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The milling machine is a common machine in machining workshops. It rotates the cutting tool on the surface of workpieces to create product shapes. After a period of use, the machinery needs to be maintained to avoid damage and problems during operation. There are some kinds of maintenance works in the milling machine. In fact, Oil level should be checked first, the checking oil level daily help the milling machine ensure engine efficiency. if the oild level is low, the machine would be overheat, leading to expensive repairs. The secondly, the guideway need to be cleaned daily. This helps to avoid interruptions and control the line of motion of fluids. The next work is examining the coolant. It should be renewed semi-annually to prevent damange and keep the mill at the correct operating temperature. Those are some the maintenance works that you have to do following recommended schedule.

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The check valve is made of cast iron. There are 6 steps you need to follow. The first step is casting. In this step, hot liquid of cast iron is poured into a container and then cooled to make the correct shape. The cast iron is then turned on a machine called a lathe. Part of the materials is removed to make the correct shape. Next, holes of check valve are made using a drill. After drilling, the next step is painting. In this step, a surface is covered with paint. Then, we will move on to step 5. This step means that holes are punched in cast iron. The final step is inspection, in this step, check valve is checked carefully. This is when we make sure that the part is made properly.

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The seven types of plastic include:

Firstly, Code 1 plastics is polyethylene terephthalate (PET), this is one of the most commonly used plastics. It’s lightweight, strong, transparent and often used to produce food and drink packaging as Water bottles and Food containers.

Secondly, Code 2 plastics is high-density polyethylene (HDPE). It ‘s much stronger and thicker than PET.  HDPE is the most commonly recycled plastics in the world because it will not break under exposure to extreme heat or cold.

Applications of HDPE: Milk cartons, toys, and grocery bags…

Thirdly, Code 3 plastics is polyvinyl chloride(PVC). It’s lightness and durability. This plastic is resistant to chemicals and weather, make it ideal for building and construction applications; Besides it doesn’t conduct electricity so it is used for making wires and cable.

However, we must note that PVC is the most dangerous plastic to human health so    it has been called the “poison plastic”.

Fourth, It is low-density polyethylene(LDPE). A softer, clearer, and more flexible version of HDPE. It’s often used as a liner inside beverage cartons, and in corrosion-resistant work surfaces and other products.

For Examples: Plastic/cling wrap, garbage bags, grocery bags and beverage cups…

Fifth, It is polypropylene (PP). This is one of the most durable types of plastic. It is more heat resistant than some others, which makes it ideal for such things as food packaging and food storage that’s made to hold hot items or be heated itself. It’s flexible enough to allow for mild bending, but it retains its shape and strength for a long time.

For Examples: Straws, bottle caps, prescription bottles, hot food containers, packaging tape…

Sixth, that is polystyrene(PS). Better known as Styrofoam, this rigid plastic is low-cost and insulates very well, which has made it a staple in the food, packaging and construction industries. Like PVC, polystyrene is considered to be a dangerous plastic.

For Examples: Cups, takeout food containers, shipping and product packaging…

Finally, This category is a catch-all for other types of plastic that don’t belong in any of the other six categories or are combinations of multiple types. It is classified in the #7 recycling code.

For Examples: Eyeglasses, baby and sports bottles, electronics, CD/DVDs…

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Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to its widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum.

Plastics have interior mechanical properties such as stiffness, strength, and temperature resistance to the materials they have replaced.

In the past, because the technology was not completely developed, plastics were not widely used and humans have not seen the seriousness of plastic waste. But now, plastics are one of the most popular ingredients in the world, they are the raw materials present in many objects. Therefore, the pollution of plastic waste is currently extremely serious. In the future, the world will find another material that can replace plastic so as not to affect people and the environment.

Plastics have many advantages but they also have some disadvantages.Firstly, they are light in weight and chemically stable. Secondly, they are easily moulded into different shapes and sizes. Beside, plastics are good insulation and low thermal conductivity. Thirdly, they have a good impact resistance and do not be rusted. Next, good transparency and wear resistance are two of their advantages. Finally, Plastics have low processing cost and can be easily deformed but not good dimensional stability.

