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An effective presentation usually follows a clear structure: an introduction, a main body, and a conclusion. Before the presentation, you should prepare your slides carefully, practice your speech several times, and make sure all equipment works properly. During the presentation, you should speak clearly, maintain eye contact with the audience, and use body language naturally. Avoid reading directly from the slides or speaking too fast. After the presentation, you should thank the audience and confidently answer their questions. Avoid arguing or showing nervousness if someone disagrees with you. To impress the audience, you can use visual aids, real-life examples, or short stories to make your ideas more memorable. Being confident, well-prepared, and friendly will help you leave a strong and positive impression.

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Dear Supervisor,

I would like to report on the bearings I have recently purchased. I bought three kinds of bearings: ball bearings, roller bearings, and thrust bearings. I ordered them from ABC Mechanical Supplies on October 15th. Each bearing includes an inner ring, an outer ring, rolling elements, and a cage. Ball bearings are used to reduce friction and support both radial and axial loads; they are mainly applied in electric motors and fans. Roller bearings handle heavy radial loads and are commonly used in conveyors and gearboxes. Thrust bearings are designed to support axial loads and are applied in car transmissions and machine spindles. All bearings meet the company’s technical requirements and have been delivered on time.

Best regards,

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Dear Supervisor,

I would like to report on the couplings I have recently purchased. I bought three kinds of couplings: rigid couplings, flexible couplings, and fluid couplings. They were ordered from ABC Mechanical Supplies on October 16th. Each coupling includes two hubs and a connecting element such as a sleeve, rubber insert, or fluid chamber. Rigid couplings are used to connect two shafts precisely and are applied in machines that require perfect alignment. Flexible couplings can absorb vibration and slight misalignment, commonly used in pumps and compressors. Fluid couplings transmit power smoothly through hydraulic fluid, often used in automotive and conveyor systems. All couplings meet our company’s technical standards and have been delivered on time.

Best regards,

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A gear is a rotating machine part with teeth that mesh with another toothed part to transmit power and motion. The main functions of gears are to change the speed, torque, and direction of mechanical movement. There are several common types of gears such as spur gears, helical gears, bevel gears, and worm gears. Spur gears have straight teeth and are used for simple, parallel shaft systems. Helical gears have angled teeth, which help them run more smoothly and quietly, often used in car transmissions. Bevel gears transmit motion between intersecting shafts, commonly found in drills and gearboxes. Worm gears can greatly reduce speed and increase torque, often used in lifts and conveyors. Each type of gear has unique features and plays an important role in various mechanical systems.

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There are two common types of drives: belt drives and gear drives. A belt drive uses a flexible belt to transmit motion and power between pulleys, while a gear drive uses meshing gears to transfer power directly between shafts. Belt drives are usually made of rubber or fabric, while gear drives are made of metal. Belt drives operate smoothly and quietly but may suffer from slippage, which reduces efficiency. Gear drives, on the other hand, provide accurate speed ratios, higher efficiency, and no slippage, but they are noisier and require more maintenance. Belt drives are commonly used in fans, sewing machines, and agricultural equipment, while gear drives are applied in gearboxes, automotive transmissions, and industrial machinery. Each type has its own advantages depending on power requirements and working conditions.

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CAD (Computer-Aided Design) and manual drafting are two different methods used to create technical drawings. Manual drafting is done by hand using tools such as pencils, rulers, and compasses on paper, while CAD uses computer software to design and modify drawings digitally. CAD offers many advantages: it saves time, improves accuracy, and allows easy editing and 3D visualization. In contrast, manual drafting requires more time and effort, and mistakes are harder to correct. However, manual drafting helps students understand basic drawing skills and geometric principles. CAD is widely used in engineering, architecture, and manufacturing because of its efficiency and precision, while manual drafting is mainly used for training or small, simple projects. Overall, CAD is more modern and practical, but manual drafting remains valuable for learning fundamentals.

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Autodesk AutoCAD is one of the most popular CAD programs used worldwide. It allows users to create precise 2D and 3D drawings for engineering, architecture, and design projects. Its main features include a wide range of drawing tools, layers management, annotation tools, and the ability to import and export different file formats. AutoCAD functions include drafting, modeling, designing layouts, and producing technical documentation. One major advantage is its high accuracy and flexibility, which helps users save time and easily modify designs. It also supports collaboration through cloud sharing. However, AutoCAD has some disadvantages: it can be expensive, requires powerful hardware, and has a steep learning curve for beginners. Despite these challenges, it remains a valuable tool for professionals who need detailed and reliable design capabilities.

