Process Validation and Additive Manufacturing (AM) -Validate your 3D Printing for Compliance and Business Success
Medical device makers are enthusiastic about 3D printing. They are not alone. As 3D printing (or additive manufacturing, AM for short) goes from niche to commonplace, players are determined for sales in this lucrative market. This manufacturing sector is expected to be worth $32.78 Billion by the year 2023. Much is at stake. Today’s firms are ramping up technology and hiring skilled programmers. In addition to these core factors, your business should diversify and include an often overlooked but required activity: process validation.
For high-risk devices, clearly defined and well-written validation is required. See FDA’s Guidance Document on the subject dated 2016.
Here’s a snippet: “It is anticipated that AM devices will generally follow the same regulatory requirements as the classification and/or regulation to which a non-AM device of the same type is subject to.”
Translation: if your facility makes medical devices for commercial sale, you must write a validation program and follow through. This article focuses on process validation only and omits design-side documentation. Design phase controls are strictly enforced by FDA 21 CFR 820 but deserving of another article.
Validation is a discipline and quality tool. FDA requires a regimen of process validation as part of your firm’s overall quality system (QS). Finessing this validation program involves your core manufacturing process framed by lots of knowledge. A process is more than a machine and G-codes. FDA considers a process the sum of many, many constituent parts. Most validation deliverables should be written (see insert for a list of validation documents) and maintained in a controlled state.
What are written parts of a robust validation program?
- Validation Master Plan – covers what’s validated with inventory of printers used
- Calibration practices
- Maintenance program
- Installation Qualification (IQ)
- Operational Qualification (OQ)
- Performance Qualification (PQ)
FDA’s Draft Guidance on the subject is clear- validate against many factors such as risk, design, physical assessment, biological consideration and printing parameters. Let’s focus on parameters and actual printing.
Parameters are machine settings that influence a printed device and inherent ability to meet desired dimensional and geometric specifications. They include:
- Printing speed
- Exposure time
- Slice thickness
- Movement along X, Y
Firms usually manage parameters in programs or dial them locally at an HMI. Industry best practices for repeatability and controllability involve using software to store programs. FDA calls this “Software Workflow”. It’s a fancy term for post-design prototype, test, and implementation. Here, parameters are optimized and many scrap prints are sacrificed. The end result is a machine-readable format. FDA requires all software is validated. Also, you should write procedures to harden file storage to prevent unauthorized program changes. Many commercial software products are developed for revision control and password protection and fulfill this need quite nicely.
SOPs and 3D Printing
You must have Standard Operating Procedures for 3D printing in a regulated world. Keep them current with a maximum revisit/revision cycle of one year. SOPs and Work Instructions (WI) are a core constituent of quality systems (QS). Examples include:
- “Setup and Operation of X Printer”
- “In-Process Inspection”
- “First Piece Inspection”
- “Control of Printer Programs”
- “Disposition of Scrap and Re-work Parts”
Process Validation Should Show Good 3D Printed Medical Devices Darn Near All the Time
Global manufacturing firms are proud of being “Centers of Excellence”. In FDA’s universe, this means companies output safe and effective products and they do it close to all the time. Is your validation excellent? Process validation involves writing protocols. These protocols should itemize, in page-by-page detail, your 3D process and how well it delivers great output. For example, the Performance Qualification (see inset above), summarizes an entire data set of a production run. If a production run consists of thirty 3D printed parts, then statistics should show very high quality and low variability.
Using statistics in your process validation involves persistent data collection and calculations using QA software for gathering and number grinding. You can use Cpk to measure capability. At its core, Cpk compares actual measurements against part specifications. The higher this index value, the better your process is performing. For instance, you can choose a part feature for dimension testing using a Keyence Inspection Vision System. This could be a troublesome feature or geometry. Trend this particular dimension and determine Cpk. You’re not limited to just Cpk as a statistical metric. Also, more capability calculations are better across numerous features. Here’s FDA’s guidance:
“The worst-case combinations of dimensions and features (e.g., holes, supports, porous regions) should be considered when determining the worst-case devices for performance testing”
Don’t forget a production flow diagram as a visual overview. A production flow diagram is essential within performance qualification. Processes such as 3D printing and milling, for example, consist of post-processing steps such as annealing, sterilization, electropolishing and other surface treatments. Use descriptive boxes connected with arrows. Be sure to include inspection points as well. A picture is worth a thousand words! Processing summaries and written descriptions of printing steps, from setup to finished objects, are useful for PQ as well. List printing parameters and/or critical dimensions as part of the overall quality program.
Environmental Concerns and Process Validation
Lastly, you should consider environmental validation within shop floor areas. Do temperature and humidity influence your printing process? If so, validation is expected for HVAC assets.
Read FDA’s Guidance: “it is critical to establish and maintain procedures to adequately control environmental conditions within the build volume”.
These procedures should be itemized and functionally tested in Installation Qualification (IQ) and Operational Qualification (OQ) protocol, respectively. Validation is obligatory science rather than occasional “do it and forget it”. Do more than hang dataloggers and store charts in a file folder. HVAC validation will reveal a system in total control and consistently within predetermined specification limits.
3D Printing or Additive Manufacturing’s’ Future
Do you realize 3D Printing could become the primary mode of design and forming for implants, prostheses or whatever can be innovated? The benefits are tangible and include precision, energy savings, and exact anatomical match potential. Serious players are marking this revolution in precision-made parts. A complete and ongoing process validation regimen for your 3D printing operation is part of the game.
By Chad Farr, Validation Expert
mdi Consultants, Inc.
(About the author – Chad Farr has been working with automated process validation for over 20 years. Chad is a hands on validation expert and has worked worldwide assisting companies prepare their validation protocol and assisting with the validation work. Chad has been involved with a lot of compliance situations and his validation work has been accepted by the FDA. If you would like to have a consult with Chad on 3D Printing validations or any other validation assistance)