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The check valve is made of cast iron. There are 6 steps you need to follow. The first step is casting. In this step, hot liquid of cast iron is poured into a container and then cooled to make the correct shape. The cast iron is then turned on a machine called a lathe. Part of the materials is removed to make the correct shape. Next, holes of check valve are made using a drill. After drilling, the next step is painting. In this step, a surface is covered with paint. Then, we will move on to step 5. This step means that holes are punched in cast iron. The final step is inspection, in this step, check valve is checked carefully. This is when we make sure that the part is made properly.

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From my point of view, there are some differences between CAD and manual drafting. CAD  is the creation and handling of pictures on a computer to assist engineers in design and drafting, while munual drafting is the practice of creating drawings by hand with pencil or ink on a media such as paper or polyester film using drafting equipment.

CAD enables the designer to quickly layout a preliminary design and change it as often as necessary. Unlike CAD, manual drafting requires designers draft every single detail by hand with pencil or ink on a media such as paper or polyester film using drafting instruments and equipment. Designers using CAD need to have just minimum skills for operation but analytical skills are more required. In contrast, manual drafting requires users must have desgining skills and explanation skills.

CAD is different from manual drafting in term of accuracy. While CAD provides high accuracy in representation and less error in interpretation, drawings made by manual drafting can be easily misread because of ambiguity and drawing errors. Moreover, CAD provides ease of use and tremendous flexibility to designers to make the required changes or modifications. But CAD is quite expensive and it is required professional training before using it, while manual drafting costs quite little and does not have to professional training.

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Computer Aided Design (CAD) is a form design in which people work with computers to create ideas, models and prototypes. CAD was originally developed to assist people with technical drawing and drafting, but it has expanded to include numerous other potential uses. Using CAD for drafting still requires many same skills as manual drafting, but by working with a computer instead of on paper, people can be much more efficient.

The CAD software has a lot of functions. Firstly, it’s used to sketch out the ideas. Besides, it helps designers to experiment with features and dimensions. Moreover, the engineers can use it to produce models and detailed drawings.

CAD has some advantages. The first is easy and intuitive to use from the beginning. The secondly, it is very easy to use for 3D modelling. Finally, CAD is quick and easy to create parts, add them to assemblies and create drawings. However, CAD also has some disadvantages. If people want to use it, they must cost big amoun of money. Besides, it contains some unnecessary features for common user.

In conclusion, I think it is still a powerful support tool for users, due to its functions and advantages.

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As can be seen in figure 1, this is the plastic extrusion moulding process. It is commonly used for projects requiring high-volume, continuous manufacturing. There are six steps in this process you need to follow. First, we move the polymer pellets from the hopper to the cylinder. Second, an electric motor turns the screw in the extrusion moulder. Third, the cord polymer pellets move along the cylinder. Next, heaters warm the polymer pellets to turn them into a liquid. After that, the warm, soft molten polymer moves along the cylinder and then it is cooled by passing through a water bath and going under powerful fans. Finally, the machine pushes the molten polymer out into the mould.

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There are 2 main kinds of bearings: rolling contact bearings and journal bearing. Journal bearings have no rolling parts and the shaft rotates inside a lubricated sleeve instead. Unlike journal bearings, rolling contact bearings use rollers to support loads. They consists of 4 types including: ball bearings, straight roller bearings , tapered roller bearings and thrust roller bearings. Firstly, ball bearings use spherical rollers to support radial and axial motion.

Secondly, straight roller bearings use cylindrical rollers to support radial motion. Next, tapered roller bearings use conical rollers to support radial forces and thrust forces. Finally, thrust roller bearings use barrel-shaped rollers to support thrust motion.

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Drives consist of two main types: chain drive and belt 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. In contrast, chain drive is one type of power transmission system that transmit motion and power by means of successive chain with sprocket special toothed wheels.

