SEMINAR ON RESOURCE EFFICIENT INJECTION MOULDING WITH LOW ENVIRONMENTAL IMPACTS UNDER THE GUIDANCE OF EBINIZER BY SHANKAR PATIL

INTRODUCTION Injection moulding ranks as one of the most widely used processes for producing plastics products. As in other forming processes, the characteristics of injection moulding procedures and products are significantly affected by the quality of moulds used i.e. tools that are mounted into injection moulding machine to produce repeatable products.Once produced, the moulds are used in production for many years. Since raw materials are becoming scarcer and more expensive, and the costs of energy is also increasing the strategy of mould design should not aim only at cost reduction but also at reducing resource consumption and emissions throughout its entire life cycle. This paper presents an approach to compare and optimize mould design and production process parameters from technical, economic and also environmental point of view.

OVERVIEW OF CASE STUDY The case study is presented with three alternative mould designs put side by side. They enable an injection of the same plastic product, shown in Fig. 1, but differ in technical solutions, which contribute to the productivity and resource efficiency during their use phase (injection moulding of plastic products). It is expected that one million products will be produced throughout the mould’s life cycle.

LIFE CYCLE OF A MOULD Life cycle of a mould is presented in Fig 3. Two main stages i.e. mould manufacturing and the use of the mould (injection moulding), are described in details in the following sub chapters. It is assumed in our case study that mould components will not be reused in similar moulds in the future; although in general some mould components i.e. guides can be reused. Mould Production For smaller moulds, such as the one investigated in the case study, the main standard metal elements are sawed to rough shape from rolled slabs and bars which are then milled, turned and grinded to final tolerance geometry. Mould components like plates, injectors, ejectors, guiding elements and others are commercially available as standard elements. The patterns which form the final product geometry within standard plates (sometimes also called active mould surfaces) are usually produced by CNC milling and/or Electric Discharge Machining (EDM). In our case only the CNC milling process was used.

INJECTION MOULDING Injection molding is a manufacturing process for producing parts by injecting material into a mould. Injection moulding can be performed with a host of materials, including metals, glasses, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and forced into a mold cavity where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mouldmaker (or toolmaker) from metal, usually either steel or aluminum, and precision machine to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panel of cars.

Parts to be injection molded must be very carefully designed to facilitate the moulding process; the material used for the part, the desired shape and features of the part, the material of the mould, and the properties of the moulding machine must all be taken into account. The versatility of injection moulding is facilitated by this breadth of design considerations and possibilities.

Current Situation Increasing demands regarding adding value, Performance of materials, Lightweight design of assembly groups, Integration of functions, Efficiency of production processes, saving of resources (e.g. material).

Trends and current developments  Production of high-value polymer surfaces.  Manufacturing technologies  Production of assembly groups with different components.  Under reduction of the process chain.  E.g. multi-component injection moulding, Skin Form  Combination of different materials to meet all the Requirements,  fluid-assisted injection moulding processes for thermoplastics.  New drive concepts for injection moulding machines.

Pro Foam –New process for foam injection moulding Of the thermoplastics

MOLD DESIGN The mold consists of two primary components, the injection mold (A plate) and the ejector mold (B plate). Plastic resin enters the mold through a sprue or gate in the injection mold; the sprue bushing is to seal tightly against the nozzle of the injection barrel of the molding machine and to allow molten plastic to flow from the barrel into the mold, also known as the cavity. The sprue bushing directs the molten plastic to the cavity images through channels that are machined into the faces of the A and B plates. These channels allow plastic to run along them, so they are referred to as runners. The molten plastic flows through the runner and enters one or more specialized gates and into the cavity geometry to form the desired part.

MOLD DESIGN

Different types of injection molding processes There are several important molding variations including, but not limited to:  Die casting Die casting  Metal injection molding Metal injection molding  Thin-wall injection molding Thin-wall injection molding  Injection molding of liquid silicone rubber.

Process troubleshooting Like all industrial processes, injection molding can produce flawed parts. In the field of injection molding, troubleshooting is often performed by examining defective parts for specific defects and addressing these defects with the design of the mold or the characteristics of the process itself. Trials are often performed before full production runs in an effort to predict defects and determine the appropriate specifications to use in the injection process. When filling a new or unfamiliar mold for the first time, where shot size for that mold is unknown, a technician/tool setter may perform a trial run before a full production run. He starts with a small shot weight and fills gradually until the mold is 95 to 99% full. Once this is achieved, a small amount of holding pressure will be applied and holding time increased until gate freeze off has occurred.

APPLICATIONS  Injection molding is used to create many things such as wire spools, packaging, bottle caps, automotive dashboards, pocket combs.packaging  Some musical instruments (and parts of them), one-piece chairs and small tables, storage containers, mechanical parts (including gears), and most other plastic products available today.  Injection molding is the most common modern method of part manufacturing.  It is ideal for producing high volumes of the same object.

Conclusion In conclusion this project was useful in exploring and understanding how different control factors have different effects on a desired characteristic for a part. Through the use of design expert it was shown how some control variables have a strong effect on a specified characteristic, while others have little to no effect. Through design expert it was found that the variables affecting the final weight of the plastic mold injected part the most, were pressure and flow weight. Each of these factors had a larger impact than the nozzle temperature, barrel temperature and dwell time combined. Even though this experiment was a half factorial, a lot of useful Data was collected about the different factors and how they interact with each other.

References  Todd, Robert H.; Allen, Dell K.; Althing, Leo (1994). Manufacturing Processes Reference Guide. Industrial Press, Inc.  "Application Overview: Injection Molding". Yaskawa America, Inc. Retrieved "Application Overview: Injection Molding"  Malloy, Robert A. (1994). Plastic Part Design for Injection Molding. Munich Vienna New York: Hanser.  Hempstead, Colin; Worthington, William E. (2005). Encyclopedia of 20th- Century Technology, Volume 2. Taylor and Francis. Retrieved 27 January 2013.Encyclopedia of 20th- Century Technology, Volume 2  Hart, John. The National CV of Britain. Edfu Books Ltd.The National CV of Britain  U.S. patent #133229, dated 19 November 1872.

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