• Fundamentals Of Metal Casting
  • Metal Casting Basics: Molds, Patterns, Cores, and Gating
  • The Metal Casting Operation
  • The Effect of Gases and Material Selection on Metal Casting
  • Gating Systems and Mold Design /Troubleshooting
• Expendable Mold Casting
  • Sand Casting
  • Plaster Mold Casting
  • Ceramic Mold Casting
  • Shell Molding
  • Vacuum Casting or V-process
  • Expanded Polystyrene Casting
  • Investment Casting
• Permanent Mold Casting
  • Basic Permanent Mold Casting
  • Slush Casting
  • Pressure Casting
  • Vacuum Permanent Mold Casting
  • Die Casting
  • Hot Chamber Die Casting
  • Cold Chamber Die Casting
  • True Centrifugal Casting
  • Semicentrifugal Casting
  • Centrifuge Casting
  • Ingot Manufacture
  • Continuous Casting

• Fundamentals Of Metal Forming
  • Metal Forming Basics
• Bulk Deformation
  • Metal Rolling
    • Shape Rolling
    • Ring Rolling
    • Thread Rolling
    • Rotary Tube Piercing
  • Metal Forging
    • Forging Hammers
    • Hydraulic And Mechanical Presses
    • Heading Or Upset Forging
    • Piercing
    • Sizing
    • Roll Forging
    • Swaging
    • Hobbing
    • Metal Ball Manufacture
    • Orbital Forging
    • Ring Forging
    • Riveting
    • Coining
    • Isothermal Forging
    • Trimming
    • High Energy Forming
  • Extrusion
    • Extrusion Design
    • Impact Extrusion
    • Hydrostatic Extrusion
  • Metal Drawing
• Sheet Metal Forming
  • Sheet Metal Basics
  • Sheet Metal Cutting
  • Sheet Metal Bending
  • Deep Drawing Sheet Metal
  • Ironing Sheet Metal
  • Metal Spinning
  • Rubber Forming Of Sheet Metal
  • High Energy Rate Forming

• Powder Metallurgy
• Pressing And Sintering
• Alternative Powder Processing Methods
• Design And Applications Of Powder Metallurgy

Manufacturing processes are applicable in all areas of our lives, so much that we often don't realize or think about it. From the cars we drive, the containers our food comes in, the TV's, computers and other devices we use, power tools, heaters, air conditioners, the pipes that deliver our water and the list goes on and on to include just about everything defining our modern society. These things are all manufactured or built from manufactured components. Manufacturing equipment itself must also be manufactured. The manufacturing process used is determined by a variety of factors.

Manufacturing Process: The Fundamental Idea

The fundamental idea of manufacturing or production is to create, (or produce), something that has a useful form. This form is most likely predetermined and calculated, with a certain physical geometry. Usually this geometry has certain tolerances that it must meet in order to be considered acceptable. A tolerance outlines the geometric accuracy that must be achieved in the manufacturing process. The "tightness" of the tolerances, or in other words the allowed variance between the manufactured product and the ideal product, is a function of the particular application of the product.

Goals and Core Principles For All Processes

1. Meeting performance requirements (ie. tolerances, strength, weight, ect.)
2. Meeting cost of production requirements
3. Ability to reproduce constant quality during mass production
4. Large manufactured components should have uniform material properties throughout the component

The Primary Consideration For A Manufacturing Process

When different manufacturing processes and methods are considered, it is fundamental to develop an understanding of the relationship between the process used and the properties of the finished product. For this it is important to know what conditions a particular process will subject a material to and how different manufacturing materials respond to different conditions, (ie. stress, heat).

Manufacturing Materials

All manufactured products are made from some sort of material. Similar to the geometric tolerance, the properties of the material of the final manufactured product are of utmost importance. Hence, those who are interested in manufacturing should be very concerned with material selection. An extremely wide variety of materials are available to the manufacturer today. The manufacturer must consider the properties of these materials with respect to the desired properties of the manufactured goods. Simultaneously, one must also consider manufacturing process. Although the properties of a material may be great, it may not be able to effectively, or economically, be processed into a useful form. Also, since the microscopic structure of materials is often changed through different manufacturing processes -dependent upon the process- variations in manufacturing technique may yield different results in the end product. Therefore, a constant feedback must exist between manufacturing process and materials optimization.

