Lesson Notes By Weeks and Term - Junior Secondary School 3

TERM: FIRST TERM

SUBJECT: BASIC TECHNOLOGY

CLASS: JSS 3

REF MATERIALS

• EVANS BASIC TECH FOR JSS BOOK 3
• NERDC BASIC TECH FOR JSS BOOK THREE

WEEK FIVE

TOPIC: PROCESSING OF MATERIALS- CERAMICS AND GLASS,PLASTIC AND RUBBER

CONTENT

• METHODS OF PROCESSING
• PRODUCTION AND USES OF CLAY, CERAMIC AND GLASS
• PRODUCTION OF PLASTICSAND RUBBER

PROCESSING CLAY 

Pottery is the act of using clay to make different objects like pots, flower vases, tea cups and dishes. 

Procedure 

1. Clay preparation: Clay is first dug from the soil. It is thoroughly mixed with water in the right proportion and pounded using hands, feet or pestle and mortal. Air bubbles are removed and it becomes soft. Sand particles as well as stones are removed during mixing.
2. Moulding of articles: There are two methods of moulding the article 

1. Pinch pot method
2. Potter’s wheel method: This is the method with a rotating disc upon which the  clay is mould

1. Firing/Baking of articles: This is the process of hardening the  article e. g. pot. This is a furnace or oven specially designed for baking finished wet clay products.
2. Decorating of articles: This can be done before or after firing.

MUD

In order to make articles, houses and object from mud, we dig pure earth that does not contain sand. Then follow the following procedure:

1. Mud preparation
2. Moulding of articles
3. Firing of articles
4. Decorating of articles

CONCRETE 

Concrete is a hard material formed when cement is mixed with aggregate of sand (coarse sand, gravel or stone) and water only. The mixture is turned into a uniform paste by using a shovel or a concrete mixer. Then made into objects e. g blocks or for construction 

EVALUATION

1. Define pottery.
2. Outline the procedure for making pottery.
3. State five uses of ceramics.
4. State five products of ceramics.

PROCESSING GLASS

The mineral glass belongs to a group of ceramic material. It is made from inorganic resin made from refining petroleum product.

The raw materials used in making glass are sand,soda,lime, potash and lead oxide. These materials are thoroughly mixed together. The mixture is melted in a furnace at a very high temperature to produce molten glass. While in its molten state various shapes of glass are made by blowing air into the mixture.  The rigid glass is heated again and allowed to cool gradually. This process of re-heating and allowed to cool is called annealing.

EVALUATION

1. Mention the five materials used in making glass.
2. Explain the process of processing glass
3. Mention FIVE example materials made from glass

PROCESSING PLASTIC

There are five methods of processing plastics material namely:

1. Vacuum forming 
2. Injection moulding
3. Extrusionmoulding
4. Calendaring
5. Compression moulding

Production of plastic involves heating at a very high temperature.

VACUUM FORMING 

This is an enclosed method from which air has been completely removed. It is a method for making plastic buckets and cup.

INJECTION MOULDING

This is a method of forming an object by injecting hot molten or plastic materials into the mould by means of plungers.

EXTRUSION

This is a method of heating a plastic material and forcing it through a mould followed by continuous cooling. It is a method used for manufactured thermoplastic pipe.

CALENDARING 

This is a method of making a continuous sheet of the thermoplastic material in paste form between heated and cooled rollers.

COMPRESSION MOULDING

This is a method of forcing plastics materials into a mould by the application of pressure and heat

USES OF PLASTIC

1. Plastics are increasingly being used in every day’s life because of its lightness in weight.
2. The top of your ballpoint pen is made of plastic.
3. The family products are obtained from plastics: buckets, cup, radio case battery case , protractors , ruler , set square, in mathematical set, button, electrical switches sockets toys , telephones, helmet  etc.

The main disadvantage of plastic products is that it is breakable.

PROCESSING RUBBER

Rubber is a non- metal product. It looks like plastics but it is more elastic than plastic. The raw rubber occurs in LATEX. If the latex is heated, it changes into an elastic, soft and sticky solid which is called rubber.

TYPES OF RUBBER

NATURAL RUBBER:this is obtained from the white milk sap-like fluid found in rubber tree. The raw rubber produced can be improved through the process called vulcanization.

SYNTHETIC RUBBER: The synthetic rubberis an artificial rubber sometimes called elastomer. It is made from petroleum products. 

Both the natural and the synthetic rubber are processed through the following stages:

1. The rubber is softened by adding chemicals such as coal, limestone, natural gas, petroleum,oil, acetylene,water and sodium chloride by a process called polymerization and mixing them thoroughly to bring it to mould able stage.
2. It is then heated in a chamberinto a molten form
3. The molten rubber is forced into a mould already designed to take the shapes of the object.

The methods of processing rubber are:

1. Vacuum forming 
2. Extrusion
3. Calendaring
4. Compression moulding.

USES OF RUBBER

1. It can be used as an elastic materials e.g. for making catapult.
2. Rubber is water proof, so it is used in making rubber sandals and gloves
3. Rubber has electrical insulating property i.e. it is an insulator. Thus, it is used in covering electrical wires that supply electricity to the iron or kettle.
4. Rubber can be used as shock absorber, thus it is used in making bumper of cars tyres and tubes of cars

EVALUATION

1. List the methods of processing rubber
2. Mention the processing plastics.
3. State two advantages of rubber over plastic. 

GENERAL EVALUATION

1. Discuss five methods of processing plastics
2. Explain the three stages of processing rubber
3. Outline four methods of processing rubber 
4. State three uses of rubber

READING ASSIGNMENT

Read about processing ceramic, rubber and plastic

REF. BOOKS:i) EVANS Basic Technology for JSS book 1.

1. ii) NERDC Basic Technology for JSS book 1.

WEEKEND ASSIGNMENT

1. All solids objects made from clay, mud or cement are called ____(a) plastics (b) rubber (c) semiconductors (d) ceramics.
2. The art of using clay to make various objects is called ____ (a) plastics (b) rubber (c) semiconductors (d) pottery.
3. Which of the following is not a method of processing rubber (a) Vacuum forming (b) Injection moulding (c) Extrusion (d) Calendaring.
4. Which of the following material is made from inorganic resin made from refining petroleum(a) rubber (b) ceramic (c)glass (d) plastic.
5.   _____ is a hard heat resistant material made by firing a mixture of clay and chemicals at high temperature(a) plastic (b) rubber (c) ceramic (d) wood.

THEORY

1. Define rubbermaterials and uses
2. List the methods of processing plastic s and state THREE (3) uses of plastics.