What is the portable generator ?
A portable generator is a gas or diesel-powered device which provides temporary electrical power. The engine turns a small turbine, which in turn creates usable electricity up to a certain level of wattage. Users can plug electrical appliance or tools directly into the generator's sockets, or the portable generator can be professionally wired into the sub-panel of a home.
Many construction teams use a portable generator to power tools and lights at a remote site. Sports officials may also bring in a portable generator to aid in night play or to run an electronic timer/scoreboard. Most commonly, residents and businesses left without power after a weather event will use a portable generator to keep vital appliances operating. A portable generator usually has enough power to keep a freezer, refrigerator, television and some lights working.

How Many Watts Do you NeedUse the charts below to determine your wattage requirements for a portable generator.

Generator Manufacturers

Caterpillar is one of the largest industrial equipment and generator manufacturing companies in the world.
Cummins is a international leader in diesel engine and power generateration equipment.
Detroit Diesel is a manufacturer of heavy-duty diesel engines for commercial trucks and diesel generators.
Generac produces industrial, commercial, and residential power generator sets, as well as automatic transfer switches, fuel tanks, and enclosures.
Honda develops a top selling line of portable home, recreational, and construction generator products.
John Deere produces industrial diesel engines that are used by generator manufacturing companies worldwide.
Kohler is worldwide manufacturer of on-site power systems, residential backup, mobile, and marine generators.
Briggs and Stratton provides portable and home generators.
Onan manufactures RV, marine, commercial, home standby, and portable power gensets.
SDMO is an international manufacturer of industrial diesel powered gensets.


Safety Precautions while using the generator There are a few safety requirements that should be adhered to while using a portable generator:

• To avoid carbon monoxide poisoning when using generators one should never run generators indoors, including garages, basements and sheds. Get some fresh air immediately if you start to feel dizzy or weak.
• Generators pose a risk of shock and electrocution, if they are operated in wet conditions. It is advisable to operate the generator under an open, canopy-like structure on a dry surface where water cannot reach it or puddle or drain under it. One should operate with their dry hands.
• For connecting appliances to the generator, use of heavy-duty extension cords that are specifically designed for outdoor use is recommended. The wattage rating for each cord should exceed the total wattage of all appliances connected to it. Extension cords that are long enough to allow the generator to be placed outdoors and far away from windows, doors and vents should be used. The entire length of each cord should be free of cuts or tears.
• One should never store fuel for the generator inside the house. Flammable liquids should not be stored inside living areas rather it should be kept in properly labeled, non-glass safety containers. One should also not store the fuels near a fuel-burning appliance, such as a natural gas water heater in a garage. Gasoline spilled on hot engine parts can cause fire.

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The Axial Piston, Electrically Depressurized, Pressure Controlled, Variable

Displacement Hydraulic Pump Assemblies, Models PV3--240--10, PV3--240--10A,

PV3--240--10C, and PV3--240--10D are engine--driven, inline, pressure--compensated

type units. When employed in an hydraulic system, the pumps provide a low--pulsating

flow of fluid in varying volume and within a predetermined pressure range. The pumps

are capable of operating in either a normal operating pressure range or in a depressurized

range, depending on system demands (see Fig. 1).

The pumps consist of several major components which are enclosed within a mounting

flange, housing adapter block, and valve block and control subassembly.

Mounting flange (1, Fig. 2), located at the coupling shaft end of the pump, is an aluminum

alloy machined casting. Its function is to provide attachment of the pump to the aircraft

engine accessory drive pad. A portion of the hydraulic seal between pump and aircraft

engine is provided by a seal mating ring (2) and retainer (3) which are located in the

mounting flange. Machined recesses in the mounting flange are provided to accept drive

shaft bearing (4) and control spring (5).

Housing (6) contains the pumping mechanism components. These components are

cylinder block (7), nine piston and shoe subassemblies (8), yoke (9), and drive shaft (10).

The drive shaft is supported in the mounting flange by drive shaft bearing (4) and in the

adapter block (11) by roller bearing (12). The cylinder block (7) is coupled with the drive

shaft by internal and external splines. The pumping action is generated by the piston and

shoe subassemblies within the cylinder block and is dependent upon the displacement

angle of the yoke.

Yoke (9) is supported in the mounting flange and swivels through an arc of 0 to 1730’ on

two yoke pintle bearings (15). The angle of the yoke is controlled by controlled fluid

pressure acting on actuator piston (16). Control spring (5) moves the yoke to the

maximum angle (1730’)when outlet fluid pressure is less than previously adjusted value.

Shoe bearing plate (17) supports the piston and shoe subassemblies which are retained

in the yoke by hold--down plate (18), retainer (19), and screws (20).

