1.If a percentage of cobalt in Tungsten carbide tool increases, then toughness of tool will
a) Increase
b) Decrease
c) Remains Constant
d) First increase then decrease
Explanation: With an increase in percentage of cobalt toughness increases. Carbides are very hard and have very good red hot hardness property and hence most suitable for machining of hard and brittle material.
2. Which of the following tools is most suitable for very hard and brittle material?
a) HSS
b) Cast-cobalt alloy
c) Carbides
d) None of the mentioned
Explanation: Carbides are very hard and have very good red hot hardness property and hence most suitable for machining of hard and brittle material.
3. High speed steels are most suitable for
a) High Positive rake angle tools
b) High Negative rake angle tools
c) Zero Rake angle tools
d) None of the mentioned
Explanation: HSS are very tough and fracture resistance and suitable for high positive rake angle tool. With an increase in percentage of cobalt toughness increases.
4. Which of the following tool material will offer lower friction and higher resistance to cracks and wear?
a) HSS
b) TiC
c) WC
d) TiCN
Explanation: TiCN is a coated tool and hence offer very less friction and there is much low chance of wear in tool due to coating on tool.
5. Which of the following tool material will offer lower friction and higher resistance to cracks and wear?
a) HSS
b) TiC
c) Cast cobalt alloys
d) Coated tools
Explanation: Coated tool offers very less friction and there is much low chance of wear in tool due to coating on tool.
6. Which of the following material can be used for coating on tools?
a) HSS
b) TiCN
c) WC
d) cBN
Explanation: TiCN can be used for coating of tool while, HSS, WC and cBN are tool materials. With the increase in percentage of cobalt toughness increases
7. Cutting tool should maintain its hardness.
a) True
b) False
Explanation: Life of cutting tool is ends when it looses its hardness. With increase in percentage of cobalt toughness increases.
8. Thermal conductivity of cutting tool must be
a) High
b) Low
c) Very low
d) None of the mentioned
Explanation: For faster removal of heat, cutting tool must have high thermal conductivity. Thermal conductivity of cutting tool must be high.
9. Hot hardness of cutting of cutting tool should be
a) Large
b) Small
c) Very small
d) None of the mentioned
Explanation: Cutting tool must be able to withstand high temperature. Hot hardness of cutting of cutting tool should be large.
10. Wearing resistance of cutting tool must be
a) High
b) Low
c) Very low
d) None of the mentioned
Explanation: Cutting tool has high capability to resist wear. Wearing resistance of cutting tool must be high.