China has become an international production base for castings and forgings (including die-castings, ordinary castings, forgings, etc.); more and more European, American, Japanese, Korean, and Australian countries, including Taiwan, etc., will be their original production or newly developed products, to the typical cost and technical advantages of mainland China production. There are two blank forming processes; they produce the blank, the appearance is very similar, non-very professional in the line, and generally not easy to separate, which is the die casting and die-casting die forging (liquid die forging) parts.
Open die casting and die-casting die forging (liquid die forging) parts
Propose to distinguish between die-casting and die-casting die forging (liquid die forging) parts, at least for two types of manufacturers units have significance: one is the domestic some intermediate institutions, including parts and whole manufacturers. They undertake external parts and components and then find some manufacturers in the country to produce. As these two types of blanks have different production processes, the current market prices are also different, with the latter generally being quoted at a higher price than the former. If you do not distinguish between these two kinds of blanks, in undertaking business quotations, such as the low price of die-casting reported, there will be operational errors, affecting the benefits and even losses; second, professional castings and forgings manufacturers. As the latter is thought to be die-casting, it can be produced with the traditional die-casting process, which will take over the business. In the open die-casting die, the last basically due to the die-casting process production of blanks exist shrinkage defects or appearance defects, the blank failed, and ultimately caused unnecessary losses.
Die-casting die forging, liquid die forging, and continuous casting continuous forging process of the relationship
The essence of the continuous casting and forging process is in using a piece of equipment in the same molds, its casting filling, and forging continuous completion. The continuous casting and forging process is not new, and it has a long history of principles. The most typical and simplest continuous casting and forging process is the familiar liquid die forging (molten soup forging) process. The die-casting and forging process, figuratively speaking, is a kind of special equipment with a higher degree of automation to produce a structure as complex as ordinary die-casting liquid die-forged parts. Because of this, die-casting die-forged parts and ordinary die-casting in appearance are not easy to distinguish. The quality of the blanks produced by the continuous casting and forging process is similar to that of the “cast first and forged later” process. We are very familiar with the cast-and-forged process: two molds are required to produce blanks, one for ordinary manual metal die casting and the other for fine forging using friction presses or hydraulic presses. Die-casting die-forging process is only in recent years in the global rise of the process; due to the limitations of the patent technology, the process in China is not yet common. Guangdong Zhaoqing Hongyin Mechanical and Electrical Technology Co., Ltd. is the earliest in the country to introduce this technology to external production. Now has produced a variety of blanks, including sports car forging pistons, small cylinder bodies, extreme sports motorbike frames (6061 material), and small wheel hubs.
Introduction to die-casting and forging process
The die-casting and forging process is completed on a special machine. Its basic process is a metal liquid first low-speed or high-speed casting filling into the die cavity, and the die has an active cavity surface. It is forged with the cooling process of metal liquid pressure, both to eliminate the shrinkage of the blank shrinkage defects and to make the internal organization of the blank to the forging state of the broken grain. The comprehensive mechanical properties of the blank are significantly improved. In addition, the process produces the blank, the external surface finish to 7 grade (Ra1.6), such as cold extrusion or machining out of the surface, like a metallic luster. Therefore, we will see a die-casting die-forging process called the “extreme forming process” and the “no cutting, less residual forming process” step. Another advantage of the die-casting and forging process is that it can produce complex parts from deformed and forged alloys in addition to traditional casting materials. These alloy grades include hard aluminum, super hard aluminum, and forged aluminum alloys such as LY11, LY12, 6061, 6063, LYC, LD, etc.). The tensile strength of these materials nearly doubles that of ordinary cast alloys. It is of more positive significance for aluminum alloy automotive wheels, frames, and other parts that wish to be produced from higher-strength impact-resistant materials.
How to distinguish between these two blanks
In terms of appearance, it isn’t easy to distinguish between the blanks produced by these two processes. It is even more difficult to distinguish between them if you are looking at a part that has been machined. Therefore, we can only reverse the analysis and judgment: one is the general die-casting is “structural parts,” while die-casting die-forged parts are “functional parts.” “Structural parts” and “functional parts” is the opposite. The latter generally refers to parts that are subjected to impact, high temperatures, pressure, strength (force), as well as surface treatment (e.g., anodizing), heat treatment (solid-melt strengthening), etc. Typical products are engine blocks, hubs, pistons, connecting rods, brake shoes, pneumatic or hydraulic valve bodies (e.g., the standard three-way five-way valve), etc. The former includes door frames, instrument panels, engine covers, etc. The second is to judge from the material composition because die-casting is generally a casting class alloy, for other grades of alloy, often with die-casting die-forging process production. Third, from the billet on its external surface processing requirements to judge. Such as aluminum die-casting parts, because of the silicon and because of the die-casting process out of the blank, the outer surface of the microscopic pores (commonly known as “water lines”), the surface of this material after anodic oxidation will have a “black spot.” Therefore, if the blank requires anodic oxidation, the blank will not be produced by an ordinary die-casting process. Four is from the metallographic organization to judge. Die-casting and die-casting mold forgings in the metallurgical phase we can easily distinguish. The former is a dendritic casting organization, and the latter is a uniform broken grain of forging organization.
Eliminate some wrong views
One is that we can no longer think that the vacuum dipping after die-casting solves the existence of die-casting shrinkage defects, nor can we think that we can use the vacuum die-casting process, production to be continuous casting and forging process to produce the functional parts too. When the line of technology has been progressing, the concept and thinking we have to keep up with the times of scientific attitude. Second, vacuum dies casting and ordinary die casting, as there are shrinkage defects; vacuum die casting, it is only a small role than ordinary die casting in the auxiliary exhaust process due to the shrinkage of the metal liquid phase change shrinkage and shrinkage (its internal is a vacuum, no gas), it is no way. Thirdly, the most common mistake professionals make is to choose a process called “indirect and partial extrusion with a reverse punch,” even though they know that the normal die-casting process cannot produce the blank. They think this process gives the same results as the liquid die forging process, which is also completely wrong. At heart, the “reverse punch extrusion” process is still a die-casting process! Only the “full projection forging with a positive punch” is a true liquid die forging process.
The distinction between ordinary die castings and die-casting forgings is still very meaningful. Although the method to be mastered is not difficult, many the concept and understanding of the skills only.
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