Manuf. Report 2010

8/7/2019 Manuf. Report 2010

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REDUCTION BOX

Introduction

First of all we decided to make a reduction box in order to understand casting and

machining processes. The movement in reduction box will enter from point of A and it turn up

from point of B. We are trying to increase or decrease power by using this box.

Processes

1. Preparing GearsWe started our project by founding

two appropriate gears, we found two tractor

gears. (In the picture the gear on the right is

after the cutting process. And the left one is

before cutting)


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After that we measured the gears with vernier caliber. We write down all diameters and

dimensions of our gears. Now, two things are important for us, one of them is gears inner

diameter because we need to apply turning process in it and second important thing is gears

outer diameter since we have to place it into a box.

Because we have to think about our box and how we are

going to fit our gears in it so we have to think about

machining. First of all, we cut unnecessary outer parts of

our gears by using cutting machine. Final shape of our

gears can be seen in the picture above.

2. Preparing ShaftsBy using the inner diameter of our

gears, we found two cylindrical iron

parts to make our shafts. First of all we

reduced the length of two shafts by using

cutting machine as seen in the picture.

The cutting tool that we used to

cut gears unnecessary parts.


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Then we reduced the

diameter of one of the shafts and

equalized with the other shaft

diameter by using lathe machine

as seen in the picture.

Then we selected our bearings according to shaft diameters and bought them from the related

market. We will need them when placing gears and shafts into the box.

3. Preparing Pattern for Reduction BoxWe have drawn the shape of our box in solidwork for casting by using our shaft and gear

dimensions. We decided how the dimension should be, before drawing in solidworks we draw it

by hand on a plain paper with showing dimensions on it.


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By using our solidworks drawing, we went to woodshop and prepared our pattern from

wood. Wooden pattern seem more possible to make for us in Magosa, we make our pattern from

two parts because it is a complicated shape and one part would require big and complicated core,

which is almost impossible to make. We made it from five parts. Each for one side and another

part for the bottom of the box. Since two each sides are identically same, 3 parts of pattern will

be enough for us to make our casting, but we make the hole pattern which is five parts to see the

complete shape of our pattern box. Casting from three parts doesnt require any core. While

making our patterns we havent make holes in it for shafts since it is difficult to make the pattern

in that way and do the casting process with a pattern complicated with holes. We decided to

make the holes on two side of the box afterwards with machining on milling machine when the

casting is complete so we havent make holes on our pattern.

As can be seen from the photos we cut the wood in required dimensions and combined necessary

parts by screws.


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Finished pattern can be seen from

the photo. We make the pattern

piece by piece because it is not

possible to make it as a whole.

There are five parts ready for

casting operation as seen. Four

side parts and one bottom part.

We decided to make our reduction box from aluminum to carry the gears. We chose

aluminum because it has lower melting point temperature compare to most of other metals so

aluminum casting requires less temperature and it is more makeable in our case.

4. DifficultiesUnfortunately it wasnt possible for us to make it from aluminum because it is a very big and

large part so it was going to cost too much for us. It required 15kg`s of aluminum so we had to

leave our casting process for reduction box. Also we didnt have any alternatives in Magosa to

do our casting from any other proper material with cheaper cost. In order to understand casting

process we decided to make a sand casting process with a ready and simple pattern by using lead

in our workshop.


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SAND CASTING

OVERVIEW

In our project, our aim is to make a shape by sand casting and to practice what we have

learned. For sand casting, the most common metals used are iron, steel, bronze, brass and

aluminum. But we used lead (Pb) because it has low melting point and easy to use while casting

in our workshop. Sand casting can produce small parts that weigh less than one pound or large

parts that weight several tons. The process is used to make medium to large parts such as valve

bodies, plumbing fixtures, locomotive components and construction machinery. Its versatility

also allows sand casting to produce small parts such as buckles, handles, knobs and hinges. It is a

cost effective and efficient process for small lot production, and yet, when using automated

equipment, it is an effective manufacturing process for high-volume production.

Sand molds are created using various materials, the sand must be bonded together using

either synthetic compounds or clay and water and molds must be rebuilt after each casting.

The design of molds is a very complicated process; however, in general, they are filled

simply by gravity without the need for any pressure differentials or mechanical action.

Casting is generally the quickest way to produce either a small amount of prototypes or

very production quantities. The casting process is used by almost every industry as all metal can

be cast. Molten metal is poured into the mold cavity formed out of sand (natural or synthetic).

Many casting processes use patterns that form the cavity of the mold and can be made of

wood, plastic, metal or other materials. Pattern which are expandable (consumed by the mold

making process or by the poured metal during casting) are made of wax, plastic, or polystyrene

foam. Patterns are oversized to make up for metal shrinkage as it solidifies.


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PROCEDURES

Step 1

We prepared our sand mixture by sieving it into small parts by hand. Also, we used sieving

machine as seen for even more smaller sand particles. The more our sand gets smaller, the more

our final product gets good surface finish.

Step2

We placed our pattern in the middle of our flask part, we used some powder on to pattern. We

filled the flask with sand and applied some pressure on it to press the sand. We also used a metal

plate to smoothen the sand surface and we used powder again on it to easy separation of flask

parts.


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Step3

We turned upside down the flask part remaining cavity of the packed sand has desired shape of

our cast part. And we placed two metal cylinders for risers. Risers prevent this by providing

molten metal to the casting as it solidifies, so that the cavity forms in the riser and not the

casting. We closed second part of the flask. We filled the second flask part with sand too and

then we applied pressure on it and pressed the sand.

Step4

And then we removed the cylindrical parts. We separated the flask parts and removed our

pattern. We can use the pattern again in other casting operations. We make the runner between

the riser and the cavity.


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Step5

We closed the second flask part on it. We made our downsprue to prevent splashes. The cope

and drag are then combined and are ready to accept the metal.

Step6

Then we melted our lead metal (300 C) and prepared it for pouring. During this procedure we

cleaned the liquid lead by separating the obstacles from it. Then the molten metal is poured into

the mold.


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The part is allowed to sit and cool. Since, we used lead. Our metal solidified quickly so we only

waited a couple of minutes. Once the casting is cooled we destroyed the sand mold in order to

remove our part from the mold. The sand can be recycled for future processes. Then we removed

our part from risers and cleaned it from sand. And finally our part is ready.

Step7

We had our part made from lead in the

end but it needed some machining to

remove unnecessary parts. We used file

to remove them. We could have used

grinding machine to fasten the process

but since we used Lead it wasnt

possible for us to use it.


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OBSERVATION

We observed that sand casting provided us a good accuracy and good surface finish. It is

hard to produce complex part shape because making core is difficult and expensive. But in our

case, it was on easy procedure because we made a simple shape in order to understand the

casting process in general. Sand can be reused again, but a new sand mold must be made for each

part produced.

CONCLUSION

In this report we have tried to explain our work when making reduction box and casting

project. We had our shape in the end which is a thermometer base for decorative use which can

be considered to be in a good shape but it still needed some machining. We saw some errors in

our part, but our aim is not producing excellent parts. Our aim is just analyzing the errors in our

casted part. Usually a weight is put onto the part during and after pouring. But we havent

considered about it so we have some unnecessary part caused by molten lead flowing between

two flask parts. In other words we had some empty space between flask parts. So it needed some

job with the file. As a conclusion we can say that we saw our mistakes, we analysed our errors

and we finished our casting project.

Manuf. Report 2010

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Transcript of Manuf. Report 2010