Microwaves: The History and Development

                              Enginnering Faculty             

Engineering Report:

Microwave Ovenbg

Teacher: Mr Mahmoud Due:24/03/17

Summary

This report presents the foundation of microwaves and states the purpose of the report. It will also give detailed background information about the history of the machine. In addition, there will be an explanation towards what it does and why it’s needed throughout the world as well as its impact on society. Moreover, there will also be a full description of the product to full extent. The description will described; how it looks like, how it works, materials used in the product, how it’s assembled, how to use it and extra features of the machine. Furthermore, two drawings will be present in the report that includes isometric and orthographic, which have full measurements and angles drawn as accurate as possible. Following this, an analysis will also display  how the appliance’s components, sustainability, choice of materials and how well it functions will be critically researched and analysed to how effective they are and if there’s any room for improvement.  Next, there will be extra photos of the product as well as any other extensive information about it. Adding to that, will be full descriptive recommendation of how it could be improved and conclusion covering up between the old and new product as well it’s major contribution towards the modern world. Lastly, there will be complete harved references to show where information’s was research from.

1.0

Introduction

1.1: The Purpose of the Report.

The purpose of this report is to show the foundation of how microwaves work and how they used throughout the present world. This report will discover the ways they influenced society and will be deconstructed to show all the features of this product. It will also contain calculations and diagrams in order to maximum the full experience to how this product works from the inside. This report will generate systematically to be simpler and will contain critical opinions and judgements on how it could be improved as well as key historical background to the machine. In addition, this report will feature an appendix to display extensive use of research and freehand drawing towards its parts and functions. The purpose of the report will also show the need for this product in the new technological world and will display every capability that it has to full extent.

1.2:  Background Information, historical research of this product.

The microwave was first invented somewhere in the year 1946 during a radar related research project. Dr Percy Spenser was part of the project but during the investigation found something very unusual.  During the project, they were testing out a new vacuum called magnetron when suddenly he realized that the candy bar in his pocket had melted. This inspired the doctor to try out another experiment where he placed popcorn kennels near the tube and watch joyfully  as they stated to pop, cracked and sputtered all over his lab. This fascinated the doctor about this unusual discovery and so prompted another experiment the next morning with his colleague.  The experiment was placing an egg next to the magnetron and the result was the egg exploding all over the doctor’s lab. Mr Spenser then came up with a logical scientific experiment; the melted candy bar, the popcorn and egg all had one thing in common they were exposed to low density  microwave energy. This conclusion led the doctor that if these foods can be cooked this quickly why others cannot be as well. Dr. Spencer then invented a metal box with an opening into which he fed microwave power. The energy entering the box was unable to escape, therefore creating a higher density electromagnetic field. When the food placed in the box and microwave energy fed in, the temperature of the food increased very rapidly. Dr. Spencer knowingly knew he just designed what was to revolutionize cooking, and form the basis of a multimillion-dollar industry, called the microwave oven and put forward a plan to the Raytheon Corporation to build this machine .

Unsurprisingly, in 1954 the Raytheon Corporation produced the first commercial microwave called the 1161 Radarange. It was large, expensive, and had a power of 1600 watts which wasn’t very efficient towards people who won’t rich. To solve this problem a  division of the company named Amana created the first domestic microwave oven in 1967 but sales were slow during the first few years, partially due to the oven’s relatively expensive price tag,  later the concept of quick microwave cooking arrived. In succeeding years, a number of other companies joined the countertop microwave oven market. By the end of 1971, the price of microwave oven units began to decrease and their capabilities expanded as time moved on.

1.3: What does the product do?

The microwave oven is a kitchen appliance that heats and cooks food by heating up the particles inside while exposing it to microwaves from the electromagnetic spectrum. The waves were implemented into the machine where the inventor was experimenting with the it.

1.4: Why is there a need for this product?

The microwave oven is one of the most in the important kitchen appliances in the modern day household. It provides the basic needs of everyday life and is important contribution towards the world.  The machine delivers the most of what modern technology has as it heats and cooks food  instead the old ways of heating them on a stove or on a bonfire. Moreover, the device is also much safer than the stove as it does not get hot when conducted by heat due to the material it’s made from, which is  stainless steel with a coating of acrylic enamel because of its low thermal conductivity.

