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How does the master grinder recognize the type of steel by looking at the sparks?

Some of the grinder masters in the factory are very knowledgeable, and you can know the type of steel by looking at the sparks they produce, and they feel very good. It is said that this can only be understood, not by words. Is it really? In fact, as long as you master the essence of things, not a master can still have this skill.


How does the master grinder recognize the type of steel by looking at the sparks? (figure 1)


  01
  The principle of spark identification


   When the steel material is ground on the grinding wheel, the high temperature fine metal particles are thrown out along the tangential direction of the grinding wheel rotation, and then rubbed with the air, the temperature continues to rise. In the process of contact with air, the carbon element in the steel will chemically react with the oxidized iron oxide to produce iron element and carbon monoxide. Carbon monoxide explodes in contact with air to form sparks, so a bright streamline is formed on the trajectory of the metal particles.

How does the master grinder recognize the type of steel by looking at the sparks? (figure 2)


   We know that steel not only contains carbon, but also may contain manganese, silicon, tungsten, chromium, molybdenum and other elements. When a spark is formed, the oxides of these elements will produce a flame color reaction, which affects the line, color and state of the spark. According to the color and shape of the spark, the chemical composition of the steel can be roughly determined.

How does the master grinder recognize the type of steel by looking at the sparks? (image 3)
  02
   Various forms of grinding sparks


  Although everyone has seen sparks, do you know how to describe the various forms of sparks?

How does the master grinder recognize the type of steel by looking at the sparks? (Figure 4)


The fire bouquet produced by    grinding is composed of root sparks, middle sparks and tail sparks, while the fire bouquet is composed of streamlines, nodes, popcorns and tail flowers.

How does the master grinder recognize the type of steel by looking at the sparks? (Figure 5)


   With the increase of carbon content, bursting on the awn line continues to produce secondary flowers and tertiary flowers. The bright dots near the awn line are called pollen.

How does the master grinder recognize the type of steel by looking at the sparks? (Image 6)


  03
  The sparks of different steels are all characteristic


   When performing spark identification, the grinding wheel speed is generally 46-67r/s. When the steel contacts the grinding wheel for grinding, the pressure is moderate, and the spark streamline is slightly higher than the horizontal direction. Carefully observe the spark color, shape, length, number of knots, and characteristics of the tail to judge the type of steel.


  1) Carbon steel


  The carbon content of steel will cause the difference in spark shape.


   Low carbon steel with a carbon content of less than 0.25%, with thick and thin streamlines, less popping and more one-shot flowers, thick and long awning lines with bright nodes. The color is yellow grass with dark red.

How does the master grinder recognize the type of steel by looking at the sparks? (Picture 7)


  20#Steel


   Medium carbon steel with carbon content higher than 0.25%, streamline is slender and many, there are nodes at the tail and middle of the streamline, the flower shape is large, there are primary flowers and secondary flowers, with a small amount of pollen. The color is yellow.

How does the master grinder recognize the type of steel by looking at the sparks? (Picture 8)


  45 # steel


   The streamlines of high carbon steel are thin, short, straight, multiple and dense. There are many popcorn flowers, small flowers, mostly secondary flowers, tertiary flowers or multiple flowers, with thin and sparse awn lines and many pollen. The color is bright yellow.

How does the master grinder recognize the type of steel by looking at the sparks? (Picture 9)


   T10 steel


  2) Alloy steel


   Chromium, manganese, vanadium can help produce spark burst, tungsten, cobalt, nickel, silicon, etc. will inhibit spark burst.


   Alloy steel with 1%-2.5% nickel, the spark does not spread out, and it is an oval flower bud.


  The tungsten alloy steel sparks resemble a fox tail, and the silicon alloy steel sparks flared.


   Chromium-nickel alloy steel sparks in full bloom, three bursts, the flower is multi-layered star, the flower center has bright buds, showing red.


  3) Chrome steel


   General chrome steel fire bouquets are white and bright, with a slightly thicker and longer streamline. The bursts are mostly one-time flowers. The flowers are larger in shape, large star-shaped, with many and thin branches, with broken pollen, and the bursting sparks are brighter.


  4) Nickel-chromium stainless steel


  The fire bouquet of nickel-chromium stainless steel is thin, with darker light, bursting into a single flower, five or six branches, star-shaped, and slightly bursting at the tip.


  5) High-speed steel


The    high-speed steel fire bouquet is slender, with few streamlines, no spark burst, dark red in color, intermittent streamlines at the root and middle, and arc-shaped tail flowers.


   Spark identification table:

How does the master grinder recognize the type of steel by looking at the sparks? (Figure 10)


   Carbon steel spark characteristic table:

How does the master grinder recognize the type of steel by looking at the sparks? (Picture 11)


  The influence of alloying elements on sparks:

How does the master grinder recognize the type of steel by looking at the sparks? (Picture 12)