Bookmarks by Văn Luân Nguyễn

Unit1

nguyenvanluan1432002 — 2023-09-16 09:55:48 UTC

To make an effective presentation, you have to make an effort and prepare it carefully. A basic structure of a presentation has three main parts, they are the introduction, body, conclusion. Before the presentation, you should outline key points of the presentation, practice presenting before your close friend, who can give you constructive feedback. During the presentation, you should keep eye contact with the audiences, which will make your presentation more attactive, you shouldn’t bring a description paper to read, in stead, you should have a free talk which will make your audiences fully engaged in your speech. After you have finished your speech, summarize your ideas, ask your audiences to make questions about the objective your have delivered. So that is my opinion to make an effective presentation.

Unit1

nguyenvanluan1432002 — 2023-09-16 14:47:54 UTC

Unit2-Writing1

nguyenvanluan1432002 — 2023-09-24 16:54:16 UTC

Couplings are one of the important parts of the mechanical structure, the main function of them is to connect two shafts together and transmit power from one shaft to another shaft.

There are many different kinds of coupling on the market but it just has two main categories, they are rigid couplings and flexible couplings. First, we have sleeve-style coupling is one of the rigid couplings, they are used for transmitting more power than another one, and they can efficiently transfer torque from one shaft to the other connected shaft. Some of the components like drive bolt, balance weight groove, coupling nut …

It permits neither axial nor radial relative motion between the shafts of the driver and driven unit.

The second is flexible couplings, they have more application than rigid, used to transmit torque like rigid even two shafts are slightly misaligned, and can accommodate some misalignment but should not be used as an excuse for poor alignment or lack of maintenance. Some of the components such as lead screws or ball screws, gearboxes, belts… main feature: protect the driving and driven shaft component from the harmful effect of condition such as vibration, shock loads, and thermal expansion.

Unit2-Writing2

nguyenvanluan1432002 — 2023-09-24 16:56:33 UTC

Bearings are used in all kinds of applications from airplanes and the car you drive to your desk chair and many other machines.

Their goal is to ensure motion is regulated in a moving part and help reduce friction

Basically, bearings are composed of two rings with the raceway, a rolling element(like rollers or balls), and a cage (used to keep the roller element). there are several different types of bearings but I just know some of them including ball bearings roller bearings, and linear bearings ...now We take a deeper look into the different types of bearings. First, Ball Bearings are mechanical assemblies that consist of rolling spherical elements that are captured between circular inner and outer races. Ball bearings are used mainly in machinery that has shafts requiring support for low friction rotation and Handles radial and axial loads with specific configurations. Ball bearings are also known as rolling element bearings or anti-friction bearings. second, we have roller bearings, their component consists of cylindrical or tapered rolling elements usually captured between inner and outer races. Roller bearings are used primarily in machinery with rotating shafts that require the support of heavier loads than ball bearings provide and can withstand axial loads. Another one is linear bearings which are mechanical assemblies that consist of ball or roller elements captured in housings and used to provide linear movement along shafts, used primarily in machinery that requires linear movement and positioning along shafts.

Unit2-speaking1

nguyenvanluan1432002 — 2023-09-26 15:06:42 UTC

Unit2-speaking2

nguyenvanluan1432002 — 2023-09-26 15:10:05 UTC

Unit3-writing1

nguyenvanluan1432002 — 2023-10-05 13:54:45 UTC

A Gear is a machine part with teeth that mesh with another toothed part to transmit torque and speed. There are many gears, such as spur gears, helical gears, bevel gears, etc.. first, one of the most common and simplest gears is a spur gear, called cylindrical gear. Spur gears belong to the parallel shaft gear group and are cylindrical gears with a tooth line that is straight and parallel to the shaft. It is used to increase or decrease the speed, torque, or power, of a given object. Second, Helical gears are used with parallel shafts similar to spur gears with winding tooth lines but they mesh more smoothly than spur gears, it is used to transmit torque and can change the speed, torque, and direction of a power source. The last one is bevel gears, they have a cone-shaped appearance, they are mounted on shafts that are 90 degrees and are used to transmit force between two shafts. Bevel gears have many diverse applications such as construction equipment, automotive drivetrains, and helicopter transmissions. That are three typical gears which you can meet in your work

Unit3-writing2

nguyenvanluan1432002 — 2023-10-05 13:56:28 UTC

Drive is one of the machine components. There are two types of drives have I known, they are belt drive and chain drive, both of them are used to transmit motion and power between two shafts and are used when synchronous rotation is necessary. Regarding material, belt drives are often made of rubber or plastic meanwhile chain drives are almost made of metal. Some main features of belt drive that we can refer to, are they can reduce noise and vibration, don’t need to lubricate, and have low production cost. Besides, they also have a few disadvantages like they can slip and stretch, and have low heat resistance, and abrasion resistance, belt drive often applicated in machine like Sewing Machines, Drilling Machines, Lathes. In contrast to belt drive, chain drive cause more noise and vibration, you have to frequently lubricate for them, and have a high cost on the market. In return, they do not slip and have high heat resistance. They are used in direct motor, speed reducer - indirect, conveyor.

