MatrixLogo horizontal white

MatrixLogo horizontal white

Injection Molding and Moldmaking
with Surgical Precision

Injection Molding and Moldmaking
with Surgical Precision

When Matrix Tooling, Inc. first acquired ISO 9001 certification in February, 1999, our primary motivation was to increase our sales potential with a larger number of OEM’s. We were good at designing and building precision plastic injection molds and molding custom parts. The quality of our work and our responsiveness to customers had earned us a good reputation over the previous two decades. Our existing customers were pleased with our performance and were not requiring us to be ISO 9001 certified. But we decided to pursue it anyway on our own terms – and on our own timeline – to stay ahead of our competition.

We quickly realized the internal benefits of modeling our quality management system (“QMS”) on the ISO 9001 standard. The consistency that ISO brought to all areas of the company yielded obvious improvements. We became more consistent in how our jobs were quoted, documented, designed, processed and inspected; this led to a greater degree of control and confidence throughout the company. Consistency in our purchasing methods and receiving inspections led to the virtual disappearance of vendor returns. Formal management review meetings took place at regular intervals, bearing targeted plans of continual improvement.

In short, ISO 9001 made us better while giving our sales force increased credibility with potential customers. Today, ISO 9001 certification is almost expected; a prerequisite for doing business in almost any industry.

Over the years, Matrix has increased our focus on medical device applications where our detailed micro-tooling, close-tolerance molding and advanced inspection capabilities provide a natural fit. We added a class 100,000 clean room and cross-sectional scanning (“CSS”) technology.

But we also discovered that the quality standard specific to the medical device industry is ISO 13485, not ISO 9001. Though its structure is based on 9001, 13485 contains additional requirements for risk management, regulatory compliance, traceability, contamination control, and device history documentation.

Our medical customers come to Matrix with device design concepts and requirements for how their devices must function. Our design engineers are often involved in the development stage from a production perspective and make recommendations for resolving part geometry, material selection and other manufacturability issues. While we are technically a second-tier supplier, not the “specifications developer,” we are certainly invested and involved in the success of these products and consider ourselves a critical link in the supply chain. If a customer gets audited by the FDA, we want to be well equipped to fully support them and provide all the documentation and traceability they may need.

To date, our customers have not required us to become ISO 13485 certified. However, we have decided to pursue it anyway. We feel that aligning our QMS with our customers’ requirements will make us an even more reliable supplier. It will also differentiate us from our competition. We like that idea.

As we adapt our ISO 9001 QMS to comply with ISO 13485, we plan to implement risk analysis, process validation, and product recall procedures as well as incorporate device master records & device history records into our quality control plans. The end result will be a more robust, hybrid QMS that will enable us to apply for dual certification (we were pleased to learn that our current registrar handles both).

Why maintain dual certification? For one thing, ISO 13485 doesn’t mean anything to our non-medical customers. Secondly, we find it interesting to note that ISO 13485 does not require an organization to demonstrate continuous improvement or monitor customer satisfaction. These are key components in ISO 9001 – components we certainly would not want to dismiss in a competitive environment where things like customer satisfaction and continuous improvement are just a couple of the reasons why our customers keep coming back to Matrix.

Written By:

Anne Ziegenhorn
Document Control Coordinator

Here at Matrix we often manufacture complex plastic components used in surgical devices and other medical applications. These parts can vary greatly in terms of size, material, and design but they all share several characteristics that can make them difficult to inspect using traditional techniques.

Performing first article inspections with these methods can be particularly time consuming and labor intensive. In addition to creating fixtures for each setup, the parts often need to be “sectioned” (sawed, cleaved, ground down) in order to inspect internal dimensions that are not naturally accessible via a touch probe or optical scope.

The associated tasks may require an inspector with a high skill level and/or experience performing similar procedures. It also opens up additional steps where operator bias and other errors can be introduced. Were all cavities saw cut and treated the same? Do different inspectors reproduce the exact same setups?