Wafer plate (13), located between cylinder block (7) and adapter block (11), provides the

valving action to direct fluid flow to and away from the cylinder block.

Case relief valve (21) in the adapter block, permits case fluid to pass directly into the

pump inlet in the event of case pressure surge. In this manner, the housing is protected

from possible rupture.

Impeller (22) is coupled to the drive shaft by impeller key (23). Incorporation of the

impeller permits pump full flow operation with an inlet pressure as low as 5 psig (35 kPa,

absolute).

The valve block and inserts subassembly (24) includes the solenoid--operated

depressurizing valve (26), and outlet blocking valve (27). The inlet, outlet and case drain

ports are an integral part of the valve block and controls subassembly. The inlet and outlet

ports provide the connection between the hydraulic system and the pump. The case

drain port provides connection between the hydraulic system reservoir and the pump.

Four seepage drain ports are provided, three of which are normally plugged. Seepage

drain from the fourth shall not be returned to the hydraulic reservoir.

Adapter block (11) contains the pressure compensator valve (25), case relief valve (21),

and case fill and bleed valve (32). The pressure compensator valve (25) consists

principally of a spring--loaded pilot valve operating within a bushing and an adjusting

screw which controls the preload on the spring--loaded pilot valve. The preload

adjustment determines the system pressure at which the pump begins to reduce its

yoke angle of displacement. Auxiliary piston (28) and control valve (29) activate the pilot

valve when the solenoid--operated depressurizing valve (26) is energized. The case

fill and bleed valve (32) minimizes trapped air pockets in the pump casewhich could contribute

to dry starts.

1. Mounting Flange    2. Mating Ring

3. Retainer                4. Drive Shaft Bearing

5. Control Spring       6. Housing

7. Cylinder Block       8. Piston and Shoe Subassembly

9. Yoke                     10. Drive Shaft

11. Adapter Block Subassembly

12. Roller Bearing     13. Wafer Plate

14.  Spring                15. Pintle Bearings

16. Actuator Piston    17. Shoe Bearing Plate

18. Hold Down Plate  19. Retainer

20. Screws                21. Case Relief Valve

22. Impeller              23. Impeller Key

24. Valve Block and Inserts Subassembly

25. Pressure Compensator Valve

26. Depressurizing Valve

27. Outlet Blocking Valve

28. Auxiliary Piston    29. Control Valve

30. Shaft Seal            31. Coupling Shaft

32. Case Fill and Bleed Valve

_________________________________________

The solenoid--operated depressurizing valve (26) enables the pump to operate in the

normal pressure range or in the depressurized pressure range. The normal pressure

range is 3025 psi (20 857 kPa) and the depressurized pressure range is approximately

1200 psi (8 274 kPa). When the pump is operating as a depressurized unit, a fluid flow of

about 1.5 gpm (5.7 liters/min) is generated by the unit. This flow provides lubrication and

cooling for the pump components. This fluid returns to the reservoir via the case drain

port.

Outlet blocking valve (27) is used in conjunction with the solenoid--operated

depressurizing valve (26) to isolate the pump from the rest of the system during periods

of depressurization, or in event of system failure. The outlet blocking valve will close

when the solenoid--operated depressurizing valve is energized and pump internal

pressure is directed to the back side of the blocking valve piston. The blocking valve will

reopen only after the solenoid--operated depressurizing valve (26) is de--energized.

Shaft seal (30) and other packings prevent external leakage. Shaft seal (30) is located in

mounting flange (1). Coupling shaft (31) connects the pump drive shaft to the engine accessory

drive. The coupling shaft incorporates a shear section to protect the pump

against sudden overload and to protect the engine accessory drive in the event of pump

failure.

The pump identification plate, located on the housing, contains areas for the following

items: model, part numbers, serial number, pump displacement (cu.in/rev), maximum

drive speed (rpm), maximum operating pressure (psi) and an inspection stamp.

Adjacent to the identification plate is a fluid plate which identifies the pump hydraulic fluid

as BMS--3--11 (Alkyl Phosphate Ester Base). The instruction plate, also located on the

housing, alerts personnel that the unit shall be filled with hydraulic fluid before starting.

The rotation plate, located on the mounting flange, indicates that the pump shall be

driven in a clockwise direction, as viewed from the coupling shaft end of the pump.

