As implied by its name,
hot forging entails heating the metal, making the heating temperature pivotal to the forming process and its outcomes. Ensuring the metal's forgeability and achieving desirable internal structural performance necessitate adhering to specific heating guidelines and conducting
forging within designated temperature parameters. Additionally, due to the high temperature of the metal blank, there's often a need to preheat the molds, imposing requirements on mold longevity and forming equipment. To guarantee the smooth progression of the forging process, the following key considerations must be taken into account during hot forging:
Managing Pre-Forging Heat Treatment
Before hot forging, the metal blank undergoes heating to a specific temperature. This process serves to decrease the material's strength threshold (represented by σb), enhancing its ductility. The higher the heating temperature, the more pronounced the reduction in σb, consequently lowering the required forming force. To minimize forming force and energy consumption, it's ideal to elevate the metal blank's heating temperature while ensuring it doesn't reach the point of metal overburning. Given the narrow temperature range for aluminum forging, meticulous attention to pre-forging heating control becomes imperative.
Lubrication in Deformation Processes
Effective lubrication between the die and the blank significantly influences forging quality, forming loads, and die lifespan. Inadequate lubrication leads to increased friction coefficients and poor fluidity of the metal within the mold cavity. Conversely, proper lubrication reduces friction coefficients, facilitating smoother metal flow. Friction coefficient's impact on forging is dual-fold.
Firstly, heightened friction forces can intensify resistance at the bridge of flyover grooves, impeding metal outflow. Secondly, reducing friction enhances material fluidity, improving filling performance, reducing forming loads, and extending mold lifespan. Thus, production endeavors should prioritize optimal lubrication conditions and control flash groove size to enhance metal flow resistance. Selecting suitable lubricants can decrease friction coefficients. Well-applied lubrication forms a protective film between the billet and mold, preventing rapid heat transfer from the stock to the mold, temperature drops, reducing forming forces, enhancing die lifespan, preventing adhesion, ensuring good surface finishes, and facilitating smooth demolding of forgings. With various lubricants available, comprehensive consideration of lubrication methods, mold specifics, and blank materials ensures optimal lubrication effects, reduced forming forces, and prolonged mold lifespan.
Mould Material Selection
Forging molds operate continuously in high-temperature environments, enduring significant deformation resistance and thermal stress. Therefore, manufacturing forging dies necessitates meticulous consideration of stress and temperature conditions to ensure mold strength, hardness, and toughness meet production demands. Selecting appropriate mold materials prevents premature mold failure and associated economic losses stemming from inadequate material performance.
In conclusion, hot forging is a complex process that relies heavily on precise temperature control, effective lubrication, and appropriate mold materials. Managing pre-forging heat treatment is crucial for optimizing material properties and reducing forming forces, especially in the case of materials with narrow forging temperature ranges like aluminum. Lubrication plays a pivotal role in forging quality and die lifespan, influencing friction coefficients and metal flow characteristics.
