Training in Injection Molding

Frontmatter

Introduction: Injection Molding-An Ideal Manufacturing Method

Abstract

In comparison to the classic methods of metal fabrication and processing (such as milling, drilling, turning, etc.), injection molding represents a manufacturing method which is still young. However, injection molding has already become the most important method in plastics processing technology.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 1. Basic Principles of Plastics

Abstract

Plastics and elastomers are the names given to synthetic organic polymers manufactured from organic compounds of low molecular weight, called monomers, (e.g. ethylene, styrene, vinyl chloride). The manufacture of plastics and elastomers can even be based on natural maciumolccular substances (e.g, natural rubber, cellulose, proteins).

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 2. The Injection Molding Machine

Abstract

In principle, of course, it could be stated that the size of the machine must be chosen in accordance with the size of the molded article: the larger the molding, the larger the machine. But this isn't always true, especially where small molded pans are concerned. It is usually much more economical to manufacture many small moldings simultaneously on a large machine, than to manufacture just one article at a time on a small machine.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 3. The Plasticating and Injection Unit

Abstract

The individual functions of the plasticating and injection unit are described here as they apply to the molding of Compact Disks, produced from a crystal clear material, so that the laser can read the information. The CD is therefore made from an amorphous thermoplastic. Being opaque-apart from other material properties-disqualifies thermosets and elastomers from CD production.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 4. The Mold

Abstract

The primary tasks of an injection molding tool consist of accommodating and distributing the melt, the forming/shaping and cooling of the molded article and its removal from the mold. (With thermosets /elastomers: also the introduction of activation/curing energy). The secondary tasks of absorbing the forces, transmitting motion, and guiding the molded parts are derived from these primary tasks.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 5. The Clamping Unit

Abstract

When you have worked through this lesson, you will be familiar with various clamping unit designs and the advantages and disadvantages of their use.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 6. Drive System and Controls

Abstract

In previous Lessons, we showed the path taken through the injection molding machine by the plastics material/melt, on its way to becoming a molded article.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 7. The Injection Molding Process

Abstract

This lesson introduces the injection molding process in all of its phases (stages): injection phase, holding pressure phase, cooling phase, feed phase, and removal. The lesson also describes the machine motions associated with these process phases. In processing elastomers and thermosets, the cooling phase - as it applies to the processing of thermoplastics - is replaced by a heating phase.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 8. Mold Design

Abstract

An injection molding tool must fulfill several primary tasks, which in turn give rise to secondary tasks.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 9. Quality Assurance in Injection Molding

Abstract

One particularly notable definition of quality describes it as 'fitness for use.' Above all, the product must satisfy the customer. Quality is a factor which is difficult to measure directly, because there is no uniform standard for evaluation. Therefore, quality must be redefined for each different part.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Lesson 10. Recycling of Plastics Waste

Abstract

The reutilization of 'waste materials' has increasingly been the subject of public discussion over past decades. In place of 'waste,' it is actually more correct to say 'scrap material' . This indicates, that we are necessarily dealing with re-usable material, although it exists in a different form. 'Reutilization' means, that collected waste materials are not left unused, but are treated, returned to the production cycle as a starting material, and processed to create new products.

Walter Michaeli, Helmut Greif, Gernot Kretzschmar, Frank Ehrig

Backmatter