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https://youtu.be/DAiOZKuM48s

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Today I will talk about a typical problem of plastic injection moulding. It is short shots, So why do short shots occur? there are 2 basic causes. One there is not enough plastic in the screw is bottoming. Or two the plastic pressure loss in the mould is too high so the plastic flow stops before each cavity is full. When you encounter short shots the first setting to check is the machine shot size setting. The plastic injection barrel must not be allowed to run out of plastic before the mold is full, Most molding is done with a cushion of plastic ahead of the screw. If the screw bottoms the molder must increase the shot size.

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Today I will give you the maintenance schedule of the milling machine. Firstly, you did well in checking the oil level daily to ensure engine efficiency. You know, if the oil level is low, your machine would overheat, leading to expensive repairs. In the fact, with the coolant, you should renew it semi-annually, not annually, to prevent damage and keep the mill at the correct operating temperature. The lubrication pump is also recommended to be checked twice a year to make sure that oil is distributed properly. Next, the electric component should be inspected every 3 months to prevent the risk of fire. Finally, the guideways need to be cleaned weakly.

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As you can see in the figure, this is the process of moulding plastic. Fin the first step, the pellets of plastic are fed from the hopper into a cylinder. After that, pellets are pushed along the cylinder by a rotating screw and heated. In the next step, the screw stops rotating then a ram in front of the screw moves straight forward. Next, the soft warm plastic is pushed toward a nozzle by the ram. Soft plastic is injected through the nozzle into a shaped cavity between 2 halves of a mould. Then, the plastic is cooled by the mould, and becomes hard inside the cavity. Finally, the mould opens and the cold hard solid plastic shape is ejected

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Today I will talk about the manufacturing process of making a check valve. The first step is casting. In this step hot liquid of metal is poured into a container and cooled to make the correct shape. Then it will be turned on a lathe to remove excessive materials. After that, the holes are drilled on the surfaces, and the materials are covered with paint. Next, when the paint is dry, the parts are held together using nuts and bolts. The final step is inspection. The work is checked carefully to make sure that there will be no mistakes

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There are five main types of gears: spur gears, helical gears, worm and worm gears, rack and pinion gears, and bevel gears. Both spur gears and helical gears transmit motion from one shaft to another parallel shaft. But helical gears work faster, more smoothly, and quietly. Bevel gears can transmit rotational power through shafts at an angle, normally 90 degrees because it has a conical form. Worm and worm gears have just one continuous tooth, which helps the machine reduce speed while Rack and pinion gears convert rotational motion into linear motion.

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CAD stands for computer-aided design while manual drafting is the practice of creating drawings by hand. CAD is a way to digitally create 2D drawings and 3D models of real-world products before they're ever manufactured. So it allows for far more accurate designs than physical drawings, making it easy to create complex shapes and surfaces, and it also provides a wide range of tools for creating high-quality, visually pleasing drawings, and models. But when we use CAD we have to update the version regularly and purchase the new system. Besides that, the working can be lost because of the sudden breakdown of computers

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There are seven types of plastic. The first one is PET. It's used for food and drink packing purposes because of its oxygen prevention. Besides that, it has widespread utility and we can recycle PET bottles. HDPE has some advantages such as relatively hard and resistant, stronger than PET and it's one of the most easily recyclable plastic polymers. People use HDPE for manufacturing agricultural pipes, shampoo bottles, and playground equipment. PVC is the world's third-most widely produced plastic. It can be divided into 2 forms rigid and flexible ones. PVC is widely used in construction, wiring, electrical cable insulation, and flooring. PVC is light and durable but still hard to recycle.
LDPE is a flexible, transparent, recyclable plastic. So it's used in plastic bags, various containers, and most famously for plastic wraps. Plastic bags are usually used for a few seconds then discarded. The fifth type of plastic is PP. PP can withstand high temperatures and is found in car parts, yogurt containers, and thermal vests. PS is very inexpensive per unit weight and easy to create. We can find PS everywhere but it's very dangerous and harmful especially when heated. If plastic can not be identified in the six types above-mentioned. then it will be included in group 7. This kind of plastic is almost never recycled.

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Plastic is a synthetic material that uses polymers as the main ingredient. Plastic is able to be molded or shaped into any form. It has many good properties such as versatile, safe, chemically unreactive, and cost-efficient. In the past, we couldn't mould plastic into complex shapes but now manufacturers can mould plastic into many different shapes and in the near future we will be able to make plastic from any kind of plant materials. Plastic also has some advantages. It is very convenient and cheap. We use plastic bags when we go to the market, or go shopping,... Besides that, Plastic is durable and resistant to all kinds of adverse outside factors. However, plastic is not biodegradable, and it can hurt the environment. It's very hard to recycle some kinds of plastic, so we should reuse plastic as possible.

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Both belt drive and chain drive are mechanical drives but the difference comes from their materials. Belt drive is made of plastic, rubber, or other substances while chain drive is usually made of metal. So, when they are working, chain drive causes noise and vibration but belt drive reduces it. However, chain drive is more effective. The efficiency of chain drive is usually above 95 percent while belt drive has low performance because of frictional loss. Belt drive requires minimum maintenance. The mechanic just has to check and re-tension belt drive once a month but chain drive needs maintenance more regularly. Like chain drive, belt drive can be used for many machines and transmissions.

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SOLIDWORKS is an industry-leading CAD (Computer-Aided Design) and CAE (Computer-Aided Engineering) software used by millions of engineers across the world. People use it to develop mechatronics systems, design mechanical machine components, or Kinematic Motion Analysis. We can name some basic features of SolidWorks such as extruded cut, revolve boss, and fillet. Especially, this software is cheap and very reliable for academics and industry. The toolbar is well-oriented and simple, so quick learning is possible. However, It still has some disadvantages like failure to make detailed drawings using raw data and don't have a high-spec design tool

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coupling is a machine component. We can divide couplings into two main types: Rigid and flexible. Rigid couplings align the shaft perfectly. They reduce wear on the machine so it maximizes the performance and efficiency of the machine. The most common example of rigid couplings is Sleeve-style couplings. Flexible couplings transmit power without perfect alignment. They can accommodate several degrees of shaft offset. The machine also works more quietly and reduces unwanted vibration. The most important type of flexible couplings are beam couplings.

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There are two main types of bearings: Rolling contact bearings and journal bearings. Rolling contact bearings accommodate different types of force and motion but load-carrying capacity is low or medium. They have 4 kinds. Ball bearings support radial and axial motion. Straight roller bearings only support the radial motion. Tapered roller bearings support radial force and moderate thrust forces. Thrust roller bearings support thrust motion. The second type of bearings is journal bearings. They have no rolling part so load-carrying capacity is high.

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An effective presentation includes 3 parts: introduction, development, and conclusion. Before the presentation, you should write all you will talk about and practice in front of the mirror. During the presentation, try to keep camp, and relax. Keep smiling and make eye contact, which helps the audience to connect with you and your subject. Don't talk normally. You should use your body language, make your gestures open, and move among the audience. After the presentation, don't forget to thank the audience for listening