. How is each design requirement tested and verified? This directly relates each requirement to test functionality.

?Process failure modes and effects analysis (pFMEA). How will the CMO prove it has built the right product in the right way? Input document is the product design FMEA (dFMEA).

Defining the What, When, and How

The What: URS. Determining the proper user requirements specification requires listing what the process must do to deliver the proper output. This includes the product description, assembly drawings, bill of materials, and step-by-step description of the process used to build the product. The URS should include any in-process testing that the medical device companies and contract manufacturers will be require and also consider any packaging, instruction sheets, and printing.

The When: SOE flow chart. A detailed flow chart is required to improve the quality of the URS's definition of what the process must do. The SOE flow chart shows when each planned step will occur in the device assembly. It also documents when any testing, lot marking, and primary and secondary packaging will occur during the process. To simplify the documentation package, the SOE flow chart may be included as a section of the URS.

The How: FRS. The next item in the toolbox, the function requirements specification, is possibly the most misunderstood transfer tool. The FRS often has different meanings to different organizations, so expectations must be agreed upon by all parties up front. To clarify the purpose of the FRS, think of it as describing how the process will meet the requirements from the URS and SOE flow chart. The FRS must focus on how the process will function and how functionality will be tested. This is where the operational capability of the process with its associated process inputs and the resultant outputs must be defined. The items in the FRS determine overall process reliability and safety. The FRS also clarifies the URS and adds additional detail regarding how the URS requirements will be met.

DS: Define the Configuration of the Process. The DS helps to define the process at the component level and then documents the intended configuration of the assembly process equipment. This record becomes the basis for the configuration specification and the starting point for the change control once the process completes validation and is released to production. The DS contains drawings and databases describing the individual elements of the system. It must address safety and installation requirements such as emergency stop switches, electrical power requirements, compressed air, guarding, and interlocks. If the DS is inconsistent with the URS and FRS requirements, problems will arise both in production and final use.

Trace Matrix: The Design Transfer Road Map. The trace matrix is the best way for manufacturers to track and map requirements. Once the considerations mentioned earlier have been thoroughly discussed and documented, the trace matrix must be formed. This is the design transfer road map that links the system requirements and specifications to verification and validation testing. The trace matrix provides a specific record for auditing that all input requirements have been tested. It also helps build efficiency by identifying any redundant testing of the requirements. The trace matrix an invaluable tool in an audit that can help a manufacturer quickly identify where each input requirement and its associated output testing is documented.

The Why: pFMEA. With the trace matrix in place, it’s time for a snapshot of the process's current ability to produce a product that will meet the design specification—pFMEA. The pFMEA is an assessment of how well the process output meets the process input requirements. If linked properly to the dFMEA, high-risk process steps and critical control points can be identified to show where in-process testing or inspection will be required. This is particularly effective when both a dFMEA and an application or user FMEA are reviewed during the process design phase. The pFMEA then follows the risk assessment process and rating scale, consistent with use in the device design process for the dFMEA.

Fundamental Considerations: Clarity is Key

For an effective device design transfer, clarity in documentation can make or break the process. There can be no validation without the predetermined specifications (URS and FRS), and because commercial pressures will not allow for errors in time management without incurring substantial cost, it is essential that medical device manufacturers and contract manufacturers define and agree on requirements up front. Time spent using the right tools ensures that all specifications are clear and documented, and will result in a better outcome for all. 

Mark McElfresh has more than 30 years of extensive technical and management experience in delivery systems for drugs, over-the-counter products, and consumer products. Over the course of his career, he has worked in product development, quality assurance, project management, validation, and operations.  He has led multiple start-ups of new manufacturing systems and facilities for both large pharma companies and contract manufacturers. A graduate of the University of Dayton’s school of engineering, he is currently responsible for managing operations, engineering, and supply chain for Tech Group North America’s (Scottsdale, AZ) seven contract manufacturing facilities located in Arizona, Michigan, Indiana, Pennsylvania, and Puerto Rico.