Views: 1 Author: Site Editor Publish Time: 2023-04-07 Origin: Site
Definition of chilled cast iron
Cold cast iron is placed in the mold to speed up the cooling rate of the casting, also known as cold cast iron. Because the surface layer of cast iron in contact with the cold iron is cooled faster, the cast iron structure is white in a certain thickness, so it has higher hardness and good wear resistance. The deep part away from the cold iron, because of the low cooling rate, the obtained structure is gray; The transition area between the white mouth and the gray mouth is pitted.
Characteristics of chilled cast iron
1. The exterior is hard and the interior is tough. The surface part is whitened, the hardness and wear resistance are greatly improved, and the interior still maintains the gray structure to prevent the overall embrittlement.
2. Cold cast iron is suitable for parts without abrasive particles under friction conditions, parts in addition to sliding but also include different degrees of rolling motion. The parts are required to have high hardness, good wear resistance, and the workpiece is required to have high enough strength and toughness, so it is generally used for manufacturing rolls, wheels and other parts.
The characteristics of hard working cold cast iron:
1. Cold cast iron is a typical hard and brittle material with high surface hardness. Rough machining, unit cutting force up to 3000MPa, strong impact is easy to cause vibration, aggravate tool wear.
2. Cold cast iron has high hardness and high thermal strength. Especially large parts, cutting tool continuous working time is long, the temperature of the tool is very high, prone to deformation of the tool body or welding blade welding phenomenon and damage the tool.
3. The surface structure of chilled cast iron is white, hard and brittle. When the cutting tool is cut in or out, it is easy to appear edge collapse phenomenon, resulting in waste products or damage to the cutting tool.
4. Cold cast iron is often used to make a variety of rolls, the structure size is large, processing allowance is also large, turning to use a larger cutting depth and feed, the strength of the tool and the rigidity of the process system is higher.
Choice of cutting fluid for chilled cast iron:
1. The microstructure of cast iron is not uniform, and it contains flake graphite and sand, which is easy to form microbatteries and cause rapid corrosion under the condition of water. The cutting fluid of cast iron machining should not be selected with more oil cutting fluid (such as emulsified cutting fluid), because the graphite components of cast iron parts and chips in the cast iron cutting fluid oil leaching, resulting in the actual concentration of cast iron cutting fluid reduction, easy to cause corrosion and cast iron cutting fluid deterioration.
2. The cast iron processing often produces crushing chips, machining tool surface wear. Therefore, the cutting fluid of cast iron should be water-based cutting fluid with good cooling and cleaning properties. The graphite in the cast iron has a certain lubrication effect, which can make up for the lack of lubrication in the cutting fluid of the water base cast iron to a certain extent.
A large amount of chip powder will be produced when cutting cast iron, which is easy to react with some chemicals in cast iron cutting fluid and generate iron oxide, which affects the stability of cast iron cutting fluid and leads to deterioration. Therefore, cast iron cutting fluid should have a better settlement and cleaning of chips, at the same time, machine tools should be equipped with chip separator and filter, in order to separate and remove the chips in cast iron cutting fluid.