Basic Concepts:

Types of Materials

1. Metals
2. Ceramics
3. Polymers

What are the properties of metals, the properties of ceramics, the properties of polymers?

Metals: Metals are hard, malleable, (meaning capable of being shaped), and somewhat flexible materials. Metals are also very strong. Their combination of strength and flexibility makes them useful in structural applications. When the surface of a metal is polished it has a lustrous appearance; although this surface luster is usually obscured by the presence of dirt, grease and salt. Metals are not transparent to visible light. Also, metals are extremely good conductors of electricity and heat.

Ceramics: Ceramics are very hard and strong, but lack flexibility making them brittle. Ceramics are extremely resistant to high temperatures and chemicals. Ceramics can typically withstand more brutal environments than metals or polymers. Ceramics are usually not good conductors of electricity or heat.

Polymers: Polymers are mostly soft and not as strong as metals or ceramics. Polymers can be extremely flexible. Low density and viscous behavior under elevated temperatures are typical polymer traits. Polymers can be insulative to electricity.

What are metals made of, what are ceramics made of, what are polymers made of?
Or in other words, what is the basic microstructure of metals, what is the basic microstructure of ceramics, what is the basic microstructure of polymers?

Metals: A metal is most likely a pure metallic element, (like iron), or an alloy, which is a combination of two or more metallic elements, (like copper-nickel), the atoms of a metal, similar to the atoms of a ceramic or polymer, are held together by electrical forces. The electrical bonding in metals is termed metallic bonding. The simplest explanation for these types of bonding forces would be positively charged ion cores of the element, (nucleus's of the atoms and all electrons not in the valence level), held together by a surrounding "sea" of electrons, (valence electrons from the atoms). With the electrons in the "sea" moving about, not bound to any particular atom. This is what gives metals their properties such malleability and high conductivity. Metal manufacturing processes usually begin in a casting foundry.

Figure 1

Ceramics: Ceramics are compounds between metallic and non-metallic elements. The atomic bonds are usually ionic, where one atom, (non-metal), holds the electrons from another, (metal). The non-metal is then negatively charged and the metal positively charged. The opposite charge causes them to bond together electrically. Sometimes the forces are partially covalent. Covalent bonding means the electrons are shared by both atoms, in this case electrical forces between the two atoms still result from the difference in charge, holding them together. To simplify think of a building framework structure. This is what gives ceramics their properties such as strength and low flexibility.

Figure 2

Polymers: Polymers are often composed of organic compounds and consist of long hydro-carbon chains. Chains of carbon, hydrogen and often other elements or compounds covalently bonded together.

Figure 3

In figure 3, (a) represents a simple hydrocarbon chain, each group of hydrogen and carbon is called a mer, there are 13 mers shown in the diagram, the dotted lines indicate that the pattern is continuing indefinitely. Polymers chains often contain thousands upon thousands of mers each. The [R] in (b) indicates a variable element or group of elements that could occupy a certain position in the chain. The [X] in (c) also represents another variable element or group that could occupy another position, this one being at the end or beginning of a polymer chain. The chains themselves bond to each other through secondary bonding forces. To simplify polymer structure, think of a bowl of spaghetti.

Figure 4

This is a polymer with a random or amorphous microstructure.

Figure 5

This is a polymer with a very high degree of order or a crystalline microstructure.

When heat is applied, the weaker secondary bonds, (between the strands), begin to break and the chains start to slide easier over one another. However, the stronger covalent bonds, (the strands themselves), stay intact until a much higher temperature. This is what causes polymers to become increasingly viscous as temperature goes up.

Manufacturing Processes

This is a summary of the basic and most commonly used manufacturing processes in industry today. Any of these processes can be employed to produce a manufactured part. Also, remember when deciding how to produce manufactured items, a part may require a combination of these processes to facilitate its completion. For example, a cast part may require some machining before it becomes the final product. Or, a part may be produced through a powder metallurgy process, then undergo some kind of metal forming operation. The following describes the methods and techniques involved in each of these manufacturing processes. Always keep in mind how material properties relate to manufacturing process. Most manufacturing processes described below are for metals. Manufacturing processes for polymers and ceramics will be discussed separately, each given its respective section. These processes are often similar in nature to those for metals, (ie. polymers are essentially both cast and formed in different techniques), however they are different enough to be classified independently.

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