MT1010 Engineering Materials Material Selection Assignment Name – Gunathilaka R

MT1010 Engineering Materials
Material Selection Assignment
Name – Gunathilaka R.A.C.K.

ID – EN18405514
Material Assignment Group – 2
Date of Submission – 28th September 2018

Introduction to Electric Hand Mixer
Functions of a Hand Mixer
Components of a Hand Mixer
Analysis of 3 key components of Hand Mixer
4.1) Beater
4.1.1) Function of Beater
4.1.2) Material of Beater
4.1.3) Related problems of material of Beater
4.1.4) Mechanical and physical properties of the material of Beater
4.1.5) Suitable candidate materials for the Beater
4.2) Cover Casing
4.2.1) Function of Cover Casing
4.2.2) Material of Cover Casing
4.2.3) Related problems of material of Cover Casing
4.2.4) Mechanical and physical properties of the material of Cover Casing
4.2.5) Suitable candidate materials for the Cover Casing
4.3) Wire
4.3.1) Function of Wire
4.3.2) Material of Wire
4.3.3) Related problems of material of Wire
4.3.4) Mechanical and physical properties of the material of Wire
4.3.5) Suitable candidate materials for the Wire
Introduction to Electric Hand Mixer
Electric mixer has a wide history with new improvements in relevant eras.
Herbert Johnson was the pioneer of inventing first electric mixer in 1908. He observed a baker mixing a bread dough by using a spoon. After his observation Herbert Johnson began to invent the electric stand mixer. His attempt was successful. After few years ago his stand mixer consequently changed to the hand mixer. After few years from the first electric mixer, features and the convenience of electric mixers were developed by various people and companies. Egmont Ahrens was a person who reduced the weight of an electric mixer and increased convenience further. Hobart Manufacturing Company, Sunbeam are some of names of companies who implemented the features of electric mixers.
Specially in bakery industry, electric mixers were very important due to satisfy their multiple needs of making bakery foods. Processes of beating, mixing, whipping were conveniently done by electric hand mixers with reducing the time wastages. Electric hand mixer was a very important appliance in bakery industry. Not only in bakeries but also in home kitchen activities.
(First Electric Mixer)
(Herbert Johnson)
Functions of Hand Mixer
Lots of functions and processes are done by hand mixers. Basically, beating, mixing, whipping and stirring are some of them. When preparing cakes, bakery foods, desserts, puddings and other stuffs, we use hand mixers for various needs. Some functions of hand mixer are below as;
Beating Mixing

Components of a Hand Mixer

Rear Cover Casing
Handle Cover
Printed Circuit Board
Shock Absorber
Capacitor Bracket
Torsion Spring
Carbon Brush
Turbo Boost Button
Turbo Boost Mechanism
Switch Selector
Switch Connector
Connector Cover
Small Switch Screw
Switch Ring
Eject Button
Eject Mechanism
Gear Compression Spring
Front Cover Casing
Torx Casing Screw
Tamper Proof Casing Screw
Analysis of 3 components of Electric Hand Mixer
4.1 Beaters

4.1.1 Functions of Beaters
Normally, a hand mixer is contained with two beaters. They are removable from the hand mixer for the cleaning purpose. Beaters are virtually got a special shape for whisk ingredients efficiently. Beaters do;
4.1.2 Material of Beaters
Beaters are made of 300 series stainless steel. 300 Series Stainless steel is a combination of Iron, Chromium, Nickel, Carbon and Manganese. 300 series Stainless steel is used for the beaters because of the human health safety. Normal steels can be rusted and those rusts are very harmful for the human health. Disease such as Tetanus is caused if iron rusts enter to the human body. If the beaters of hand mixer get rusts, it easy to access them to our bodies through the ingredients of foods we are processing by hand mixer. To avoid this dangerous situation, beaters are made of stainless steel to minimize the risk of human health. Stainless steel can be divided as Austenitic Stainless Steel, Martensitic Stainless Steel and Duplex Stainless Steel.
(300 series Stainless Steel)
4.1.3 Related problems of material of Beaters
Some problems were identified after analyzing about 300 series stainless steel. They were;
High Cost
Less Stiffness
Less Durability
4.1.4. Mechanical and physical properties of material of beaters
Stainless steel is fulfilled with following properties;
Corrosion resistance – Stainless steel is protected from corrosions by its owned layer of oxide. If there any cut or damage on the stainless steel, again a layer of oxide is covered the steel and protected from corrosions.

