Page 169 - Module DMV20173

6. The surface to be joint also must be cleaned. Any grease or oil present in the

joint prevents the flow of filler metal.

EXERCISE 6.3

List six (6) advantages of welding process compare to riveting.

Solution:

a) Welding is usually a cheaper process than riveting for any particular joint, and
the joint can often be made much more quickly.
b) Weld seams are normally pressure tight, and do not need caulking as do
riveted joints. Joints are smooth, which is important in many applications. For

example, painting is much easier on welded joints, and turbulence in pipes is
reduced.
c) Designs not practicable for riveting may be constructed by welding.
d) Plate preparation for welding is generally cheaper than for riveting.

e) Labour necessary can often be cut to less than one- third of that necessary
for riveting.
f) Welding is not as noisy as riveting, and permits building and alterations to
proceed with the least disturbance to occupants.

EXERCISE 7.1

An injection-molding machine is divided into two principal components; identify them.
Answer: The components of an injection-molding machine are (1) the injection unit

and (2) the clamping unit.

What are the two basic types of clamping units?
Answer: The clamping units are: (1) mechanical toggle clamp and (2) hydraulic. In

addition, there are hydromechanical units which combine hydraulic and mechanical
actuations.