Unit3-speaking1

nguyenvanluan1432002 — 2023-10-05 14:06:20 UTC

Unit3-speaking2

nguyenvanluan1432002 — 2023-10-05 14:10:53 UTC

Unit4-writing1

nguyenvanluan1432002 — 2023-10-16 15:32:50 UTC

CAD software stands for “Computer-aided design” software that refers to a type of software program used by designers and engineers to create two-dimensional and three-dimensional models of physical components, now it has replaced manual drafting across a wide range of industries. CAD has plenty of features like Ease of modifying the design of a model and the production of multiple versions, Simulation of designs without building a physical prototype, Automatic generation of standard components of the design, etc... The purpose of CAD is to optimize and streamline the designer's workflow, increase productivity, improve the quality and level of detail in the design, improve documentation communications, and often contribute toward a manufacturing design database. About advantages, it easily generates detailed manifold and non-manifold models, making it easy to turn designs into models, and it can create photorealistic rendering which shows customers early design ideas. Besides, it has some disadvantages: Work can be lost because of the sudden breakdown of computers, Work could be easily “hacked”, High production or purchasing cost for new systems...

Unit4-writing2

nguyenvanluan1432002 — 2023-10-16 15:34:11 UTC

CAD (Computer Aided Design) is the use of computer software to design and document the design process of a product. Artboards and manual drawings are not always accurate and fast: traditional designs are often slow, especially during revision and modification. For this reason, manufacturing companies have replaced manual drawings with computer-aided design (CAD) to perform functions related to design and manufacturing. On the upside, it's easy to generate rich and non-detailed models, makes it easy to convert designs into models, and it can generate realistic renderings to show clients ideas. Original design. Besides, it has some disadvantages: Work can be lost due to sudden computer failure, Work can be easily "hacked", High cost of production or purchase of new system...

Unit4-speaking1

nguyenvanluan1432002 — 2023-10-16 15:38:51 UTC

Unit4-speaking2

nguyenvanluan1432002 — 2023-10-16 15:38:51 UTC

Unit5-writing

nguyenvanluan1432002 — 2023-10-16 15:45:04 UTC

A check valve is a flow-monitoring device typically used in pipeline systems to allow fluid to flow in only one direction and prevent backflow or backwash. They can be used for a variety of fluid applications such as liquids, gases, and slurries, ... the manufacturing process of a check valve is not overly difficult. The main property of the check valve is cast iron. First, we have to do the casting process. in this process, hot liquid iron that contains 2 to 4 percent carbon is poured into a container and cooled to make a valve shape. Next, the workpiece will be put into the lathe, The cutting tool feeds into the rotating workpiece and cuts away part of the material. Then the workpiece is drilled with about 4 holes to fitting bolts on each side. After the drilling process, it is moved to the painting process, the coat of paint gonna be covered whole surface of the valve prototype to Improve appearance, Enhance productivity, Extend equipment service life, Rust and corrosion prevention, ... next step, the valve is joined with other parts. After the final step, we have to check carefully the working process of the valve, make sure that it’s not happening any fault.

Unit5-speaking1

nguyenvanluan1432002 — 2023-10-16 15:54:30 UTC

Unit5-speaking2

nguyenvanluan1432002 — 2023-10-16 16:01:53 UTC

Unit6-writing1

nguyenvanluan1432002 — 2023-11-02 19:14:17 UTC

Plastic is synthetic materials that use polimers as a main ingredient. Plastic is able to be moulded or shaped to any forms. Plastic has many properties. First pro is versatile, it is shaped easily into a wide range of forms, and it can be used to make a variety of products. Next, property of plastic is safe, it is used in food wrapping, containers and medical applications. Beside, plastic is lightweight, it is often used in manufacturing airplane interior and exterior parts. Moreover, plastic is durable and resistant to all kinds of adverse outside factors such as heavy rain or storm. However, plastic has some disadvantages, it can hurt the environment, isn’t biodegradable and can not be recycled. In the past, we weren’t able to mould plastic into complex shapes. But now, manufacturers can be moulded plastic into a variety of complex shapes. And in the future, we will save money and increase efficiency by using smart plastic coatings on manufacturing components.

