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Njection Mold Structure Design Process And Skills
Jun 25, 2018

Core Tip: First of all, after we get a product, we don't need to rush to mold. The most important thing is to inspect the product structure first, including mold-drawing and thickness molding problems. Of course, these may be more difficult for a person who has just engaged in the design of mold structures. Because they may not know what is more suitable for mold design products, these do not matter, just a routine of their own accumulation. After you have analyzed the draft, the wall thickness, and the downturns in the direction of the die, you basically know the direction of the die parting surface and the location of the gate. Of course, these will eventually meet the customer. comfirmed.

Some people say that after I analyzed the product structure, I could start designing the mold. The answer is of course NO. In order to avoid detours during design, some items that affect the mold structure must be confirmed.

The details are as follows:

1. Tonnage and type of injection molding machine used by the customer.

This confirmation is not good, you can not confirm the inlet diameter of the sprue bushing of your mold, the diameter of the locating ring, the size and position of the top hole, the depth of the injection molding machine into the mold, or even the size of the mold frame. Closed heights and so on. You have worked so hard to design a mold structure that uses a fuel tank to pull the core. You also have a sense of accomplishment. You can't manufacture the mold to your customers because the customer only has an electric injection molding machine, and there is no additional neutron. It is estimated that When you have a feeling of crying and tears.

2, the customer injection molding machine code mode.

Commonly used are platen code model, screw code model, hydraulic code model, magnetic code model and so on. After confirming this, you only know that when designing your mold, you don't need to design the coding screw through hole or the mold groove.

3. The problem points of our analyzed products, as well as product clips, product materials and shrinkage rates.

Do not take it for granted that PP's plastic shrinkage must be 1.5%, this must be confirmed with the customer well, to know what material they used to produce the final grade, there is no added any modified material and so on.

When conditions permit, it is best to be familiar with the assembly relationship of the product and the use of the product, etc. This information is very helpful for the future mold structure design. Because you understand this, you know what are the appearance of the surface, which is the non-appearance, where the draft angle can be easily increased, and where can not be changed. Even including the structure of some products, if you understand the actual assembly relationship and use of the product, you know which flip structures can be canceled or changed to another simple form.


It must be kept in mind that the process of making a mold is a process of simplifying a complex problem. I often see people proud and proud about how complex a structure is. I think it is very ignorant. Because many product engineers may design some unreasonable structures because of their own experience, if they can't correct them as a downstream process, they may always feel that design is not a problem. The progress of our product engineers will be very slow.

External parameters of the mold waterway, external parameters of the oil circuit, external parameters of the circuit, and external parameters of the gas circuit. Only after understanding the customer's requirements before design can you have a predictable way to design the gas path of the waterway. When you don't work hard to design the mold, you discover that the customer needs to connect the oil circuit inside the mold. Then you will Changes, it is estimated that will die half tired, because your waterway, the top rod, screws, or something is very easy to line up. The design sequence of this four-way route is generally to ensure the oil circuit first, because the oil circuit should be distributed in a balanced manner, especially the mold structure that requires the cylinder to be ejected. If the oil line is unbalanced, the movement of the cylinder will have a sequential movement, which is easy to top. Out of balance. Of course, gear separators can also be used, but that's more complicated. Followed by the waterway, because the waterway to ensure cooling effect, uneven distribution will affect product quality and mold life. The last is the air circuit and the circuit. The order of placement on the mold is that the circuit closest to the TOP direction is the circuit, then the water path, the air path, and the bottom is the oil circuit connector.

Other issues. With this information in hand, we can start designing the mold. The first is the model division. This process is estimated to be a process that everyone likes. Because there is a sense of accomplishment from the mold. The principle of pulling the parting surface is simple, that is, good, can not be scanned by stretching, or use other advanced commands. Secondly, when drawing the sub-surface, it is necessary to have an overall view. Try to simplify the parting surface. Do not engage in the seven or seven-eighths. If it is not a precision mold, those 0.1 to 0.5 insertion points can be avoided. In addition, the parting surface must follow a principle that is to follow the product trend. The parting surface that is made like that will be beautiful. If you want to learn a three-dimensional software, be sure to remember that the principle of each command is clear. Then you know when you can use that command. Most of the time, it's not that you don't use software. It's not that you don't learn to use software. The same command, experienced people will have a lot of flexible usage, this is reflected in the UG is the most obvious. In a word, it is important to think, not the tool itself. When you make a parting surface, you only need to know that the angle of the piercing surface can be large, and the area of the piercing surface can be large, and the pulled out pillow can be wide and wide. To fully consider the fact that you are now pulling this parting surface in the future after the actual mold is made, the person in charge of the person in charge of the flying die will not marry you on the line. If you dont think its going to be awkward, then OK, go ahead. When youre really paralyzed in the future, these are your experiences.


