Improve Work Performance with Continuous Training

When trying to obtain a respectable knowledge base for your job in the moldmaking/molding field, you may have come across a book entitled Injection Molding—Theory and Practice. It's an excellent book covering a wide range of topics, but perhaps more importantly, it made obvious the difference between theory and practice. Most textbooks turn out to be classroom exercises, but in the manufacturing world there is a need to understand when and where to apply the technology.

Moldmakers are trained in how to build molds, so what's wrong with that? The apprentice program at Lucent Technologies offers special training involving an explanation of how plastic flows in an injection mold. If you challenge the reasoning behind this, perhaps the goal of cultivating a team environment will never be achieved.

In this facility, there were mold builders and technicians who needed to work as a team. In the spirit of this concept a lot of time was spent explaining to technicians why molds were built the way they were. To close the loop, some insight was offered into why a technician handled a mold the way he did. The two programs were promoted to improve work performance and satisfy some of the tenets of certification—having a training program and ensuring that training was continuous.

What makes an employee buy into a program such as this? The most popular answer is additional pay. How does the company benefit? There will be productivity improvements. For example, prior to the introduction of the Master Molding Technician training program at Lucent there was regular mold damage caused by many different actions. Since educating most of the shop personnel in correct techniques, these incidents have all but disappeared. In addition, the technology level has increased dramatically as a new process monitoring system was introduced and additional science adopted on the shop floor. Continual training is also usually encouraged to satisfy a certification audit.

Another twist that was added to technician training at Lucent, Omaha Works was that trainees for the technician job were required to pass tests as they progressed through the training program. As the tests were passed, the pay scales were graduated. Since the union saw benefit in the program for its employees, it endorsed the sequence of events.

Logistics of Actual Training Classes

Although each series of classes had its own uniqueness, the last set offered a novel approach to scheduling—Saturday mornings. Since the courses were run for personnel on all three shifts, the classes were held every other Saturday morning for four hours. Each curriculum was broken down into four gates comprising a total of 2 1/2 years of classroom work coupled with on-the-floor exercises to demonstrate the theory (see Four Gates sidebar). Last, but not least, failure in any gate would lead to dismissal from the program.

The intent of establishing a program such as this is to also maintain continuity when employing new technology on the shop floor. This would determine what topics would be covered in future offerings.

Course Descriptions

So what should a company ask of a moldmaker that he's not expected to have learned through his apprenticeship and journeyman tour of duty?

As alluded to above, usually moldmakers learn the complete how-to's of the mold itself, as well as design principles. The technician learns the tricks of the trade to make a mold work with a specific combination of machinery. Many of the traps exist due to a misunderstanding of the cause and effect relationships within the injection molding process. Indeed, there is much questionable material presented at seminars that suggests a profound truth, when in fact the theories are flawed.

All moldmakers should learn more about the materials, which are heated and then injected into their crafted works. Plastics are different from metals in many ways, and there are many different types of plastics. Injection molding is a fairly unique process, and in many cases it is experience that will suggest why a problem exists, and what the corrective action should be. The moldmaker should learn enough about these facets to be able to look at the product from the first and last shot of the production run and determine what to do to the mold before it is sent out to the shop for the next run.

If the mold has a runner, much can be learned from examining it. For example, measuring the runner thickness can tell you if the mold is being blown open; finding that the sprue bushing is wearing out due to the processing of glass-filled plastics may be causing the runner to hang up, resulting in the technicians use of a hammer and brass rod to continually remove the sprue, or even worse, increase the material temperature to a dangerous level.

Machine Operation and Process Control

Mold damage is essentially a team effort—man and machine. Once a person understands the process, one can comprehend the several ways that mold damage could occur with the possible result a decrease in productivity. An injection molding machine has many parameters, and one can readily see how a quick change may result in a near catastrophe.

While escorting a class out onto the shop floor a plastic part was observed that exhibited underfills (short shots). There are usually several possible adjustments that will overcome this defect, and one of the trainees in the group decided to adjust the VPT transfer point (from velocity to pressure) by just a fraction of an inch. When the mold opened the part was completely filled, but the mold opening had ripped the part from a huge piece of flash that required mold removal to get rid of the stuck plastic. In the span of one cycle—less than 90 seconds—two days worth of work was created.

Preventive Maintenance

Looking at the parts from the last shot of a production run can show you where flash may have started to appear because of wear in the mold. Unless there are abrasive fillers in the plastic, virtually all wear results from metal components rubbing on each other or corrosion from the process.

This is a case where one might rightfully think, "It ain't broke, but I better start planning to fix it!" When wear starts to show, that's when to take action toward producing replacement details for when complete failure occurs. As these patterns unfold with new facilities, a preventive maintenance schedule can be developed, so production can be maintained.

It is also handy to have a complete short shot to verify that in any multicavity mold, all of the cavities fill at approximately the same rate. Why? Because the technician is trying to make good product from all cavities of the mold and "will make whatever machine adjustments have to be made" in order to accomplish this. So if all cavities are filled but one, that one will control the destiny of the others in the quest to make all good product. One possible result will be that some or most of the cavities will be overpacked. This can lead to ejection problems and ultimately, mold damage.

Learning by Doing

There's an adage, which states, "If you always do what you always did, you always get what you always got!" Sometimes a moldmaker has to start using his skills in deductive reasoning after damage continues to occur on a regular basis. This will likely require fact-finding to determine the causes for the effects.

One of the favorite techniques used in Japan is the five whys. That is, you start with a description of the problem and as you answer the question "Why?" five times, the root cause will pop out.

Working As a Team

The effectiveness of teamwork relies on how a company culture evolves and the fairness of management's administration of employment. Creating an environment that thrives on teamwork can make or break an operation. In an extreme case, if technicians and moldmakers hate each other, they can easily make their work lives miserable.

Why do moldmakers and technicians need to work as a team? One obvious answer can be gleaned by the fact that in the troubleshooting guide of the Technician's Toolbox, for many cases the causes of problems are broken down into several possibilities. Most of the examples show where a mold correction may need to be made.

You should have started to think about how to run a more efficient operation. There are other courses that can be offered for your employees to satisfy the self-imposed requirements of certification. For example, safety and problem solving, among others.

Improving Performance and Productivity

The most important factor to consider is that the training is methodical and leads toward a specific goal. The goal of the Master Molding Technician Training Program developed at Lucent Technologies, Omaha was to realize a distinct improvement in performance and productivity. Most of the goals have been realized and all who have participated in the program have achieved major benefits. Now all of the technicians can speak intelligently to the moldmakers and most of the moldmakers understand the lingo associated with the injection molding process.