As discussed in our previous article on Polymer Testing Equipment, plastic is fast becoming the most popular choice of material in manufacturing industries. As many readers have been asking me to give some details about Plastic Processing Equipment and methods, I took out time to inform our readers about the various methods involved in procuring finished plastic parts.
The family of polymers is extraordinarily large and varied. There are, however, some fairly broad and basic approaches that can be followed when designing or fabricating a product out of polymers or, more commonly, polymers compounded with other ingredients. The type of fabrication process to be adopted depends on the properties and characteristics of the polymer and on the shape and form of the final product.
In the broad classification of plastics there are two generally accepted categories: thermoplastic resins and thermosetting resins.
Plastic Design
Plastic design is a highly specialized area of designing where continuous improvements are necessary to get high quality and low price plastic products. As polymer manufacturing is becoming the major source of our daily use necessities, this is one field of design engineering that cannot be ignored. We see the same sort of approach being applied in plastic part designing and mold tool designing, over and over again. This means that the progress in designing and manufacturing is a real minimum, where most of the companies are just concerned with getting the parts at the lowest costs. But they tend to forget that advancements in technology involves the investment of time and money for one time only, and after the research part has been completed, it reaps benefits for the whole industry for coming years. So it is essential that the manufacturing giants get together and start thinking about advancing the injection mold designs and polymer part designs. This will help all the smaller industries to follow the Plastic Design Guidelines and implement them in their system.
Polymer Testing Equipment
In today’s article, we will be discussing an important part of materials development and proper materials selection, i.e., testing and standardization of polymers with the Polymer Testing Equipment. The latter part of this article is therefore devoted to this aspect. It presents schematically (in simplified form) a number of standard test methods for plastics, highlighting the principles of the tests and the properties measured by them.
There are two stages in the process of becoming familiar with plastics. The first is rather general and involves an introduction to the unique molecular structures of polymers, their physical states, and transitions which have marked influence on their behavior. These have been dealt with in article “What is a Polymer”. The second stage, which will be treated in this article, is more specific in that it involves a study of the specific properties of plastics which dictate their applications.
What Is A Polymer- Polymer Engineering Solutions
A lot of plastic and polymer processing engineers often want to know what is a polymer. In an easy to understand engineer’s language, polymer is described as a material that is capable of flowing through the mold runner and gates to take a defined shape, when heated to a temperature, which is more than its melting point. To describe in the engineer’s language: A molecule has a group of atoms which have strong bonds among themselves but relatively weak bonds to adjacent molecules. Examples of small molecules are water (H2O), methanol (CH3OH), carbon dioxide, and so on. Polymers contain thousands to millions of atoms in a molecule which is large; they are also called macromolecules. Polymers are prepared by joining a large number of small molecules called monomers. Polymers can be thought of as big buildings, and monomers as the bricks that go into them.
Monomers are generally simple organic molecules containing a double bond or a minimum of two active functional groups. The presence of the double bond or active functional groups act as the driving force to add one monomer molecule upon the other repeatedly to make a polymer molecule. This process of transformation of monomer molecules to a polymer molecule is known as polymerization. For example, ethylene, the prototype monomer molecule, is very reactive because it has a double bond.
Molding Plastic Components
A good knowledge of Plastic Injection Mold Design is undoubtedly the single most important factor in Molding Plastic Components. A lot of improvements have been made in the Molding processes over time, but the basics still remain the same. Mold design has been more of a technical trade than an engineering process. Traditionally, practitioners have shared standard practices and learned tricks of the trade to develop sophisticated molds that often exceed customer expectations.
However, the lack of fundamental engineering analysis during mold design frequently results in molds that may fail and require extensive rework, produce moldings of inferior quality, or are less cost effective than may have been possible. Indeed, it has been estimated that on average 49 out of 50 molds require some modifications during the mold start-up process. Many times, mold designers and end-users may not know how much money was “left on the table”.
The word“Injection Mold Engineering”in implies a methodical and analytical approach to thermoplastics mold design. The engineer who understands the causality between design decisions and mold performance has the ability to make better and more informed decisions on an application by application basis. Such decision making competence is a competitive enabler by supporting the development of custom mold designs that outperform molds developed according to standard practices. The proficient engineer also avoids the cost and time needed to delegate decision to other parties, who are not necessarily more competent.
This site is geared towards professionals working in a tightly integrated supply chain including product designers, mold designers, and injection molders. This site aims to provide working examples with rigorous analysis and detailed discussion of vital mold engineering concepts. It should be understood that this textbook purposefully investigates the prevalent and fundamental aspects of injection mold engineering.
We will keep updating this article to include more information on both, resin and polymer parts and tool design. Meanwhile feel free to check out the Common Injection molding troubleshooting guide and other engineering plastics articles on our site.