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Most cooling systems, from residential air conditioners to large commercial and industrial chillers, employ the refrigeration process known as the vapor compression cycle. At the heart of the vapor compression cycle is the mechanical compressor. A compressor has two main functions: 1) to pump refrigerant through the cooling system and 2) to compress gaseous refrigerant in the system so that it can be condensed to liquid and absorb heat from the air or water that is being cooled or chilled .
There are many ways to compress a gas. As such, many different types of compressors have been invented over the years. Each type utilizes a specific and sometimes downright ingenious method to pressurize refrigerant vapor. The five types of compressors used in vapor compression systems are Reciprocating, Rotary, Centrifugal, Screw and Scroll.
We can classify compression process into to types :
(a) Compression by decreasing volume:-

• Required pressure is developed by trapping a gas in a chamber, reducing the volume of the chamber and increasing the pressure of the gas by the ratio of initial chamber to the final volume.

(b) Compression by accelerating fluid :-

• The second method of compressing gases is based on the conversion of kinetic energy into the potential energy. Accelerating fluid to a higher velocity and then decelerating it by changing its direction of flow transforms the accumulated energy into potential energy

We are going to talk about Centrifugal Compressor
Centrifugal Compressors
Centrifugal compressors use the rotating action of an impeller wheel to exert centrifugal force on refrigerant inside a round chamber (volute). Refrigerant is sucked into the impeller wheel through a large circular intake and flows between the impellers. The impellers force the refrigerant outward, exerting centrifugal force on the refrigerant. The refrigerant is pressurized as it is forced against the sides of the volute. Centrifugal compressors are well suited to compressing large volumes of refrigerant to relatively low pressures. The compressive force generated by an impeller wheel is small, so chillers that use centrifugal compressors usually employ more than one impeller wheel, arranged in series. Centrifugal compressors are desirable for their simple design and few moving parts.

• Centrifugal compressor works on the principle of accelerating a gas to a high velocity and converting its KINETIC ENERGY (velocity) into POTENTIAL ENERGY (pressure) by decelerating the gas. The gas enters the eye of the impeller and is accelerated to the outward edge of the impeller as it rotates. It then enters a diffuser where its direction is changed, causing deceleration. This deceleration converts the KE into the PE, pressure. If the gas is to be further compressed, then a return chamber directs it from the diffuser to the eye of the next impeller in series. The gas enters a collector or volute when it is to leave the compression stage. It is discharged to the process through a discharge nozzle.

§ The centrifugal compressor has no connecting rods, pistons and valves; so the shaft bearings are the only points subject to wear. The compressor discharge pressure is a function of gas density, impeller diameter and design, and impeller speed. Centrifugal compressor impellers rotate very rapidly:
                 Low speed                                    3,600 RPM
                 Medium speed                              9,000 RPM
                 High speed                         above 9,000 RPM
Power is supplied by an electric motor or steam turbine. Vapor enters the on the center of impeller around the shaft and is directed through the impeller blades. As the impeller accelerate the gas, by the kinetic energy of the impeller is converted to the kinetic of fast moving gas. As the gas enter the volute, it is compressed, and the kinetic energy is converted to the potential energy of compressed gas. The velocity of the gas leaving the impeller is extremely high.

In order to pass from the low pressure in impeller to the higher pressure of the diffuser, the refrigerant necessarily needs high velocity In absence of sufficient velocity, the refrigerant will stuck in the impeller and the compressor will stall (surge) .
Therefore one of the fundamental parameter of centrifugal compressor design is the “tip speed ‘

Which must be in the range of 240 to 231 m/sec. This parameter determines the speed and the dimension of the impeller:

RPM=[TipSpeed(m/s)*1910]/ Diameter(cm.)
A centrifugal compressor must be specifically designed for the right pressure difference we want to achieve.
Part load conditions are the most critical for centrifugal compressors
Gas speed is even more critical in unloaded condition, when the gas flow decreases and therefore could not be able to overpass differential pressure to the diffuser. If this happens, the flow can go back into the impeller bringing compressor to stall .

One of the most innovative technologies which allows to keep sufficient gas speed also in strongly unloaded conditions and extends unit working range, is the movable impeller discharge technology.

• Based on the type of casing design,centrifugal compressors are classified into two types:

1) Horizontally split casing design(MCL/MCH type):- This design is used for low working pressure below 40ata.These casings are in two halves with horizontal parting plane.DMCL Compressor have two stages of compression in parallel in a single casing.The solution is most balanced.The other aspects of construction are the same as for the MCL Compressor.
2) Verically Split Casing design (BCL/BCH type):-This design is made of barrel construction closed on the sides by end covers with help of studs.This type of construction is suitable for high pressure operations up to 750kg/cm2. Another type of compressor is the PCL(Pipeline compressor),which has casing in the form of a cup with a single closing flange in the vertical plane instead of two as with the BCL.
Example of Designation of BCL Compressor:
Example :        2    BCL   40    7 /  b
2 BCL 40 7 / b

