Forging Die Manufacturing
Forging die manufacturing is the first step to forging parts. Our engineers will design forging dies based on the drawings of new forgings. The design of the forging die depends on the processing steps, the nature of the workpiece material, the flow stress, and the working temperature, among other factors.
Generally speaking, we need to accurately calculate the volume of the blank to avoid under-filling or overfilling. The choice of parting line (referring to the line where two molds intersect) is also very important. Sometimes for forged parts, there are multiple options to choose the parting line. Note that the parting line ensures the flow of materials is divided evenly. In other words, if there is no way to determine the parting line, forging is not feasible.
Classification Of Forging Dies
Hot die forging is a type of forging technology and generally refers to a precision forging method in which the metal blank is heated before forging. The metal blank is heated to a temperature higher than the recrystallization temperature of the material, and then it’s plastically formed into the shape and size of the forging.
Forging Process Design
When designing the forging process, first perform a process analysis on the forging product. Then determine the die forging forming method (upsetting, top upsetting, upsetting, and extrusion), and then propose a process plan (that is, the forming process). The next step is designing the forging drawing and forming process drawing (blanking drawing, pre-forging blank drawing, and final forging drawing, and forming digital model drawing).
The forming process diagram should allocate the volume of each part of the forging, and control the flow direction of the blank of each part in the next process (by practical experience and numerical simulation), to control the forming and performance of the forging. The process design should achieve excellent forgings, stable process, and achieve high material utilization, high labor productivity, high mold life, and low energy consumption.
Forging Die Processing
Forging die is the main process equipment for producing forgings, How to meet market demand, ensure the quality of forging die production parts, and how to choose more effective processing methods are the main problems facing the current forging die production and processing. The processing of forging dies has experienced the development stages of profiling processing, electrolytic and EDM processing, numerical control processing, and high-speed processing technology.
The profiling processing has a long production cycle, low processing accuracy, and poor mold size consistency, which is why it is rarely used at present. Electrochemical machining is mainly used for rough machining of forging dies, with high machining efficiency but low precision. The EDM processing has low efficiency and is mainly used for auxiliary processing of small forging dies or parts with deep grooves and subtle features. Its processing cost is high.
High-speed machining technology has high machining accuracy, low cutting force, and high efficiency. It is the main development direction of forging die manufacturing. In the future, CNC machining is the main means of forging die production and processing.
Selection Of Mold Material
The forging die not only bears the repeated action of high-stress dynamic and static loads but also bears the repeated action of stress. Usually, the hot forging die needs to be preheated at 150℃～400℃ before use. During die forging, under the action of impact or static high pressure, it will be in close contact with the hot forgings at 450°C (aluminum alloy), 950°C (titanium alloy), 1160°C (high-temperature alloy), or even 1230°C (carbon steel) for a short time under impact or static high pressure.
The temperature of the chamber rises sharply. After the forging is taken out, the surface temperature of the die chamber drops rapidly: the instantaneous temperature and stress rise sharply during loading, and the mechanical stress disappears during unloading. At the same time, the temperature drops rapidly to the use (preheating) temperature. This means the mold is always working under the environmental conditions of both mechanical load and thermal load, as well as impulse loading and unloading. The working environment is very harsh.
The mold material must have the following characteristics: high-temperature strength, high wear resistance and certain high-temperature hardness, excellent heat fatigue resistance, good oxidation resistance, appropriate impact toughness, better hardenability, and thermal conductivity. These are features making an ideal die material.
After the forging die design is completed, we will start the manufacturing process. In order to obtain high precision, the forging die must be processed by CNC. Therefore, in addition to the high material cost of forging dies, the processing cost is also quite high, which is why forging dies are much more expensive than casting dies.
After the forging die is completed, we will forge several samples to check whether the die can be used for production. If a forging defect is found, then we still need to repair the mold until it can be put into production perfectly. Therefore, as a professional forging supplier, we not only have large forging equipment to meet the various needs of forgings, but we also have our own mold workshop.
Another focus of forging mold manufacturing is the use of mold materials. Commonly used mold materials include tool steel, high carbon, and high chromium mold steel. The high cost of mold materials directly leads to the high cost of forging dies