MATERIALS SELECTION (MKMB 2463)
Group Assignment MATERIAL AND PROCESS SELECTION FOR HAMMERS
Member’s Name
:
1) Ikhwan Hafiz B Hassan (MKM161038) 2) Mohd. Naif Hanis B Mohd Sokri (MKM161036) 3) Nur Suhaili Bt Ismail (MKM161035) ( MKM161035)
Lecturer
:
Dr. Norhayati Bt Ahmad
Submission Date
:
29th May 2017
Abstract
In the module MKMB 2643 this year, students are assigned to investigate and discuss the right r ight material and process for any tool and its application, which in this particular report will be focusing on hammers. Students are expected to have the knowledge in choosing the best material and processing method by considering all important f actors such as cost, performance, efficiency and environmental impact based on appropriate level of analysis for robustness. The analysis of factors affecting in choosing the material and process will be further discussed in this report. Overall, this assignment did give students the understanding and help in making a wise and sound decision specified the standard components in the chosen tool.
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TABLE OF CONTENT CHAPTER
TITLE
Page
1
INTRODUCTION
4
1.1 Introduction 1.2 Background 1.3 Design and Variations
2
5 6
SELECTION METHOD: HAMMER’S HEAD
8
2.1 Introduction
8
2.2 Selection of Hammerhead
8
2.3 Design Plan
10
2.4 Weight Property Index of Materials
11
2.5 Raw Materials
11
2.5.1 Iron Making
11
2.5.2 Steel Making
12
2.5.3 Bessemer Converter
12
2.5.4 Basic Oxygen Process
13
2.5.5 Open Hearth Furnace
13
2.5.6 Electric Arc Furnace
13
2.5.7 Argon Process
14
2.5.8 Vacuum Degassing Process
14
2.5.9 Ingots, Blooms, and Billets
14
2.5.10 Continuous Casting Process
3
4
16
2.6 Hammerhead Forging
18
SELECTION METHOD: HAMMER’S HANDLE
20
3.1 Selection of Hammer’s Handle
20
3.2 Selection of Material Using MPI
20
3.3 Wood Fabrication Process
26
3.3.1 Primary Stages
26
3
4
3.3.1.1 Cutting and Pruning
26
3.3.1.2 Bark Removing
27
3.3.1.3 Sawing
27
3.3.1.4 Drying
27
3.3.1.5 Planing
28
3.3.2 Secondary Process
28
3.3.2.1 Wood Turning
28
3.3.2.2 Surface Finishing
30
PERFORMANCE AND COST
31
4.1 Performance and Functionability
31
4.2 Cost 4.3 Life Cycle Analysis of Hammers
33 34 34
4.4 Reuse and Recycle
5
CONCLUSION
35
4
CHAPTER 1
INTRODUCTION
1.1 Introduction Generally, a hammer is a tool or device that delivers a blow (sudden impact) to an object. Most hammers are hand tools used to drive nails, fit parts, forge metal, and break apart objects. Hammers vary in shape, size and structure, depending on their purposes and they are basic tools in many trades. There are several types of hand tool hammer available in the market such as boiler scalling hammer, cross pein hammer (most common ones), cow hammer,
etc.
and there are also mechanically-powered hammers work on the same
principle despite the different in look. In professional framing carpentry, the manual hammer has almost been completely replaced by the nail gun meanwhile in upholstery, staple gun is commonly used.
Figure 1: Cross pein hammer and mechanically-powered hammer
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1.2 Background
The use of simple hammers dates to about 2,600,000 BCE when various shaped stones were used to strike wood, bone, or other stones to break them apart and shape them. Stones attached to sticks with strips of leather or animal sinew were being used as hammers with handles by about 30,000 BCE during the middle of the Palaeolithic.
While there are many types of hammer being used these days, the basic ones are still favoured in most household. A hammer is an integral part to a basic tool collection. In fact, a decent hammer is probably the first thing in consideration when looking to start a home assortment of tools. Thus, fabricating it in high efficiency is crucial to make it work best. Basically, a hammer can be parted into two; the handle and head where both play important roles in delivering the driving force to nails, anvils, and others.
