Take you in-depth understanding of steel balls

1. What is a steel ball?

  Steel balls are divided into grinding steel balls, forged steel balls and cast steel balls according to the production and processing technology. According to the processing materials, it is divided into bearing steel balls, stainless steel balls, carbon steel balls, copper bearing steel balls, alloy balls, etc. Among them, the bearing steel ball is an important basic component of the industry. Alloy steel ball is a kind of spherical iron alloy wear-resistant body produced by forging, spinning, rolling and casting with carbon, chromium, manganese, molybdenum as the main added metal elements. It is the most important part of crushing industrial mine balls and cement balls.

2. Classification of steel balls

  The classification of steel balls can be classified according to several aspects such as material, grade, size and use.

  Steel balls are mainly divided into carbon steel balls, bearing steel balls, stainless steel balls, etc. according to their materials. Carbon steel balls are divided into two types according to whether they are heat-treated, that is, added to the fire. After heat treatment, the hardness of carbon steel balls increases, and the surface hardness can reach about HRC60. The hardness of unheated carbon steel balls is similar to that of steel, and the hardness is about HRC28, commonly known as iron balls. Carbon steel balls after heat treatment cannot be welded. If you weld, you must choose carbon steel balls that are not heat treated. Bearing steel balls, the most important thing is that there are grades, that is, bearing steel balls have a lot of precision. According to the grade list in the national standard GB/T308-2002, it is divided into G5, G10, G16, G28, G40, G60, G100, G200, G500, G1000, etc. G is the first letter of Grade in English, and the numbers behind it indicate different grades. The smaller the number, the higher the precision, and the better the steel ball. Those with high precision are generally used in industries with relatively high requirements such as precision machinery, auto parts, and aerospace. Those with low precision are generally used in grinding, crushing, mixing and other industries. Stainless steel balls are mainly divided into 201, 304, 302, 316, 316L, 420, 440, 440C and so on according to the material. There are national standard stainless steel materials, but there are many non-standard materials on the market. The main reason is that the components of nickel and chromium are not up to standard, so the ability of anti-rust and corrosion resistance is relatively poor.

  According to the classification of grades, the grades of steel balls are as follows:

1. Stainless steel series include: SUS201/202, SUS304, SUS316/316L, SUS440C

2. Bearing steel: AISI52100

3. Carbon steel series are: AISI1010, AISI1085

  According to the classification of steel ball diameter and size, it can be divided into miniature steel balls, general steel balls and large steel balls.

1. Miniature steel ball, diameter ≤ 3.175mm

2. Ordinary steel balls, the diameter ranges from 3.5mm to 50.8mm

3. Large steel ball, diameter > 50.8mm

  According to the purpose of classification, steel balls can be divided into: silent steel balls, bearing balls, special steel balls, etc.

3. How are steel balls made?

1. Materials

  Through the multi-dimensional inspection of the surface quality of raw materials, metallographic structure, decarburization layer, chemical composition, tensile strength, etc., materials with high cleanliness are used after vacuum deoxidation treatment, with very few impurities such as non-metallic media.

2. Ball forming (cold heading)

  In the ball forming machine, the wire is cut into a certain length, and the ball is formed after being compressed by the female and male molds on the hemispherical ball seat on both sides. (Under normal temperature conditions, the wire is cut to a specific length, and is compressed by a cold heading machine to undergo plastic deformation to form a ball blank)

3. Polishing

  The forged steel ball is sandwiched between two hard casting discs, and pressure is applied to rotate it to remove burrs and surface rings, and at the same time improve the surface roughness of the steel ball to make it initially spherical.

4. Heat treatment

  The steel ball is carburized in the heat treatment furnace, then quenched and then tempered to make the ball have a certain carburized layer, hardness, toughness and crushing load. Now some manufacturers with advanced technology use mesh belt heat treatment lines to effectively control the process parameters of quenching and tempering time and temperature through various instruments to ensure the stability and controllability of product quality.

5. Strengthen

  A processing method in which steel balls collide with each other through a strengthening machine to cause plastic deformation and strengthening on the surface of the steel balls to improve the compressive stress and surface hardness of the steel ball surfaces.

6. Hard grinding

  The surface quality and shape of the steel ball are further improved by fixing the iron plate and rotating the grinding wheel plate under a certain pressure for grinding.

7. Primary research

  Two cast iron primary grinding discs are used, and abrasive materials are added to achieve the surface quality of the precision specified in the process through a certain pressure and mechanical movement.

8. Appearance flaw detection

  After 100% manual selection, plus AVKIO flaw detector: through three methods of photoelectricity, eddy current and vibration to select various defect balls, such as surface defects (flat head, burr, pad damage, crushing, cracking, burns, etc.), shallow surface Layer cracks, internal material defects.

9. Intensive research

  Similar to the preliminary grinding process, two cast iron lapping plates are used, and abrasives are added to remove the excess under the action of certain pressure and mechanical movement, so as to further improve the precision and surface quality of the steel ball.

10. Cleaning and dehydration

  The cleaning quality is improved and the damage to the surface of the steel ball is reduced through the spiral cleaning machine and the lifting turnover box. In addition, the cleaning liquid needs to be continuously circulated to ensure the cleanliness of the steel ball.

11. Photoelectric ball picking

  Through the optical automatic appearance sorting machine, the steel ball surface quality is judged, and products with material defects and processing defects are removed.

12. Finished product inspection

  For each batch of steel balls, the final inspection is carried out according to the requirements of the process, such as the roundness, hardness, metallography, stress, etc. of the steel balls, for details, refer to the inspection reference book.

13. Anti-rust packaging

  Use anti-rust oil, spray anti-rust and complete the packaging according to the customer's packaging requirements.

4. The use of steel balls

  Steel ball is a kind of spherical ferroalloy wear-resistant body produced by forging, spinning, rolling, grinding and casting with carbon, chromium, manganese, molybdenum as the main added metal elements. It is the most important part of the crushing industry and bearing industry today.

  Speaking of steel balls, steel balls have too many functions. Probably the most used can be divided into the following categories:

First, special bearings with high speed and low noise;

  Second, high-precision, low-noise motor bearings, household appliance bearings;

  Third, steel balls and microballs for electronic industry used in general industry and special bearings for automobile, motorcycle and bicycle