When making the parting surface, it is definitely necessary to consider the arrangement of the slider and the inclined roof, because those also need to involve changes to the parting surface. The typical slider structure is a trigonometric function. This is all right and it is OK to calculate it. However, it is necessary to ensure that the angle of the inclined guide column is not too large. Try to achieve it below 30 degrees. The principle of choosing the inclined guide column is to be coarse and thick, and not too insignificant, because the inclined guide column is subject to force. In addition, the slider is also divided into a number of mutated structures, for example, uphill slider, downhill slider, internal pumping slider, cylinder pumping, front mold slider, slider with slider, slider with anti-top, slider belt Inclined roofs, etc., these special structures are full use of the trigonometric relationship, the purpose is to achieve the product down buckle demoulding, and mold normal opening and closing mold action. The calculation formula of the slider has been introduced in detail in each major forum, so I will not go into details here.

Followed by inclined roof, inclined roof is more flexible, but the angle of the typical inclined roof is not too large, try not to exceed 15 degrees, of course, you do not have to do 20 degrees, but life is difficult to guarantee, and the action will be very Not smooth, the specific principles of reference trigonometric and theoretical mechanics. The shape of the inclined roof has many evolutionary forms, for example, slope uphill, slope down slope, sloping neck slope, large inclined roof with inlaid inclined top bar, large inclined roof with inlaid round bar, and inlaid The small inclined roof, the inclined top of the top block, the inclined top of the slider, the inclined top of the inclined top, the top of the inclined top, and so on, all of these structures are a purpose, using the triangle The function reverses the product. This shows how important it is to learn the trigonometric functions! Therefore, as for all kinds of special structures, they are all come out of the mind. You can make full use of your imagination. No matter what kind of structure you can think about, you can think boldly and design yourself. There is a new invention, but after the design, we must verify the relationship of the lower trigonometric function, that is, the actual simulation of the mold opening and closing mold action, and consider whether there will be problems in the injection molding and so on.

Talking about it, we divide it up. The next step is the ranking of the mold structure. These contents are all prioritized. According to the actual conditions of the product, different types of mold structures are used. For example, two-plate mold, three-plate mold, hot runner, IMD, IML, Two-color, stacked mold and so on. All mold structure types are designed to serve the mass production of products. When selecting a mold base, we must fully consider the four points mentioned earlier.

Choosing the mold frame we must consider the molding of the mold, the principle of inlaying is to simplify the processing, save material, and facilitate product molding, such as exhaust and so on. You think that there is a particularly thin place on the mold, which must be put together separately for easy replacement in the future. When inserting, it is necessary to fully consider the strength of the insert, the workability, and the designability of the waterway in the future. After the mosaic is complete, standard parts will be added. The principle of adding standard parts is to focus on the first part and try to arrange balanced symmetry. Generally, it is necessary to add the top rod first. When adding the top rod, it is necessary to consider the arrangement of the water channel. Under normal circumstances, priority should be given to the arrangement of the jacks, and then the waterway should be designed in general, and then the waterway jacks should be adjusted according to the actual situation to balance the two. The principle of adding top-out is the place where there is a great deal of strength, and it must be added to places where the strength, structure, and strength of the product are relatively good, so as to avoid unbalanced white tops or tops. The principle of the drainage road is to add the principle of top-out, because in general, the place where the product has a high holding power is the hot spot of the product, and the part that needs to be strengthened is needed. This contradiction needs to be adjusted well. As for whether to use a top bar or a top block or a push plate, specific questions need to be analyzed. This should be combined with the structural characteristics of the product to analyze, such as the product is easy to stick to the front mold, it is necessary to consider whether to add back up button after the mold, or the top mold top out, these are natural things, but many friends will not want to fully What is the reason? It is because there is no sufficient analysis of the product structure and no actual consideration has been given to the state of the product during the injection molding process. This is the key to the problem. After the top pole waterway is added, the rest is a mess of standard parts. Everyone should think about symmetry balance when they add.

After the complete mold design is completed, the following inspections must be done. The first is the draft analysis of the inserts to see if there is an upside down position, followed by the interference inspection of the various parts of the mold. Today's 3D software has this function and is very convenient. Then the simulation of mold opening and closing mold movements, and then simple mold as long as they are not too clear, it must be the actual simulation, the other is the mold parts of the processability and mold assembly process, do not work hard to design a Ingenious structure, theoretical calculations are no problem, finished processing, the results can not be installed, or bad assembly.

At this point, you can congratulate you, the general process is over. In fact, mold design is full of contradictions. If you want to design a perfect one, the cost of the mold will be high. If you want to design something simple, you may want to change the product or the strength of the mold. The service life will have an impact. So there is no absolute mold design. As long as the balance point is found, the mold you design is successful. Therefore, other people's designs may not be suitable for you. As long as the above points of mold design are followed, it is estimated that everyone can design a reasonable mold structure.