I was first introduced to mold making in 1963. Prior to that, I had worked for an architectural firm in downtown Chicago. I enjoyed working on building designs and I had my own ideas, but my mentor stressed the need to learn and understand the basics of designing and building a safe structure that would last a long time. I knew I had to learn all of that in order to design a sound structure, but that portion of architectural design was not fun. My creative thoughts were put on hold and I lost interest - so I quit.
I got a job at Jewel Tea and got pretty good at playing pool around town. I lost some, made some, and met a girl - pool took a back seat. Then I received my draft notice: “OH BOY, what should I do?” At the same time, my best friend Bert started a tooling apprenticeship with a neighbor who had a mold shop in his basement. After I found out about the deferment the government offered, I asked Bert if I could possibly get a job there, too, and he set up the meeting for me. I recognized some of the equipment, but it was the drawings I saw and understood. “I can create those types of drawings for you.” It was a deal and I started my mold making career!
Since tool makers supplied the armed forces with the mechanical products they needed, they were held in the same esteem as doctors. My boss, George, requested that I be deferred from military service. I had already passed my induction physical and was within three weeks of heading to boot camp when the deferment was granted. Needless to say, I was very happy!
George was a great tool maker - but more importantly, he was a great teacher. He had patience which helped us to learn, either by his instructions or from our mistakes. “DO IT AGAIN, DO IT AGAIN.” I heard that a lot, but it finally sunk in. It felt great creating inserts, plates, pins, polishing, fitting and all the rest that goes into mold building.
Two years later, I got a job at Woodland Molded Plastics in Broadview. I learned a lot about all types of tools and the molding process. I realized how interwoven the tool and the molding press are. One does not work without the other, and a mediocre tool will only produce a mediocre part.
In 1977, I started my “design only” career and contracted for some of the finest mold makers in the Chicagoland area. This was the best learning experience I could ever have had. In those days, all mold designs were created using a drafting board. The designer’s challenge was to envision the entire tool - without it actually being there. As a mold maker, I had that gift of being able to visualize a tool, and then build from that visualization. AutoCAD was just around the corner, and I had also seen an early version of UG. While it was absolutely something I wanted, it was out of my reach at over $150,000.
Then in 1990, one of my customers, Matrix Tooling, Inc., wanted to hire an in-house designer. We came to an agreement and it’s been nineteen great years since then. That was the beginning of my CAD life in the world of plastic injection mold design. Matrix purchased UG (McDonald Douglas then.) Electronic design was very different from board design and there was much to learn. What makes 3D so exciting today is that anyone can view the lifelike, colorful model on screen.
Learning about molds has always been very exciting to me. I enjoy the challenge of creating a tool that will form a particular piece part, either as a single cavity or multiple cavity tool, and thinking about: how the inserts will be shaped for machining purposes, how the cooling lines will affect the processing of a given resin used, the ejection of the part from the tool, etc. etc. Learning about why and how a particular tool has to be built has me thinking and studying all the time.
In many ways, designing a tool is like designing a great structure; every aspect is important. It must be strong enough to withstand injection pressures. It must be machined, polished and fitted correctly. It must eject the part correctly. It must have sufficient cooling. It must fit properly into a certain molding press. With so many issues that need to be defined, there is never a boring moment.
And it’s worth all the effort when I see a part come out of a mold that I designed and built; it’s breathtaking. And years later, when I see that part in the course of daily life, I’m filled with the same pride I felt on that initial run: “I BUILT THE TOOL THAT MAKES THAT PART.” Usually, it’s the only tool in the whole world like it, one of a kind. And that is a great feeling!
So why am I so thankful? Because plastic injection mold making has given me the opportunity to create, work, make a very good living, and enjoy life, family and friends. So many products we use on a daily basis were created by some kind of tool - mold making is a trade that will endure!
June 16, 2020
Here at Matrix we manufacture complex plastic components used in medical devices and other critical 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 methods.
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. They also open 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. So if you want to go back later on and inspect any additional dimensions, the setup would have to be recreated with the original parts.
To sum it up, performing a First Article Inspection (FAI) on complex parts using traditional methods often involves the following concerns:
In the end, our application of CT scanning technology reduces the amount of time and labor required for first article inspections, 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 repeatedly for any number of data points at any time in the future.
August 19, 2009
DOE or design of experiments (sometimes called "experimental design") can be a powerful tool for any molder. We live and mold in a demanding era. We must mold with tighter tolerances, less scrap, and quicker cycles than ever before.
Back in the day, 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. Establishing a robust process or curing a defect was often a matter of days, weeks or more back then. But DOE can dramatically cut the time for process establishment, process validation, or defect remedy to a fraction of what the old “trial and error” method took.
DOE may sound complicated, but where it was once the territory of statisticians and engineers, new software developments have simplified the process and interpretation of the resulting data.
At Matrix Plastic Products, we use Nautilus, a software package designed for injection molding process development and mold qualification. 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. 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 output.
DOE is a recognized tool for process evaluation and validation, especially for FDA requirements of 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.
Aside from process development, DOE is also great for troubleshooting. If you are trying to cure a defect, you may not find the problem during the first DOE, but you will likely be pointed in the right direction.
DOE is a powerful tool for quickly identifying key process influences and arriving at a robust process that is defect free. All astute molders should know how and when to use it.