METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 2
c.
Technique of Comparison.
Table 1, on the following page,
together with the sketches provided in figures 4 and 5 are employed
to indicate the important differences among sparks from a wide
variety of metals. The terms used in the table are relative rather
than absolute.
The length of the spark stream depends on the
pressure between the wheel and work. Apparent color depends upon the
light in which the inspection is made.
The difference between red
and orange, as tabulated in Table 1, is very slight.
The colors
straw and white, listed in the table, might be called yellow,
depending on the extraneous light. Figures 4 and 5, cannot convey a
true picture of sparks as seen by the human eye. But, these figures
will help to classify and illustrate pronounced differences.
d.
Operation of Equipment. When making a grinding test, neither the
grinding wheel nor the machine on which it is mounted need be selected to
FIGURE 5.
SPARK TEST CHARACTERISTICS OF
METALS (CONTINUED).
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