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Forming Processes - Forging
This unit addresses aspects of the following syllabus outcomes:
A student:
H1.2 differentiates between properties of materials and justifies the selection of materials, components and processing in engineering.
H2.1 determines suitable properties, uses and applications of materials in engineering
H5.1 works individually and in teams to solve specific engineering problems and in the preparation of engineering reports.
Source: Board of Studies (1999) Stage 6 engineering studies syllabus preliminary and HSC courses. Sydney: Board of Studies
Introduction - A Historical Perception
Forging is perhaps the oldest mechanical method of metalworking known to humans and its origins can be followed from ancient Egypt through the blacksmith shops of the pre-industrial period, and directly to high technology forging plants used in industry today.
As the needs of industry have changed and developed, forging has evolved to incorporate the vast advances in equipment, computers and electronic controls that have occurred in the last years of the 20th century and into the beginning of the 21st century.
However, all forged components, which are manufactured using sophisticated tools, are also the result of creative human skills. These skills are essential to the success of every forging made. Contemporary forging plants of the 21st century are capable of producing higher quality metal parts in an almost limitless array of shapes, sizes, materials and finishes.
Forging Defined
Activity 1
Go to the URL http://www.scotforge.com/sf_facts_solution.htm#facts and find the words which give an accurate definition of forging. Complete the definition by inserting the correct terms into the text box provided below.
“At its most basic level, forging is the process of ...............
The forging process
The process begins with a cast ingot or a billet (which has already been forged from a cast ingot). This is then heated to above its plastic deformation temperature, and worked between steel dies to the desired shape and size by:
- drawing out the metal - reducing its sectional area but increasing length.
- upsetting the metal - increasing the section size and reducing length.
- squeezing or hammering between special dies so that the metal flows and takes up the shape of the die cavity.
Effects on Structure
During this hot forging process, there are many internal structural effects that occur.
Activity 2 Summary of structural effects
Visit the web address http://www.scotforge.com/sf_facts_solution.htm#facts to identify the effects on the following areas during forging. Answer the questions.
- What happens to the cast, coarse grain structure?
- What effects are there to low-density areas, micro shrinkage and gas porosity inherent in the cast metal?
- Describe the effects on mechanical properties:
- What does forging do to the grain flow?
- What can be done after forging to further refine the part?
Activity 3 The Effects of Forging
Examine the diagram of the forging process below then visit the web address http://www.scotforge.com/sf_facts_solution.htm#facts to identify the effects of forging on the grain structure of a forged component. Type the effects of forging directly into the text boxes provided below.
Activity 4 Forging Products
Visit the web address http://www.scotforge.com/sf_facts_opendie.htm and locate a suitable image that typifies the process of forging. Compare the image to the one provided in the answers.
Forging Advantages
The principal advantages of forging involve the integrity of the part in three main areas.
Activity 5
Visit the webaddress http://www.scotforge.com/sf_facts_forgingadv.htm and click on Forging Facts and identify the advantages of forging in the three areas of:
- Directional strength
- Structural Strength
- Impact Strength
The effect of a forged grain structure graphically illustrates the relationship between structure and properties.
Activity 6
Visit the website http://www.scotforge.com/sf_facts_forgingadv.htm 
and click on Forging Facts to complete the table below illustrating this structure\property
relationship through conducting a comparison of grain flow for
forging, machining and casting. Download and paste an appropriate
image illustrating the grain flow for each process.
| GRAIN FLOW COMPARISON | |
|---|---|
| PROCESS | GRAIN FLOW IMAGE |
| Forged Bar: | |
| Machined Bar: | |
| Cast Bar: | |
Comparative Analysis between forging and other processes
When forging is compared to other forming processes, there are clear differences.
Activity 7
Visit the web address http://www.scotforge.com/sf_facts_companalysis.htm and click on Forging Facts to locate, identify and illustrate a comparative analysis between forging, machining, welded/fabricated components, casting, centrifugal casting and flame cutting.
| PROCESS | IN COMPARISON, FORGING OFFERS.... |
|---|---|
| Machined Bar | |
| Weldments/Fabrications | |
| Castings | |
| Centrifugal Castings | |
| Torch Cut Plate |
Reference
http://www.scotforge.com/index.htm
OTHER WEB ADDRESSES FOR FURTHER RESEARCH:
www.geocities.com/SiliconValley/Campus/8262/htdocs/forg/forg.html
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