1.5: Impact on Society

The microwave oven has made a significant contribution towards society as it made life easier with a cooking and heating foods at your fingertips. This helps with timesaving and allows to serve individuals within the family at different times when necessary.  This is important because it helps  many people whom are busy due to the technological world and don’t have the needed time to cook food on the stove. In addition, the microwave allows the food to be cooked much cheaper compared to the olds ways as all the components built inside, making life much more simple. This helps many people in the long run with paying the bills and assisting them to pay the more important fees.

2.0

Description

2.1: Describe the product

i) What it looks like?

The microwave oven is a quick and efficient machine that uses electromagnetic radiation to cook food. This fascinating machine allows people to cook food whenever they are busy or tired after a long day at work. This machine’s design is a rectangular prism with to vertical and horizontal lines. In addition, it also has a built in light bulb to see how your food is cooking and has a timer whenever it’s finished. Most microwaves will have three ventilations systems to keep the air in the microwave flowing and is used to take the radiation out. This method is necessary otherwise; the quality of the food will suffer.  Moreover, the machine also has a container at the back where it stores up the microwave energy and short circuit where it’s connected to the cable that is plugged towards the power point.

ii) How it works?

The microwave is actually quite a simple machine to how it actually works. The inside generator called the magnetron takes electricity from the power outlet and converts it to high-powered microwaves. These waves then travel through the food compartment and blasted out towards the spinning turntable in order to cook the food evenly. Furthermore, the microwaves then bounce of the reflective metal wall however when these waves meet the food they don’t bounce but instead penetrate it and oscillate the molecules within it. Therefore, allowing the food to become hotter and let enjoy your meal.

iii) Materials used:

The following materials used to make microwaves are:

• Stainless steel with a coating of acrylic enamel.
• Ceramic or glass:
• Electromechanical components
•  Steel metal: A mixture of cast iron, steel and bronze:
•  Stainless steel
• Polymer:
•  Medium carbon steel
• Hardened steel
•  Plastic and Copper wire:

Why are these materials used?

Material	Uses	Why?
Stainless steel with acrylic enamel	Used for the outside layer of the microwave	Corrosion Resistance Ductile Low heat absorption
Ceramic or glass	Used for the cooking surface	Corrosion Resistance Insulator
Electromechanical components	Timer motors, switches and relays	Simple mechanics Conductors
Steel metal	Used to make magnetron tube , the waveguide, capacitor  and the stirrer fan	Great conductivity Great durability Ductile
A mixture of cast iron, steel and bronze	Used to make the gears	High tensile strength High endurance  strength Low coefficient of friction
Stainless steel	Used to make pulleys	High strength
Polymer	Used to make belts	High Strength
Medium carbon steel	Used to make screws	High tensile strength Malleable
Hardened steel	Used to make washers	Wear resistant Brittle
Plastic and copper	Used to make the cables	Great conductivity
Silicon Steel	Used to make the transformer	Magnetic Properties

iv) How is it assembled

1. The process of manufacturing the microwave oven starts with the cavity that creates the microwave radiation. First, the frame is formed using automatic metal-forming presser with all of the other parts already made.

2. The parts then move through a paint operation where the paint is heated up to 300 degrees for 20 minutes and all the parts are coated in paint.

3. Following this, the front door receives a coat of paint and metal plate is attached to its window.

4. The microwave then moves onto the next phase where it obtains the anode cylinder that will provide with its electricity to generate to power. Moreover, a powerful magnet is then put around the cylinder to create an electromagnetic field, creating microwaves. A thermal protector is attached directly on the magnetron to prevent damage to the tube from overheating and causing an explosion.

5. Additionally, an antenna enclosed in a glass tube is mounted on top of the back of the microwave. The waveguide is connected to the magnetron that is a on top of the antenna, while a blower motor is attached directly to the tube. Finally, a plastic fan is attached to the motor. In addition the capacitor and the high voltage transformer  are added in as well.

6. The main frame placed on the assembly tray and the cavity is screwed on to the chassis, which is the component that makes all the parts work together. Next, the door is attached to the cavity and chassis. The magnetron tube is  bolted to the side of the cavity and the main chassis.

7. The circuit that produces the voltage required to operate the magnetron tube is  then mounted directly on the frame, close to the magnetron tube.