Aforementioned, a traditional hand-held hammer consists of a separate head and a handle, fastened together by means of a special wedge made for the purpose, or by glue, or both. This two-piece design is often used, to combine a dense metallic striking head with a non-metallic mechanical-shock-absorbing handle (to reduce user fatigue from repeated strikes). If wood is used for the handle, it is often hickory or ash,[3] which are tough and long-lasting
materials
that
can
dissipate shock waves from the hammer head.
Rigid fiberglass resin may be used for the handle; this material does not absorb water or decay, but does not dissipate shock as well as wood.
Figure 2: An addition functionality of a hammer
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A loose hammer head is hazardous because it can literally "fly off the handle" when in use, becoming a dangerous uncontrolled missile. Wooden handles can often be replac ed when worn or damaged; specialized kits are available covering a range of handle sizes and designs, plus special wedges for attachment.
Some hammers are one-piece designs made primarily of a single material. A one piece metallic hammer may optionally have its handle coated or wrapped in a resilient material such as rubber, for improved grip and reduced user fatigue. The hammer head ma y be surfaced with a variety of materials, including brass, bronze, wood, plastic, rubber, or leather. Some hammers have interchangeable striking surfaces, which can be selected as needed or replaced when worn out.
1.3 Design and Variations
A large hammer-like tool is a
maul (sometimes
called a "beetle"), a wood- or rubber-
headed hammer is a mallet , and a hammer-like tool with a cutting blade is usually called a hatchet . The essential part of a hammer is the head, a compact solid mass that is able to deliver a blow to the intended target without itself deforming. The impacting surface of the tool is usually flat or slightly rounded; the opposite end of the impacting mass may have a ball shape, as in the ball-peen hammer. Some upholstery hammers have a magnetized face, to pick up tacks. In the hatchet, the flat hammer head may be secondary to the cutting edge of the tool.
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Figure 3: Design of a hammer
The impact between steel hammer heads and the objects being hit can create sparks, which may ignite flammable or explosive gases. These are a hazard in some industries such as underground coal mining (due to the presence of methane gas), or in other hazardous environments such as petroleum refineries and chemical plants. In these environments, a variety of non-sparking metal tools are used, primarily made of aluminium or beryllium copper. In recent years, the handles have been made of durable plastic or rubber, though wood is still widely used because of its shock-absorbing qualities and repairability.
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CHAPTER 2
SELECTION METHOD: HAMMER’S HEAD
2.1 Introduction
This chapter will discuss in detail on the selection process of the hammerhead, normally made in variety design. The selection process is made using different methods.
2.2 Design Plan
The two major components of a hammer are the head and the handle. The design of these two components depends on the specific application, but all hammers have many common features. The striking surface of the head is called the face. It may be flat, called plain faced, or slightly convex, called bell faced. A bell-faced hammer is less likely to bend a nail if the nail is struck at an angle.
Another face design is called a checkered face. It has crosshatched grooves cut into the surface to prevent the hammer from glancing off the nail head. Because it leaves a checkered impression on the wood, it is usually only found on framing hammers used for rough construction. The surface of the head around the face is called the poll.
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The poll is connected to the main portion of the head by the slightly tapered neck. The hole where the handle fits into the head is called the adze eye. The side of the head next to the adze eye is called the cheek.
On the opposite end of the head, there may be a claw, a pick, a semi-spherical ball peen, or a tapered cross peen depending on the type of hammer. There may also be a second face, as in a double-faced hammer.
Hammers are classified by the weight of the head and the length of the handle. The common curved claw hammer has a 0.2-0.6 kg head and a 30.5-33.0 cm handle. A framing hammer, which normally drives much larger nails, has a 0.5-0.8 kg head and a 30.5-45.5 cm handle.
