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Write a short paragraph (120-140 words) about different kinds of couplings using the following suggested questions.

How many kinds of couplings do you know?

What are they used for?

What are their components?

What are their main features?

What are their applications?

Answer

Coupling is a machine component used to transmit power from one shaft to another. The input shaft connects to the power source. The output shaft connects to the destination. There are two primary types of couplings: Rigid couplings and Flexible couplings. Rigid couplings align the shafts with each other with perfect alignment they help to reduce wear on the machine. Rigid couplings maximize performance and efficiency. Sleeve-style couplings are the most rigid coupling. Flexible couplings transmit power without perfect alignment. These can accommodate several degree of shaft offset. Flexible of couplings help reduce noise and unwanted vibrations. Couplings are used in machine motors and engines.

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Write a short paragraph (120-140 words) about different kinds of bearings using the following suggested questions.

How many kinds of bearings do you know?

What are they used for?

What are their components?

What are their main features?

What are their applications?

Answer

Bearing is a machine component uses to support loads. There are two main types: Rolling Contact Bearings and Journal Bearings. Rolling Contact Bearings uses roller to support loads. They have an inner and outer race. There are 4 typical types of Rolling Contact Bearings: ball bearings, straight roller bearings, tapered roller bearings and thrust roller bearings. Ball bearings use spherical rollers. They support radial and axial movement. Straight roller bearings use cylindrical roller. They support radial motion. Tapered use conical rollers. They support radial forces and moderate thrust forces. Thrust roller bearings use barrel-shaped rollers. They support thrust motion. Journal bearings have no rolling elements. Their shaft rotates inside an alternate lubricated sleeve. Their load-carrying capacity is high.

Bearings are used in machine motors and industry engines

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Write a paragraph (120 - 140 words) about different types of gears using the following suggested questions.

·       What is a gear?

·       What are its functions?

·      How many common types of gears are there?
. What are they?

·       What are their features?

·       What are their applications?

Answer

Gear is a machine component with teeth which is used to transmit torque, change speed, torque and direction of a power source. There are 5 common types of gears: Spur gears, Helical gears, Worm and worm gears, Rack and pinion gears, Bevel gears. Spur gears have teeth projecting towards or away from the center, they are used in low-speed application and they can't control noise at high speed. Unlike spur gears, helical gears have their teeth cut in a spiral shape, they are used in high-speed applications or large power transmission, they run more smoothly and can control noise. Worm and worm gears, their worms have just one continuous tooth and pair with a worm gear, they are used to reduce speed. Rack and pinion gears are used to convert rotational motion into linear motion. And bevel gears usually used to transmit rotational power through shafts at an angle, normally 90 degrees.

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Write a paragraph (120 - 140 words) to compare two types of drives using the suggested questions below.

·     What are two types of drives?

·      What are the functions of each type?

·      What are the differences between them (materials,   operation, slippage, efficiency, maintenance, etc.)?

·       What are some applications of each type?

Answer

There are 2 main types of drives: belt drives and chain drives. They are both used to transmit motion and power from one shaft to another. Belt drive is usually made of rubber, plastic ... while chain drive is often metal. The operation of belt drive is different from that of chain drive as it can reduce noise and vibration. Slippage occurs in belt drive when load exceeds frictional force and no such slippage occurs in chain drive. As a result, efficiency of chain drive is high, usually above 95% while belt drive is comparatively low due to frictional loss. Chain drive requires regular maintenance and belt drive requires minimum (frequent re-tension). Applications of belt drive are flour mills, coolant pump, lathe machines and a lot of other machines. Chain drive is used in bicycle and motorcycles.

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Write a paragraph (120 - 140 words) to compare CAD and manual drafting using the suggested questions below:

·        What is CAD and manual drafting?

