Injection Molding Advanced Troubleshooting Guide (eBook)

The 4M Approach

Randy Kerkstra, Steve Brammer (Autoren)

eBook Download: PDF | EPUB

2021 | 2. Auflage
530 Seiten
Carl Hanser Verlag GmbH & Co. KG
978-1-56990-836-5 (ISBN)

Infos

This highly practical troubleshooting guide solves injection molding problems systematically and quickly. The rigorous but user-friendly approach employs the authors' proven »STOP« methodology, considering molding process, mold, machine, and material (4M's) as possible sources of part defects. Importantly, the interaction between tooling, processing, and material is emphasized, allowing successful resolution of difficult
problems where »by-the-books« approaches fail.
Starting from troubleshooting methodology and tools, there is a focused discussion of key areas impacting troubleshooting, in particular the 4M's, followed by an in-depth troubleshooting guide for various molding defects, structured logically by type of problem / solution. Insightful case studies throughout show the strengths of the STOP method to get real processes to run smoothly and reliably, producing quality parts with optimal cycle time and cost.
Drawing on a wealth of hands-on experience, this book serves as an ideal reference to be consulted at the machine, or as a learning and training manual, suitable for both beginners and experienced molders. With valuable information on robust process windows, cycle time evaluations, scrap savings, and runners / gates with no existing standard in the industry, no other book provides the unique insights found here. The 2nd
edition is updated with new discussion and case studies on topics including additive manufactured inserts, unmelts, buildup, burns, cycle time, gloss variation, and read-through.

Randy Kerkstra has worked in the plastics industry for over 29 years, with particular experience in troubleshooting injection molding. He is a well-known columnist for magazines covering this area.

Textauszug

1	Troubleshooting Methodology

1.1	Troubleshooting

Troubleshooting is problem solving. Molding troubleshooters are called upon to resolve problems with the part, mold, machine, or process. There are many problems encountered in injection molding including these general categories:

       Cosmetic defects

       Dimensional problems

       Part breakage

       Long cycle times

       High scrap rate

All of the above lead to increased cost to manufacture a molded part, which often makes the difference between profit and loss. A molding operation that is consistently running high scrap or long cycles is going to struggle to succeed.

1.2	What Makes an Effective Troubleshooter?

The role of a troubleshooter is to find the root cause of a problem and do what is necessary to resolve the problem. Effective troubleshooters will look beyond their initial impressions and ensure that the true root cause has been addressed. Good troubleshooters take a great deal of pride in having the perseverance to solve a problem and ensure that it does not reoccur.

The Merriam-Webster dictionary defines a troubleshooter as:

A skilled worker employed to locate trouble and make repairs in machinery and technical equipment.

A person skilled at solving or anticipating problems or difficulties.

Troubleshooting is a skill that can be learned and this book is intended to help convey some of the knowledge that the authors have learned through many years of troubleshooting. Some of the key things that will help anyone improve at troubleshooting include:

       Willingness to listen to others. Anyone can provide the crucial piece of information that helps solve a problem. A good troubleshooter will listen to people.

       Being observant. A good troubleshooter will always be looking for what might have changed. Good observation skills are critical to troubleshooting. Good troubleshooters live by the motto “show me” rather than trusting that things have been set up correctly. Anyone who has spent time troubleshooting will tell you that there are plenty of cases where they were told that the material was dry or the mold was clean but verification showed otherwise.

       Willingness to learn. Many times when working on a problem a troubleshooter will have to dig deep into a subject to learn what the root cause really is. Be open to learning and use all resources available to become better at troubleshooting. There is always more to learn.

       Perseverance. This is critical to being a good troubleshooter. There are many times when standing at a molding machine for hours gets very tiring. A good troubleshooter is willing to put the time and effort in to ensure the problem is corrected. This also means that they will check back on the problem to ensure that it is corrected.

       Willingness to try things. If a troubleshooter is afraid to try something out of fear of a negative result they will struggle to reach the solution of the problem. A perfect example is a processor who is afraid to open up vents on a mold because of flash. If you do not try to fix the problem it will not be resolved.

       Taking a systematic approach. A good troubleshooter works through a problem using a systematic methodology. Change one thing at a time in an organized fashion and give the change a chance to stabilize.

