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 hole 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 modeling 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
