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CHAPTER ONE

INTRODUCTION

1.1    Background of the Study

Foundry is a manufacturing process by which metallic products are formed by preparation of mould, melting the required metal, pouring it into a cavity formed by the mould and allow to solidify.  In this way the molten metal takes the shape of the cavity.  This product is cleaned and machined to desired dimension. Moulds can be made of metals or non-metals but generally they are prepared in Sands (Oshungbure, 1998). Foundry Technology can also be described as the beginning and the end of Engineering. Foundry Technology can best be described as underdeveloped in Nigeria.  Considering the fact that Technological development of a nation is anchored on the state of her foundry Technology.  Knowing the fact that machine component even for further production depends on the casting industry. Thus, it can be rightly said that, the country is still in the development process.  Foundry Technology cannot be said to really make impact in Nigeria until the early part of the 1970’s when product of the industry were cast iron and non-ferrous material like aluminium.  Before this period, aluminium product was the prominent product and then very few cottage foundry work shop were around producing aluminum pots.

Foundry industries in Nigeria have moved from its traditional arm chair status to a more progressive, more customer emphatic and progress driven activity. The major issues that would drive foundry industry in this country are globalization and Technology.  One common thread that runs through this issue is quality product for the customers is no doubt an imperative for the foundry industry to meet the current and future challenges (Howard, 1959), Sand used to make moulds must be carefully conditioned and controlled in order to give satisfactory and uniform results.  Ordinary Silica Zircon or Olivine are compounded with additives to meets some requirements or alternatively Bentonite, Silica Sand and moisture with additives will also meets some requirements.

Refractoriness is provided by the basic nature of the sand, cohesiveness, bind or strength obtain by coating the sand grains with clay, such as Bentonite, Kaolite, illite that become cohesive when moistened.  Collapsibility is obtained by adding cereals or other organic materials that burn out when exposed to the hot metal thereby reducing the volume of solid bulk and decreasing the strength of the restraining sand.  Permeability is the ability of moulding sand to allow gasses to escape to atmosphere during pouring of molten metal into a well prepared mould. Good moulding sand always represent a compromise between conflicting factors, such as grain size of the sand particles, the amount of bonding agents such as clay, moisture content and organic matters combined so as to obtain a satisfactory result.  Consequently, some factors must be carefully controlled to assure satisfactory results.  Sand control is little concern to the designer of casting but, it is a matter of great concern to the foundry worker who expected to deliver casting of good and consistent quality.

In foundry practice, moulding mixtures of varied composition are used.  These multiple varieties result from the varieties in the nature of the castings and the quality of input materials. These exists however some general characteristic on the basis of which moulding mixture are classified. In hand moulding, usually facing and backing sand are used.  Facing mixture are prepared usually from fresh initially material and has good technological properties.  The fine grain structures of sand are been used hence the working layers of the mould which enters into direct contact with the liquid metals made.  The thickness of this layer is 10 – 15mm depending on the thickness of the casting.

Backing sand is meant for filling the remaining part of the mould and consists of already used mixture, which periodically is refreshed by addition of small amounts of silica sand (2 – 3%) and clay (1-2).  Integrated moulding mixtures are used mainly in machine moulding mixtures are used mainly in machine moulding mixtures are used mainly in machine moulding with aim of simplifying the process of preparation, transportation and compaction of the mixture of the mixture, as well as ensuring high labour productivity. They have sufficient good technological properties and produced through refreshing of already used moulding mixtures with sand, clay and other materials moulding mixtures for green moulds must have good permeability and as far possible with little gas forming ability. In this regard, it is recommended that bentonite be used as binder, their compressive strength must be within the range (0.3 – 0.6von/m2) source.

All materials used for the manufacture of sand mould and cores are termed moulding materials. In foundry practice, the quality of the mould determines to a large extent the quality of the cast metal product, with the exception of special moulding materials used in the foundry for the casting non-ferrous or light alloy products.  Thus, the study of foundry and is very important. In general, the control of sand preparation to ensure the appropriate limits of moisture, permeability, strength and other properties is a necessary consideration in order to guarantee good mould and minimize fetling work, with maximum output of cast metal products.  Principal ingredients of moulding sands are:

i. Silica sand grains

ii. Clay or binder

iii. Additives and of course moisture

1.2          Statement of the Research Problem

Determining the responsibility of conditioning foundry sand, how it is measured and the main difficulties face in its implementation of producing the cast object within the manufacturing sector. Determining the impact of foundry sand on Aluminium casting and possible defect after casting of the propose object. Understanding the widely practice of sand how it being carried out in the foundry shop. Consistency of quality is particularly important when casting most especially Aluminium and it alloys.  Nowadays, in developing economics because of the downstream implication.  In its application sand preparation is taken as prerequisite and important as casting itself.  Any deviation from the characteristics known with a particular mixture of sand could affect the strength of the casting (Aluminium) thereby holding both current and intending customers. The time dimension and varies services the foundries offers coupled with the level of technology in use are measure of quality improvement over the last few years in Nigeria manufacturing of Aluminium casting and responses to foundry sand preparation in the casting industry. In the developing optimum sand for Aluminium casting bring some changes in casting, which automatically reduces wastage in casting.  Considering the pouring of molten metal into mould cavity and solidification of an aluminium alloy.

1.3              Objective of the Project

The objectives of this project are:

i.   To make recommendation for the best foundary sand mixture for Aluminium casting especially big component like flenge.

ii.   To understand and to determine the best sand to be used between natural moulding sand and synthetic moulding sand.

iii.   To determine the quality of sand being used and the grain structure of sand applied.

iv.   To contribute towards inceasing the existing body of knowledge in the implementation of the effect of foundry sand on quality of Aluminium casting.

1.4         Purpose of the Project

The purpose of this study includes the following:

i.  To evaluate the impact of foundry sand preparation on the quality of aluminium casting.

ii.  To make recommendation for the best foundry sand mixture for Aluminium casting especially big component like flange.

iii.  To understand and to determine the best sand to be used between natural moulding sand and synthetic moulding sand.

iv. To determine the quality of sand being used and the grain structure of sand applied.

1.5              Significance of the Project

To contribute towards increasing the existing body of knowledge in the implementation of the effect of foundry sand on quality of Aluminium casting. To determine and to understand the best sand to be used between natural moulding sand and synthetic moulding sand.

1.6              Limitation of the Study

The study base on the research methodology (i.e. primary source data, Yaba College of Technology Yaba Lagos) as strategy and vital information are not forthcoming as expected due to problem faced during the construction of moulding box and the moulding for my project i.e. (FUTA LOGO). Failure of electricity supply during the casting of my project and a lot of difficulties during feeling and finishing operations.

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