Manufacturing Processes and Techniques

Front

What is the primary advantage of cold working over hot working in metal forming?

Back

Increases material strength

Cold working is performed below the recrystallization temperature, causing strain hardening (also called work hardening).

This process increases the strength and hardness of the metal due to a higher dislocation density. However, it also reduces ductility.

Answer explanation

The primary advantage of cold working is that it increases material strength through strain hardening, making the metal stronger and more durable compared to hot working, which does not provide this benefit.

Front

Casting process suitable for large production runs of non-ferrous metals with tight tolerances and excellent surface finish.

Back

Die casting

Die casting involves forcing molten non-ferrous metal (like aluminum or zinc) into a high-precision steel mold under pressure. It’s ideal for mass production due to its fast cycle times, tight dimensional control, and smooth surface finish.

Answer explanation

Die casting is ideal for large production runs of non-ferrous metals because it provides tight tolerances and excellent surface finishes, making it more efficient despite higher initial costs compared to other methods.

Front

What is a primary disadvantage of sand casting compared to other casting processes?

Back

It produces parts with a poor surface finish

Sand casting uses coarse sand molds, which lead to rough surface textures and lower dimensional accuracy. As a result, additional machining is often required to meet surface and tolerance specifications.

Answer explanation

A primary disadvantage of sand casting is that it produces parts with a poor surface finish compared to other casting methods, which can require additional machining or finishing processes.

Front

What is an advantage of investment casting?

Back

It can achieve tight tolerances.

Investment casting uses a wax pattern and ceramic mold, allowing for precise detail, smooth surface finish, and tight dimensional tolerances.

This makes it ideal for complex components such as turbine blades and medical implants.

Answer explanation

Investment casting is known for its ability to achieve tight tolerances, making it suitable for complex and precise components. This advantage outweighs the other options, which do not accurately represent the process's strengths.

Front

What is a key difference between injection molding and compression molding regarding the materials they typically process?

Back

Injection molding processes thermoplastics, while compression molding processes thermosets.

Answer explanation

The correct choice highlights that injection molding typically processes thermoplastics, which can be melted and reshaped, while compression molding is used for thermosets, which harden permanently after being shaped.

Front

What is a common application for 3D printing due to its characteristics?

Back

Rapid prototyping and custom part creation.

Answer explanation

3D printing is ideal for rapid prototyping and custom part creation because it allows for quick iterations and the production of unique designs, which is not feasible with traditional mass production methods.

Front

Manufacturing process for producing a long aluminum window frame with a constant cross-section: Sand casting, Extrusion, Injection molding, Rolling.

Back

Extrusion

Extrusion involves forcing heated aluminum through a shaped die to create long components with a uniform cross-section. It is ideal for window frames, tracks, and structural profiles.

Answer explanation

Extrusion is ideal for producing long shapes with a constant cross-section, like aluminum window frames. It allows for continuous production and efficient shaping, unlike sand casting or injection molding, which are not suited for this application.

Front

Which manufacturing process involves plastically deforming metal using a hammer and closed dies?

Back

Forging

• Forging is a manufacturing process where metal is plastically deformed using:

  • - A hammer or press

  • - Closed dies (also called impression dies) that shape the material

• The metal is typically heated before forging (hot forging), but cold forging is also possible for some applications.

• It results in:

  • High strength parts due to grain refinement and directional flow

  • Excellent mechanical properties, making it ideal for aerospace, automotive, and tools.

Memory hook:

Forging = Force + Form
Hammer + Dies → Strong shaped metal

Answer explanation

Forging is the manufacturing process that involves plastically deforming metal using a hammer and closed dies, shaping the metal into desired forms through compressive forces.

Front

Why is injection molding most commonly used for large-scale plastic part production?

Back

It is fast and highly automated

Injection molding allows for rapid production of complex plastic parts with high repeatability.

The process is easily automated, making it cost-effective for mass production with minimal labor and consistent quality.

Answer explanation

Injection molding is preferred for large-scale production because it is fast and highly automated, allowing for efficient manufacturing of large quantities of plastic parts with consistent quality.

Front

Disadvantage of sand casting?

Back

Produces poor surface finish and low dimensional accuracy

Sand casting uses coarse sand molds, which result in rough surfaces and imprecise tolerances, often requiring extra machining to meet final specifications.

Answer explanation

The correct choice highlights a key disadvantage of sand casting: it often results in a poor surface finish and low dimensional accuracy, making it less suitable for applications requiring high precision.