Compressor Components
§ Casing
§ Counter Casing (If Applicable)
§ Diaphragm
§ End Cover (If Applicable)
§ Shaft
§ Impellers
§ Shaft Seals
§ Journal Bearing
§ Thrust Bearing
§ Coupling
COMPONENETS OF BCL COMPRESSOR



Construction of centrifugal compressor:
§ Every centrifugal compressor consist of two parts:- An impeller which forces the gas into the rotary motion by the action of blades, and the casing which directs the gas to the eye of the impeller and then leads it away from the impeller perimeter at a higher pressure. For most multistage compressors, shaft end seals are located inboard of the bearings. The internal passages are formed by a set of diaphragms.
BARREL PULLING ARRANGEMENT

Rotor Assembly

Assembly of Diaphragms in Counter Casing

Assembly of Journal Bearing


BALANCING DRUM
There exists some amount of thrust generated at each impeller because of the differential pressure prevailing across it. The cumulative thrust generated across all the impellers is huge and it needs to be supported by the thrust bearing. The thrust bearing size becomes huge if all the gas thrust has to act on the bearing. For this purpose a rotating element called “Balancing Drum” is incorporated on the rotor. The drum is acted upon by a pressure differential which pushes the rotor in a direction opposite to that of the gas thrust. The thrust so generated balances the thrust produced by the impellers. Amount of balancing depends upon the size of the drum and pressure differential created across it. The pressure differentiated is maintained by an efficient seal placed over the balancing drum.

Cross-section of a BCL Compressor

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This topic isn't like any other one on this blog .Cause what we want to say this time can't be written on one or two internet pages.

We will put Modern Refrigeration and Air Conditioning referance on your hands

We hope that this book can help you if your work or study is related to Refrigeration and Air Conditioning

this book is a ( pdf ) file it's size is about 457 MB

ً We have devided the file into 5 parts 

Every part is about 95 MB

Here you are the download links

1st part

2nd part

3rd part

4th part

5th part

And here you are some related vedios 

Rotary Screw Compressors - Air System Fundamentals

The Compressor

The Refrigerant Circuit

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Welcome to solar city

For an airplane to be controllable, control surfaces are necessary. The 4 main surfaces are ailerons, elevator, rudder and flaps as shown below:

 Focus on the 4 control surfaces ailerons, elevator, rudder and flaps

Before i discuss how every surface effect the plane motion you must know the center of gravity of the plane ( The point from which the weight of the plane effect downwards ) . From this point we can take three axis as shown below .(All 3 axis pass through the Center of Gravity)

As shown  the orange axis (z) When the plane rotates about it then the plane can be turned right or lift .
The  green axis (y) when the plane rotates about it then the plane can move upward or downward .
 The blue axis (x) rotating about it makes the plane roll .


Let's talk about the surfaces ( in the designing of the plane ) that controls these motions . 


1- Elevator:

The elevators control the movement of the airplane about its lateral axis. This motion is called pitch. The elevators form the rear part of the horizontal tail assembly and are free to swing up and down. They are hinged to a fixed surface—the horizontal stabilizer. Together the horizontal stabilizer and the elevators form a single airfoil. A change in the elevator's position modifies the camber of the airfoil, increasing or decreasing lift.
The elevators are connected to the control stick by control cables. Pushing the stick forward moves the elevators downward. This increases the lift produced by the horizontal tail surfaces and causes the nose to drop. Pulling back on the stick causes the elevators to move upward, decreasing the lift produced by the horizontal tail surfaces and forcing the nose upward.


 2 - FLAPS

Flaps are located on the trailing edge of each wing, between the fuselage and the ailerons, and extend outward and downward from the wing when put into use.
The purpose of the flaps is to generate more lift at slower airspeed, which enables the airplane to fly at a greatly reduced speed with a lower risk of stalling. When extended further flaps also generate more drag which slows the airplane down much faster than just reducing throttle power.
Although the risk of stalling is always present, an airplane has to be flying very slowly to stall when flaps are in use at, for example, 10 degrees deflection.

So all these factors are why and how airplanes fly. Radio control model airplanes can of course be more simple - for example, just have rudder and elevator control or perhaps just rudder and motor control. But the same fundamental principles always apply to all airplanes, regardless of size, shape and design.

  3- Ailerons :

Ailerons can be used to generate a rolling motion for an aircraft. Ailerons are small hinged sections on the outboard portion of a wing. Ailerons usually work in opposition: as the right aileron is deflected upward, the left is deflected downward, and vice versa. This slide shows what happens when the pilot deflects the right aileron upwards and the left aileron downwards.
The ailerons are used to bank the aircraft; to cause one wing tip to move up and the other wing tip to move down. The banking creates an unbalanced side force component of the large wing lift force which causes the aircraft's flight path to curve. (Airplanes turn because of banking created by the ailerons, not because of a rudder input). 

