General Properties of Titanium Alloys

Titanium, though discovered as an element in 1791, commercially produced titanium has been available only since the 1940s, so it is among the newest of engineering metals. Titanium can be the answer to an engineer’s prayer in some cases. It has an upper service temperature limit of 1200 to 1400°F (650 to 750°C), weighs half as much as steel (0.16 lb/in3 {4429 kg/m3}), and is as strong as a medium-strength steel (135 kpsi {930 MPa} typical). Its Young’s modulus is 16 to 18 Mpsi (110 to 124 GPa), or about 60% that of steel. Its specific strength approaches that of the strongest alloy steels and exceeds that of medium-strength steels by a factor of 2. Its specific stiffness is greater than that of steel, making it as good or better in limiting deflections. It is also nonmagnetic.

General Properties of Aluminum and Aluminum Alloys

Aluminum

Aluminum is the most widely used nonferrous metal, being second only to steel in world consumption. Aluminum is produced in both “pure” and alloyed forms. Aluminum is commercially available up to 99.8% pure. The most common alloying elements are copper, silicon, magnesium, manganese, and zinc, in varying amounts up to about 5%. The principal advantages of aluminum are its low density, good strength-to-weight ratio (SWR), ductility, excellent workability, castability, and weldability, corrosion resistance, high conductivity, and reasonable cost. Compared to steel it is 1/3 as dense (0.10 lb/in3 versus 0.28 lb/in3), about 1/3 as stiff (E = 10.3 Mpsi {71 GPa} versus 30 Mpsi {207 GPa}), and generally less strong. If you compare the strengths of low-carbon steel and pure aluminum, the steel is about three times as strong. Thus the specific strength is approximately the same in that comparison. However, pure aluminum is seldom used in engineering applications. It is too soft and weak. Pure aluminum’s principal advantages are its bright finish and good corrosion resistance. It is used mainly in decorative applications.

General Properties of Steel Alloys

Cast Steels

Cast steel is similar to wrought steel in terms of its chemical content, i.e., it has much less carbon than cast iron. The mechanical properties of cast steel are superior to cast iron but inferior to wrought steel. Its principal advantage is ease of fabrication by sand or investment (lost wax) casting. Cast steel is classed according to its carbon content into low carbon (< 0.2%), medium carbon (0.2–0.5%) and high carbon (> 0.5%). Alloy cast steels are also made containing other elements for high strength and heat resistance. The tensile strengths of cast steel alloys range from about 65 to 200 kpsi (450 to 1380 MPa).

General Properties of Cast Iron Alloys

Cast Iron

Cast irons constitute a whole family of materials. Their main advantages are relatively low cost and ease of fabrication. Some are weak in tension compared to steels but, like most cast materials, have high compressive strengths. Their densities are slightly lower than steel at about 0.25 lb/in3 (6920 kg/m3). Most cast irons do not exhibit a linear stress-strain relationship below the elastic limit; they do not obey Hooke’s law. Their modulus of elasticity E is estimated by drawing a line from the origin through a point on the curve at 1/4 the ultimate tensile strength and is in the range of 14–25 Mpsi (97– 172 MPa). Cast iron’s chemical composition differs from steel principally in its higher carbon content, being between 2 and 4.5%. The large amount of carbon, present in some cast irons as graphite, makes some of these alloys easy to pour as a casting liquid and also easy to machine as a solid. The most common means of fabrication is sand casting with subsequent machining operations. Cast irons are not easily welded, however.

