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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.

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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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From my point of view, there are 3 typical problem of plastic injection moulding. They are short shot, sink mark and void. As I know, short shot is cause of 2 reasons. Firstly, there is  not enough plastic in the shot. Secondly, the plastic pressure loss in the mould is too high. We have 2 ways to avoid these causes. The first one is increasing fill speed, plastic and moud temperature. Next, we could increase gate size and runner. The void is created by shrinkage. It is volume change of plastic when plastic is heated or cooled. To attack this problem, we have 3 ways. The firt way is reducing wall thickness. Then, you should slow down cooling rate. Beside, we can increase gae size and locate it at the thick oart of the moulding. The final problem is sink mark. There are some reasons of this phenomena as the internal stress is too high and the part has low surface rigidity. The ways to solve  is pretty simple. We need to have enough shot size and increase holding pressure, holding time. Beside that, we should reduce mould temperature and wall thichness for faster. Those are some typical problems of plastic injection moulding and the ways to attack them.

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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 in to a cylinder. In the second step is plasticization, pellets are pushed along  the cylinder by a rotation screw, and heated to creat  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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As far as I know, plastic is a synthetic material that use polymers as a main ingredient. Plastic is able to be molded or shaped to any forms. The properties of plastic are versatile, lightweight, durable and some kind of plastic are saft . Plastic brings us a great number of benefit. The firstly, the plastic is versatile help them be shaped easily in to a wide range of forms. The secondly, it is lightweight, which is used in manufacturing airplane interiors and exterior parts. The next, plastic is cost-efficient because it formed into final useful form quickly and inexpensively. first of all, Most plastics are non-degradable and they may take a long time to break down once they are landfilled. Moreover, most of plastic product is not recycled and disposed of directly into the environment, which is hurt the enviroment. now, Human lifestyle and plastic inseparable. Nowaday, plastic are made from oil, coal and natural gas but in the near future, we will be able to make plastic form any kind of plant material. In short, plastic is a useful material for life and production, but besides that, there are still many plastic problems that we need to solve.

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

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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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 lathe machine.
Next, the check valve is drilled to make holes.
After drilling process, the next step is painting, the surface of the check valve is covered by paint.
Next is bolting process, pieces of it 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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Manual drafting is simply known as the practice of creating drawings by hand, you use pens, rulers and erasers to create the drawing. In general, CAD can solve all of the difficulties you meet when draft manually and helps you produce very accurate designs, the error is very small. Your drawings can be created in 2D or 3D. It 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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Nx first time released in 1973, it is a simple, useful and powerful software. It's used in aerospace and automotive companies. The functions of Nx including creating drawings, 2D or 3D models, editing data and collecting multiple design elements into a single feature.  It's fast and flexible, it helps reduce 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.

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There are two types of drives include belt drive and chain drive. The belt drive is used to transmit motion and power form one shaft to another . It is made of rubber, plastic urethane, or other substances. The belt drive can reduce noise. The belt drive is comparatively low due to frictional loss . It minimum maintenance and frequent tension.The application of belt drives is flour mills and coolant pumps. Lubricant pump, AC, CAM shaft and lots of other machines and belt conveyors. The chain drive is made of metal with a number of links. It cause noise and vibration.The chain drive should regular maintenance (including frequent lubrication).  The application of the chain drive is bicycles, material handling equipment.

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Gear is a rotating circular component of the machine with teeth, which mesh with another toothed part to transmit torque .There are five types of gear include: spur gear, helical gear, worm and worm gears, rack and pinion gear, and bevel gear. The first, Spur gears have teeth projecting towards or away form the centre. It is used in low-speed applications and cannot control noise at high speed. And the helical gears  used in high-speed applications, runs more smoothly with teeth cut in a spiral shape. Next, the worm has just one continuous tooth and a worm paired with a worm gear can reduce speed. The rack and pinion gears include a circular gear engaging a linear . They are used to convert rotational motion into linear motion. The last, bevel gears have a conical form. The function of the bevel gears is to transmit rotational power through shafts at an angle, normally 90 degrees

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U2 Speaking- Make a video (1-3 minutes) to talk about different kinds of bearings using the following suggested questions.

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U2 Speaking- Make a video (1-3 minutes) to talk about different kinds of bearings using the following suggested questions.

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Speaking U2-Make a video (1-3 minutes) to talk about different kinds of couplings using the following suggested questions.

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Speaking U2-Make a video (1-3 minutes) to talk about different kinds of couplings using the following suggested questions.

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Writing U2- Write a short paragraph (120-140 words) about different kinds of bearings using the following suggested questions.

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Writing U2- Write a short paragraph (120-140 words) about different kinds of bearings using the following suggested questions.

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Roller contact bearing uses rollers to support the load. They have an inner and outer race. Average load capacity is low. There are two main types: Contact Roller Bearings and Jounal Bearings. Main contact roller bearings include 4 types: 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 bearings. They support radial movement
tapered roller using conical roller. They support moderate radial and repulsive forces
Thrust roller bearings use barrel-shaped rollers. They support propulsion motion
Jounal:
Jounal bearings have no rolling elements. Their shaft rotates inside an alternate lubricated sleeve High load capacity

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Speaking-Unit1:Make a short video (1-3 minutes) following the situation below.Situation: Your friend is going to make his/her first presentation in English. He/ She asks for advice. Make a short talk to show him/ her how to make an effective presentation using the following suggested questions

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Speaking-Unit1:Make a short video (1-3 minutes) following the situation below.Situation: Your friend is going to make his/her first presentation in English. He/ She asks for advice. Make a short talk to show him/ her how to make an effective presentation using the following suggested questions

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Writing U2- Write a short paragraph (120-140 words) about different kinds of couplings using the following suggested questions.

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Writing U2- Write a short paragraph (120-140 words) about different kinds of couplings using the following suggested questions.

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There are two primary types of couplings: Rigid couplings and Flexible couplings
Rigid couplings align the shafts with each other. Perfect alignment reduces wear on the machine. Rigid couplings maximize performance and efficiency. Sleeve-style are the most rigid coupling.

Flexible couplings transmit power without perfect alignment. Beam couplings are cut in a spiral shape. These can accommodate several degree of shaft offset. Flexible of couplings help reduce noise and unwantes vibrations
Couplings transmit power from one shaft to another . The input shaft connects to the power source. The output shaft connects to the destination.

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Writing Unit1 -Write a paragraph (120- 140 words) about how to make an effective presentation using the following suggested questions

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Writing Unit1 -Write a paragraph (120- 140 words) about how to make an effective presentation using the following suggested questions

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A presentation has three basic structures: title, content, and layout. Good presenters should prepare the presentation content accurately and attractively to be confident in front of the audience. I think you should memorize all the content to prepare with your friends to practice speaking. In your presentation, I think you should list some key points, feature visuals, and use body language to communicate with your audience. Especially, if you keep your audience interested, they will enjoy your presentation. After the presentation, you should ask some people “do you have any questions about my presentation” and answer them.
At the end, you thank the audience.