DESIGN AND FABRICATION OF A COST-EFFECTIVE PLASTIC EXTRUDING MACHINE
CHAPTER 1
INTRODUCTION
1.1 Extrusion process
The extrusion process began in the 1800s by preheating the metal and forcing it through a die via a hand driven plunger known as squirting (Rauwendaal, C., 2001). Extrusion is now possible for metals, polymers, ceramics and concrete. Plastic extrusion began in the 1930s and the continuous process has been applied to manufacturing at high volume. Plastics have been very popular in the modern world because of its low cost and ease of manufacturing.
Plastic extrusion is a deformation process used to produce long, straight, semi-finished plastic product such as plate, solid and hollow sections, tubes and wires and strips. The principle is very simple: under a high load, a billet is squeezed under closed container through a die, to give a desired product. It is commonly used industrially to produce domestic and industrial products such as, chairs, pipes etc.(Michaeli, W., 2003)
Extrusion process may involve many stages through a single hole die or multiple hole die to obtain the final shape of a component. Dies of appropriate shape and sizes are then required to impart the right shape and specified tolerance in their respective passes. A welding chamber die (bridge, spider etc.) under hot condition is common for extrusion of hollow component. Square dies for single and multi-hole extrusion under hot condition have been widely used. Continuous dies such as streamlined, conical, elliptical, hyperbolic and cosine dies are becoming important for manufacture of better plastic product, in plastic extrusion, the required shape of the product is produced with a die.
Extrusion through multiple holes dies, using a high capacity extrusion press is preferred for reasons of economy and high productivity.
Completion of this project will give us a great deal of knowledge of experience in the engineering field, knowledge of the extrusion process and troubleshooting skills for the future.
Plastic extrusion is used to create a multitude of different products ranging from garbage bags to plastic tubing. Extrusion comes in three different forms; direct, indirect and hydrostatic which all have their pros and cons. The type of extrusion we are studying is direct extrusion, also known as forward extrusion, and is the most popular of the three forms of extrusion. It is the process of moving material through a die of the desired shape of the cross-section. An extruder works by melting down plastic pellets, called resin, that are then forced down a barrel by a screw where they continue to melt and are finally pushed out through a die that gives them their final shape. The extrusion process can be continuous, potentially producing any desired length of material, or semi-continuous to produce many pieces of material. The process may be hot or cold.(Crawford, R., 1998)
1.2 Statement of the Problem
All over the globe, and in recent time plastics have made a benchmark in virtually all areas of industrialization. In Nigeria, the use of plastic both for domestic and industrial purpose cannot be neglected. It is widely seen in our environment that plastic waste constitutes largest percentage of waste products. There is a need to design a cost-effective plastic extruding machine. Successful completion of this project will create new job opportunities in Nigeria.
1.3 Aim of the project
The aim of the project is to design and fabricate a cost-effective plastic extruding machine used to produce a hollow pipes for domestic and industrial purpose.
1.4 objectives of the project
The objectives of this project will include the following;
i. Design consideration of a low-cost pipe extruding machine.
ii. CAD modelling of the proposed machine with solid works
iii. Fabrication and testing of the proposed extruder.
1.5 Methodology to be adopted
The methodologies to be used in this project are classified into the three stages; firstly, literature review of the existing design will be researched, followed by the design calculations and CAD engineering models with Solidworks, then the final stage which will be fabrication and testing. In the construction stage, materials will be sort locally in Nigeria, material/weight reductions will be put into consideration
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 HISTORICAL DEVELOPMENT OF ANAEROBIC DIGESTION TECHNOLOGIES
Historical evidence indicates that the anaerobic digestion process is one of the oldest technologies. Very old sources indicate that using wastewater and so-called renewable resources for the energy supply is not new but were already known before the birth of Christ. (Monnet F, 2011). The first allusion to animal manure comes from Humphrey Davy, who reported early in the nineteenth century the presence of this combustible gas in fermenting farmyard manure. Davy is known for the invention of the miner’s safety lamp.
However, the industrialization of anaerobic digestion began in 1859 with the first digestion plant in Bombay. By 1895, biogas was recovered from a sewage treatment facility and used to fuel street lamps in Exeter, England (Monnet, 2011). Research led by Buswell (Monnet,2011) and others in the 1930s identified anaerobic bacteria and the conditions that promote methane production. As the understanding of the anaerobic digestion process and its benefits improved, more sophisticated equipment and operational techniques emerged. The result was the use of the closed tank, heating and mixing systems to optimize anaerobic digestion.
In 1900 a methane (biogas) generating plant from human wastes was constructed in a leper asylum in Matunga, India. In the years around 1940, many municipal sewage treatment plants in the United States and elsewhere were already employing anaerobic “digestion” as part of the treatment of municipal waste and thereby generating methane which was used to generate electricity for the plant. This indicated that for pollution control, the anaerobic digestion process is proven effective with additional benefits in the form of a supply of a useful gas(Mindy, 2013). In Indonesia, fixed dome type biogas plants of 18m3 capacity with biogas purification plant have been constructed across communities. Efforts are on to develop the technology to the level of gas bottling and electricity generation,(Widodo & Hendriadi, 2014).
In Kaunas – Lithuania, the Rokai pig farm biogas plant operates on a daily 60m3 of manure from 11,000 pigs. The produced biogas is by co-generation converted into electricity and heat. About 600m3 of biogas is produced per day and 2,400kwh of electricity per day (Maramba, 2014). Carrasco et al. (2011) studied the feasibility of dairy cow waste to be used in anaerobic digestive systems. Because the animal’s wastes are more reactive than other cow wastes, the study suggests dairy cow wastes should be chosen over other animal wastes.
As Taleghani and Kia (2005) observed, the resource limitation of fossil fuels and the problems arising from their combustion has led to widespread research on the accessibility of new and renewable energy resources. Solar, wind, thermal and hydro sources, and biogas are all renewable energy resources. But what makes biogas distinct from other renewable energies is its importance in controlling and collecting organic waste material and at the same time producing fertilizer and water for use in agricultural irrigation. Biogas does not have any geographical limitations or requires advanced technology for producing energy, nor is it complex or monopolistic.
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