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Write a short paragraph (120-140 words) about different kinds of couplings using the following suggested questions.

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?

In simple words, couplings are popular mechanical devices used to transmit power from one shaft to another shaft. Currently, on the market there are many types of couplings, but there are a few typical types. Sleeve coupling is most widely used in industries and machines. Sleeve couplings are nothing but just sort of thick hollow cylinder/pipe called as sleeve or muff. Sleeve coupling is used to transmit power from the driving shaft to the driven shaft. Beam coupling consists of a single piece of material made flexible by the removal of material in a helical pattern along its length. As with all couplings, the purpose of a beam coupling is to transmit torque between two shafts, but unlike a rigid coupling, a beam coupling can accommodate angular misalignment, parallel offset. Flexible couplings are more commonly used to transmit driving torque between a prime mover and a rotating element of the equipment.

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Write a paragraph (120- 140 words) about how to make an effective presentation using the following suggested questions:

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?

Most presentations have three main parts including introduction, body and conclusion. Before the presentation, you need to structure your talk clearly and logically so that the audience can understand it more easily. Next, you will focus on only a few important points if you intend to design your talk by Powerpoint. The last thing is to make a list of questions you expect to be asked at the end of the presentation. During the talk, you should repeat the main points to help your audience to remember them. You must often make eye contact with each individual and spread attention around the audience while you are communicating with audience. You should also not look at the ceiling or floor. All of these actions are likely to distract the audience. Finally,after the presentation, you can tell a joke or a funny story in the conclusion to create relaxed atmosphere. Also,you should summarize the maint points.Presentation is a skill that can be learned day by day to improve. Effective communication skills will help in the further education and futher careers.

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Write a short paragraph (120-140 words) about different kinds of bearings using the following suggested questions.

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?

Currently, there are many types of bearings on the market, but we can see that there are some common types of bearings. The first is a rolling contact bearing. Rolling contact bearings use rollers to support loads. They have an inner race and an outer race. Rolling contact bearings are divided into 4 main types: ball bearing, straight roller bearing, tapered roller bearings and thrust roller bearings. Ball bearings are found in everything from inline skates to hard drives. These bearings can handle both radial and thrust loads, and are usually found in applications where the load is relatively small. Tapered roller bearings use conical rollers. Tapered roller bearings can support large radial and large thrust loads. Tapered roller bearings are used in car hubs. The second is journal bearings. Journal bearings have no rolling parts. Journal bearings are most often used in industrial machines that require high loads like turbines and pumps.

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Your friend is going to make his/her first presentation in English. He/ She asks for advice. Make a short talk to show him/ her how to make an effective presentation using the following suggested questions:

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?

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Make a video (1-3 minutes) to talk about different kinds of couplings using the following suggested questions.

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?

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Make a video (1-3 minutes) to talk about different kinds of bearings using the following suggested questions.

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Gear is a rotating circular 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. There are 4 common types of gears: Spur gears, Helical gears, worm and worm gears, Pack and pinion gears, Bevel gears. Spur gears are the simplest types of gears with teeth projecting towards or away from the centre. Spur gears are used in pumps, power plants, … . Helical gears are similar to spur gears except that their teeth are cut in a spiral shape. Helical gears are used in high-speed applications: automobiles (transmission systems). Helical gears with only one tooth continuously call worms . A worn pairs with a worm gear, which helps reduce speed. Rack and pinion gears comprise a circular gear (the pinion) engaging a linear gear (the rack), which operate to convert rotational motion into linear motion. Bevel gears have a conical form and can be used to transmit rotational power through shafts at an angle, typically 90 degrees to each other.

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There are 2 types of drives: belt drive and chain drive. Belt drive is one type of mechanical drive where motion and power are transferred from one shaft to another by means of friction between belt and pulleys mounted on each shaft. On the contrary, chain drive is one engagement type power transmission system that transmits motion and power by means of successive chain with sprocket special toothed wheels. If the belt drive is made of rubber or plastic, the chain drive is made of metal. However, the operation of chain drive is different from that of belt drive as it can cause noise and vibrations. As a result, belt drive requires minimum maintenance but chain drive requires regular maintenance including lubrication. Belt drive is used in flour mills, coolant pump, AC… Chain drive is used in motorcycles, agricultural machinery and material handling equipment.

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What is CAD and manual drafting?

Manual drafting is all about creating all these technical drawings by hand using drafting pencils, scratch paper, scale rulers. On the other hand, CAD drafting using software simplifies and speeds up the production of technical drawings as it features composing sheet templates and automatically duplicating repetitive design elements. Documents drawn in CAD can be updated simply and quickly if modifications or changes are required. Most architects, building designers and drafters prefer to use CAD software mainly because it speeds up this tedious process. Using CAD software makes their work more precise. Easily modify planning documents using CAD software. CAD creates ready-made templates and databases. Traditional drafting is often repetitive and can sometimes be inaccurate.