       Being data driven. Good troubleshooters utilize data to make decisions, and do not rely on assumptions or opinions. If a change is made the data should provide feedback on the whether or not there was an improvement.

       Patience. This may be one of the hardest parts of troubleshooting. Often times a change is made but the troubleshooter is not patient enough to determine the effect and immediately makes another change. Allow processes to stabilize during troubleshooting to determine the ultimate impact.

1.3	What Makes an Ineffective Troubleshooter?

Many of the above characteristics help people to become effective troubleshooters. There are also many traits that make people struggle when troubleshooting including:

       The “know it all”. People that believe they know everything about every aspect of injection molding will one day be in for a rude awakening. Injection molding problems tend to have a humbling effect on troubleshooters, and everyone has something more to learn. Remember every mold, machine, and material combination can create a new opportunity.

       The “this worked last time” syndrome. Many times people get caught in an approach that completely relies on what they have experienced, which in turn puts blinders on them. First understand the problem before trying to implement what worked last time.

       The “Band-Aids and duct tape fixes everything” troubleshooter. This type of person will always look for the simplest thing that can be done whether or not they solve the problem. This mentality often happens in production where the approach can be just “get me the parts I need to make shipment.” While a “duct tape” type of fix may help to limp through a run, the root cause must be addressed and corrected. Putting “Band-Aids” on top of duct tape to keep a job running will lead to scrap and downtime.

       The “flavor of the month”. This often happens when a specific problem is identified and corrected on a given mold in the plant. Often since this solution solved that problem people will try to implement that solution everywhere whether it fits or not.

Overall many people that struggle to effectively troubleshoot are lacking either the time or the tools to be successful. There is always only going to be 24 hours in every day and customer demand for quality parts will persist. This book was written to help provide some tools that can make troubleshooting more efficient and hopefully help people wisely use their time spent troubleshooting.

1.4	Troubleshooting Methodology

As mentioned in Section 1.2, a good troubleshooter uses a systematic approach. The following is a reminder to help with keeping a systematic approach to troubleshooting;

Systematically

Think

Observe

Proceed

This STOP methodology of troubleshooting is meant to do exactly what it says and stop before jumping to conclusions.

Development of STOP

This thought process came years ago while interviewing process engineers and technicians. I would always try to gauge their knowledge by asking questions about how they would handle a problem such as a short shot. The answers I received were usually correct to a point but obviously quite diverse. Often times the answers provided could be the right ones, but, without knowing what was happening, could also lead to disaster. When I reviewed my own mentality, I came to understand that the first thing I would do when troubleshooting was to stop and really examine what was happening. The concept of STOP troubleshooting came about as an easy way to train people in the methodology of troubleshooting.

1.4.1

STOP: Systematically

In the STOP methodology, the S stands for systematically. All troubleshooting should be conducted in an organized and systematic approach. Having a systematic approach will help ensure the root cause of the problem is truly resolved. As a problem is addressed a systematic approach will make it easier to avoid missing a potential cause.

Part of the systematic approach to troubleshooting breaks the problem into four key categories. Many people are familiar with the 5M’s often used for fishbone diagrams which are man, method, machine, measurement, and material. For systematic injection molding troubleshooting the 4M’s we focus on are:

1.      Molding process

2.      Mold

3.      Machine

4.      Material

These 4M’s are the key items that a troubleshooter can impact. The “man” is not included because a person can impact any of the 4M’s. Each of the 4M’s must be considered for potential root causes when troubleshooting. By reviewing the 4M’s it is much easier to troubleshoot with a systematic approach. By considering which of the 4M’s could contribute and working through one category at a time a list of potential root causes can quickly be gathered.

All of the defects discussed in this book will use the 4M method for description of potential causes. Utilize the possible causes to systematically work through...

Produkt-Details

• Erscheint lt. Verlag: 6.4.2021
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Chemie
• Themenwelt: Technik
• Schlagworte: Cavity Balance • Cycle Time • Decoupled Molding • Delamination • Gating • Injection Mold • injection molding • Jetting • Plastic • runners • Scientific Molding • Short Shot • Sink marks • Specks • Spritzgießen • Troubleshooting • venting • Voids • Warpage • Weld Lines
• ISBN-10: 1-56990-836-2 / 1569908362
• ISBN-13: 978-1-56990-836-5 / 9781569908365