 4 - rudder

 for Airplane The rudder is located on the back edge of the vertical stabilizer, or fin, and is controlled by 2 pedals at the pilot's feet. When the pilot pushes the left pedal, the rudder moves to the left. The air flowing over the fin now pushes harder against the left side of the rudder, forcing

the nose of the airplane to yaw round to the left .And the same thing happen when the pilot pushes the right pedal but to right .



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Welcome to solar city
A pattern is a shaped form of wood or metal around which sand is packed in the mold. When the pattern is removed the resulting cavity is the exact shape of the object to be cast.
The pattern must be designed to be easily removed without damage to the mold. It must be accurately dimensioned and durable enough for the use intended. Either one time use or production runs.PATTERN MAKING
Each different item we wish to cast presents unique problems and requirements. In a large foundry there is a close relationship between the pattern maker and the molder. Each is aware of the capabilities and limitations of his own field.
Throughout the industry, pattern making is a field and an art of it's own. The pattern maker is not a molder nor the molder a pattern maker. This is not to imply that the pattern maker cannot make a simple mold or the molder make a simple pattern but each may soon reach a point in the other's field beyond his own skill and experience.

In the hobby or one man shop, however, pattern and mold making are so closely interrelated as to become almost one continuous operation. This chapter will acquaint you with some of the various types of patterns and their requirements.

Types of Patterns

Patterns can be of different types depending on the shape and size of the part to be manufactured. Given below are some of the commonly used pattern types.

• A solid pattern is the most simple of all and is used to make simple shapes. As the name itself suggests, a solid pattern is a single solid piece without any subparts or joints.

• Shapes which are more intricate are manufactured using patterns which are made out of 2 or more pieces. These pieces are aligned together with the help of dowel pins, and such patterns are known as split patterns

• Sometimes it is convenient to produce multiple parts in one go and a single pattern is used to make the cavity for all the part spaces. There are runners between these pieces, which are also known as gates. Hence these patterns go by the name of gated patterns.

• In several cases it could be economical to save the money and efforts of making the full pattern because of symmetry. The cavity in such a case could be made by sweeping the pattern (which is a part of the full shape) around a central axis, hence these are known as sweeping patterns.

The above list is not exhaustive and there are several other types of patterns as well such as loose piece patterns, follow board and odd-shaped patterns which are used for different situations. Yet the description above should have given a broad idea to the reader about the patterns, their types and usefulness in the casting manufacturing process.
The two images show a solid pattern and a split pattern (both having same shape)


We will talk about wood pattern
Wood patterns used for sand casting are given several coats of Orange Shellac to which a pinch of oxalic acid has been added. This gives them a good waterproof smooth hard surface.
The majority of wood patterns are made of white pine (sugar pine) as it is easily worked and when shellacked properly will not warp under ordinary foundry use.
The approximate weight of a casting can be determined by weighing the wood pattern and multiplying by the appropriate factor indicated. Aluminum 8, cast iron 16.7, copper 19.8, brass 19.0, steel 17.0.
A white pine pattern weighing 1 lb, when cast in aluminum will weigh 8 pounds, in brass 19 pounds etc.

The first thing to do is to choose your PARTING LINE

Parting direction of a mold segment is the direction generally along the axis of the mold segments and is introverted from the adjoining mold segment. Draw direction is the other name of parting direction.

Parting surface is known as the surface of contact within any two segments of the mold.

Parting line is the line where parting surface meets with the casting surface of the mold. After choosing your parting line you now are going to make the pattern . When you are going to make the pattern you must add three allowances  to

the dimensions :

1* Machining allowance .
2* Draft allowance .
3*shrinkage allowance .

• . 1-Machining allowance : and we take it from this table :

This is a simple table

Metal	dimension (inch)	allowance (inch)
Cast iron	Up to 12 12 to 20 20 to 40	0.12 0.20 0.25
Cast steel	Up to 6 6 to 20 20 to 40	0.12 0.25 0.30
Non ferrous	Up to 8 8 to 12 12 to 40	0.09 0.12 0.16

The finish and accuracy achieved in sand casting are generally poor and therefore when the casting is functionally required to be of good surface finish or dimensionally accurate, it is generally achieved by subsequent machining. Machining or finish allowances are therefore added in the pattern dimension. The amount of machining allowance to be provided for is affected by the method of molding and casting used viz. hand molding or machine molding, sand casting or metal mold casting. The amount of machining allowance is also affected by the size and shape of the casting; the casting orientation; the metal; and the degree of accuracy and finish required.

and this a simple example:

The casting shown is to be made in cast iron using a wooden pattern. Assuming only machining allowance, calculate the dimension of the pattern. All Dimensions are in Inches

