Manufacturing Engineering : Practice Questions and Answers

Oxide films should be removed before welding. Heavier oxide films may be removed by acid pickling, emery or by wire brusing.

Mild steel does not require flux to eliminate the oxides, due to the fact that iron oxide has relatively low melting point when compared to other non-ferrous metals given.

Both acetone and carbon tetrachloride are used to remove the oil substances from the interface.

No explanation is available for this question yet.

The strength of perfectly welded joint is more than the parent metal, due to the formation of alloy. The alloy formation at the welded portion makes it the strongest portion while the nearby zones where uncontrolled cooling take place because of heat is the weakest zone (heat affected zone). In general we can say that on the basis of strength: welded portion > parent material > heat affected zone.

In welding one needs to melt the base metals to fuse them.

Welding joins metals by melting and fusing them together, typically with the addition of a welding filler metal.

Contact ratio = arc of contact/circular pitch.

Working depth of two mating gear is numerically equal to sum of the addendum of two gears.

Full depth is the sum of addendum and dedendum.

Maximum depth to which tooth can penetrate into the tooth space of mating gear is known as working depth of teeth.

Total radial depth of tooth space is known as full depth of teeth.

Clearance of gear is generally taken equal to 0.157 modules.

Clearance is the radial difference between addendum and dedendum of tooth.

Dedendum of gear is generally taken equal to 1.157 modules.

Dedendum is the radial depth of tooth below pitch circle.

Circle passing through the root of teeth is known as root circle.

Circle passing through the root of teeth is known as dedendum circle.

Addendum of gear is generally taken equal to 1 module.

Addendum is the height of tooth above pitch circle.