·        Compare CAD and manual drafting (functions, advantages and disadvantages)

Answer

Manual drafting is simply known as the practice of creating drawings by hand, you use pens, rulers and erasers to create the drawing. CAD stands for Computer-Aided Design which is the use of computer to aid in the creation, modification, analysis, or optimization of a design. In general, CAD can solve all of the difficulties you meet when draft manually. CAD helps you produce very accurate designs, the error is very small. Your drawings can be created in 2D or 3D. It support PDES and IGES, CAD program also has the ability to create exploded views of machinery parts. However, CAD has some disadvantages too. You have to have a computer to use a CAD program. Nowadays lots of people have the ability to access to computer but in some remote areas few engineers don't. Moreover, with some people a CAD program is not easy to use, it will take them few days or months to get used to using it.

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Write a paragraph (120 - 140 words) to describe a specific CAD program using the following suggested questions.

·        What is the name of the CAD program?

·        What are its features?

·        What are its functions?

·        What are its advantages and disadvantages?

Answer

Today I want to talk about a CAD program called Siemens Nx. Nx first time released in 1973, it is a simple, useful and powerful software. It's used in aerospace and automotilve companies. The functions of Nx including creating drawings, 2D or 3D models, editing data and collecting multiple design elements into a single feature. Nx brings us a lot of advantages. It's fast and flexible, it helps reduce the companies mistakes and maximize the productivity. It can also track your product through every phase of the production cycle easily. However, before you can use Nx, you have to be trained professionally. Nx is also can not be able to handle super complex parts or assemblies. So overall, Nx is a very useful program for drawing, make it more easily for companies and factories to design. It's suitable for engineers who work in mechanical fields.

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Look at the diagram, write the manufaturing process of a check valve (120 - 140 words).

Use some useful languages of sequence and the time clause when, as, before…… as followed.

The check valve is made of cast iron.

First...............

The cast iron is then ……r………….

Next,…………………………..

After drilling……………., the next step is………………….

Finally/ the final step…………………………………………

This is when we make sure that the part is made properly.

Answer

The check valve is made of cast iron.

First step is casting, hot iron is poured into a container and cooled to make the correct shape.

The cast iron is then turned on a machine called a lathe. Part of the materials removed to make the correct shape.

Next, that process step is drilling, the check valve is drilled to make holes.

After drilling process, the next step is painting, the surface of the check valve is covered with paint.
Next is bolting process, pieces of iron are joined together using nuts and bolts

The final step is inspection.

This is when we make sure that the part is made properly.

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The manufacturing process of a car wheel

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The manufacturing process of a car wheel

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Write a paragraph (120-140 words) about basic information of plastic (qualities and uses of plastic) using the following suggested questions.

·        What is plastic?

·        What are the properties of plastic?

·        What could/ couldn’t people do with plastic in the past? What can/ can’t people do with plastic now? What is the future of plastic?

·        What are the advantages/ disadvantages of plastic?

Answer

As far as I know, plastic is a synthetic material that uses polymers as a main ingredient. Plastic is able to be molded or shaped to any forms. It’s versatile, lightweight, durable and some kind of plastic are saft . In the past, people couldn't sort plastic and
didn't recycle plastic. Now, people can sort and recycle plastic into products
that use everyday. In the future, people can create plastics that are not
harmful to the environment. The advantage of plastic is that it is convenient
because it is used for shopping plastic bags,moreover it is durable and
resistant to all kinds of adverse outside factors as rain or storms. The
disadvantage of plastic is that it has a low melting point, which is harmful to
the user’s health.

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Write a paragraph (120-140 words) about your understanding of plastic.

You should mention the seven types of plastic and their codes, a common type of plastic with its properties and its applications.

Answer

As far as I know, plastic is a synthetic material, that uses polimers as a main ingredient. Plastic is able to be shaped or formed any forms. There are 7 main types of plastics inluding PET, HDPE, PVC, LDPE, PP, PS, orther plastic. But the most popular plastic is PET. PET plastic is made of polyethylence terephthalate. PET is widely used because it has some properties as oxygen prevention, widely recycled and it is safe for health of users. It mostly used for food and drink containers and medical applications bsecause oxygen prevetion property help them don’t react with air, water or some various chemicals. Beverage bottles are among the main plastic items that use PET, this plastic is safe for user’s helth. Also, PET bottles are the most easily recycled plastic in the world. they will be recycled and remanufactured into new products. Plastic are a useful and important material with life and production. but beside that, using much plastic everyday, we may face a lot of plastic problems and we need to solve them.