8. The stirrer fan is mounted on top of the cavity attached directly to the fan.  Following this, the stirrer shield is screwed on top of the fan assembly. The shield prevents dirt and grease from entering the waveguide, where they could produce damage to the magnetron.
9. The relay provides power to the transformer and a timer for the microwave. The relay is mounted close to the power transformer, while the timer is mounted on the control board. Also mounted on the control board are a timer bell that rings when your food’s heated and a light bulb that allows viewing of the inside.  Furthermore, a number of interlocking switches  are secured  near the top and bottom of the door area to enable cooking options.

10. A front panel is attached next to the front door. Behind the front panel, the control circuit board is attached. The board, which controls the various programmed operations in their proper sequence when the switches are placed on the front panel, is connected to the various components and the front panel using plug-in sockets and cables.

11. The outer case of the microwave is made of stainless steel metal with coating acrylic enamel and assembled on a roll former. The case  is strapped onto the preassembled microwave oven and is bolted in firmly. This finally completes the process and the oven is sent for packaging.

v) How to use it?

The microwave oven is quite a simple machine to use with basic knowledge of a human being. The machine’s main purpose is to cook/heat food and requires minimal effort by having a choice of how to do it. There are many options to cook your food such as defrost, fruits, desserts options and many more. When your choice has been made just click the option and the microwave oven does it automatically for you without the need of lighting the gas stove.

vi) Features and extra.

There  known to be three different types of oven that have been used throughout the modern world.  The original solo microwave oven, the striking grill microwave oven and the new convention microwave. These microwaves have a different variety of cooking options but use the same basic design with  components and little adjustments such as moisture sensors and LED lights.  There have also been variations changes to outside layer with it just primarily stainless steel. This design could be viewed as a disadvantage because of its electrical conductivity that wouldn’t make it safe and would conduct even more heat that leads to  greater chance of the microwave overheating and being significantly damaged. Nevertheless, the microwave is still a great kitchen appliance that has proven itself to be a vital part for the modern world.

4.0

Analysis

4.1: Critical Judgment of the product

i) Components

The components of the microwave such as the magnetron, relay, motors, gears, capacitor, high voltage transformer, chassis and the cavity all do their job efficiently and effectively. However, they are known to have overheated in microwaves causing health hazards over a long period of time due to the immense amount of radiation. In addition, if the microwave is physically damaged or leaks it may also cause a problem as it has the chance of causing cancer if the insulator is cracked from high chemical exposure. To combat these issues the immense radiation should decrease to stop overheating and the use of less chemicals should be introduced. Overall, most of the components are safe and useful compared to some of the old ones used in the first microwave oven.

ii) Materials

The materials used in the microwave oven are quite great and work professionally but there a number of significant problems with them. An example of one is the steel used for the components, which may start to corrode after a  period of time. This is a major problem as if these components are damaged the microwave may have the potential of permanently shutting down.  Moreover, the extensive use of steel may cause the microwave overheating due the high electrical conductivity, which would damage its components . To solve this problems the steel metal should be replaced with less amounts of stainless steel to prone electricity and has high corrosion resistant.

iii) Sustainability

The microwave oven is a great sustainable kitchen appliance. Their almost no problems that is present towards the natural environment except for the usage power and possible chemical leak. Furthermore, the use in domestic industry is also not much of a problem as they can be placed where people decide especially for seniors who old and fragile.  But, this comes to a disadvantage because if microwaves are place within low heights children can play with and cause damage and may even drop it which may lead to high chemical leak if it cracks.  In addition, some children could even  place a metal object that will likely spark up and cause a fire .The immense radiation may also not be the best suitable options towards kids and seniors as their body’s aren’t strong enough to take the energy.  A new design should come around with there is less radiation used , the containment for the microwave energy  should be reinforced with stronger metal  and sensors which can detect between food and metal objects.

iv)  How well it Functions?

The microwave is an excellent, simple kitchen appliance that requires no work effort but basic human knowledge. The machine almost never lets you down which is why up to 92% of American households have it according to a study conducted in 1994. In addition, the appliance has had improvements over the past 50 years in order for it to be more effectively useful and safe. But, it does need a minor improvement towards the immense radiation and to reinforce the dangerous microwave energy stored in the back, Nevertheless, the microwave oven functions greats with all the components and materials needing slight developments.

v) Pros and Cons of the Product

Pros

• Great simple machine with energy efficiency.
• Lasts for a long period of time.
• Almost never fails.
• Portable.
• Best way to cook food without lighting a gas stove.
• Keeps all nutrients stored in the food untouched.

