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To make an effective presentation, you should first organize it with a clear structure: an introduction, the main content, and a conclusion. Before the presentation, prepare carefully by researching the topic, creating visual aids, and practicing your speech. During the presentation, speak clearly, maintain eye contact, and use body language to engage the audience, but avoid reading directly from your slides or speaking too fast. After the presentation, answer questions politely and thank the audience; you should not ignore their feedback or rush to leave. To impress the audience, show confidence, use interesting examples, and design attractive slides. A good presentation is not only about sharing information but also about connecting with the audience and making your message memorable.

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1. Report on Bearings Purchase

Yesterday, I went to Hanoi Mechanical Supplies Co. to buy different kinds of bearings as our stock had run out. I purchased three types: ball bearings, roller bearings, and needle bearings.

Ball bearings include an inner ring, an outer ring, balls, and a cage. Their function is to reduce friction between rotating parts, and they are widely used in electric motors and household appliances. Roller bearings consist of cylindrical rollers, inner and outer rings, and cages. They can carry heavier radial loads and are often applied in gearboxes and conveyors. Needle bearings are made of long, thin rollers and rings. Their function is to support compact designs with high load capacity, and they are commonly used in automotive transmissions.

These purchases will ensure smooth operation of our machines.

2. Report on Bearings Purchase

Yesterday, I went to Hanoi Mechanical Supplies Co. to buy different kinds of bearings as our stock had run out. I purchased three types: ball bearings, roller bearings, and needle bearings.

Ball bearings include an inner ring, an outer ring, balls, and a cage. Their function is to reduce friction between rotating parts, and they are widely used in electric motors and household appliances. Roller bearings consist of cylindrical rollers, inner and outer rings, and cages. They can carry heavier radial loads and are often applied in gearboxes and conveyors. Needle bearings are made of long, thin rollers and rings. Their function is to support compact designs with high load capacity, and they are commonly used in automotive transmissions.

These purchases will ensure smooth operation of our machines.

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1.

A gear is a rotating machine part with teeth that mesh with another toothed part to transmit power and motion. Its main functions are to change speed, torque, and direction in mechanical systems. There are several common types of gears, including spur gears, helical gears, bevel gears, and worm gears. Spur gears are the simplest type, with straight teeth and used for parallel shafts. Helical gears have angled teeth, which make them smoother and quieter. Bevel gears are shaped like cones and are applied when shafts intersect at an angle. Worm gears consist of a screw-like shaft that meshes with a gear, often used for large speed reductions. These gears are widely applied in machines, vehicles, clocks, and industrial equipment, making them essential in engineering and daily life.

2. There are two common types of drives: belt drives and gear drives. A belt drive uses a flexible belt to transmit power between pulleys, while a gear drive uses toothed wheels to transfer motion directly. The main function of a belt drive is to transfer power smoothly over long distances with less noise. In contrast, a gear drive provides precise motion control, high torque transmission, and no slippage. Belt drives are usually made of rubber or synthetic materials, whereas gear drives are made of metal for durability. Belt drives may slip under heavy loads, but they are cheaper and easier to maintain. Gear drives, however, are more efficient, reliable, and long-lasting, though they require careful lubrication. Belt drives are widely applied in bicycles and fans, while gear drives are common in automobiles, clocks, and industrial machinery.

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1. Computer-Aided Design (CAD) and manual drafting are two different methods of creating technical drawings. Manual drafting is the traditional way of drawing with pencils, rulers, and paper, while CAD uses computer software to design and edit drawings. Compared to manual drafting, CAD is faster, more accurate, and more flexible because it allows designers to modify, copy, and store drawings easily. It also provides 3D visualization, which manual drafting cannot. However, CAD requires computers, software, and training, which may be costly. On the other hand, manual drafting does not need expensive tools and can be done anywhere, but it is time-consuming, less precise, and harder to edit. In conclusion, CAD is more efficient and widely used today, while manual drafting is simpler but less practical for modern design needs.