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2.3 Weight Property Index of Materials for Hammerhead
Table 1: Material selection for hammer’s head Properties
1/2 1/3 1/4 1/5 2/3 2/4 2/5 3/4
Density
0.5 0.5 0.5 0.8
Young’s Modulus
0.5
0.5 0.5
Tensile Strength
0.23
2.3
0.23
2.3
0.23
0.8
2.3
0.23
0.2 0.2
0.8
0.08
0.5 0.8 0.5
0.2
Cost
2.3 0.5 0.5 0.8
0.5
Yield Strength
3/ 4/ Tota Alph a 5 5 l
Total
0.5 0.2
10
Table above being constructed by using weightage method whereby its point does not exceed 10 points. Each column represent comparison between attributes of relative’s importance to another relative’s importance to achieve 10 points. Meanwhile respective row represents attributes to calculate total attributes and divided by sum of each attributes by calculation as mentioned below:
Sum of Density = 0.5 + 0.5 + 0.5 + 0.8 = 2.3
Alpha = 2.3 / 10 = 0.28
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Table 2: Type of materials Materials
Density, g/cm3
Young’s Modulus Elasticity, GPA
Yield Strength, MPA
Tensile Strength, MPA
Cost, USD per kg
High Carbon Steel, AISI 1080
8.00
210
480
800
0.8
Medium Carbon Steel, AISI 1040
7.80
200
600
430
0.5
Martensitic Alloy Steel, A 1010
7.87
190
275
455
0.4
Bronze, B 62
8.8
105
95
205
2.0
Brass, B 21
8.4
117
140
345
5.0
Min
Max
Max
Max
Min
To calculate for Beta it is depending on desired properties selection. For instance we are selecting Fracture Toughness to become the desired properties then it is considered as Maximum. Maximum and minimum scaling factor, Beta is then calculated as follows respectively:
To achiev the best materials to be selected, it i s determine from the Performance Index described below:
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Table 3: Beta Materials
Density, g/cm3
Young’s Modulus Elasticity, GPA
Yield Tensile Cost, Strength, Strength, USD MPA MPA per kg
Total
Beta
High Carbon Steel, AISI 1080
0.975
1.000
0.800
1.000
0.625
4.400
0.253
Medium Carbon Steel, AISI 1040
1.000
0.952
1.000
0.538
1.000
4.490
0.259
Martensitic Alloy Steel, A 1010
0.991
0.905
0.458
0.569
1.250
4.173
0.240
Bronze, B 62
0.886
0.500
0.158
0.256
0.250
2.051
0.118
Brass, B 21
0.929
0.557
0.233
0.431
0.100
2.250
0.130
Total
17.364
Min
Max
Max
Max
Min
Table 4: The selected material Materials
α1β1
α2β2
α3β3
α4β4
α5β5
Total
Selection
High Carbon Steel, AISI 1080
22.425
23.000
18.400
23.000
5.000
91.825
2
Medium Carbon Steel, AISI 1040
23.000
95.468
100.230
12.363
8.000
239.061
1
Martensitic Alloy Steel, A 1010
22.795
20.810
10.542
13.081
10.000
77.228
4
Bronze, B 62
20.386
50.230
3.642
5.894
2.000
82.152
3
Brass, B 21
21.357
12.814
5.367
9.919
0.800
50.257
5
To select the best materials, the highest value of performance index is the most desired. For this case, Medium Carbon Steel is having the best performance value thus it is ranked as number 1 based on Column Selection.
13
Table 5: Attributes of a hammer Assumption
Value
Mass, kg
0.8
Section thickness, mm
60
Roughness, µm
12
Economic batch size, per day
600
Tolerance, mm
5
Shape
Sledge (solid round)
2.4 Selection of Hammerhead
According to Table 1 as mentioned below, the list may be further explain as shown below: 1. Mass
- Hammer selected for this study is weighing less than 1 kg. This assumption in accordance light duty works expected to be done in the household vicinity. 2. Section thickness
- The width of typical hammer for household usage typically within 60 mm thick. 3. Roughness
- Due to for heavy duty application in the household, surface roughness maybe negligible. Thus 12 µm is adequate to give friction resistance to be applied upon the subject of interest. 4. Economic batch size
- Manufacturing capacity for small to medium enterprise may be able to produce less than 1 000 of hammer per day.