Unit6-writing2

nguyenvanluan1432002 — 2023-11-02 19:15:19 UTC

There are 7 types of plastic. Group number one is made out of polyethylene terephthalate, the property of PET is oxygen prevention and can be widely recycled. PET is used in food or drink packaging. Secondly, it is HDPE, code of HPDE is 2, it is hard, resistant to impact and subjected to high temperatures. It can be used in grocery bags, milk jugs, recycling bins, agricultural pipes… Number three is PVC, it is versatile, light, durable and easy of process ability. PVC has two forms: rigid form is able to use in building and construction industry, flexible form is used for plumbing, wiring. Next, LDPE has number code 4, LDPE is flexible, odorless and transparent, it suitable for plastic bags, six-pack rings, containers… Having number code 5 is PP, it is hard, sturdy. PP can be used in car parts, thermal vests, yogurt containers. Next, PS has number code 6, the pro of it is solid, foamed, easy to create, highly inflammable but dangerous. It can be found from beverage cups, insulation, packing material. Finally, OTHER is number 7, it is never recycled so it is used in lenses for sunglasses, sport and safety goggles.

Unit6-speaking1

nguyenvanluan1432002 — 2023-11-03 03:21:11 UTC

Unit7-writing1

nguyenvanluan1432002 — 2023-11-03 03:29:21 UTC

As you can see in the figure 1, this is the process of plastic extrusion moulding. There are 6 steps in this process. 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. Beside,The warm, soft molten polymer moves along the cylinder. Finally, the machine pushes the molten polymer out into the mould.

Unit7-writing2

nguyenvanluan1432002 — 2023-11-03 03:31:32 UTC

There are many processes happening in the plastic injection molding process, here are some typical ones. The first is warping that occurs when different parts of the product cool and solidify unevenly during plastic processing. As a result, the product is bent and twisted. The main cause is the premature cooling of the material. We must ensure the cooling process is slow and long enough to avoid uneven stress on the material. The burn marks are followed by dark spotsThe most common cause behind burn marks is air bubbles or plastic trapped in the mold cavity that is too hotTo overcome this problem we need to reduce the melting temperature and mold temperature to avoid overheating

Unit7-speaking1

nguyenvanluan1432002 — 2023-11-03 03:33:56 UTC

Unit7-speaking2

nguyenvanluan1432002 — 2023-11-03 03:36:02 UTC

Unit8-writing1

nguyenvanluan1432002 — 2023-11-03 03:39:34 UTC

One of the popular methods to ensure lathe productivity while still saving costs is regular lathe maintenance. Moreover, this also helps prolong the life of the machine and makes the operation of the machine more convenient and faster. The following is the lathe maintenance schedule. Every day, we need to do the following things to maintain the lathe, first is Check the water and air line pressure gauges, next we moisten the spindle at low speed for 5 minutes and finally clean the chip filter. This helps the lathe machine to work well, ensure safety and stability according to technical standards, and reduce consumption of electrical energy.

Every week, we need to check all filters, coolant levels, oil and grease, and finally load oil to help the lathe to help the machine's mechanical structure need to operate smoothly, with less noise, and less friction between transmission mechanisms. Finally, every 6 months, we need to check the main bearing, transmission belt, change and oil the machine.

Unit8-writing2

nguyenvanluan1432002 — 2023-11-03 03:40:02 UTC

Proper maintenance of the CNC machine will help the machine operate smoothly and stably, reduce the wear and tear of the parts, and at the same time detect damage and repair techniques to promptly fix the problem. thereby increasing the life of the machine. Fully and regularly performing CNC machining machine maintenance procedures will bring many benefits such as: Increase the processing readiness of machinery and equipment,

reduce machine downtime, reduce production costs by reducing machine breakdowns, improve machining productivity. The following is the CNC machine maintenance schedule:

Every day, we need to check the oil level in the lubricating oil tank of the machine, chip cleaning in contours, trays and tool changers, clean the spindle cone head with clean oil and light oil, check the parameters through the main shaft cooling oil filter and clean or replace parts, machine parts if necessary.

Every week, we need to clean the chips on the cooling oil tank, clean the tank cover and remove the residue in the tank, Attention before working on the coolant tank, it is necessary to carefully remove the coolant pump from the control unit and cut off the power completely,

check pneumatic controller at 85 psi, check air pressure regulation at 17 psi, check spindle gas pressure adjustment at 20psi, clean the outer surfaces with a gentle wipe. Avoid the use of solvents as this can cause the machine's exterior paint to peel off.

Every month, we need to check the hydraulic pressure balance of the machine.

Finally, every year, we need to change the gearbox oil, drain the oil from the bottom of the gearbox, remove the main shaft inspection cap, add more oil until the oil begins to drip from the spill tube at the bottom of the container, check the oil filter and clean all dirt at the bottom of the oil filter and

replace the air filter on the control box every 2 years.

Unit6-speaking2

nguyenvanluan1432002 — 2023-11-03 03:41:11 UTC

Unit8-speaking

nguyenvanluan1432002 — 2023-11-03 03:51:02 UTC