Above that, the sectioning process itself is inherently flawed. Sawing a plastic part to access a cross section will almost certainly introduce its own level of error, and this error can often exceed the tolerances of the dimension and distort inspection results. Warp, burrs, rolled edges, inaccurate trimming, inaccurate positioning of the section line and melting are all possible byproducts of manual sectioning methods.

And after all is said and done, you end up with first article data that is historically limited to the original points in your inspection layout. If you want to go back later on and inspect any additional dimensions, the setup will have to be recreated with the original parts.

To sum it up, performing a first article inspection (FAI) on complex parts often comes with the following issues:

• Time consuming & labor intensive
• Require highly-skilled technicians
• May introduce operator bias
• Allows for subjectivity in results depending on operator
• Historical reference data is limited to inspection points taken from original sample parts, making any future inspections from those samples very time consuming and possibly inaccurate.
• Requires inherently flawed sectioning process which can introduce error that exceeds dimensional tolerances (warp, burrs, rolled edges, trim marks, melting)

This is where cross-sectional scanning (CSS) comes into play. CSS is a unique process developed by CGI of Eden Prairie, MN. It offers an automated alternative to traditional first article inspection techniques that provides consistent and objective results. Using reverse engineering principles, CSS begins with an actual part and rapidly deconstructs it, cross-section by cross-section, to create a comprehensive set of measurement data capturing every dimension on every surface of the part, both external and internal. This video demonstration of the Cross-sectional scanning process will help clarify the process.

In the end the CSS capability reduces the amount of time and labor required for inspections, nearly eliminates operator bias and human subjectivity from the process, minimizes the dimensional stresses caused by manual sectioning, and leaves you with easily retrievable, electronic historical data that can be interrogated at any point in the future.

Posted by:

Gary Johansson

DOE or design of experiments (sometimes called experimental design) can be a powerful tool for any molder to have in his or her arsenal.  We live and mold in a demanding era.  We must mold with tighter tolerances, less scrap, and quicker cycles than ever before.

I was brought up by my mentors to change only one variable or parameter at a time, then measure the part or observe the outcome of that change. Curing a defect or establishing a robust process was often a matter of days, weeks or more.

DOE can cut the time for defect remedy, process establishment, and process validation to a fraction of what the old “trial and error” method took.

DOE may sound complicated to many Molders, but where once DOE was the territory of statisticians and engineers, new software developments have simplified the process and interpretation of the resulting data.

At Matrix Tooling/Matrix Plastic products, we use a software package designed for injection molders.  It supports up to Taguchi Level 8 experiments.  We can focus on, say, three inputs or factors in an attempt to achieve one or more desired responses or outputs, also called outcomes.  Factors could include: mold temperature, melt temperature, injection speed, and pack pressure among others.  The response could be anything from warp, flashing, a change in physical properties, or certain dimensions. Choosing inputs and responses requires knowledge of and experience with the injection molding process. This is much more important than being a statistician.

Taguchi L8 experiments require eight runs, and each run will have changes to multiple inputs. Results are measured, noted, and entered into the software which then maps the results on various graphs and charts for analysis, including: response surface graphs, scatter plots, main effects plots, Pareto Diagrams, ANOVA and other high powered statistical tools. In short one can see graphically what parameters or combination of parameters affect the desired outcome. You may not necessarily cure the problem during the first DOE if it is a hunt for a defect cure, but you will likely be pointed in the right direction.

Aside from troubleshooting, DOE is a recognized tool for process evaluation and validation, especially for FDA requirements for the medical device industry. There are a number of methods and tools recognized for FDA evaluation: SPC control charts, capability studies, Failure Modes and Effects Analysis (FMEA), error proofing, and DOE.  Many nonconformities are the result of excessive variation.  DOE can be a great tool to reduce and control variation. Different types of designed experiments are used here to identify key input variables and one kind of Taguchi experiment actually emulates the variation that could be found in a process over time through small but structured parameter changes.

A Molder must use all the tools at his or her disposal to quickly identify key process influences and arrive at a robust process that is defect free.  DOE is a powerful tool, and astute molders should know how and when to use it.

 

 

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