Ductility – Stainless steel has a high ductility.
Magnetic response – Austenitic stainless steel which is a family member of stainless steels are not usually respond to a magnetic flux, but there will be a small response for magnetic flux after cold working of austenitic stainless steel.
Strength – Usually stainless steels are contained a high strength. According to the tensile strength of types of stainless steels, Duplex stainless steels have a tensile strength higher than Austenitic stainless steels.
Numerical data of Stainless Steel
Property Value
Density 8.03g / cm3
Melting Point 1455 0C
Modulus of Elasticity 193 GPa
Electrical Resistivity 0.072 × 10-6 ?m-1
Thermal Conductivity 16.3 Wm-1K at 100 0C
Thermal Expansion 17.3 × 10-6 K-1 at 100 0C

4.1.4 Suitable candidate materials for the Beater
Stainless steel is non rusted metal. This is happened due its composition of various metals. Stainless steels are categorized by the amount of alloyed compositions. Beaters of selected hand mixer was manufactured by using 300 series Stainless Steel. Due to some related problems, 300 series stainless steel can be replaced by 200 series Stainless Steel.
200 series Stainless Steel
This type of stainless steel is specified due to its alloyed compositions.
Chromium Content Nickel Content
Stainless Steel 200 series 16 – 18% 0.5 – 4.0%
Stainless Steel 300 series 18 – 20% 8 – 10.5%
(200 series Stainless Steel)
4.2 Cover Casing
4.2.1 Function of Cover Casing
A cover casing is used to cover all interior components and avoid liquids and dirt accessing inside the device.

4.2.2 Material of Cover Casing
Cover casing of our hand mixer is made of ABS Plastics. ABS is defined as Acrylonitrile Butadiene Styrene. These three of monomers are combined together and ABS plastics are originated as a result of that combination. This material is commonly used to manufacture toys, barrels, artificial flowers, helmets, bathroom fittings etc.

ABS plastics are made by a method named as ‘Continuous Mass Polymerization’. Propylene, ammonia and petroleum hydrocarbons are some of raw materials which are used to manufacture ABS plastics.
lefttop (ABS plastics)
4.2.3 Related problems of material of Cover Casing
ABS plastics are easily flammable at high temperature. Especially considering the usage of hand mixer, it can be heated when using it for a long time. This might can be a factor to get flamed. Burn of constituents of ABS such as Acrylonitrile and Butadiene may be generated fatal toxics. As a result of burning Acrylonitrile and Butadiene can be emitted carcinogenic toxics. It’s very dangerous situation and a disadvantage of using ABS plastics as a cover casing of hand mixers.
4.2.4 Mechanical and physical properties of the material of Cover Casing
Ductility – ABS plastics have a high ductility.
Resistance against chemicals – ABS plastics are shown a resistance against to Aliphatic hydrocarbons, dilute acids, alkaline solutions, greases and oils.
Strength – An average strength is contained in ABS plastics.

Weight – ABS plastics have a light weight.
Properties Value
Tensile Strength 30 – 52 MPa
Tensile Modulus 2070 – 2760 MPa
Izod Impact Test 134 – 320 J/m
Hardness 105 – 112 HR
4.2.5 Suitable candidate materials for the Cover Casing
According to the mechanical and other properties of material of cover casing, Polycarbonate can be suggested instead of ABS plastics. They are not almost same to ABS plastics, but approximately they are consisted with same physical and mechanical properties of ABS plastics.