5. Tolerance 14
- Since the hammerhead is not critical item to be used 5 mm tolerance is seem adequate to serve it purpose. 6. Shape
- We are manufacturing type of Hammer. It has almost solid round circular shape.
Figure 4: Different types of hammer’s head
2.5 Raw Materials
Hammer heads are made of high carbon, heat-treated steel for strength and durability. The heat treatment helps prevent chipping or cracking caused by repeated blows against other metal objects. Certain specialty hammers may have heads made of copper, brass, babbet metal, and other materials. Dead-blow hammers have a hollow head filled with small steel shot to give maximum impact with little or no rebound.
2.5.1
Iron Making
The making of steel for hammer begins with the smelting of iron ore found in deposits in the crust of the earth throughout the world in forms such as hematite and magnetite. In preparation for the smelting process, the iron ore may be treated by any of several methods to convert it into a suitable form for introduction into the blast furnaces.
15
One method is sintering, which converts ores into a porous mass called clinkers. Another is smelting, which is performed in a blast furnace. The process involves the chemical reaction of iron ore with limestone, coke, and air under heat, reducing the iron ore to iron. The ‘‘ pig’’ iron obtained from the blast furnace is used as the basic component in the steel making process.
Figure 4: Steel making process
2.5.2
Steel Making
Steel for hammer can be produced in several ways as shown on Figure 1, depending on the facilities available and the desired characteristic of the steel. Generally, steel requires the removal of carbon from the pig iron to a degree required by the carbon steel properties desired. Alloy steel also requires the addition of alloying elements such as chromium, nickel, manganese, and molybdenum to provide the special properties associated with the alloying element.
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2.5.3
Bessemer Converter
The Bessemer method of making steel (due to Sir Henry Bessemer in 1856) consisted of blowing a current of cold air through the molten pig iron, thereby using the oxygen in the air to burn carbon and other impurities from the melt. After burning out the carbon in the pig iron, the exact amount of carbon required for the steel is reintroduced into the heat.
2.5.4
Basic Oxygen Process The basic oxygen process (BOP) is essentially the s ame as the Bessemer process except that it uses pure oxygen (instead of air) together with burned lime converted from limestone. This process burns out the impurities more quickly and completely and provides for more precise control of the steel chemistry.
2.5.5
Open Hearth Furnace
The open-hearth furnace is used to produce much of the steel in the United States; however, it is being superseded by the basic oxygen process. Its significant advantage is the ability to use scrap steel as well as pig iron as ferrous stock in producing steel. The open-hearth furnace is a large rectangular brick floor, or hearth, completely covered with a brick structure through which the charge of ferrous stock and limestone is introduced.
It is fueled with coke gas, oil, or tar introduced through a burner playing a flame across the hearth while the products of combustion escape through the furnace wall away from the burner. An advantage of the open-hearth process is that testing for carbon content during the heating is possible, allowing adjustments to be made to the feed stock at that time to control the chemistry of the product.
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2.5.6
Electric Arc Furnace The electric arc furnace is a large kettle-shaped chamber lined with fire brick, into which a charge of steel scrap with coke is melted by means of heat produced by an electric arc. Since no burning of fuel is required, the oxygen of the steel can be controlled and kept to a minimum. Alloying elements can be added without the f ear of oxidation. Because of the control of heat time, temperature, and chemistry, the electric arc furnace is used in the production of high-quality alloy steels.
2.5.7
Argon Oxygen Process The argon oxygen process (AOP) is used in the production of specialty steels with low carbon and sulfur and high chromium content. A charge of steel of almost the desired properties is introduced into a basic oxygen furnace like vessel, and controlled amounts of oxygen and argon are introduced into the melt. This reducing process conserves valuable chromium.
