A lesson on shear induced melt variations ends some confusion regarding balancing runner systems
for multi-cavity molds.
The Beaumont Effect is recognized as the source of mold filling imbalances and product variations in molds
with four or more cavities. The worst failures caused by the phenomena can be most easily (visually) recognized
in molds with 8 or more cavities. However, shear induced melt variations impact every injection molded
part, with a greater influence than most realize….
It is curious that in a world that relies increasingly on documentation, the attention to the details of polymer composition receive so little attention. Companies will fill volumes with procedures for various aspects of their manufacturing processes. However, no serious consideration is given to verifying the composition of the raw materials that are used to produce the various molded parts until there is a problem. Instead, there is a tendency simply to refer back to whatever published information is available from the material supplier….
Viscosity is a very large category that has huge effects on standardizing molding processes. It is also one of the most important factors in a molder’s arsenal of making process changes. This article will first explain viscosity, and then delve into different situations where viscosity may help or be hurting a processors goal of zero scrap and high output…..
When trying to establish process control in plastic injection, watering the tool is a key variable that is often overlooked. Water set-up and design are every bit as important as establishing and recording a repeatable process. The steps taken when watering a mold are key to a processor’s goal of consistency. If during the design and development stage, watering is put on the back burner as an “unimportant” variable, the potential for lost process control is huge.
Below are some insights into the most important facets of cooling or heating your mold, as well as what recordable data are important in the initial stages of process engineering…
I once had a plant manager who had the perfect analogy for the use of visual management, by implementing an engineered shop floor layout with clear and concise instructions at each employee’s workstation. The question he asked our team was this: “Why is it that when you look at a shampoo bottle, there are directions to ‘Rinse, Lather and Repeat’?” His answer was simple, yet thought-provoking. ”Someone at some point stood there with the bottle, trying to figure out what to do with it.”
Simply put, the better you are able to remove complexity from the shop floor and provide concrete visual and descriptive aids, the more control you will have over your plant’s overall performance…..
In lean manufacturing, changeover times are a vital component of shop performance. Minimal down time assures that multiple changeovers have little effect on a plant’s available machine time available. After all, less down time in the production equation offers more opportunities to take on more work and increase company profits. This article outlines specific approaches towards color changes that will support the potential of completing color changeovers in 3 to 7 minutes. This may seem like an impossible task to some, but with the proper planning, methods and equipment, it is an attainable and repeatable goal…..
Dealing with so many variables can get confusing. One way to get a handle on them is to organize or categorize the processing variables into groups. To do this I use Don Paulson’s four plastic variables (Don founded Paulson Training Programs Inc.), but I change the word “variables” to “categories.” This helps separate plastic variables from machine variables. So I review the process problem relative to four categories of variables—from the point of view of the plastic: flow rate (encompassing shear rate and injection velocity); temperature; pressure; cooling rate and time….. Click HERE to read John’s PTOnline article
Scientific Molding is a phrase that followers of John Bozzelli’s teaching and readers of his Plastics Technology columns should be familiar with by now. But what is Scientific Molding?And why do molders seem to have such a difficult time embracing its concepts?
The answer to the first question is straightforward: Scientific Molding is a practice for achieving optimal control of the injection molding process to deliver faster molding cycles, higher yields, and a more robust molding process. This optimal control of the molding process is realized by focusing mainly on the behavior of the material in the mold, rather than on the machine…. Click HERE to read this Plastics Technology article
In today’s fast paced plastic injection industry, lean manufacturing is a primary driver of profitability. Without lean, organizations find their operations are sluggish and ineffective. This not only affects a company’s ability to successfully grow and prosper, the capability of taking on new work suffers because current systems have not been effectively streamlined. This article addresses cycle time optimization, outlining the different variables within the molding process that can be used to maximize profits.
One of the first points that needs to be made when addressing this topic is that it is possible for machines to run too fast. Every molding job is different, and the following conditions must be satisfied to properly assure that the optimization is successful:………