Why is heat treatment necessary for machining?
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2021-09-30 10:33:37
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The heat treatment requirements for machining are actually a technical requirement for the design process.
The knowledge of heat treatment design requirements for parts is basically based on the knowledge of the changes in material use and processing, so it is a very systematic knowledge structure, which does not exist in isolation.
First of all, we need to understand how many ways are included in the so-called heat treatment of parts during mechanical processing? In view of the frequency and importance of the various ways in the machining process, we choose the following for analysis, i.e., a focused analysis.
In the machining process, we use the most four types of heat treatment: annealing, normalizing, quenching and tempering.
Annealing treatment
Definition of annealing treatment: a metal heat treatment process in which metal parts are heated to a certain high temperature, held for a period of time, and then allowed to cool naturally.
Its main function.
A, reduce the hardness of the parts, improve the cutting performance.
B, eliminate residual stress in the parts, stabilize the size, reduce the probability of deformation and cracking.
C, refine the grain, adjust the organization, eliminate material defects.
D, uniform material organization and composition, improve material properties or for the subsequent heat treatment process to do tissue preparation.
2. Normalizing treatment
The definition of normalizing treatment: the metal parts are heated to a certain high temperature, maintained for a period of time, and then let it cool in the air using water spray, spray, blowing, etc. Its different from annealing treatment is that its cooling rate is faster, so the material obtained is finer, and mechanical properties have been improved.
Its main functions are.
A. Removing the internal stress of the material.
B, reduce the hardness of the material, improve plasticity.
3. Quenching treatment
Definition of quenching treatment: the metal parts are heated to a critical temperature of Ac3 or Ac1 above the temperature, held for a period of time, so that all or part of the austenitization, and then faster than the critical cooling rate of the cooling rate to below Ms for martensitic transformation of the heat treatment process.
Its main role.
A, substantially improve the rigidity, hardness, wear resistance and fatigue strength of the parts.
B, to meet the ferromagnetic properties of some special steel, corrosion resistance and other physical and chemical properties.
4. Tempering treatment
Definition of tempering treatment: refers to the quenching and hardening or normalization of steel after treatment and then immersed in a lower than the critical temperature for a period of time, to a certain rate of cooling down to increase the material toughness of a heat treatment.
Its main role.
A, eliminating the residual stress generated by the quenching of the workpiece, to prevent deformation and cracking.
B, adjust the hardness, strength, plasticity and toughness of the workpiece, to achieve better performance requirements.
C, stable organization and size, to ensure accuracy.
D. Improve and enhance the processing performance.
As a mechanical design engineer, we design the parts need to be used when heat treatment, is only the following requirements:
A, eliminate the casting stress of the material, the purpose of which is to get more stable machining size and accuracy.
B, improve the cutting performance of the parts, the purpose is to process the parts in the process of machining more efficient, better processing quality, lower processing costs.
C, improve the rigidity, hardness and wear resistance of the parts, this will not need to explain it.
Our heat treatment requirements for most parts are designed around the above three major aspects, so you just need to use the above four heat treatment methods corresponding to your requirements on the line.
Now because the CNC performance of the equipment is getting better and better, the degree of automation is getting higher and higher, many people feel that the traditional mechanical knowledge has been in decline, in fact, no, these things are a foundation, if not this foundation, you will find that you still can not make good use of these advanced technologies, this is a gradual deepening of the process, the technology needs to be practiced step by step on the road.