Polycarbonate is categorized under ‘Thermoplastics’. Polycarbonate can be melted when heating at its melting point and also can be rigid when it cools below its melting point. This characteristic is belonged to the thermoplastics. Polycarbonate is used to manufacture sport equipment, medical equipment etc.
Properties of Polycarbonate Value
Specific Gravity 1.2
Tensile Modulus 2.4 GPa
Tensile Strength 66 MPa
Flexural Strength 93 MPa
Flexural modulus 23 GPa
Elongation to break 110%
Impact test (Izod) 854 Jm-1
Heat deflection temperature 138 0C
lefttop(Structure of Polycarbonate and its applications)

4.3 Wire

4.3.1 Function of Wire
Transfer electricity from power supply to the hand mixer.

4.3.2 Material of Wire
Basically, wire has two parts. Inner part and outer part. Inner part is made of a conductive metal such as Copper. Outer part is made of nonconductive metal such as Rubber. These materials are selected to their applications because of following requirements.
Copper Wire (Inner part of a Wire) – Electric hand mixers are fully operated by electricity. When supplying electricity to the hand mixer, electrons from the power supply are transmitted through the copper wire. Copper is contained with lots of free electrons. Thus, copper is behaved as a good conductive metal. Furthermore, copper is fulfilled as a good metal for conducting heat. A material which has a good electrical conductivity is definitely needed for the component of transmitting electricity.

Rubber Casing (Outer part of a Wire) – As discussed above details, copper is a very good conductive metal due to its unique electrical properties. Usually power to the electric hand mixer is supplied from a home power supply. Voltage of a home power supply is 230V. Without the rubber casing of a wire, there will be dangerous accidents such as current leaks and electric shocks. As a nonelectric conductive material, rubber is secured users from dangerous hazards. That kind of material is compulsory needed as the casing of the electric conductive wire.
4.3.3 Related problems of material of Wire
Rubber wire can be damaged by rats or some kind of insects. Furthermore, wire can be damaged when it using for a long time due to often bending, unrolling and twisting. If there dents or damages on the wire, there will be possible ways to current leakages and electric shocks.
4.3.4 Mechanical and physical properties of the material of Wire
Electrical Conductivity – Copper has a good electric conductivity. According to the values of conductivity of different materials, Copper is only retreated to the Silver metal.

Thermal Conductivity – Copper also has a good thermal conductivity.
Ductility – Copper has a precious ductility. Wires, coils can be made because of this property.

Resistance against corrosions – Reactivity of copper is at a minimum point. Due to this situation copper has a high resistance against corrosions.
Magnetic Response – Copper is not fulfilled with magnetic properties. Then copper is not responded (attraction or repulsion) to any magnetic source or a flux.
Properties of Copper Values
Porosity 0.90
Permeability 4.28 x 10-7 m2
Friction Coefficient 0.17
Density 8663 kgm-3
Thermal Conductivity 401 Wm-1C-1
Specific Heat Capacity 385 Jkg-1C-1
Tensile strength – Rubber has a high tensile strength
Hardness – Usually rubber is contained with a good hardness. Value of the hardness is depended on the application of the rubber as a raw material.

Ex- Rubber mixer which is used to manufacture hockey pucks has a hardness more than the rubber which is used to manufacture pencil erasers.
Resistance for abrasions – Rubber has a specific quality of resistance for abrasions. Due to this property rubber is used to design machinery parts such as conveyor belts.