The machining allowance for cast iron for size, up to 12 inch is o.12 inch and from 12 inch to 20 inch is 0.20 inch .
For dimension 18 inch, allowance = 0.20 inch
For dimension 14 inch, allowance = 0.20 inch
For dimension 8 inch, allowance   = 0.12 inch
For dimension 6 inch, allowance   = 0.12 inch
The pattern drawing with required dimension is shown in Figure below

2-Draft allowance :


By draft is meant the taper provided by the pattern maker on all vertical surfaces of the pattern so that it can be removed from the sand without tearing away the sides of the sand mold and without excessive rapping by the molder. Figure  shows a pattern having no draft allowance being removed from the pattern. In this case, till the pattern is completely lifted out, its sides will remain in contact with the walls of the mold, thus tending to break it.



 Figure below is an illustration of a pattern having proper draft allowance. Here, the moment the pattern lifting commences, all of its surfaces are well away from the sand surface. Thus the pattern can be removed without damaging the mold cavity.

We take the draft allowance from this table :

Pattern material	Height of the given surface (inch)	Draft angle (External surface)	Draft angle (Internal surface)
Wood	1 1 to 2 2 to 4 4 to 8 8 to 32	3.00 1.50 1.00 0.75 0.50	3.00 2.50 1.50 1.00 1.00
Metal and plastic	1 1 to 2 2 to 4 4 to 8 8 to 32	1.50 1.00 0.75 0.50 0.50	3.00 2.00 1.00 1.00 0.75

3-Shrinkage allowance

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A shrinkage allowance for metal casting is something that must be figured into a design from the very beginning. As the molten metal cools and solidifies it will begin to contract. This means that although the molten metal completely filled up a mold, by the time the casting was cold, the casting is smaller than the mold.
What this mean is that a pattern must be made larger than the design drawing. The difference between the size or dimensions of the desired casting and the size of the pattern used to create the mold is called a shrinkage allowance.
The shrinkage allowance for metal casting varies by the type of metal. It takes experience in metal casting to be able to accurately judge the proper shrinkage allowance to be built into a pattern. Below is a basic shrinkage allowance and pattern oversize factor chart based on metal type.

Metal	Pattern Oversize Factor	Finish Allowance	Win Wall mm/(in)
Aluminum	1.08 – 1.12	0.5 to 1.0%	4.75 (0.187)
Copper Alloys	1.05 - 1.06	0.5 to 1.0%	2.3 (0.094)
Gray Cast Iron	1.10	0.4 to 1.6%	3.0 (0.125)
Nickel Alloys	1.05	0.5 to 1.0%	N/A
Steel	1.05 – 1.10	0.5 to 2%	5 (0.20)
Magnesium Alloys	1.07 – 1.10	0.5 to 1.0%	4.0 (0.157)
Malleable Irons	1.06 – 1.19	0.6 to 1.6%	3.0 (0.125)

The shrinkage allowance for metal casting is linear meaning that these allowances apply in every direction. In addition, the shrinkage allowances in the chart above are approximations. The actual size and shape of the casting actually determines the actual shrinkage allowance.
To complicate things further, different parts of a casting may require a totally different allowance. This is often found in the portion of the casting that is at the very top of the mold where impurities and air bubbles end up when the molten metal is poured.
If a casting is to be sand cast, then often the rough surface of the final casting will require surface finishing. Thus a machining allowance or “finish allowance” must also be configured into the casting pattern.
After taking all these allowances we make this table for the dimensions of our pattern .

Nominal Dimensions	Machining allowance	draft (Taper )allowance	Shrinkage allowance	Total pattern Dimensions
PARTING LINE Dim.
		0.0
		0.0
		0.0
		0.0
		0.0
		0.0
		0.0
		0.0

NOTE >>> We take add the draft allowance only to the parting line dimension .
               Fill the table with your pattern dimensions .
The new dimensions now that you will take to make the pattern is in the last column of the upper table .
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Aluminium Alloy




There are many kinds of Alloys to choose from but often, Aluminium is chosen as it is lightweight (about 2700 kg/m3 density), it is comparatively soft and its process-ability is good. From a machining viewpoint pure aluminium (JIS A1000) greatly differs from Al-Cu alloy (JIS A2000) .
Pure aluminium is easy to bend but it is difficult to process as it is too soft and easily clogs cutting tools. On the other hand, the Al-Cu alloy, such as A2011 or A2017 (called duralumin) is easy to handle and cut with several of the grades having strength similar to that of steel. However, one of the drawbacks of aluminium is that it is difficult to weld, solder and bend.
It is very difficult to distinguish between the pure aluminum, the Al-Cu alloy and etc. When they are cutting with a machine, we may recognize the material.(₁₃Al) is a silvery-white metal with many desirable characteristics. It is light, nontoxic (as the metal), nonmagnetic and nonsparking. It is somewhat decorative. It is easily formed, machined, and cast. Pure aluminium is soft and lacks strength, but alloys with small amounts of copper, magnesium, silicon, manganese, and other elements have very useful properties. Aluminium is an abundant element in the earth's crust, but it is not found free in nature. The Bayer process is used to refine aluminium from bauxite, an aluminium ore.