     Cons

• The microwave may overheat due to radiation that can cause damage.
• Not healthy for young children or seniors due to heat radiation.
• If physically broken, chemical leak may damage cell tissues, which can cause cancer.
• Components will eventually rust causing major damage towards the machine.

5.0

Appendix

5.1 Drawings and Photos

Magnetron                                                                   Inside view

^{High Voltage Transformer                                                          Capacitor}                                                         

5.2: Extra Relevant Information 

The microwave oven converts only part of its electrical input into microwave energy. An average consumer microwave oven consumes 1100 W of electricity in producing 700 W of microwave power which has an efficiency of 64%. The other 400 W is used as heat mostly in the magnetron tube. In addition, any wasted heat or any microwave radiation is sent out through the cooling vents. Additional power is used to operate the lamps; AC power transformer, magnetron-cooling fan; food turntable motor and the control circuits, which only need about 100 W to all operate. In addition, the microwave oven also uses less energy compared to the gas stove due to all major components already built in. Therefore,  the microwave oven is not only cheaper than a gas stove but also uses less energy that could be life-saving towards many people who have to pay more important bills.

6.0

Recommendations/Conclusions

6.1: Recommendations

1. The first recommendation I will make is for the type of material used in the components to be changed as most of them are made from steel metal. This metal is a great option to conduct electricity but over time, it will corrode and cause a major damaged towards the microwave oven. To solve the problem I will recommend is to replace the steel metal with stainless steel as its corrosion resistance. Therefore, allowing it to last much longer.

2. The second recommendation that should be designed into the machine is less radiation used in the microwave. Microwave energy is not harmful but people such as seniors or young children may not be able to take the amount of heat present. In addition, even sometimes the immense radiation might overheat the microwave oven causing high damage towards its components due to them being next to the cavity. To combat this I will recommend reducing the amount of energy the magnetron produces but enough to heat food.

3. The third recommendation that should be introduced to the microwave is the amount of chemicals used in the magnetron. Some magnetrons contains beryllium oxide which if leaked can cause a dangerous lung condition which sometimes could be fatal. Furthermore, all magnetrons contain thorium mixed with tungsten that if leaked and inhaled , can damage cell tissues and cause cancer. To fix this I will recommend taking out most of the chemicals from the magnetron so it does present a health hazard.

6.1: Conclusion

The microwave oven has a significant impact on the modern world with its extensive abilities to cook and reheat food. The original form of cooking food can be dated back to Stone Age with the use of fire. Next, came the invention of gas stove in the 1820’s which required great amounts of gas with a huge price on its tag. In addition, sometimes the gas stove will fail continuously but this issue was brought to the end in the 20^th century. The brilliance of Dr Percy’s Spencer intellectual mind brought out around one of the most important kitchen appliances of today’s technological world called the microwave oven. Even though, this machine had a few problems before becoming perfect. However, the advancement of technology repaired these few problems with companies eager to get their hands of this discovery and made further adjustments to its design to make it look incomparable, magnificent and stunning. Furthermore, the microwave oven uses the  technology of electromagnetic radiation to bring new life towards cold and frozen food supplying it with the most effective and efficient way possible. The microwave oven has a major influence of how the world works with its outstanding and striking capabilities that has been indeed a great achievement by mankind.

7.0

Bibliography

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2. Woodford, C. (2016). Microwave ovens | How do they work?. [online] Explain that Stuff. Available at: http://www.explainthatstuff.com/microwaveovens.html [Accessed 18 Mar. 2017].

3. Riaz, R. (2017). How microwave oven is made – manufacture, making, used, parts, components, structure, product, Design. [online] Madehow.com. Available at: http://www.madehow.com/Volume-1/Microwave-Oven.html [Accessed 18 Mar. 2017].

4. Sharpe, E. (2007). Microwave Oven. [online] Smecc.org. Available at: http://www.smecc.org/microwave_oven.htm [Accessed 23 Mar. 2017].