2.5.8
Vacuum Degassing Process When exceptionally high quality steel is required, steel can be ‘‘degassed’’ in a vacuum environment. This vacuum degassing process provides strong reduction in hydrogen, oxygen, nitrogen, inclusions, and contaminants such as le ad, copper, tin, and arsenic.
2.5.9
Ingots, Blooms, and Billets
Ingots, blooms, and billets are the shapes into which the molten metal is solidified before using it in a particular hammer making (or other) process. An ingot is poured from the molten steel and after solidification goes to the blooming mill to be rolled into square blooms, which are further formed onto bar rounds.
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Figure 5: Continuous casting process
2.5.10 Continuous Casting Process
Although the development of the continuous casting process as shown at Figure 2, began in the nineteenth century, it was after World War II that its use became of great commercial interest. In the continuous casting process, molten steel is poured from the melting furnace to a ladle feeding a reservoir called a tundish. The tundish feeds a lubricated mold that has a cooled copper surface, and the solidifying steel is continuously drawn from the mold.
There are many types of continuous casting processes, ranging from vertical to horizontal, with variations of bent sections in between. This process is now used in more than half the world’s steel production. In Japan, 85 percent of the total steel produced is by the continuous casting process.
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According to score as calculated as below, forging process is having the highest cumulative points compared to the other processes. Thus, to produce hammerhead for type of hammer require forging process to be utilized to satisfy all required parameter.
Table 6: Process selection for the head
Mass
Section thickness
Roughness
Economic batch size
Tolerance
Shape
Score
Sand casting
0
1
1
0
1
1
4
Die casting
1
0
0
0
0
1
2
Investment casting
1
0
0
0
0
1
2
Low pressure casting
1
1
0
1
0
1
4
Forging
1
1
1
1
1
1
6
Extrusion
0
1
1
0
1
0
3
Sheet forming
1
0
0
0
1
0
2
Powder methods
1
0
0
0
0
1
2
Electro machining
1
0
0
0
0
1
2
Conventional machining
1
1
0
0
1
1
4
Process
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2.6 Hammerhead Forging
Figure 6: Hammerhead forging
1. The head is made by a process called hot forging. A length of steel bar is heated to about 1,200-1,300 °C. This may be done with open flame torches or by passing the bar through a high-power electrical induction coil.
2. The hot bar may then be cut into shorter lengths, called blanks, or it may be fed continuously into a hot forge. The bar or blanks are positioned between two formed cavities, called dies, within the forge. One die is held in a fixed position, and the other is attached to a movable ram. The ram forces the two dies together under great pressure, squeezing the hot steel into the shape of the two cavities. This process is repeated several times using different shaped dies to gradually form the hammer head. The forging process aligns the internal grain structure of the steel and provides much stronger and more durable piece.
3. During this process, some of the hot steel squeezes out around the edges of the die cavities to form flash, which must be removed. As a final step the head is placed between two trimming dies, which are forced together to cut off any protruding flash. The head is then cooled, and any rough spots are ground smooth.
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4.
In order to prevent chipping and cracking of the hammer head in service, the face, poll, and claws are heat treated to harden them. This is done by heating those areas, either with a flame or an induction coil, and then quickly cooling them. This causes the steel near the surface to form a different grain structure that is much harder than the rest of the head.
5. The heads are cleaned with a stream of air containing small steel particles. this process is called shot blasting. The head may then be painted.
6. The face, poll, claws, and cheeks are polished smooth. This removes the paint in those areas. As part of this operation, the v-shaped slot in the claws is smoothed using an abrasive disc.
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CHAPTER 3
SELECTION METHOD: HAMMER’S HANDLE
3.1 Selection of Hammer’s Handle
For the handle of the hammer, the concern is focused on the failure of the handle beam due to bending load acting on it when there are impact load acted. For this case we will use Material Performances Index method introduced by Ashby to select best material for handle that can sustain high impact load without failure with lightest material so t hat it will not wearing out user’s energy when using it. After the selection of the material w e will proceed on the process selection for handle fabrication.