2. AutoCAD is one of the most popular CAD programs used in engineering, architecture, and design. It provides powerful features such as 2D drafting, 3D modeling, dimensioning, and rendering. With AutoCAD, users can create, edit, and store technical drawings quickly and accurately. It also supports layers, blocks, and libraries that make the design process more organized and efficient. One of its main advantages is the high precision and flexibility it offers, along with the ability to save time by reusing and modifying existing drawings. Moreover, AutoCAD files can be easily shared and are compatible with many other programs. However, the software has some disadvantages: it is expensive, requires strong computer hardware, and can be difficult for beginners to learn. Overall, AutoCAD is an effective tool for modern design and drafting.

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The manufacturing process shown in the pictures is called aluminum casting. The product is made of aluminum. There are five main steps in this process. First, molten aluminum is poured into a mold to form the basic shape of the wheel. When the metal cools and solidifies, the casting is removed from the mold. Next, the rough surface of the wheel is machined to make it smooth and precise. After that, holes are drilled in the center for bolts, and the edges are shaped carefully. Then, the surface is polished to give the wheel a shiny appearance. Finally, a worker inspects the finished product to ensure it meets quality standards before it is delivered. This process helps create strong and beautiful aluminum wheels for vehicles.

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1. Plastic is a synthetic material made from polymers, mainly derived from petroleum. It has many useful properties such as being lightweight, durable, flexible, and resistant to corrosion and chemicals. These characteristics make plastic widely used in packaging, construction, automotive, and electronic products. The main advantages of plastic are its low cost, ease of molding into different shapes, and high strength-to-weight ratio. However, plastics also have serious disadvantages, especially their non-biodegradability, which causes pollution and harm to the environment and wildlife. In the future, I believe plastics will become more sustainable as researchers develop biodegradable and recyclable alternatives. With advancements in material science, new types of eco-friendly plastics will help reduce waste and maintain the essential benefits of this versatile material.

2. There are seven main types of plastics, each with unique properties and uses. Type 1 (PET) is lightweight and strong, commonly used for bottles and food containers. Type 2 (HDPE) is tough and resistant to chemicals, used in detergent bottles and pipes. Type 3 (PVC) is durable and flexible, often used for pipes, cables, and flooring. Type 4 (LDPE) is soft and flexible, used for plastic bags and film wrap. Type 5 (PP) is heat-resistant and lightweight, ideal for food containers and car parts. Type 6 (PS) is rigid or foamy, used in cups, trays, and insulation. Type 7 (Other plastics) includes advanced materials like polycarbonate, used for safety glasses and medical devices. These types allow engineers to choose the right plastic for mechanical and industrial applications.

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1. The process shown in the figure is called injection moulding of plastic. It consists of three main steps: feeding, melting and injection, and moulding and cooling. First, plastic pellets are poured into the hopper, which feeds them into the heated cylinder. Next, the screw inside the cylinder rotates, pushing the pellets forward while heat melts them into a molten plastic. Then, the molten plastic is injected through the nozzle into the mould cavity under high pressure. Finally, the plastic cools and solidifies in the mould, forming the desired shape. Once cooled, the mould opens and the finished product is ejected. This process is widely used in manufacturing to produce plastic components with high accuracy and repeatability.

2. There are several typical problems in plastic injection moulding, including short shots, flash, burn marks, and warping. Short shots occur when the molten plastic does not completely fill the mould cavity, often caused by low injection pressure or insufficient temperature. Flash happens when excess plastic leaks out of the mould, usually due to poor clamping force or damaged moulds. Burn marks appear as dark spots on the surface, caused by trapped air or overheating of the material. Warping occurs when the part bends after cooling because of uneven cooling or stress in the mould. To solve these problems, operators should adjust injection pressure and temperature, ensure proper mould maintenance, improve cooling systems, and regularly inspect machine settings to maintain high product quality.

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To maintain a milling machine in good condition, customers should follow a regular maintenance schedule. There are five types of maintenance work to be done. First, clean the guideways daily to avoid interruptions and control fluid motion. Second, inspect the oil level every day to ensure engine efficiency and prevent overheating. Third, renew the oil semi-annually to ensure smooth operation of the machine. Fourth, clean the entire machine thoroughly once a week to remove dust and dirt that may affect its performance. Finally, inspect bearing slackness annually to prevent slippage and keep the machine running accurately. By following these maintenance steps regularly, customers can extend the machine’s lifespan and maintain high working efficiency.