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AUTOCAD

AutoCAD is drafting software for drawing or creating technical drawings with 2D vectors or 3D surfaces released in late 1982 by Autodesk Corporation. Features of AutoCAD: Support drawing to scale easily; Size and alignment tools for increased accuracy; Quickly determine the actual size of the model; Calculate the quantity of detailed production materials. AutoCAD software is often used by people mainly in the fields of industry, construction, and architecture. Because these areas when using CAD will help users create creative designs according to their personal desires, and also support other technical steps to be performed more accurately and better. Disadvantages of CAD: Time and cost for implementing a CAD system is large; The time and cost of training CAD users is large. However, now, thanks to the abundant resources on the Internet and open discussion forums, it is also a bit easier.

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The check valve

A check valve is a device that is used to prevent backflow in a piping system. It is often used for water, gasoline, compressed air and heat. It is often made from cast iron. Here are some steps to make a check valve. In the first step, the part is cast. In this process hot liquid of metals is poured into a container and then cooled to make the correct 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 drill. After drilling, the material is covered with paint. When the paint is dry, the parts are bolted together using nuts and bolts. The final step is inspection. The work is checked carefully to make sure that the part properly made properly

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Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. They are light in weight and are chemically stable; easily moulded into different shapes and sizes. Not only that, they also have good insulation and low thermal conductivity, good impact resistance and they do not rust. In the past, we couldn't mold plastic into complex shapes, but today with the development of technology we can easily mold plastic to create the shapes we want. Although the ease of plastic production generates cheap goods, the linear plastic economy adopted sees 90% of products used once and then discarded, thus creating a global environmental crisis. A new plastic future in which biodegradable polymers replace conventional plastics could be the answer. The growth in the use of plastic is due to its beneficial properties which include: Comparatively lesser production cost and good safety for food packaging. Human bodies absorb chemicals which are applied to plastics. Any of these substances have been found to modify hormones or other possible effects on human health

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Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Some of the most significant properties of Polyethylene or PET are : PET does not react with water and PET is very strong for its lightweight. PET is widely used for packaging foods and beverages. HDPE (High Density Polyethylene) is used to make bottles for milk, water and even furniture. It has the following properties: Stiffness, strength, toughness and resistance to chemicals. Some of the most significant properties of PVC are: lightness, durability and easiness of process ability. PVC is used to make pipes, cables and clothes.  LDPE is very flexible, soft and translucent in appearance. LDPE is used for manufacturing various containers and many caps and closures. The properties of Polypropylene include: Semi-rigid, translucent and good chemical resistance. Applications of Polypropylene is buckets,toys and medical components.Polystyrene (PS) is rigid, brittle and relatively hard. Polystyrene is used in plastic models, DVD and CD cases. Number 7 is for all plastics other than those identified by number 1-6. Polycarbonate (PC) is the most common plastic in this category. PC is typically used for baby bottles and sippy cups,…

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Plastic injection moulding process

There are all 7 steps in the process included:

Step 1:  Pellets of plastic are fed from the hopper into a cylinder

Step 2: The pellets are pushed along the cylinder by the rotary screw and heated

Step 3 :The screw stops rotating and then a ram in front of the screw moves straight moulding forward.

Step 4: the Soft, warm plastic is pushed towards a nozzle by ram

Step 5: The soft plastic is injected through the nozzle into a shaped cavity between to introduce the two halves of a mould.

Step 6: The plastic is cooled by the mould, and becomes hard inside the cavity.

Step 7: The mould opens and the cold, hard, solid plastic shape is ejected

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There’s a lot of room for expensive errors when it comes to injection molding. The first problem that we often encounter in the plastic molding process is: short shot. The most common cause of short shots is flow restriction resulting from narrow or blocked gates. Consider the following step to prevent short shot: Redesign the mold with wider channels or gates for better flow. The next problem is: flash. Flash appears because material has flowed outside of the intended flow channels and into the space between the tooling plates or at the injector pin. Common method for addressing flash in molded product is: Retool or redesign the mold if plates don’t fit together properly or allow material to flow outside the channel. The last problem is jetting. The chief cause for jetting is excessive injection pressure. The solution to the problem is increasing material and mold temperature to keep the initial jet of material from solidifying early.

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A lathe  is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis. So if you do get a lathe, it’s absolutely critical that you keep it fully functional for as long as possible, getting the most value for your money. To do that, you need to stay on top of lathe maintenance. Check air pressure - this is best done daily. Check the coolant levels is a task that you have to do every week. Finally, the task you have to do semi-annually is change the oil. The goal of any lathe maintenance is twofold: to keep your lathe running as long as possible, and to make sure that it is running as smoothly as possible. The better it runs, the more accurate and precise your lathework will be.

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A milling machine is machine used to remove material from a workpiece by feeding the workpiece against a multi-bladed or -pointed cutting tool. Like any other machine, milling machines are subject to wear and tear. Such wear can be reduced by regular maintenance and servicing of the milling machine by the operator. In order for the milling machine to work well and for a long time, cleaning of the guideway must be done regularly on a daily basis. Thorough cleaning of the machine is a task that you have to do every week. Finally, the task you have to do semi-annually is Inspection of lubrication pump. Maintenance, repair and technical service are significant since they affect lifetime of milling machines and ensure them to work non-stop at desired levels. If regular and good maintenance is not performed, machines cannot work for long years.