Besides, they have many other differences. Firstly, belt drive is made of polymers, while chain is made of alloys. Secondly, chain drive can operate in high temperature and moist conditions but belt drive cannot. Thirdly, belt drive mustn’t lubricate, whereas the chain drive needs to be lubricated regularly. Moreover, chain drive can operate under high loads, whereas belt drive can operate under high speed conditions. Finally, when operating belt drive is silent but chain drive is noisy.

Application of belt drive are flour mills, coolant pump, lubricant pump, belt conveyor… Whereas, chain drive is used in bicycle, motorbike and material handling equipment.

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Gear is a rotating circular component of machine which mesh with another toothed part. The function of gear is to transmit torque, change the speed, and directions of power. Gear is divided into five main types: spur gear, helical gear, bevel gear, rack and pinion, worm and worm gear.

Firstly, spur gears are the most common and simplest types of gears with teeth projecting towards or away from the centre. They are used in low-speed applications but they can’t control noise at high speed.

Secondly, helical gears are similar to spur gears except that their teeth are cut in spiral shape. Helical gears are used in high-speed applications, large power transmission, or control noise.

Thirdly, bevel gears are types of gears that have a conical form and they can be used to transmit rotational power through shafts at an angle, normally 90 degrees to each other.

Next, rack and pinion comprises a circular gear(the pinion) engaging a linear gear(the rack), which operate to convert rotational motion into linear motion.

Finally, these are worm and worm gear. A worm has just one continuous tooth and pairs with a worm gear, which helps reduce speed.

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The couplings are used to connect shafts together to transmit power and disconnect shafts for maintenance. It includes two types: input shaft and output shaft. The input shaft is used for connecting to the power source while the output shaft is used to connect to the destination. Couplings are divided into rigid coupling and flexible coupling. Rigid coupling is used to hold shaft in perfect alignment. While flexible coupling transmits torque without perfect alignment. The rigid coupling consists of sleeve-style coupling and it is used for reducing vibration of the shaft. The flexible coupling includes beam coupling, it is cut in sprial shape to accommodate misalignment.

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How to make an effective presentation

There are 3 main parts in a presentation: the introduction, the body and the conclusion. Before the presentation, you need to follow some tips. Firstly, you should make sure about the content and organize it logical. Then you can choose a suitable presentation style and practice for many times. Don’t forget to check the equipments and turn off the phone if you don’t want any mistakes. During the presentation, you ought to use gestures and body languages to express the ideas. Beside, make eye contact and look at the audience, not the paper or screen. Sometimes, instead of just talking continuously, asking the listeners questions is also a good tip to get attention. After the presentation, you need to thank the audience and try to answer their question. In case you don’t know the answer, admit that and promise to provide the answer later. Remember these tips and you will have an effective presentation

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My name ‘s Hieu, a maintenance staff of Samsung company. Here is the maintenance list of this lathe machine that you need to know better when using it.

Firstly, you must check water line pressure gauges and air pressure everyday to avoid interruptions. Secondly, coolant levels and oil levels are need to be checked everyweek to make sure that the engine operates efficiency. Finally, you had better inspect spindle bearing and drive belt semi-annually to help lathe machine can operate more smoothly, besides, you need changing oil regularly about twice a year.

In order to help the lathe machine can operate durable, we need to comply and fulfill the requirements of it.

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There are 3 typical problems of plastic injection moulding that may occur.

First, that is short shots. It is a phenomenon when the air is trapped in the cavity to create bubbles in the part. To solve this problem, you should check the shots continuously and use plastic with high melting capability. Besides, you need to increase gate size and runner.

Second, that is void. It is a phenomenon when pocket of air is trapped withiin or close to the surface of an injection moulded prototype and causing some voids in the part. To deal with this problem, you need reducing wall thickness and slow down colling rate. Moreover, you had better increase gate size and locate it at the thick part of the moulding.

Third, that is sink mark. It is a phenomenon in which the mold cavity cannot be completely filled by molten plastic, resulting in a portion where there is no plastic. To solve this problem, you should reduce mould temperature, have enough shot size and reduce wall thickness for faster cooling.