Sponsored By
Bill Tobin

October 7, 2016

8 Min Read
Molding tricks for higher profits, part 1: The expert syndrome

When I first got into the molding business, I was a new kid on the block. I had the typical two weeks of follow-Bob-around training, then I was dumped onto the midnight shift. All the hourly workers were old enough to be my parents.

Image courtesy Sira Anamwong/freedigital-

My greatest asset was Bill. He was a few years away from retirement and a mentor. When I had a problem, I would stay over and ask him. He'd pull out a collection of notebooks and somehow find the same question I had with a solution and an explanation. He encouraged experimenting. He was a firm believer in making mistakes: "You rarely take the time to learn why your successes work. Learning why you failed is the best education."

In molding, when you make one change, you're upsetting a system. Hopefully you get the result you were troubleshooting. Most always, you also get a few other changes along with it. It's always a question of balancing all the variables for the best productivity. This comes as a result of learning.

Acquiring knowledge comes from many sources. Take advantage of them all. Even though I've been teaching courses on molding for decades, I almost always learn something new from each class or client that I work with.

Book learning: There are many publications on molding. Many dive into highly complex math and chemistry. All are limited by the knowledge of the author. I read one book that espoused the view that everything could be solved by using a design of experiments technique. In a certain sense, this is correct. However, the economics of being a molding engineer employed by a production company won't allow you to spend an entire day making scrap and collecting data to solve a processing problem. Books are a good knowledge base, but just because the author has a degree in “plastics” from a university doesn’t make him an expert.

Computer training: There are several good electronic training courses. This is a more dynamic form of book learning but, unfortunately, e-courses also are limited by the expertise of the author. There's a very good comparison to those battlefield computer games and actually being in the armed forces. While the theory might hold in both situations, it's very different in real life.

Bill Tobin is holding a one-day seminar this month that reviews the methodology and application of scientific molding, including the experiments that need to be performed to optimize each portion of the molding cycle, along with a method of troubleshooting that scientific molding doesn’t address. The seminar will be held in Schaumburg, IL, on Oct. 19. For more information or to register to attend, click here.

Gadgets: One machine manufacturer has come out with a program that will walk you though a series of experiments when a new mold is to be qualified. It helps you optimize the cycle. Wow! Nevertheless, it doesn't explain why it told you to adjust this and that. It neatly stores this information inside the machine's computer in a proprietary code that cannot be downloaded to any other machine.

There are several manufacturers of transducers/signal processors. These take a peek inside the mold to tell you what's happening to the plastic. Once you've got things all set, they'll automatically adjust the machine to repeat those conditions. Nifty! However, you need to optimize the settings first. In reality, all this equipment does is minimize or eliminate machine variability. (Isn't that really a preventive maintenance issue?) If you wander through your molding machine's menu, you'll find something similar concerning screw position and oil pressure. While this is secondhand information compared to an in-mold transducer, with a well maintained machine, the information is excellent.

Computer simulations: Several companies sell programs that neatly mesh with your CAD drawings and mold designs. These are excellent for seeing how the plastic will flow in the mold and where to put the gate. Keep in mind that simulations work in a “perfect world” of heat transfer and material properties. Since most molders or customers will not pay to have their specific material (grades, additives, coloring agents, etc.) characterized, they use generic properties for their simulations. Garbage in usually results in garbage out. Computer simulations are excellent tools to help you avoid some common mistakes in design and processing, but use them only as tools. The data they give you are indications of what will happen when you start up the mold. They are never perfect predictors.

Lectures, trade shows, professional publications and consultants: Just because you've been doing things for years doesn't mean you know it all. We are all constantly learning. The problem with seminars, trade shows and consultants is simple: Time and money. Sending a few folks to a show or a seminar should be done with the idea that—and this is important—those who go, will teach those who didn't. Managers manage, engineers build stuff. While it's a nice perk for them, they are usually useless when it comes to passing along this information to those who need to use it. If the seminar, webinar or tradeshow is about molding, send the techs! If you bring in a consultant, make sure he or she doesn’t leave without demonstrating that the problem has been solved and that the folks have been educated so you won't have to bring him or her back to do the same thing on another machine! If it's an in-house seminar, demand that a textbook be included. Otherwise, two weeks later the attendees will be lucky to remember 5% of what was taught.

The school of hard knocks: China has not signed the copyright treaty. Technical publications are nearly impossible to find, unless you use the Internet. They tend not to like consultants: “What's to stop you from learning from us and then showing it to our competition?”

When I was consulting in China, I watched my client's troubleshooting expert: He'd stand in front of the machine and start adjusting stuff. When I asked through my interpreter why he made an adjustment, I was told, "I fix it." Even though I bought him lunch, he never referred to having seen a particular defect before and applying a similar solution or what the generic cause of a defect was and the technique he'd use to correct it. It was his form of job security. Knob twisting in the dark isn't a particularly profitable way to run a company.

The beauty of the school of hard knocks, however, is that if you keep an open mind, listen to others, and try to learn something each time you face a problem, you just might learn a few new tricks that weren't in the books you read, the seminars you attended or the simulations you ran. In this school, you work with those who are more experienced than you and you ask a lot of questions. When you get the “we always did it that way” answer, look it up on the Internet. Very few things are actually novel. Someone else, who'll explain the reasons, has dealt with most problems. All you have to do is find it.

How to be a molding expert

  • Always keep learning. If you truly understand it, you can explain it to someone else. Keep in mind that this business is about maximizing profits, not molding parts.

  • Don't be afraid to experiment or fail. If it's a huge problem (“yields are too low”), do a shooting star experiment: Pick one defect on one mold and solve the problem. Based on what you learn, apply that to all the other parts.

  • Never fall for the "acceptable yields," "scrap allowance" or "explainable variance" excuses. Always aim for 100% salable parts, produced at or below the projected cost. Settle for nothing less. Saleable parts are rarely cosmetically or dimensionally perfect. They do what they are supposed to do and the end user is satisfied with the quality. Being too critical in-house is your worst enemy.

  • Time and money are two commodities that, once lost, are never recoverable. Think efficiently—you don't have to think outside the box, because there is no box.

  • Learn the tricks that aren't in the books, simulations or on YouTube.

  • An expert can be described as someone with 20/20 vision in a room full of blind people. You're an expert when you can draw on experience and "book learning," admit you don't know it all but are willing to learn and are able to show others.

This is the first of a series of articles on “Molding tricks for higher profits.” I'll discuss a few things you might consider to improve your profits. I'll also show a few tricks on how to deal with your customer who pulls the job after you've spent the time and money to figure out everything. When the mold arrives at your competition's doorstep, it won't run at your cycles or yields because you undid your trick. Many times the job will be returned to you and you run the mold as you did before it was pulled.

Bill Tobin is a consultant who teaches seminars and helps clients improve productivity. He can be contacted at www.wjtassociates.com or by e-mailing him at [email protected].

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