3.2 Selection of Material Using Material Performance Index (MPI)
In order to choose a material using this method, we should know criteria that must be fulfilled by the component itself. It can divide into material function, constraint, objective, and free variables. All these criteria are crucial to determine performance index of materials. Table 3.1 below will show the function, objective, constraint, and free variables for the handle properties.
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Table 6: Criteria for material selection of the handle using Material Performance Index method
Function
To fasten nail into wood or concrete
Constraint
Length L is specified
Beam must support bending load F without yield or fracture
Objective
Minimize mass of handle
Cross-section area, A
Material
Free Variables
Figure 7: Impact load acting on hammer
Figure 7 shows impact load acting on hammer where the end of the handle assumed to be fulcrum for the hammer body. For initial calculation of material selection, we will construct free body diagram first on the body of the handle as shown in Figure 8.
L
d F
Figure 8: Free body diagram of force acting on handle
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The objective is to minimize the mass, giving the objective function
=
eq 3.1
Then, failure function of the handle beam where the cross sectional of the beam is cylinder. From table A.4 (Materials Selection in Mechanical Design, Micheal Ashby)
= = 32 = 32 =32
eq 3.2
From table A.2
eq 3.3
Deriving objective function to eliminate “area” variable
= = 4 = 4
eq 3.4
Substitute eq 3.3 into eq 3.4. The objective function gives the mass of the beam that will just
= 4 32 support the load
:
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32 = 4 ( ) =. . The mass is minimized by selecting materials with the largest values of the index:
=
3.1.1
Primary constraint:
>10 The handle will expose to extreme condition and it main application is be use for destruction work, for breaking through drywall or masonry walls. So the s trength required will be high and the moment produced will be fairly critical.
<10
The density of the material cannot be too high or it will give trouble for users to use the
hammer as it will increase its weight and will lower the ergonomics value. The head of the hammer will be high so adding weight to handle will be impractical.
3.1.2
Secondary Constraint:
==20
Same condition of the Primary constraints, the strength needed by the handle must be high as the impact force is very high based on its application but the weight should be low as to not giving added weight to the whole component.
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= =20
Figure 9: Selecting material from material selection chart
Based on the material selection chart on Figure 9, we can shortlist some material that can be use such as: 1. Rigid polymer foam
High porosity and not rigid. Rough and will not give good contact with users.
2. Wood
Lightest material compared to other shortlisted material. Easy to process and natural resources that is renewable. No corrosion will take place. The strength of material is lower than most of others.
3. Mg Alloy
High corrosion resistance. Expensive fabrication method.
4. GFRP
Lightweight material and have good strength but fairly ductile material and ri sk of deflection.
5. Al Alloy
Lightweight material. High thermal conductivity, thus will increase temperature of the handle easily when use in hot environment.
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Based on the shortlisted material, we will use material 1 (wood) as it is the lightest material compared to another as the density is the lowest. The density also should be low as it for the ergonomics value of the products. The cost of wood is also relatively cheaper compared to others, easy to process, and have unlimited resources.
3.3 Wood Fabrication Process
In this part, we will focus on the selection of process for cylinder wood production prior to the first assumption that the handle will be cylinder and have free diameter. We will skip on the general process selection as the variability process of wood production is extremely limited. Mostly, wood fabrication will undergo conventional machining to produce shaped wood as wood cannot be melt or turn into powder for shaping.
3.3.1
Primary Stages
Cutting and Pruning
Transport
Bark removing
Sawing
Drying
Planing
3.3.1.1 Cutting and Pruning Trees will be cut normally by a chainsaw to get the wood in the first place.
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3.3.1.2 Bark Removing Bark of the trees will be removed by slicing thin outer bark layer from the log using cutting machine. Bark of trees wouldn’t be used in making up rigid wood structure such as furniture and tools.
3.3.1.3 Sawing Tree’s log will be saw into smaller pieces that called timber. It will be cut into few types of shapes such as wood planks, boards, and beams. In this cas e we will focused on wood planks that will be turn into cylindrical handle.
