Years of Experience in Injection Mold Design

Who Am I?

I am engaged in the injection mold structure design at Five-Star Tooling, once has designed the electrical appliances, the automobile, the electronic product kind of mold.

The design level is not necessarily very high, but the work is done more, more complex. Today just idle, nothing to discuss with you about the injection mold structure design issues.

What I do?

We first got a product, do not hurry to die, the most important thing is to check the product structure, including the draft, the thickness of die forming problems.

Of course, these may be difficult for a person who has just engaged in the design of die structures. Because they may not know how to be more suitable for mold design products, these do not matter, but their daily accumulation of a process.

When you analyze the end product draft, wall thickness, and in the direction of the mold is inverted place, you basically already know the parting direction, and the location of the gate, which will eventually have to confirm with the customer.

Some people say that, whether I have analyzed the product structure, you can begin to design the mold, and the answer is NO.

How To Do?

In order to avoid detours in design, some projects that affect the structure of the mold must be confirmed. The specific contents are as follows:

Step One

Injection molding machine used in the production of customer’s tonnage and type, this confirmation is not good, you can not confirm you the entrance gate set of die diameter and the diameter of the positioning ring, ejection hole size, and position, and the function of injection mold in-depth, and even die size the height of the closed and so on.

You have a good design a set of mold structure cylinder core pulling, you have quite a sense of accomplishment, but there is no mold to the customer production, because customers there is only electric injection molding machine, and no extra neutron, presumably you will have a feeling of tears.

Step Two

Customer injection molding machine code mode, commonly used are press plate mold, screw code mold, hydraulic code mold, magnetic code mold, and so on.

OK, so you know when you design the mold, do you need to design the code, the screw, the through-hole or the die slot?

Step Three

We have just analyzed the problem points of the product after, and product clip line, product material, and shrinkage.

Don’t believe the PP most probably it did not actually happen plastic shrinkage rate must be 1.5%, this must confirm with the customer, they want to know what the material is used for the production of the final grade, there is no add what modified materials, etc..
When conditions permit, it is better to be familiar with the assembly relationship of the product and the use of the product and so on.

This information is very helpful for the future structural design of the die. Because of the understanding of these. You’ll see which is the appearance of the surface, which is non-appearance, where the draft angle can easily increase, where can’t change.

Even including the structure of some products, if you understand the actual assembly relationship and use of the product, you know which structures can be canceled or changed into another simple form.

It is important to keep in mind that the process of making a mold is a process of simplifying complex problems. I often see some people proud and proud of what a complex structure they have made.

I think it is very ignorant. Because many product engineers may be due to the problems of their own experience, design some unreasonable structure, as if the downstream process, could not help them.

Then, they may never think that design is no problem. Then the progress of our product engineer will be very slow.

Step Four

The external parameters of the water channel, the external parameters of the oil circuit, the external parameters of the circuit, the external parameters of the gas path.

Only after understanding the customer design before these requirements, you can foresee the design of oil gas water, not when the hard design of the mold, later found that customers need to mold series circuit, then you can change, is estimated to be tired out, because you water, a push rod, screws are not what to line up.

Like the design order of the four roads is generally the first to ensure the oil, because the oil distribution to balance, especially to the top of the cylinder of the mold structure, if the oil is not balanced, the top of the cylinder out of action will have to push out successively, imbalance.

Of course, gear oil can also be used, but that is more complicated. Followed by waterways, because the water to ensure the cooling effect, uneven distribution will affect product quality and mold life.

Finally, the gas circuit and the circuit. The order of placement on the die is the circuit closest to the TOP, followed by water, gas, and at the bottom of the circuit.

Step Five

Other unfinished matters. With this information in hand, we can start designing the injection mold.

Analytical Products

First of all, the division process, the process is estimated that everyone is more like the process. Because there is a sense of achievement.

The parting surface principle is simple, that is good, can stretch out, resolute not scanning, or with other advanced commands.

Secondly, we should have a general view of the parting surface and simplify the parting surface as much as possible.

Do not engage in 7788, if not the precision mold, those 0.1~0.5 plugs through the potential to avoid, we must avoid.

In addition, the parting line also follows a principle, which is to follow the trend of the product as much as possible. The parting surface will be beautiful.

Choose Design Tools

On an aside, in the study of 3D software, we must bear in mind that the principle of each command is understood, then you’ll see used the command at that time.

Most of the time it is not important that you will not use the software, but you will not use the software. Similarly, a command, an experienced person, has many flexible uses, which are most obvious on UG.

In a word, the important thing is the train of thought, not the tool itself. When making parting faces, you only need to know that the angle of inserting and wearing faces can be big, and the area that touches the face can be large, and the width of the pillow that is pulled out is wide.

