By Victor Hernandez, Sr. Development Engineer
Characterization is stage one of process validation in medical device manufacturing. It is the transition from working prototype to repeatable, measurable process. Engineers know this. Everyone involved in the project knows it’s important. The problem is that in medical device development, it is consistently the phase most likely to be abbreviated under schedule pressure, and that decision consistently produces worse outcomes than the time it was meant to save.
Where does the gap come from?
The characterization gap is not primarily a knowledge problem. Characterization gets pushed aside as timeline and sequencing problems arise. Project teams take on more scope than available time allows, and characterization is treated as compressible when it is not. The work does not disappear, it shifts into OQ or PQ, where it is more disruptive and more expensive to address.
The second driver is communication. Characterization requires the right people engaged at the right time: manufacturing engineers, quality personnel, lab resources, and press operators. When those conversations happen after material selections are fixed and tooling is committed, the options for resolving what characterization reveals are narrower.
Early warning signs typically surface during feasibility, anomalies in material behavior, adhesive performance, or die cutting tolerances. If investigated during characterization, they are solvable problems. If moved past, they reappear during qualification as failures requiring root cause analysis before the run can continue.
How does Innovize approach characterization?
Characterization at Innovize is a protected phase in the product lifecycle, not grouped into adjacent stages and not treated as optional. The work is structured and progresses as follows.
Entry into characterization requires a functional working part, a complete BOM, a DFM review, and initial drawings with R&D samples. From there, the phase covers statistical process capability analysis (Cpk/Ppk), definition of setup conditions (speeds, temperatures, dwell times, control limits), and measurement system validation through TMV and Gage R&R. Measurement method selection, OGP, vision systems, calipers, or overlays, is a documented decision, not a default.
Throughout the phase, Innovize maintains active client communication: tolerancing decisions, material selection rationale, and test findings are summarized and reviewed in a package delivered to the client. That record is the audit trail that supports regulatory review and carries process knowledge forward.
The output that hands off to the next stage is operational qualification and includes web path documentation, setup instructions, measurements, and a pre-OQ readiness checklist. To enter OQ, the following must be in place: passed TMV and Gage R&R, an approved quality plan with defined critical features and acceptance criteria, a press diagram, a setup reference video, updated controlled drawings, and drafted work instructions. Ambiguity about setup, measurement, or acceptance criteria is resolved before qualification begins.
What it looks like when characterization is skipped
A project involving adhesive lamination to foam illustrates the cost. The materials were already selected and determined. Multiple press setup configurations were evaluated without success. The adhesive anchoring issue appeared to be a process problem, but at the end of the day it came down to the material selected. The eventual solution, pre-treating the foam surface prior to lamination, required multiple engineering runs to establish and required delaying OQ entry by several months.
That delay, absorbed during characterization, produced a process that was both stable and faster to run. The same problem surfacing during OQ would have been more disruptive and more costly, with a qualification run in progress and a project timeline already committed. This delay was caused by the material selection; we weren’t able to explore all the solutions. We’re still working on this, we would have approached it differently, we learned a lot, but it’s still a struggle. We are flexible, we can make it work, but it’s not ideal or sustainable.
The direct answer to schedule pressure
It cannot be overstated: do not abbreviate the characterization phase. Some activities can be broken out and run in parallel. Testing approaches can be adapted. But the underlying work, establishing process capability, validating measurement systems, defining the process envelope, cannot be removed without transferring that uncertainty downstream. The time is spent either way. The question is whether it is spent in a controlled characterization activity or in an unstructured failure investigation during validation.
Build characterization time into project expectations before kickoff. The projects that skip it do not finish faster. They finish later, with more rework, and with a process that carries unresolved questions into production.
Ready to see the Innovize difference? Let’s talk and get your next medical device product headed to market.
