Manufacturing Technology I Set 7

Answer: cold cracking

Explaination:
cold cracks are those that occur after the weld metal has cooled to room temperature and may be hydrogen related.

Answer: true

Explaination:
in precision type forging operation, the volume of the metal stock and the dies are controlled very tightly. such operations are called as precision forging which is a modern technique of forging.

Answer: forging

Explaination:
connecting rods are generally manufactured by the forging operation. in forging, a hammer is used which strikes on the heated metallic part to get into the desired shape. the properties like strength, toughness, etc are greatly enhanced by

Answer: false

Explaination:
in open die forging process, the deformation is not homogenous as bulging occurs due to the presence of friction at the interface of die and billet. this friction opposes the motion of billet; this effect is generally called as barreling effect.

Answer: false

Explaination:
isothermal forging is a hot forging operation in which the metal part is maintained at some high temperature. the forging dies are also maintained at the same high temperature. in this method, the metal flows readily that reduces the amount of force required. but this process is expensive than the conventional forging and mainly used for materials like titanium and super-alloys.

Answer: true

Explaination:
metal forging is a forming operation that performs hammering to shape the metal component. in forging process, the metal component is heated sufficiently, and then it is hammered by using a hammer which can be performed manually or by automation, depending on the scale of production and properties required in the forged metal component.

Answer: true

Explaination:
in roll forming, a flat strip is gradually formed to the finished shape. the forming is almost exclusively accomplished by rotating contoured rolls while the material passes through the mill.

Answer: a smooth flow of material

Explaination:
the probability of having a good set of rolls is to follow few rules:

Answer: it distorts the product

Explaination:
“too quick” forming (too few passes) will distort the product because of the unacceptable level of stresses generated in the metal. on the other hand, too many passes will make the tooling and the process uneconomical.

Answer: the maximum vertical dimension of the profile

Explaination:
the depth of the section, also called as “leg length” or “leg height”, is the maximum vertical dimension of the profile as it exits from the last pass. sometimes it called as “depth of corrugation”.

Answer: 0.04%

Explaination:
here, h = 1in; number of passes

Answer: true

Explaination:
if the strain (elongation) exceeds the elastic limit, then the edge of the finished product will become permanently strained. due to which the finished product will be wavy or the product will have a bow, camber or twist.

Answer: deviation of the strip edge from a straight line in horizontal plane

Explaination:
camber is the deviation of the strip edge from a straight line in the

Answer: a twist

Explaination:
when an asymmetrical section is a roll formed, the finished product will

Answer: true

Explaination:
a common method used to compensate for the anticipated twist is to twist the product in the opposite direction in the mill, from pass to pass. this principle is used when forming “z” sections. in other cases, the counter-twisting is accomplished just in the last one or two passes.

Answer: all of the mentioned

Explaination:
classification of extrusion processes are shown below.

Answer: molten glasses

Explaination:
for steels, stainless steel, and high temperature materials, glass is a good excellent lubrication. the reasons for this are as follows. i. glass contains its viscosity at elevated temperatures, ii. has good wetting characteristics, and 3. glass acts as a thermal barrier between the billet, the container and the die, thus minimizing cooling.

Answer: hydrostatic

Explaination:
in hydrostatic extrusion process frictional loss is eliminated at the billet container interface. this elimination increases the quality of the product.

Answer: hydrostatic

Explaination:
in hydrostatic extrusion process fluid medium is used to apply the load on the billet. as hydro stands for fluid and static for rest.

Answer: rolling

Explaination:
extrusion is similar rolling in producing constant cross-sectional shape.

Answer: tearing & surface cracking

Explaination:
the defects such as, surface cracking and tearing, occurs with high friction or speed. these can also occur with stickling of billet material on die land.

Answer: surface cracking

Explaination:
bamboo defects are periodic surface cracks that develop due to the extruded product sticking to the die land.

Answer: pipe defect

Explaination:
pipe defect is the formation of sin hole at the end of the billet. it is associated with direct extrusion. the use of

Answer: pipe defect

Explaination:
in extrusion, the pipe defect is also termed as “tail pipe”, and “fish tailing”. it occurs during hot extrusion due to the presence of impurities and oxides.

Answer: all of the mentioned

Explaination:
cracks that are developed in the centre of extruded material is known as