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The manufacturing process shown in the pictures is aluminum wheel production. The product is made of aluminum. There are five main steps in this process. First, the molten aluminum is poured into a mold to form the basic shape of the wheel. After that, the wheel blank is machined on a lathe to achieve precise dimensions. Next, holes are drilled into the wheel for mounting bolts. Then, the wheel surface is milled to create the final design and remove any excess material. Finally, a quality inspection is carried out to ensure the wheel meets all technical specifications. Each step is crucial: pouring forms the shape, machining and drilling ensure accuracy, milling gives the wheel its final design, and inspection guarantees quality. This process produces durable and precise aluminum wheels.

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Plastic is a versatile material made from polymers, either synthetic or naturally occurring, that can be shaped when soft and then hardened to retain a specific form. Plastics have properties such as light weight, corrosion resistance, electrical insulation, and durability. These characteristics make plastics widely used in automotive components, packaging, electrical insulation, medical devices, and household products. The advantages of plastic include its low cost, ease of manufacturing, and ability to be molded into complex shapes, which supports mass production and design flexibility. However, plastics also have disadvantages, such as low biodegradability, potential environmental pollution, and limited heat resistance in some types. In the future, I predict the development of biodegradable and recyclable plastics will grow, combining the practical benefits of plastics with environmentally sustainable solutions, reducing their ecological footprint while maintaining performance.

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Plastics are generally classified into two main types: thermoplastics and thermosetting plastics. Thermoplastics, such as polyethylene (PE, code 1), polypropylene (PP, code 5), polystyrene (PS, code 6), and polyvinyl chloride (PVC, code 3), soften when heated and can be reshaped multiple times. They are lightweight, corrosion-resistant, and easy to process, making them suitable for packaging, bottles, pipes, and automotive components. Thermosetting plastics, including epoxy, polyester resin, and urea formaldehyde, harden permanently after heating and cannot be reshaped. They are strong, heat-resistant, and electrically insulating, which makes them ideal for electrical fittings, adhesives, and structural parts. Understanding the properties and code numbers of these plastics allows engineers to select the right material for specific mechanical applications, balancing performance, durability, and cost. With increasing demand for sustainability, recycling thermoplastics is becoming more important.

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The manufacturing process shown in the figure is called injection moulding, which is widely used to produce plastic parts. There are typically four main steps in this process: melting, injection, cooling, and ejection. First, plastic pellets are heated and melted in a barrel until they become soft and fluid. Next, the molten plastic is injected under high pressure into a mould cavity, taking the shape of the final product. After injection, the plastic is cooled inside the mould to solidify and maintain its shape. Finally, the mould is opened, and the finished part is ejected carefully for further processing or assembly. This process is highly efficient and suitable for producing complex shapes in large volumes, making it essential in automotive, packaging, and household product manufacturing.

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Plastic injection molding can have several common problems that affect product quality. One issue is warping, which happens when parts cool unevenly or develop internal stress. This can be solved by adjusting cooling time and keeping the mould temperature uniform. Another problem is short shots, where the cavity is not completely filled due to low injection pressure or insufficient material. Increasing injection speed or pressure and checking material flow can prevent this. Sink marks occur when thick sections shrink faster than surrounding areas, and they can be reduced by optimizing wall thickness and cooling channels. Flash, or excess material along parting lines, often results from worn moulds or high injection pressure and can be fixed by maintaining moulds and adjusting pressure. Proper monitoring and process optimization ensure consistent high-quality production.

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The machine tool we are discussing is a milling machine. There are five kinds of maintenance work that customers should perform to ensure proper operation and longevity. First, clean the guideways daily to avoid interruptions and maintain proper fluid motion. Second, inspect the oil level daily to ensure engine efficiency and prevent overheating. Third, renew the oil semi-annually to guarantee smooth operation of moving parts. Fourth, clean the machine thoroughly weekly to remove dust and dirt, which can affect performance. Finally, inspect bearing slackness annually to prevent slippage and potential damage. Following this maintenance schedule helps maintain the milling machine’s precision, efficiency, and reliability while reducing the risk of breakdowns and extending its service life.