Manufacturing processes for mechanical components, exam 3

In view of the following rolling process, which statement is true?

- Roll force is proportional to the contact length

- The reduction of thickness per each pass need to be maximized

- Roll diameter must be increased to reduce roll force

- Friction is desirable to reduce power consumption

Roll force is proportional to the contact length

When small rolls are used for flat rolling process, compressive residual stress is developed on the metal surface.

True, for small rollers its on the metal surface for larger rollers its at the center of the metal

Through this process, spherical shapes can be formed continuously. What is it?

- Thread rolling

- Skew rolling

- Flat rolling

- Ring rolling

Skew rolling

Which one is made by forging? (a), (b), or (c)

(c) is forged because it has lines flowing with the features

(a) is cast because it just shows a grain structure

(b) is machined because it just shows constant lines running through the piece regardless of the features

Radial impact force by a set of reciprocating dies is used to produce tubes with varying diameters by this process.

- Orbital forging

- Centrifugal casting

- Rotary swaging

- Drawing

Rotary swaging

What is the proper design of parting lines for a closed die forging process? A, B, C, or D

A is not correct

B is not correct

C is not correct

D is correct

(Parting lines should be located at the largest cross section and should be in the same plane from one side of the part to the other, no side thrust)

When an insufficient volume of material is used to fill the forging die cavity, what is the primary failure mechanism?

- Creep

- Buckling

- Porosity

- Internal cracking

Buckling, for insufficient volume

Internal cracking, for excessive volume

Which statement about "central burst" is INCORRECT?

- This can be found in an extrusion process

- A smaller reduction ratio can mitigate this

- This can be suppressed by making two plastic zones meet

- This can result in total failure of the part

A smaller reduction ratio can mitigate this.

Central burst is internal cracking along the centerline of an extruded piece. It is also known as a chevron crack. It is mitigated by reducing the die angle or increasing the reduction ratio.

Which statement is correct?

- Extrusion is better suited for a longer part as compared to drawing

- Hot-drawn products show more residual stresses than cold-drawn products

- A surface finish is not required for hot extrusion or hot drawing

- Powdered glass can be used for a lubricant for hot extrusion

Powdered glass can be used for a lubricant for hot extrusion

Most drawing is done at RT while drawing large sections is done at elevated temperatures to reduce forces.

True