Something Need to Take Care Before Injection Mold Design

To take full account of the hand you now pull the parting surface, the future of the actual mold out, the others responsible for flying the mold master will not curse you on the line.

If you feel will not be scolded, then OK, continue, when you really be scolded, these are your experience.


In doing the parting surface at the same time, must consider the slider and oblique top arrangement, because those also involve the parting surface change.

The typical slide structure is a triangular relationship, this right himself calculate on the line, but to ensure that the oblique guide pillar angle is not too big, try to be 30 degrees below.

The guiding principle of the oblique guide column is to be rough and not too stingy, because the slanting guide column is to be forced.


In addition, the slider can be divided into many variations, for example, uphill downhill slide, slide, slide pumping, pumping cylinder, front mold slider, slider with slider, slider with anti-slide with inclined top, top, and so on.

These special structures are made full use of the trigonometric function, the purpose is to achieve product upside down release, mold and die normal action.


The second is the sloping roof, sloping roof is more flexible, but the typical slant angle is not too large, so as not to exceed 15 degrees, of course, you have to do a 20 degree line, but life is difficult to ensure, and the action will be very smooth, specific reference and theoretical mechanics principle of trigonometric function.

There are a lot of oblique top shape evolution forms, for example, uphill downhill sloping roof, sloping roof, sloping roof crooked neck, large inclined top inlaying inclined push rod, large inclined top inlaying round rod, small inclined top inlaying hanging table, the top block to go below-inclined top, slide walking on the sloping roof.

Walking on the sloping roof, sloping roof with a countertop, and so on, all of these structures is a purpose, using the trigonometric function to pour out products. It can be seen how important it is to learn trigonometric function well!

So as for a variety of special structure, are people who want to come out, you can give full play to your imagination, no matter what kind of structure are able to think, think good, go to the bold design, well you have new inventions, but after the design must verify the relationship trigonometric function, is simulated under the mold clamping action, and consider the injection will not be a problem.

With the words, we divided into good. The next step is to die structure in qualifying, these contents are prior to sorting out, according to the actual situation of the product, such as the selection of mold structure, different types, two plate mold, three plate mold, hot runner, IMD, IML, double color, double model, etc..


All types of mold structure are to be able to achieve good production and service. In the selection of formwork, we should take full account of the 4 points mentioned earlier.

We will consider the selected mold die insert, insert the principle is to simplify the processing, material saving, conducive to product molding, such as exhaust, etc.

Do you think there are special thin places on the mold, must separate insert, easy to replace. In the insert when you want to take full account of the insert strength, workability, and future waterway design.

The finished, we must add the standard parts. The principle of adding standard parts is to focus on the first and the latter and to balance the symmetry as much as possible. In general, it is necessary to add a rod at first. When adding a pole, we must consider the arrangement of waterways.

In general, we should give priority to the arrangement of the top rod, then design the waterway in general, and then adjust the waterway ejector lever according to the actual situation to balance the two.

The principle of “extra push out” is to hold the big force. Besides, it should be added to the places with better strength structure such as the wall, platform and edge of the product so as not to be white or out of balance.

The principle of the drainage Road is the principle of adding the top, because generally speaking, the product holds the place of great force, that is the hot spot of the product, and needs to strengthen the part of the cooling, and this contradiction needs to be adjusted.

As for whether to use a top pole or a top block or a push plate, it is necessary to analyze the specific problems.

This should be based on the structural characteristics of the product analysis, such as the product easy to stick to the cavity, we must consider whether after the mold with a buckle, or die with top, which is a natural thing, but many of my friends will not want to complete what is it or because there is not sufficient for analysis of product structure, no considering the actual product in the process of injection molding of the state.

That’s the point. The top of the waterway is finished, and the rest is the standard parts of the mess. When we add, we should try to consider symmetrical balance.

Suggestion to New Mold Designer

Complete set of mold design, we must do the following check, the first is the analysis of insert draft, to see if there is no upside-down place, followed by the interference check mold parts, priority among priorities. Now the three-dimensional software has this function, very convenient.

Then there is a mold clamping motion simulation, and simple die as long as they are not too clear, it must be the actual simulation, the other is the assembly process of mold parts of the processing and die, not working in a clever structure, theoretical calculation and processing finished, no problem, then the result is not going in, or not good assembly.

So far, Congratulations, the general process is over. In fact, injection mold design is full of contradictions. Want to design more perfect, mold cost will be high, want to design simple, maybe product will change, or die strength, service life will be affected.

So there is no absolute die design. As long as the balance is found, the mold you design is successful. Therefore, the structure of others may not be suitable for you.

As long as follow the above mold design points, it is estimated that we can design a more reasonable mold structure.

Design, injection mold, die-casting mold, sense of achievement, how, influence…

Scroll to Top