Basic structure of mold
Quality
Core side
Cavity side
The mold could be roughly divided into the following systems：
- 1.Forming system：
After core and cavity are closed, a space will be formed in the tooling. According to the difference of product design, the features could be designed in cavity or core 100% or be designed in cavity and core in a special ratio. the engineer needs to consider draft angle, the ruin of molten metal, the location of parting line and difficulty of inspection. - 2.Mold base：
This system contains tooling plates and base structure units, the function of these parts is assembled and fix mold, and make sure this mold could be put on die casting machine correctly. - 3.Guild system：
Guild parts will make mold to close and separate correctly and make mold could match the requirement from customers. - 4.Ejector mechanism system：
The function of this system is pushing the product out of the mold. This system contains ejector pin and reset parts. About the push rod at the important and vulnerable part (sprue gate), it should be made form the same material as the product. - 5.Gating system：
This system refers to the channel connecting the cavity and the sprue gate.
This channel will guild molten metal into cavity in the correct direction and the design of channel will determine the speed and pressure of the molten metal during the forming stage. - 6.Overflow system：
It contains exhaust groove and overflow groove system. The function is removing the gas in the channel and cavity.
The overflow is usually placed at the end of molten metal channel. This system also could maintain the mold temperature. - 7.Core pulling system：
This system usually is used when the core extraction direction and the parting line direction are different (such as the side hole of the product).
It could help products to be pulled out from the mold easily. - 8.Cooling – heating device：
This system could make the temperature match the process requirements, and this device also could make tooling life being extended. - 9.Other extra parts：
It generally refers to bolts and positioning parts that connect and fix each structural unit parts , or some parts which are suitable for special products.
The mold design is provided by the customer with drawings, and the mold department of Fuchia Industry develops the mold based on the drawings. The following factors need to be considered when designing the die casting mold
Minimize the weight of die castings
When designing die-casting parts, attention should be paid to reducing the volume as much as possible to achieve the purpose of reducing weight and manufacturing cost. The heavier the die casting, the more time it takes to fill the cavity during the die casting process, and the longer it takes for the die casting to cool before being ejected.
Reinforce the die casting with "ribs"
The thin wall can be reinforced with "ribs" in the design. The ribs must be selected in a suitable place to facilitate the ejection of the thimble and the flow of metal.
Cold shrinkage of die castings
All alloys will shrink during the die casting process from high temperature to room temperature cooling. Shrinkage also makes the die-casting part easy to separate from the mold, but it may also get stuck with the protruding part of the mold. Design can use draft angle to reduce shrinkage.
Application of Draft in Die Casting
The draft angle is the slight slope of the inner wall of the mold to help the die-casting part to leave the mold. The surface with draft angle is usually very smooth.
Consistency of die casting profile
The more consistent the cross-sectional area of die castings, the more favorable the flow of metal materials. The drastic change in the cross-sectional area will cause the alloy to fluctuate when it flows, resulting in porosity. In addition, the drop in cross-sectional area will also cause uneven shrinkage
Fillet and corner of die casting
In addition to avoiding sharp angles and drastic changes in cross-sectional area, the design of die castings should have corners in the inner corners, while the outer corners should be designed with rounded corners as much as possible. Both can enhance the strength and filling of die castings.
Smoothness of die casting
The surface smoothness of die castings depends on the surface smoothness of the mold. The higher the smoothness of the mold, the smoothness of the die casting is also the same. For die casting plants, it is very easy to produce matte surface effects. Such as prominent trademarks and imprints are just as simple
Parting line and eject pin distribution of die casting
The Parting line is the joint of the two halves of the mold, and its surface effect is the key factor for the success of die casting production. It should be designed as straight and flat as possible. The thimble is a steel column used to push the die casting away from the mold. A good mold factory will minimize the traces left by the thimble. The designer of the die casting can suggest the appropriate position of the thimble.
Identification mark of die casting
The original designer of the die casting should provide a place where various signs (such as company logo, product serial number, etc.) can be placed. Usually the die-casting engineering staff can decide the final place of these signs based on this. Die casting plants usually also mark the mold cavity number and casting date for tracking purposes. Such marks are usually easy to emerge rather than sink into the surface of the casting mold.
Slider for die casting
The original designer of die-casting parts should try to avoid designing acupuncture points parallel to the parting line. The slider will greatly increase the manufacturing cost, so the product designer should cooperate with the die casting personnel to avoid it.
Combination of die casting functions
Designers can combine parts with multiple functions to design a die-casting part to reduce processing, storage and assembly costs.
Multi-cavity mold
Multi-cavity molds may reduce the price of a single piece, but the following conditions are required: @Extra points should not lead to the need to switch to a larger tonnage die-casting machine, because the larger the tonnage of the die-casting machine, the higher the startup cost. @The complexity of the workpiece caused by additional points cannot greatly reduce the production yield of die castings
If you need several similar parts, you can consider using the same mold but different processing and processing, which can save mold opening costs
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Hot chamber die casting process
1.The mold is closed, the piston is raised, the injection port is opened, and the molten metal is poured into the cylinder
2.After that, the plunger seals the entrance of the column and pushes the metal broth into the mold cavity, where the molten metal is kept under pressure until solidified
3.The mold opens. The casting remains on one side of the mold, and the remaining molten metal flows back through the nozzle and gooseneck.
4.The ejector pin ejects the casting from the ejector edge of the mold. When the plunger opens the injection port, the molten metal flows through the inlet to backfill the gooseneck.
The ejector pin ejects the casting from the ejector edge of the mold. When the plunger opens the injection port, the molten metal flows through the inlet to backfill the gooseneck.
1.The mold is closed and the molten metal is poured into the die-casting cylinder of the cold chamber
2.The plunger presses the molten metal into the mold cavity, where the molten metal is kept under pressure until solidified
3.The mold opens and the plunger advances to ensure that the casting stays on the ejection side
4.The ejector pin ejects the casting from the ejection side of the mold, and the plunger returns to the original position
After the mold design is completed, it is necessary to test whether the product produced by the mold meets the requirements. The samples produced by the designed mold will undergo various strict inspections, including the product structure inspection, product material condition, size measurement, and environment Resistance test:
Construction test
After the first batch of samples come out, the staff will start to check whether the product roughly meets the shape required by the customer, whether there are defects such as blistering or strain on the surface, and if any defects occur, the cause will be explored and the mold will be corrected.
Material condition
After the sample comes out, it will be sent to the quality assurance department, and the metallographic grain condition of the material will be observed with a measuring microscope. The metal is heated to a molten state and enters the mold after it is molded and cooled. There will be two problems. One is the cooling rate gradient will cause the grain The change in the product further affects the strength of the product. Second, the manufacturing process causes the product to produce defects that are invisible to the visual test. If the above situation occurs, it is necessary to modify the cooling rate gradient during the die-casting process and find other gate locations.
Dimension measurement
Dimension measurement is the most important part of tooling test. Most die-casting products are used in components of precision instruments. Therefore, the size requirements will be accurate to the third to fourth decimal place, because if the error is too large, the components will fail on assembly with other components of the customer, so we will use various methods and provide various solutions to achieve the standard