3.3.1.4 Drying Woods will be dried under the sunlight to reduce the moisture content of wood before its use. The drying process can be done in a kiln but air drying under sunlight is the more traditional method. Woods will be dried mainly is for woodworking and wood burning.
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3.3.1.5 Planing Act as polishing and shaping wood using muscle power to force the cutting blade over the surface of a material to the wood to flatten, reduce the thickness of, and impart a smooth surface to a rough piece of lumber or timber.
3.3.2
Secondary Process In this part, wood will be shaped onto a cylinder and will be fasten onto hammer head
for end use. Basically, it can be break onto two stages which are wood turning and surface finishing.
3.3.2.1 Wood Turning This process will be done using lathe machine where the wood will be turned into cylinder shape. The wood will be turn in high velocity along the center of its cross section (zaxis) where the wood will be held on cross section center end-to-end. Turning velocit y is crucial in order to get high quality surface based on wood texture and properties. Then a cutter will be moved slowly onto its surface where it will cut the surface of the wood and produced cylindrical shape such as shown in Figure 3.4. Mechanism of turning can be seen in Figure 10. The shape of the cut can be varied too according to applicati on as we can see on Figure 11.
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Figure 11: Wood being turn in lathe machine to produce cylindrical shape
Figure 12: Schematic diagram of wood lathe
Figure 13: Variability of shape for wood lathe
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3.3.2.2 Surface finishing Hardwood products are finished to enhance or alter the natural beauty of the wood, and to protect the wood from damage by moisture and handling. A quality finish must offer acceptable performance and meet the project's aesthetic requirements. Wood surface will undergo sanding process to ensure that it will have smooth surface and it done by decreasing the grid level of the sanding process. After that it will be cleaned to remove dust and fiber created during sanding process. Then wood surface will be stain to give better appearance of the surface and provide strength by cover up porosity of the wood, protect from moisture and environment, and also provide extra strength for the wood. A wood stain consists of a colorant suspended or dissolved in an agent or solvent. The suspension agent can be water, alcohol, petroleum distillate, or the actual finishing agent (shellac, lacquer, varnish, pol yurethane, etc.). Surface finishing machine comprises all the process discussed in line as can be seen in Figure 14.
Figure 14: Surface finishing machine including sanding, cleaning, and staining process
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CHAPTER 4
PERFORMANCE AND COST
4.1 Performance and Functionability
The hammer includes a single metal unit having a shaft and a hammer head. A soft handle is fitted to an end of the shaft for gripping. The hammer head includes a body portion connected to an end of the shaft, a head at a front end of the body portion and a V-shaped claw at a rear end of the body portion. The head is a column-like member for hammering. The claw is a taper member with a tip end for crack something, which has a gap at the tip end to draw the nail. The body portion is provided with two slots at opposite thereof, which are parallel to the shaft, and two bores with opposite ends on bottoms of the slots respectively.
Figure 15: A broken hammer due to rust and decomposition
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The frame has two parallel arms and a fulcrum portion with opposite ends connected to ends of the arms. Each of the arms has three bores, and an interval between the neighbouring bores is identical to that between the bores. The arms are received in the slots of the hammer to be moved between a first position and a second position. When the frame is moved to the first position, the bore proximal to the fulcrum portion and the middle bore are aligned with the bores respectively, and when the frame is moved to the second position, the middle bore and the bore distal to the fulcrum portion are aligned with the bores respectively.
Figure 16: Failed when removing nails due to wrong usage
A fastener has a base and pins on the base. An interval between the pins is identical to that between the bores and. Each of the pins has an elastic portion at a distal end thereof, which has a diameter greater than that of the bores and may be compressed to narrow the diameter thereof. The pins of the fastener may be inserted into the bores and of the frame and the hammer the frame on the hammer when the frame is moved to the first position or the second position. When the pins of the fastener are inserted into the bores and the elastic portions are extruded out of the bores of the frame to prevent the fastener from escaping.
