College of Engineering

Magnesium has been used in manufacturing notebook computer frames, video cameras, digital cameras, PDAs and other consumer electronics products because of its high strength to weight ratio. When magnesium is alloyed with aluminum, the resultant material is very light and strong, and easily machinable.

The main concern in machining magnesium alloy is the danger of fire ignition when dry cutting. Fire may occur when the melting point of the alloy (400-600 degrees Celsius) is exceeded during machining. The small chips and fine dust generated during cutting are also highly flammable and pose a serious fire risk if not properly handled.

There are several points to note when machining magnesium:

Firstly, use a lower cutting speed when compared to cutting aluminum. The workpiece temperature goes up with an increase in cutting speed and also smaller undeformed chip thickness. In other words, the slower the machining speed and the larger the chips, the lower the workpiece temperature will be. Due to this reason, some companies have modified woodworking tools for machining magnesium so as to achieve larger chips and lower fire hazard.The cutting tools used should have relief and clearance angles that are sufficiently large to prevent unnecessary cutting tool-workpiece friction, thus lowering the heat generated during the cutting process.

Second, keep the machining center clean. Cleaning the machining centers regularly and storing the magnesium chips correctly are important aspects of machining magnesium. Keep a container of cast iron chips near by when machining magnesium, If fire occurs, smother the fire with the cast iron chips.

Thirdly, if coolants are necessary for high speed machining, do not use water-based lubricants. Instead use a light mineral oil, or a water-soluble cutting fluid such as Castrol Hysol MG specially formulated for machining magnesium. Some companies in Japan use semi-dry machining via a misting system.

The fourth point is to monitor the workpiece temperature during machining. Experiments were carried out using thermocouples mounted into the workpiece to monitor the workpiece temperature during machine. Dry cutting of magnesium alloy thin walls was achieved using cutting speed of 440m/min for roughing and 628m/min for fine finishing.

Despite the fire hazards, as competition from overseas low-cost production bases intensifies, and magnesium becomes increasingly used in electronics products, most machining job shops could very well find machining of magnesium a niche worth pursuing.

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Chemistry is generally divided into two broad branches: organic chemistry and inorganic chemistry. Other types of chemistry include physical chemistry, biochemistry, and analytical chemistry, with each field branching off into several specific subfields. Here’s a brief description of the most common branches of chemistry.

Organic Chemistry

Organic Chemistry has to do with the study of compounds that contain carbon (and sometimes hydrogen). Even though carbon is only the fourteenth most common element on the planet, it produces the greatest number of different compounds on Earth. Not surprisingly then, much of the study of chemistry involves organic chemistry.

The most studied groups of organic compounds are those that contain nitrogen. These organic compounds are important because they are often linked to the amino group. When the amino group combines with the carboxyl group, amino acids are born. Amino acids are important because they are as the building blocks of proteins.

Inorganic Chemistry

Inorganic chemistry involves the study the properties and reactions of compounds that do not contain carbon and which are not organic. Inorganic chemistry studies all non-living matter, such as minerals found in the Earth’s crust. There are many branches of inorganic chemistry, including geochemistry, nuclear science, coordination chemistry, and bioinorganic chemistry.

There is much overlap between organic and inorganic chemistry. For instance, organometallic chemistry studies the use of compounds that are capable of creating a covalent bond between carbon and metal.

Physical Chemistry

As its name implies, physical chemistry has to do with the physical properties of materials. Physical properties that are studied may include the electrical and magnetic behavior of materials, as well as their interaction with electromagnetic fields.

There are several subcategories of physical chemistry. These include thermochemistry, electrochemistry, and chemical kinetics. Thermochemistry studies the changes of entropy and energy that naturally occur during chemical reactions. Electrochemistry is concerned with the study of interconversions of electric and chemical energy of matter, as well as the effects of electricity on chemical changes. Chemical kinetics involves the study of chemical reactions. Specifically, chemical kinetics studies the equilibrium it reached between products and their reactants.

Biochemistry

Biochemistry is a branch of chemistry concerned with the composition and changes of living matter. Biochemists commonly focus on the physical properties and structures of biological molecules. Common biological molecules include carbohydrates, proteins, lipids, and nucleic acids. Biochemistry is sometimes referred to as physiological chemistry and biological chemistry. Biophysics, molecular biology, and cell biology are research fields closely related to biochemistry.

Analytical Chemistry

Unlike the other main types of chemistry, analytical chemistry doesn’t deal specifically with specific elements. Analytical chemistry is concerned mainly with the various techniques and laboratory methods used to determine the composition of materials. Qualitative and quantitative analysis are the two most basic methods used in analytical chemistry. Qualitative analysis has to do with identifying all the atoms and molecules in a sample of matter, with attention paid to trace elements. Quantitative analysis also involves determining the atomical and molecular structure of matter, but includes also measuring the exact weight of each chemical constituent.