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I have many idea about the presentation, but a presentation have 3 basic structure are heading, content, compilation. If you want to be good at presentation, you spresent should prepare a lot of it. I think you should remember all content and spend about 30 minutes to prepare with your friends. During the presentation, I think you should list some main gist in your presentation. You should use body languages to communicate to audience. And you shouldn't use confusing words, wrong colors, big and small words, ... I think you should not be self-deprecating. Special, if you make the audience excited, your presentation will be credibilitied. After the presentation, you should ask some people “ you have any question about my presentation”. You can re-answer all of questions. At the end, you send gratefulness to audience.

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Couplings are used to connect shafts together to transmit power and disconnect shafts for maintenance. Couplings consist of the input shaft and the output shaft. The input shaft can be used to connect to the power source. And, the output shaft is used to connect to the destination. Couplings are divided into two types: rigid couplings and flexible couplings. Rigid couplings serve to align the shafts with each other perfectly. While, flexible couplings are for accommodating a slight misalignment between shafts. The most common type of rigid couplings is sleeve-style couplings. The purpose of sleeve-style coupling is to maximize performance and efficiency of the machine. Beam coupling is a common kind of flexible couplings. It is cut in a spiral shape. Moreover, it also can be used to accommodate several degrees of shaft offset.

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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. Taper using conical roller. They support moderate radial and repulsive forces. Thrust roller bearings use barrel-shaped rollers. They support propulsion motion. Jounal bearings have no rolling elements. Their shaft rotates inside an alternate lubricated sleeve High load capacity.

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There are five types of gears that we have learned in the lesson. They are spur gears, helical gears, bevel gears, worm and worm gear and rack and pinion gear. Firstly, spur gears are easy to install and cheap. They are also the most common and simplest type of gears. Secondly, helical gears have some outstanding features such as stronger and smoother than spur gears. They can reduce noise and vibration during operation as well. They are used to reduce speeds. Regarding bevel gears, their feature is to transmit power at angle. It means their gears meet each other at an angle, usually 90 degree. Next, worm and worm gear are special because they have one continuous tooth. Like helical gears, when operated, worm and worm gear have quiet and smooth meshing actions as well as can act as speed reducers. Lastly, rack and pinion gears are a circular gear engaging a linear gear to convert rotational motion to linear motion.

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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 by means of friction between the belt and pulleys and the chain drive can transmit motion and power between successive chains with sprocket special toothed wheels. The belt drive is made of rubber, plastic urethane, or other substances and the chain drive is made of metal with a number of links. The belt can reduce noise and vibration and the chain drive can cause noise and vibration. The belt drive is comparatively low due to frictional loss and the chain drive is high (usually above 95%). The belt drive is minimum maintenance and frequent tension. The chain drive is regular maintenance (including frequent lubrication). The application of belt drives is flour mills and coolant pumps. Lubricant pump, AC, CAM shaft, alternator, lathe machines, and lots of other machines and belt conveyors. The application of the chain drive is bicycles, motorcycles, agricultural and textile machinery, and material handling equipment.

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Manual drafting is all about producing all these technical drawings by hand using drafting pencil, or drafting pen, drafting paper, a scale ruler . CAD , on the other hand, uses software that simplifies and speeds up the production of technical drawings because it features drafting sheet templates and automatically duplicates repeating design elements. CAD drawn documents can be updated simply and quickly if a  revisions or change needs to be made. Manual drawings, being done by hand, often have a lot of human errors that need to be corrected.CAD software helps the draftsman produce more accurate scale drawings. It features a toolset that calculates the sizes, alignments, and dimensions.

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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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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 boltsThe final step is inspection.This is when we make sure that the part is made properly.

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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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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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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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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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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 more_vertical

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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.