Properties of Rubber Value
Specific Gravity 0.92
Heat of combustion 10547.084 calg-1
Thermal Conductivity 0.00032 calm-10C-1
Coefficient of cube expansion 0.00062 0C-1
Dielectric Constant 3937 Vmm-1
4.3.5 Suitable candidate materials for the Wire
Basically wire of an electric hand mixer is contained with two materials. Inner part is Copper and outer part is Rubber. Considering basic requirements of these materials, some alternative materials can be suggested instead of them. Mostly those alternative materials are fulfilled with same mechanical and other properties of materials of chosen components.
Inner part
Inner part of the wire is consisted of Copper wire. With studying the basic properties of Copper, Bronze material was identified as an alternative material for Copper. Both have electrical and thermal conductivity. Copper is absolutely applied to the wire because of electrical conductivity. That requirement is fulfilled by Bronze. Not only electrical conductivity but also other properties are probably similar to Copper.

Properties of Bronze Value
Density 6.6 gcm-3
Tensile Strength 14000 psi
Electrical Conductivity 15000000 ?m-1
Rockwell Hardness H45
lefttopBronze Wires

Outer Part
Outer part of a wire is made of rubber. Rubber is used for wire to avoid current leakages because of its low electrical conductivity. Browsing about similar materials to rubber, 2 alternative materials were found to use instead of rubber.

Silicone is consisted with a low level of heat conducting and a toxicity level. Silicone rubber is used in cookware and electrical components.
Type of Silicone Rubber Tensile Strength
(MPa) Tear Strength
High Consistency Rubber 4 – 13 9 – 55
Flurosilicone Rubber 9 – 12 18 – 46
Liquid Silicone Rubber 4 – 12 11 – 52
Room Temperature Vulcanize 6 9
(Silicone Wire)
Using Neoprene, flexible and durable products can be manufactured. Some special qualities such as waterproof, oil resistant, flexibility are qualified to use as an alternative for the rubber.

Properties of Neoprene Value
Density 710 kgm-3
Tensile Strength 250 psi
Flexibility 3 max
(Neoprene Wires)
According to the analysis of materials of three selected components in an electric hand mixer, those materials are used for a unique reason with corresponding some unique properties of them. Some materials are used for some components to ensure the human health. Some materials are used to ensure the human safety from dangerous hazards. Furthermore, some materials are used to increase the efficiency of the hand mixers. Not only the efficiency but also to protect interior components from dusts, liquids and other particles. Considering the analysis of materials of selected components, some of them can be substituted from another material with regarding their similar mechanical and other properties. However, some of components are not supported to substitute from another material due to their unique qualities.
Finally, some alternative materials were suggested after deeply analyzing the physical and mechanical properties of materials of an electric hand mixer. As a summary;
Component Identified Material Suggested Material(s)
Beaters 300 Series Stainless Steel 200 Series Stainless Steel
Cover Casing ABS Plastics Polycarbonate
Wire Copper (Inner part) Bronze
Wire Rubber (Outer part) Silicone, Neoprene
This group project was successfully done with a great contribution among every group members
Name of group member Contribution
Perera M.J.S. Dismantled an old electric hand mixer and analyzed the material of beaters and their related problems.

Suggested a candidate material for beaters
Gunathilaka R.A.C.K Explored and studied about exterior and interior materials of the wire.

Suggested three materials instead of them.

Atukorala D.A.I.I Analyzed the material of cover casing and suggested alternative material for it.

Peiris P.T.D. Browsed about all related problems of materials which are applied for selected components of hand mixer.

Abeysinghe W.A.M.B.J. Browsed about numerical data of physical and mechanical properties of materials which are applied to selected components of hand mixer.

Mixer History
Available from : on 15th September 2018
Function and mechanism of hand mixer
Available from : on 15th September 2018
Stainless Steel
Available from: on 15th September 2018
Copper properties and application
Available from: on 15th September 2018
ABS plastic: Production, market, price and its properties
Available from: on 16th September 2018
Physical properties of rubber – a buyer and designer’s guide
Available from: on 25th September 2018
Thermoplastics properties, types, uses, advantages and disadvantages
Available from: on 25th September 2018
Material substitutes for rubber
Available from: on 25th September 2018