Application of extrusion die casting process on ordinary die casting machine

SCZY LTD(www.sczyltd.com)  has dealt with a lot of Die Casting projects in the previous more than ten years. An important feature of the traditional die casting machine is that its model is named after the clamping force as the main parameter. We now often say how many tons of a die-casting machine is the tonnage of the clamping force. The extrusion die casting machine not only has the parameters of the clamping force, but also has a parameter requirement of the extrusion force, and this extrusion force parameter is still the most important index.

As described above, since the conventional die casting machine has two different models of full hydraulic type and elbow type, there is no difference in the conventional ordinary die casting, but it is different if it is used for extrusion die casting. The difference between extrusion die casting and ordinary die casting is that after the casting is filled, the extrusion die casting increases the step of the main cylinder power to advance and feed, while the ordinary die casting is only natural cooling, and there is no step of feeding.

Here we also subdivide and clarify the two concepts, the clamping force and the clamping force (or clamping force). The clamping force refers to the forward power required to propel the moving mold, and the clamping force is the resistance required to resist the filling and expanding. It can be just a static force (reaction force). Therefore, the conventional die-casting machine directly applies the extrusion die-casting process, and can only use its clamping force, and only the clamping force is a driving force for forwarding. The size of the clamping force determines the amount of extrusion force. Therefore, the full clamping force of the full hydraulic conventional die casting machine is its maximum clamping force, and it can also be used as its extrusion force. The maximum forward pressing force of the elbow die casting machine is equal to the clamping force of the clamping cylinder multiplied by the clamping ratio of the clamping mechanism, but the maximum can not exceed the compressive strength of the clamping mechanism. Extrusion die-casting with this equipment, because the initial position of the clamping does not reach the self-locking "dead point" of the clamping mechanism, and the extrusion end position is the "dead point" of its maximum clamping force, if the same Die casting is less than the press-fill type, and the projected area of the parts that can be produced is reduced.

3. Define the technical characteristics of the main body of extrusion casting

The highest extrusion-compression ratio pressure of extrusion die-casting is about 5-10 times that of ordinary die-casting injection pressure. According to the extrusion specific pressure of extrusion die casting, in addition to the vertical open-die casting and casting machine modified by four-column hydraulic press, it meets the technical specifications of the main body of extrusion casting, and the other devices are only belonging to the process range of traditional die-casting. Still not in the true sense of squeeze casting. We must define this concept clearly.

4. The feasibility of extrusion die casting process with traditional die casting machine

At present, no matter which kind of clamping mechanism is used in the traditional die-casting machine, the designed injection force is about one tenth of the clamping force. The current die casting process generally requires an injection specific pressure of between approximately 80 MPa and 130 MPa, and the projected area per 100 ton of clamping force can withstand a die casting of approximately 150-250 square centimeters. Since the extrusion casting process requires a specific pressure rather than a die-casting specific pressure, the extrusion-compression specific pressure is required to be between 500 MPa and 1000 MPa. For a small-sized in-situ die-casting part, we cannot take shots. The cylinder or auxiliary cylinder is squeezed or "pressurized" for cooling and feeding, and must be squeezed by the main cylinder to be effective. If the extrusion molding is carried out in a "fine, fast, dense" die-casting manner, it is necessary to increase the size of the inner winding to have the characteristics of sequential solidification. Since the gate is generally cooled prior to the casting, without increasing the size of the gate, it is impossible to achieve extrusion. This method is not suitable for many die castings. In order to achieve the above-mentioned extrusion-compensation specific pressure, the projected area of the extrusion die-casting parts that can be produced by the die-casting machine is only one tenth of the original. The original "die-casting projection area" of the blank produced by the traditional die-casting machine is not large, and the reduction of 90% is obviously uneconomical. In practice, the meaning of its application is lost. At present, the die-casting machine has the "pressurization" link in the late stage of die-casting filling, but the air-tightness defects of the die-casting parts are still the same. The method of producing large parts and parts of the "big cattle pulling trolley" with an enlarged model has no effect. Where to go, the so-called "fine, fast, dense" die-casting is just a beautiful name. No substantial progress has been made in 40 years. The commercial propaganda of this kind of die-casting machine manufacturer has strengthened the engineering technology and application personnel. Knowing the misunderstandings makes people lose their way.

5. Understand the main technical characteristics of extrusion die casting technology and its strong technical and economic advantages

The main technical features of extrusion die casting are the principle of "common die casting filling, extrusion casting feeding". It is based on the perfect injection system of the existing die casting machine for filling, while at the same time avoiding the metal liquid to the maximum extent. Pascal's law governs the filling conditions (parts fillable area) when filling. This is of great significance. It is also an important feature of the extrusion die-casting process: the extrusion die-casting process emphasizes that the lowest filling pressure and speed are used as much as possible under the filling conditions. It is a great advantage to have a variety of thick parts for low pressure filling and successful implementation of core die casting. This is why it can replace low pressure, differential pressure, gravity casting and partial core casting process. The introduction of the extrusion die-casting process has greatly expanded the range of application of the traditional die-casting machine and die-casting process. The great economical effect is that a conventional die-casting machine, such as a low-pressure filling of 1.4Mpa, has a projected area of the produced parts. It is the original 80----100 times. It can be said that the size of the mold that can be installed on the workbench of the existing equipment can produce many large-sized parts. Using a traditional J1140 full-hydraulic 400-ton die-casting machine to transform into a 400-ton extrusion-clamping die-casting machine, it can basically meet the process requirements of large-size parts such as automobile and motorcycle wheels for extrusion die-casting. According to the process of extrusion die casting, a squeeze die casting machine with 500 tons of clamping force and 500 tons of extrusion force can deal with the current production of more than 90% of die-casting parts, using more than 500 tons of clamping force. Conventional die-casting machines are a very uneconomical practice and have great investment risks for small die-casting plants. 

Shenzhen SCZY Technology Co., Ltd
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