Pure aluminium has a tensile strength around 50 MPa but this can be increased perhaps ten-fold by alloying plus thermal treatment and/or mechanical working. The major alloying elements are manganese (Mn), magnesium (Mg), copper (Cu), zinc (Zn), and silicon (Si). These attributes of alloying, heat treatment and cold working produce a selection of the most versatile and easily formed materials available to the homebuilder.
When pure aluminum surfaces are exposed to the atmosphere, a thin invisible oxide skin forms, permanently protecting the metal from further oxidation; this resistance to normal atmospheric corrosion also applies to the alloys. However there are other types of corrosion and the alloys' resistance to these depend on the alloying elements; see the section on corrosion below.
There are a number of national systems for designating the many available aluminium alloys but the American Aluminum Association's four digit numbering system is universally recognized. In this system, and except for the near pure 99%+ aluminium, the major alloying element is indicated by the first digit thus:
      1nnn     Aluminium content greater than 99%
      2nnn     Copper
      3nnn     Manganese
      4nnn     Silicon
      5nnn     Magnesium
      6nnn     Magnesium-silicon
      7nnn     Zinc
      8nnn     Other
In the 1nnn group the last two digits represent the purity above 99% thus alloy 1030 is 99.30% pure aluminium.
Some aluminium alloys in sheet metal form, are manufactured with an added surface foil of near pure aluminium to provide a sacrificial corrosion resistant surface. For the thin (maybe 0.6 mm/0.025 inch] aluminium sheet used for light aircraft skins the layer is very thin, perhaps 25 micron/0.001 inch; generally the layers form about 10% of the total thickness i.e. 5% on each side and impart a mirror-like finish. Such material is identified as 'Alclad' [a trade name] or 'clad' and a non-clad form may be identified as 'bare'. Some sheets of less corrosion resistant alloys may be clad with a more resistant alloy rather than the near pure aluminium.
--> The following alloys, although far from specific to the aircraft industry, are prominent in light aircraft construction but there are many others and selection is generally a matter of balancing particular needs, availability, strength, weight and cost. Very thin aluminium sheet (perhaps 0.5 mm and below) is easily damaged#151; even by rather light hail. The lower strength materials are probably more readily available, and certainly cheaper when measured in $/kg, but then thicker dimensions will be needed to meet flight loads, thus more weight and more cost.
One square metre of 1.0 mm thick aluminium alloy sheet weighs about 2.7 kg so 0.5 mm sheet would weigh 1.35 kg/m². If an aircraft's wing area is 8 m² then about 16 m² of sheet is used in the skin [top and bottom]. Using an expensive high strength 0.5 mm alloy the skin weight is 21.6 kg; if the builder opted for a weaker less expensive alloy and increased the thickness to 0.8 mm to compensate then there would be a 13 kg weight penalty. Unnecessary additions to airframe weight detract from aircraft performance (range and rate of climb for example) and add to ongoing operating costs associated with the increased fuel consumption; so those factors must also be taken into consideration.

