• A good
knowledge of metals and their properties is important for a machinist so that
the part manufactured performs well in service.
• The three
most common basic types of steel are low-carbon steel, medium-carbon steel, high-carbon
steel. All other steels are an alloy of one of these types.
• Chemical
elements such as carbon, silicon, sulfur, manganese, and phosphorous can change
the properties and characteristics of a steel.
• Alloys such
as chromium, molybdenum, nickel, tungsten, and vanadium can provide a steel with
properties such as hardness, toughness, wear resistance, corrosion resistance,
and increased tensile strength.
• A machinist
can identify metals by their appearance, spark testing, manufacturers stamp,
and code color.
- Briefly define the following
metal properties:
(a) brittleness
(b) ductility
(c) hardness
(d) malleability
Ferrous Metals
- Define a ferrous metal.
- Give the carbon content and
one use for each of the following:
(a) low-carbon
steel
(b) medium-carbon
steel
(c) high-carbon
steel
- What are the advantages of
alloy steels?
- Describe the composition of
high-speed steels.
- Why is high-speed steel used
for cutting tools?
- Explain how carbon affects
steel.
- What two alloys help cutting
tools maintain their hardness and cutting edge when hot?
Nonferrous Metals
- Define nonferrous metals and
state why they are used.
- Briefly describe and give one
use for:
(a) aluminum
(b) copper
(c) nickel
(d) tin
- What is a nonferrous alloy?
Identification of Metals
- Name four methods of
identifying metals.
- Describe the appearance of the
following metals and give one use for each.
(a) cast
iron
(b) machine
steel
(c) tool
steel
(d) brass
- Why do sparks from different
materials vary?
- What are the spark
characteristics of:
(a) high-carbon
steel?
(b) high-speed
steel?
Shapes and Sizes of Metals
- Why are metals manufactured in
a wide variety of shapes and sizes?
- How much larger than the
finished piece should work that requires machining be ordered?
- Explain how round and flat
material should be ordered.
Copyright 2004, Industrial
Press, Inc., New York, NY