E6B CTO 9 Welding

After spending six months preparing a report on climate change in the Gulf countries, several university scientists are certain that their report will add to the scientific knowledge on this topic for the governments in the Gulf countries.

knowledge means:

• data about government research

• unscientific collection of facts

• understanding of specific information

• information about government organizations

When Ali arrived home from vacation last night, he realized that he didn’t have his key. Since it was late in the evening and his parents were asleep, he had to pound on the door for a few minutes until they heard him and let him in.

pound means:

• use a key

• push only once

• hit hard

• hit only once

Ali was given a large number of reports to organize. He put the reports in the correct order and then put paper clips on them. The paper clips held the reports together.

clips means:

• equipment used to separate things

• devices that hold things together

• tools used to hammer pieces of metal together

• devices that measure

When the reinforced concrete dries, it will form a strong bond with the steel bars and it will last a very long time. Almost all large structures, including tall buildings and bridges, require the steel and concrete to be firmly joined together.

bond means:

• separation

• connection

• agreement

• process

Inert gases are often used by companies because they stop unwanted chemical reactions from happening. For example, nitrogen is used by food companies to stop food from going bad during shipping.

inert means:

• able to heat up

• able to grow bacteria

• unable to go bad

• unable to react

In order to increase truck production by 50 percent, Ford Motor Company decided to install modern machines and computers in their factories to make the production lines more automated.

automated means:

• operated by machines and computers

• operated by workers

• designed by computer programs

• designed by machines

People who work as quality control inspectors often have to do repetitive jobs. For example, they have to repeat the same tests on all products before they are shipped to stores.

repetitive means:

• repeated

• complex

• different

• interesting

Several Japanese companies have spent a lot of money developing robots to help make some of the work in the auto industry more automated. Robots are used to do repetitive and dangerous jobs like welding parts and painting without the need for much human control.

robots means:

• machines that need a lot of human control on repetitive jobs

• devices that can solve simple engineering problems

• machines that operate automatically or by computer

• equipment that does not do repetitive jobs

Welding is the process of joining pieces of metal permanently. This is done by heating the metal pieces to be joined and melting a filler material (electrode wire or rod) between them

to form a joint. Because of the strength of a welded joint, welding is used in automobile manufacturing, shipbuilding and repair, the manufacture of space products, and thousands of other jobs. Nearly everything people use in their daily lives today has been welded or made by equipment that has been welded together. In the construction industry, welders construct buildings, connect steel beams, and join pipes in pipelines and refineries. Also, welding can be done outdoors, indoors, under water, and in outer space.

Skilled welders usually plan their work by either following blueprints or using their knowledge of fluxes and base metals to analyze the metal pieces to be joined. Fluxes are chemical substances that protect the weld area from rust and contamination by producing carbon dioxide gas during welding. Welders then choose and set up the welding equipment, perform the planned welds (the joint formed by welding), and examine the welds to ensure that they meet industry regulations. They even examine a weld while they are welding. By observing problems with the weld, they can adjust the speed, voltage, or amount of electrode rod filler they use. In addition to working with steel, highly skilled welders are trained to work with other materials such as aluminum or plastics.

Pieces of metal have been welded together for thousands of years in Europe and the Middle East. Originally, the process was known as “forge welding.” In this type of welding, the welder would heat up the pieces of metal to be joined and then pound them until they came together. When electricity became available during the nineteenth century, welding became easier and faster. Welding played an important part in industry during World Wars I and II. Although there are about one hundred different types of welding processes in use today, the most common welding process is arc welding.

Arc welding is a common process of joining metal together using an electric arc between the pieces of metal being welded and the electrode rod filler. Arc welding uses two clips that are fastened to the metal pieces. One clip is fastened to the piece of metal being welded. The second clip is fastened to the welding rod. When the rod touches the pieces of metal, a powerful electrical circuit is produced. The heat created by the electrical current causes both the metal piece and the steel core in the rod to melt together. As the metal piece and steel core cool, they form a solid bond. The two most popular types of arc welding are shielded metal arc welding (SMAW) and gas metal arc welding (GMAW), which is also known as metal inert gas (MIG) welding.

Shielded metal arc welding is also referred to as covered electrode welding process. It is the most widely used welding process. As the electric arc melts the base metals and the electrode wire, the flux covering the electrode rod melts into the weld. This produces vapors that protect the weld area from oxygen contaminating the electrode filler as it hardens. SMAW accounts for more than 50 percent of the welding done in some countries. It is very popular in the maintenance and repair industries because it is versatile and easy to learn.

GMAW (or MIG) is another welding process (see Figures5 and 6) that uses a continuous electrode wire supply and an inert gas mixture to protect the weld. The welder does not have to keep using new electrodes. Also, this process lets the welder join longer pieces of metal without having to stop to replace the electrode rod. However, the welder must use more 70 expensive and more complex equipment than with SMAW, and the equipment takes longer to prepare. This type of welding is commonly used for repairing oil pipelines. It is also used in making jewelry and plastics.

Over the past twenty years, welding has become more automated. It is now common in the car industry for repetitive work like welding to be done by robots.

This article is mainly about the _____.

• advantages and disadvantages of welding

• history of welding

• different welding methods used

• knowledge welders have about welding

Welders then choose and set up the welding equipment, perform the planned welds (the joint formed by welding), and examine the welds to ensure that they meet industry regulations. They even examine a weld while they are welding. By observing problems with the weld, they can adjust the speed, voltage, or amount of electrode rod filler they use.

The underlined word “they” in paragraph 2 refers to _____.

• base metals

• welds

• welders

• blueprints