·        What is the basic structure of a presentation?

·        What should you do before the presentation?

·        What should and shouldn’t you do during the presentation?

·        What should and shouldn’t you do after the presentation?

 

 

A presentation is divided into three sections: introduction, development, and conclusion. You must prepare and organize thoroughly before the presentation. To begin, you must understand your target audience. You'll be well on your way to a successful presentation if you can put yourself in their shoes and understand what they require. Furthermore, the style of spoken English differs greatly from that of written English.If you are preparing your script from text in a research paper, you must convert the written phrases into spoken phrases. Remember to use gestures and body language to express ideas during the presentation, and to maintain eye contact with the audience. Individual stories or your experiences can make awesome presentation key points. Finally, remember to thank the audience after they ask you a question. If you do not know the audience's answer, you can admit it and promise to find out and return to the questioner later. Presentation is a skill that can be practiced over time

·        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?

 

·        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?

Couplings are devices used to connect two shafts together for the purpose of transmitting power. I know some couplings such as flexible couplings, rigid couplings. Flexible couplings are used to transmit torque from one shaft to another when the two shafts are slightly misaligned. They can also be used for vibration damping. In applications, a flexible coupling can protect the traction and drive shaft components from the harmful effects of the condition. Rigid couplings do not have the ability to compensate for shaft misaligments and are therefore used where the shafts is aligned. Rigid couplings by virtue of their simple rugged design are generally able to transmit more power than flexible couplings of comparable size.

 

 

·        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?

Gear is  a rotating cicrular component of machine with teeth, which mesh with another toothed part to transmit torque. Geared devices can change the speed, torque, and direction of a power source. Gears of different sizes produce a change in torque, creating mechanical advantage. There are 5 common types of gears again that are spur gear, helical gear, bever gear, rack and pinion, worm and worm gear. Spur gears are the simplest types of gears and they are used in low-speed applications and in situations where noise control is not a problem. Helical gears run smoothly and quietly and they are used in high-speed applications,large power transmission. Bever gears have a conical form and can be to transmit rotational power through shafts. A worm pair with worm gear, which helps reduce speed. Rack and pinion gears engage, they form a gearset. 

·        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?

There are 2 types of drive that are belt drive and chain drive. Belt drive is used to transmit motion and power from one shaft to another by means of fruction between belt and pulley. Chain drive iss use for transmitting motion and power between successive chain with sprocket special toothed wheels. Belt drive is made of rubber and plastic, unlike belt drive, chain drive is made of metal. The operation of chain drive is different from that of belt drive as it can cause noise and vibrations. Slippage orcurs in belt drive, chain drive is different from because slippage doesn’t offten orrcur. Efficiency of belt drive is comparatively low to trictional loss, while the chain drive is high, ussually about 95%. Belt tenssion of belt drive is affected by atmospheric condition and temperature unlike belt drive, chain drive isn’t. belt drive requies freqrent retension. Chain drive different from belt drive because it requires regular lubration. Belt drive is use in flour mills, coolant pump. Chain drive is appled in bicycle and motorcycles. 

·        What is CAD and manual drafting?

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

CAD is the use of computers in the process of sketching, 3D modeling, assembly, and drawing production. Manual editing is understood as a concept, an application part that allows users to do operations such as typing text, entering text or editing manually,The advantages of CAD include: the ability to producing very accurate designs; drawings can be created in 2D or 3D and rotated; other computer programmes can be linked to the design software. With manual drafting, you must determine the scale of a view before you start drawing. This scale compares the size of the actual object to the size of the model drawn on paper. Some disadvantages of using cad: Time and cost of training large CAD users. However, now, thanks to the abundant resources on the Internet and open discussion forums, it is also a bit easier,  Maintenance and upgrade costs for CAD software are relatively large.

·        What is the name of the CAD program?

·        What are its features?

·        What are its functions?

·        What are its advantages and disadvantages?

NX is 2D and 3D drawing software. It was released for the first time in 1973 and it was simple useful and powerful software. It can be used in aerospace, automotive companies. The program is used to create drawings, 2-D or 3-D models, edit data, link data from various sources, collect multiple design elements into a single feature. It has many advantages. Firstly, it is fast, flexible. Seconly, the CAD program create a very high level of control. Thirly, NX Reduce the companies mistakes and maximize poductivity. Finally, it track your product through every phase of the production cycle easily. In addition, it still has some deadvantages. Firstly, NX is lack ease of use. Secondly, the software is required professional training before using it. Finally, it isn’t able to handle super complex parts or assemblies. it's a great software 

·        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?