Types of Heat Exchangers

A heat exchanger is a system used to transfer heat between two or more fluids. Heat exchangers are used in both cooling and heating processes. There are different types of heat exchangers

1. Double-pipe (pipe-in-pipe) heat exchanger - simplest type of heat exchanger consists of two concentric pipes of different diameters. Following two types of flow arrangement are possible

Types of Steel and its Manufacturing

Steel is an alloy of iron and carbon, with carbon content up to a maximum of 1.5%. Most of the steel produced now-a-days is plain carbon steel or simply carbon steel. Steel is divided into the following types depending upon the carbon content:

• Dead mild steel — up to 0.15% Carbon
• Low carbon or mild steel — 0.15% to 0.45% Carbon
• Medium carbon steel — 0.45% to 0.8% Carbon
• High carbon steel — 0.8% to 1.5% Carbon

Inspection Methods to Find Defects in Casting

In casting process, first few castings will be inspected dimensionally and the pattern is qualified afterwards, only few random inspection will be done. Every casting must be inspected to find out the defects in casting process.

Different methods of inspection to find out defects in casting process are discussed below

• Radiographic Examination
• Ultrasonic inspection
• Visual Inspection
• Hydrostatic Pressure Test
• Magnetic Particle Inspection
• Dye Penetrant Inspection
• Coin Testing

Effects of Welding on Your Eyes?

Between UV radiation and flying debris, welding can certainly cause damage to your eyes, but only if you don’t observe the correct safety protocol. Since 25% of all welding injuries are eye-related, proper eye protection on the job is a serious issue.

The good news, though, is that most of these eye injuries are preventable, and the bulk are also reversible. To put that into perspective, fully 95% of welders sustaining eye injuries are back at work within a week, while over 50% return within two days.

Air-cooling System in Reciprocating Engine

In an air-cooling system, the outer surface of the cylinder and cylindrical head in reciprocating engine is cooled by air flowing over them. To increase the heat transfer rate from the surface, the metallic fins are cast on the cylinder and cylinder head. These fins increase the heat transfer area and thereby heat transfer rate.

Air cooling system is a very simple, reliable and maintenance-free cooling system, with no operating cost. It is very suitable for small engines of automobiles.

Applications of Air-cooling System

• Air-cooling system is used in small engines, i.e., motor cycles, scooters, mopeds, airplanes and combat tanks, where speed of the vehicle gives a good velocity to the air to cool the engine.
• It is also used in small stationary engines used for agriculture and industries.

Application of Superchargers

Super charger acts as an air compressor. It is used to increase the density and pressure of the air that is supplied to the internal combustion engine. In the engine, during the intake of the cycle it takes more oxygen and burn more fuel to accomplish the work. This is due the power increase.

By using the belts, gears, shafts, chains all of these are connected to the engines crank shaft to produce super charge.

We can see two types of the super chargers. To that matter after super charging, the air enters into the engine. After compression the pressure in the air is compressed and it super charges the system by 1.5 to 2 times to increase the entry of the pressure.

Forging Process

 Forging process is perhaps the oldest metal working process and was known even during prehistoric days when metallic tools were made by heating and hammering.

Forging is basically involves plastic deformation of material between two dies to achieve desired configuration. Forging is carried out as open die forging and closed die forging depending upon complexity of the part.

In open die forging process, the metal is compressed by repeated blows by a mechanical hammer and shape is manipulated manually.

In closed die forging, the desired configuration is obtained by squeezing the work-piece between two shaped and closed dies.

In forging process the forces are applied on the raw material such that the stresses induced are greater than yield and less than ultimate so that material is experiencing permanent deformation (plastic) to get required shape. But in forging operation force applied can be either continuous or intermittent impact loads.

Types of forging methods:

1. Based on the method of force application

1.      Hand forging (Drop hammer type)

2.      Machine forging (Mechanical or hydro-static forging)

All About Compressed Air

Purification of Compressed Air from Generation to Application:

Compressed air is widely used through industry as an essential and safe power source in production process. However, the compressed air will contain too much much contaminants, such as water, dirt, wear particles, and degraded lubricating oil, which rapidly wears tools and pneumatic machinery, blocks valves, and corrodes piping systems causing high maintenance and costly air leaks. 

The quality of air required throughout a typical compressed air system can vary. Treatment of compressed air prior to entry into the distribution system, as well as at each usage point or application, is highly recommended. This approach to system design provides the most cost effective solution to system purification.