Alloy 2024: an alloy [heat-treatable to high strength] of copper-magnesium-manganese [Cu 4.5%, Mg 1.5%, Mn 0.6% plus a number of other elements] which, many years ago, was introduced to replace 2017 (Duralumin) in aircraft structures and is available in forms including bars, plates, rolled shapes and both bare and alclad sheet. The bare 2024 material has poor corrosion resistance so it is usually purchased in the alclad form, which can be recognised by that mirror-like finish; but slight skin damage will expose the 2024 metal to corrosion. Alloy 2024 is the standard commercial aircraft structural material; it is also used for stock components like (expensive) spring aluminium undercarriage legs.
Alloy 6061: a magnesium-silicon alloy ( Mg 1.0%, Si 0.60%, Cu 0.25%, Cr 0.25%) that develops strength through heat treatment and has good corrosion resistance. A very versatile alloy preferred for shapes such as extrusions, angles and channels for spar caps and longerons, drawn tubes [see following note], bars and skin material. The high silicon content provides good fatigue resistance and the 6061-T6 alloy is easy to work in the home workshop. Though expensive, 6061-T6 is probably the most common alloy used by homebuilders because of the availability of forms and sizes. Alloy 6082 is similar and probably the strongest of the readily available 6000 series alloys. Aluminium can be built into an airframe structure using metal fasteners, welding and even epoxy bonding but simple hand air-gun riveting predominates in all-metal aircraft, so ease of drilling very large numbers of accurate holes in very thin sheets and thicker angles is an important characteristic.
Note: the more expensive drawn tubing generally has higher strength and tighter tolerances than plain extruded or rolled tubing. After extrusion the material is "drawn" through one or more die-and-mandrel stations to strengthen the grain structure and to ensure uniform diameter and wall thickness.
Alloy 7075: a very high strength zinc, copper and magnesium alloy with an exceptional strength/weight ratio, but difficult to work and very difficult to weld, and has poor corrosion resistance unless clad. Mainly used in the aerospace industries in plate, rod and bar forms for high quality machining of parts, but not normally used in home-built aircraft, except perhaps for purchased components such as (very expensive) spring aluminium undercarriage legs for heavier aircraft.
Alloy 3003: a widely used manganese alloy, sometimes used for aircraft skins and for pitot and similar fluid lines because it is readily flared and bent. It is about two-thirds the price of 6061-T6 and half the price of 2024-T3 clad but not heat-treatable and thus weaker.
Alloy 5005: a magnesium based alloy with similar properties to 3003.
Alloy 5052: another magnesium based alloy which is the highest strength alloy of the common non heat-treatable grades and has particularly good resistance to the sea atmosphere and salt water corrosion. It is highly workable, fatigue resistant and finds application in fluid lines, fairings, engine cowlings and similar formed parts.

Heat treatment in manufacture. The 2nnn, 6nnn and 7nnn alloys are heat treatable, that is they develop strength through various thermal treatments during manufacture. The basic heat treatments for these alloys are identified by the designation 'T' plus a number and this temper condition is added to the alloy designation, thus '6061-T6'. Additional numbers may be appended to identify variations on the basic processes. The heat treatable alloys are generally unsuitable for welding,
The term solution heat treatment refers to a thermal hardening process where the material is soaked at fairly high temperatures for a number of hours during which the alloying elements are put into solid solution, i.e. some of the alloying element's atoms replace aluminium atoms within the normal aluminium crystal lattice. Usually the temperature is then rapidly lowered [quenched] which leaves an unstable structure. Aging is the process of allowing the material to rest without load at room temperature while the internal structure stabilizes itself.

• T1 — naturally aged to a substantially stable condition. Applies to products for which the rate of cooling from an elevated temperature-shaping process, such as casting or extrusion, is such that their strength is increased by room-temperature aging; rather than artificial aging in a low temperature oven for perhaps 24 hours.
• T2 — annealed (cast products only). Designates a type of annealing treatment used to improve ductility and increase dimensional stability of castings.
• T3 — solution heat-treated and then cold-worked. Applies to products that are cold-worked to improve strength. For example 2024-T3 cold-rolled sheet material.
• T4 — solution heat-treated and naturally aged to a substantially stable condition. The most common form of driven rivet is manufactured from 2117-T4 wire but the riveting process is a cold working or strain hardening process which results in the strength of the driven rivet being equivalent to T3.
• T5 — artificially aged only. Applies to products that are artificially aged after an elevated-temperature rapid-cool fabrication process, such as casting or extrusion.
• T6 — solution heat-treated and then artificially aged by sequential heating to around 175° C. Applies to products that are not cold-worked after solution heat-treatment and are readily available in many forms at affordable prices. For example 6061-T6 bars, rods, angles, tubes and sheet.
• T7 — solution heat-treated and then stabilized.
• T8 — solution heat-treated, cold-worked, and then artificially aged.
• T9 — solution heat-treated, artificially aged, and then cold-worked.
• T10 — artificially aged and then cold-worked.

When welded the heat-treated alloys lose maybe 30% — 40% of their strength in the weld area, which cannot be recovered in a home workshop environment and must be compensated for in the joint design.
Non heat-treatable alloys: there are different designations for those alloys which have their mechanical properties adjusted by strain hardening [cold working] rather than thermal treatment. Cold working entails such processes as rolling [stretching], compressing or drawing to change the shape of the material. The letter “H” is followed by 2 or more digits, the first indicates the particular method used to obtain the temper as follows:

• H1 — strain hardened
• H2 — strain hardened, then partially annealed
• H3 — strain hardened, then stabilized.

The degree of strain hardening is indicated by the second digit:

• 2 — quarter hard
• 4 — half hard
• 6 — three quarter hard
• 8 — full hard
• 9 — extra hard.

Thus 5052-H32 indicates the alloy has been strain hardened then stabilized and is quarter hard.

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