Plastic is synthetic material that use polymers as a maining redient. Plastic is able to be moulded or shaped toany forms. As I said earlier, plastic has lots of properties. Firstly, lightweight can be used in manufacturing airplane interiors and exterior parts. Secondly, safe can be used in food wrapping, containers and medical applications. Next, versatile can be shaped easily into a wide range of forms. It is used to make a variety of products.

 Using plastic brings  us a great number of benefits: cheap, convenient(shopping plastic bags), reusable,…However, using too much plastic everyday, people may face with different problems: hurt the environment, not be biodegradable, not be recycled.

In the part, we couldn’t mould plastic into complex shapes. At present, it posible to replace components in engines with plastic. In the future, we will be able to make plastic from any kind of plant materials.

Plastic is synthetic material that use polymers as a maining redient. Plastic is able to be moulded or shaped toany forms. There are 7 types of plastic with different uses and features including PET, HOPE, PVCV, LDPE, PP, PS, and OTHER PLASTIC.

PET-1. This type of plastic holds the mumber one spot because of its widespread unity. It os mudly used for food and drink packaging purposes due to its strong ability to prevent oxygen from geting in and spelling the product inside. PET bottles are the most widely recycled plastic in the world.

HDPE-2 is the second type. Its technical name is High-Density Polyethylene-it's an incredible resistant resis used for grocery bags, milk jugs, recycling bins, shampoo bottles. This type of plastic s much younger and thicker than PET. Also, it is relatively hard and resistant to impact and can be subjected to temperatures of up so 120 °C without being affected. As far as its disposal is concerned, HDPE is accepted at most recycling centers in the world, as it is one of the easiest plastic polymers to recycle.

Polyvinyl chloride (PVC) is the world's third-most widely produced synthetic plastic polymer, It comes in two boo forms: rigid and flexible. Thanks to its versatile properties, such as lightness, durability, and casiness of proces ability, PVC is now replacing traditional building materials like wood, metal, concrete, rubber, ceramics, et in various applications. Despite its many advantages and efforts made by the plastic industry to increase in reusability, PVC is still hardly recyclable and should therefore be avoided, whenever possible

The check valve is made of cast iron.
 First part is cast, in this process hot liquid of metals is poured. Into a container and then cooled to make the cored shape. The cast iron is then turned on a lathe to remove excessive materials. Next, the holes are drilled on the surfaces of the materials with a di After drilling,the next step is panting, the material is covered with paint. The final step is ínpection. This is when we make sure that the part is made properly.

as can be seen in figure, this is the process of plastic moulding. There are 6 steps in this process. First, pellets of plastic are feed from the hopper into a cylinder. Then, The pellets are pushed along the cylinder by a rotating screw and heat. Next, the screw stops rotating and then a ram in front of the screw moves straight forward. After that, the soft warm plastic is pushed toward a nozzle by the ram. Then, plastic is cooled by the mould and become hard in the cavity. Finally, the mould opens and the cold hard, solid plastic shape is eject.   

From my point of view, there are 2 typical problems of plastic injection moulding. There are short shot and sink mark. As I know, short shot is caused of 2 reason. Firstly, there is not enough plastic in the shot. Secondly, the plastic pressure loss in the mould is too hight. There are 3 ways to avoid these causes. The first one is that increase fill speed, plastic and mould temperature. Next, increase gate size and runner.finally,check the shots continuously and use plastic with high melting capability  . Sink mark is caused of 2 reason. Firstly, the internal stress is too high. Secondly, the part has too low a surface rigidity. There are 2 ways to avoid these causes. The first one is that have enough shot size and reduce mould temperature.

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.

CNC (Computer Numerical Control) machines are a highly evolved step from NC (Numerical Control) machines. CNC machines have a computer that sets up the software used to control the machine's displacement functions. CNC machines can cut metal according to easy curves such as straight lines, even hollow holes inside the workpiece, trimming precise, sharp and beautiful patterns. The following is a maintenance list that I use for my cnc machine. Every day, I will Check the hydraulic pressure to make sure it's at 4.5 MPa, Clean off the window of the door and the light. Have the radiator cleaned and make sure the radiator fins are straight. If your CNC machine has a cooling system, make sure the cooling unit level is at the right operating level. After a long time of operation, the machine also needs to change the lubricating oil to operate more smoothly. Finally, Check the spindle for radial and end the annual play. CNC machines have a working speed that requires fast and accurate techniques. Moreover, CNC milling machines have extremely high friction. Therefore, the wear and tear of components is inevitable. Therefore, maintenance of CNC machines is extremely important.