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https://drive.google.com/file/d/1ST2ZU4vS9cfN44ZCzFdqss7xeXuY1EiQ/view?usp=drive_link

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Get access to files anywhere through secure cloud storage and file backup for your photos, videos, files and more with Google Drive.

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Write a paragraph (120-140 words) to describe the following plastic moulding process using the diagram below

Suggested questions:

·        What is the name of process?

·        How many steps are there in the process? What are they?

·       Describe each step.

ANSWER

The most common process of plastic moulding is the injection moulding process. the injection molding products are accurate in size, easy to be replaced, and can be formed into complex shapes. There are 5 steps to in the moulding process. The first step is feeding. In this step, the pellets of plastic are fed from the hopper into a cylinder. In the second step is plasticization, pellets are pushed along  the cylinder by a rotation screw, and heated to create  moulten plastic. Then the screw stops rotating and a ram in fornt of the screw moves straight forward. The next step is the injection, the soft and warm platic are pushed toward a nozzle by the ram. They are injected through the nozzle into a shape cavity in the mould. After the plastic is filled the cavity, the plastic is transferred the cooling step. In this step, the plastic is cooled  in the mould and becomes hard, strong. The final step is ejection, the mould opens and plastic shape is ejected. Those are the basic steps in the injection moulding process.

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From my point of view, there are 3 typical problems of plastic injection moudling. They are: Short shot,Void and sink mark. The reason for short shot is not enough plastic in the shot; the fill speed and pressure is low. To solve this problems, we have the following solutions: increase fill speed, plastic and mould temperature. About Void, there are two main reasons for this phenomenon: First: the injection pressure is low,second the gate is too small.When faced this problem,we can increase gate size and the injection pressure to force more materials into the mold. Final, sink mark. There are two reasons for this phenomenon. First, the internal stress is too high. Second, the part has low surface rigidity. There are 2 ways to avoid these causes: Increase holding pressure and holding time and the next one is reduce mould temperature

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Write a paragraph (120-140 words) to present maintenance schedule of a machine tool using the following suggested questions and information in the table.

·        What is the name of the machine tool?

·        What are its features/ functions?

·        What are some kinds of maintenance work and their schedule for the chosen machine tool?

·        Why do we need to carry out these kinds of maintenance work?

Answer

There is the maintenance list above, you can see there are 7 components which need maintaining. Firstly, you have to check the hydraulic pressure daily to make sure it’s at 4.5mpa. Secondly, it is also necessary to clean off the window of the door and the light every day. If your CNC machine has a cooling system, make sure the cooling unit level is at the right operating level. You should check this system once a week. Every month, you need time to have the radiator cleaned and make sure the radiator fins are straight. Next, have the lubrication unit drained and cleaned out, then add fresh way lube semi-annually. If your machine is equipped with a cooling unit, have the unit drained and refilled twice a year. Lastly, please have the spindle checked for radial and end play every year

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Write a paragraph (120-140 words) to present maintenance schedule of machine tools using the following suggested questions.

·        What is the name of the machine tool?

·        What are its features/ functions?

·        What are some kinds of maintenance work and their schedule for the chosen machine tool?

·        Why do we need to carry out these kinds of maintenance work?

ANSWER

CNC machine is one of the most important industrial machine tools. Because of the high cost, workers have to maintain it regularly. There are many components which need maintaining. Firstly, we have to check the hydraulic pressure daily to make sure it’s at 4.5 MPa. Secondly, it is also necessary to clean off the window of the door and the light every day. CNC machine has a cooling system so make sure the cooling unit level is at the right operating level. We should check this system once a week. Every month, we need time to have the radiator cleaned and make sure the radiator fins are straight. Next, have the lubrication unit drained and cleaned out, then add fresh way lube semi-annually. Lastly, please have the spindle checked for radial and end play every year.