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4.2 Cost
Normally, a hammer is designed to function for almost 25 years where some guarantee a lifetime functionability. Every household typically own one hammer and it will last long. For a cost to qualify as a production cost it must be directly tied to the generation of revenue for the company. Manufacturers experience product costs relating to both the materials required to create an item as well as the labour need to create it. In production, there are direct costs and indirect costs. For example, direct costs for manufacturing an automobile are materials such as the plastic and metal materials used as well as the labor required to produce the finished product. Indirect costs include overhead such as rent, administrative salaries or utility expenses. To figure out the cost of production per unit, the cost of production is divided by the number of units produced. Once the cost per unit is determined, the information can be used t o help develop an appropriate sales price for the co mpleted item. In order to break even, the sales price must cover the cost per unit. Amounts above the cost per unit are often seen as profit while amounts below the cost per unit result in losses.
Table 8: Raw material prices as in 2017 Material
Price per tonne (RM)
Wood (Mixed Heavy Hardwood)
830
Low Carbon Steel
2223
One hammer can cost around RM15 and higher considering all aspects and this also depends on the quality and hammer’s head design. Higher quality usually gives better performance also better ergonomic aspect. The handle’s material also plays important role where wood and metals handles cost more than plastic ones.
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4.3 Environmental Impacts A hammer consists of the head and handle which made of low carbon steel and wood respectively. The carbon footprint released must be cal culated from the plantation of trees and extraction of iron until fabrication process. As a hammer generally serves for a long time, no VOC released throughout the time.
Figure 17: Trees and steels are essentials in making of hammer
4.3.1 Impact of wood logging In general, the volume of wood used for a hammer is not high relativel y compared to other products that it directly contributes to deforestation. However, in mass productions this eventually affect environmental problem where according to Maryland University researchers, Malaysia is considered among the highest deforestation rate countries in the world. The logging business have long had a presence in many regions expansive jungles, but the rate of deforestation has increased in the past decade as developers clear cuts the forests. It can be seen from a vantage point high up in the mountains, the scale of the destruction is s triking. As producing hammers’ handle requires tonnes of wood, this too, becomes the issue.
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Figure 18: Logging activities is required to produce raw materials for
hammers
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4.3.2 Impact of Carbon Steel
Carbon steels contain trace amount of alloying elements and account for 90% of total steel production. Among the impacts of producing carbon steels are fossil fuel depletion. This is because during manufacturing process, coal, oil and gas are not being directly used. Instead, electricity used for production purpose is the main factor. Climate change is also the main issue when producing carbon steels. To produce a tonne of crude steel is equivalent to 1.8 tonnes of CO2 according to the World Steel Association. In term of recyclability, most steels manufactures allow for 100% reused materials to be added where 42% of crude steel produced is recycle materials. This helps reducing climate change. Other than that, coke production is one of the major pollution sources from steel production. Air emissions such as coke even gas, ammonium compounds, crude light oil, and sulphur are released from coke ovens. There are a lot of waste when producing steels. Slag, the limestone and irom ore impurities collected at the top of the molten iron, make up the largest portion of iron-making by-products. Sulfur dioxide and hydrogen sulphide are volatized and captured in air emissions control equipment and the residual slag is sold to the construction industry.
4.4 Reuse and Recycle As hammers have a high lifetime, reuse is a normal case where recycle is possible as well. Carbon steels from the head can be recycled into other products where globally, around 85% are recycled. The handles which are made from wood will be decomposing over time depending to environment condition and working habit. This is different to hammers made of polymer, where it has different recycle methods.
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CHAPTER 5
CONCLUSION
The primary objective of the present report is to provide the material and process selection of a hammer tool which merely made from steel and wood using WPI and MPI methods respectively. For the head, it was found that the best material is Low Carbon Steel using Forging for its strength. Meanwhile wood is the selected material for the handle due to its lightweight and good properties. In general, a hammer i s sold around RM15 and can go higher depending on the raw material market price. This report also has successfully discussed the variations of hammer designs, also t he impact of wood and steel productions to the environment. Overall, it gives students the understanding on material and process selections for any applications.
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