How to do a good job in injection mold design service?

Sungplastic not only provides injection mold building and injection molding production services, but also provides injection mold structure design services. We have designed many molds for home appliances, automobiles, and electronic products. In this article, we will discuss with you what aspects plastic mold manufacturers need to do well to provide high-quality injection mold design service.

Check the plastic product structure

Creating a good injection mold begins with knowing the product’s structure well. This step is key to making sure the plastic parts are just right. We’ll look at how to analyze the product’s shape, thickness, and angles.

Evaluate the Product Geometry

The product’s shape and form are called its geometry. It’s important to study this to spot any molding problems. Look at product geometry, complex shapes, and small details that might need special tools.

Optimize Wall Thickness

The thickness of the plastic part affects its strength and look. Thinking about the wall thickness helps avoid problems like sink marks and warpage. By adjusting the thickness, you can make the part stronger and more attractive.

Consider Draft Angles

Draft angles help the part come out of the mold easily. It’s important to check the draft angles to avoid damage. Good draft angles make the molding process work better.

By carefully looking at the product’s structure, you can make a strong injection mold. This step is crucial for making parts that are high quality and consistent. It’s the first step to a successful molding project.

Analyze the factors affecting the mold structure

Creating a good mold structure needs a deep look at many factors. As someone who designs molds, it’s key to understand material properties, shrinkage rates, and cooling needs. This ensures the mold works well and makes quality plastic products.

Material Properties

The type of plastic used is very important in mold design. Each plastic has its own material properties like how it flows, how it conducts heat, and how it changes shape with temperature. Knowing these helps pick the right mold materials and design parts like gates and cavities.

Shrinkage Rates

Plastics shrink as they cool and solidify. It’s important to know and plan for these shrinkage rates when designing molds. Things like the shape of the part, the plastic used, and how it’s made can change how much it shrinks. This must be thought about to meet size needs.

Cooling Requirements

Cooling well is key in mold design. It affects how good the product is and how fast it can be made. Looking at the part’s shape, the plastic’s heat properties, and how long it takes to cool helps figure out the best cooling system for the mold.

By carefully looking at these important factors, mold design experts can make molds that use materials well, reduce defects, and make high-quality plastic products.

Understand the assembly and use of plastic products

Additionally, it is advisable to acquire knowledge of the assembly and utilization of plastic products. Whenever possible, it is recommended to understand the product’s assembly relationships and its intended usage. This knowledge can be useful in designing the mold structure for future productions.Because after understanding these, you will know which are the exterior surfaces and which are non-exterior surfaces, where the draft angle can be increased at will, and which places cannot be changed. It even includes the structure of some products.

If you have a good understanding of the assembly relationship and the intended use of the product, you’ll be able to identify which structures can be eliminated or simplified into another form. The early understanding work will make the mold design work more overall and constructive. We must keep in mind that the process of making injection molds is the process of simplifying complex problems.

Design the mold oil circuit, water circuit and air circuit

Prior to designing the mold oil circuit, water circuit, and air circuit, one must comprehend the external parameters of each circuit and then design each circuit predictably. Typically, the design order for these four circuits is to prioritize the oil circuit. The distribution of the oil circuit should be balanced (especially the mold structure that requires the cylinder to be ejected). If the oil circuit is unbalanced, the ejection action of the oil cylinder will have a sequence, and it is easy to be unbalanced.

Of course, a gear oil separator can also be used, but that is more complicated. The second is the waterway, which must ensure the cooling effect. Uneven distribution of waterways will affect product quality and mold life. The last is the gas path and the circuit. The placement order on the plastic injection mold is as follows: first, the circuit is positioned closest to the top direction, followed by the water circuit, then the air circuit, and finally, at the bottom, the oil circuit connector.

Mold parting design

Designing the parting line of an injection mold is key. The parting line is where the mold halves meet to create the plastic part. Finding the best spot for this line is crucial for easy part removal and fewer defects.

When setting the parting line, think about the parting line, the mold halves shape, and a good ejection system. The line should be placed for easy part removal without harming the mold or product.

1. Identify the Parting Line Location: Look at the plastic part’s geometry to find the best spot for the parting line. Consider part complexity, ejection needs, and mold design limits.
2. Design the Mold Halves: Design the mold halves based on the chosen parting line. Make sure they fit well and align properly. Include features like locating rings and guide pins.
3. Integrate an Effective Ejection System: Create a strong ejection system for reliable part removal. Use ejector pins, air ejection, or other methods.

By focusing on these aspects in mold parting design, injection molders can enhance part quality, boost productivity, and cut costs.

Mold slider design

When making the parting surface, the arrangement of the slider and the inclined roof must be considered, because those also involve changes to the parting surface.
The typical slider structure is a trigonometric function relationship. It is necessary to ensure that the angle of the inclined guide post is not too large, and try to keep it below 30 degrees. The principle of selecting the inclined guide post is to be as thick as possible, because the inclined guide post is subject to force.

In addition, the slider is also divided into many variant structures, for example, uphill slider, downhill slider, inner pumping slider, cylinder pumping, front mold slider, slider with slider, slider with reverse top, slider with Inclined roof, etc. These special structures make full use of the trigonometric function relationship, the purpose is to realize the demoulding of the undercut of the product, and the normal opening and closing action of the injection mold.

Mold lifter design

The second is the inclined roof, which is more flexible, but the angle of a typical inclined roof should not be too large, try not to exceed 15 degrees. Of course, you can do it at 20 degrees, but the lifespan will be difficult to guarantee, and the movement will be very smooth. For specific principles, refer to trigonometric functions and theoretical mechanics.

There are many evolution forms of the shape of the sloping roof, for example, uphill lifter, downhill lifter, crooked neck lifter, large lifter inlaid with lifter rods, large lifter inlaid with round rods, small lifter inlaid with hanging table, under the top block The lifter, the lifter on the slider, the lifter with a reverse top, etc., all these structures have one purpose, using trigonometric functions to make the product reverse. After the design is completed, it is necessary to verify the relationship of the trigonometric function, that is, to actually simulate the opening and closing action of the mold, and to consider whether there will be problems during injection molding, etc.

Ranking of mold structure

We’ve split the mold. Next is the ranking of the mold structure. According to the actual situation of the product, different types of mold structures are selected, for example, two-plate mold, three-plate mold, hot runner, IMD, IML, two-color mold, stack mold and so on. All mold structure types serve for the mass production of products. When choosing a formwork, we must fully consider the 4th point of attention just mentioned.

Mold insert design

After choosing the mold base, we have to consider the inlay of the mold. The principle of inlaying is to simplify processing, save materials, and facilitate product molding, such as exhaust and so on. If you think there is a particularly thin place on the mold, it must be inlaid separately for easy replacement in the future. When inlaying, it is necessary to fully consider the strength, processability, and designability of the future waterway of the mold inserts.

After the mosaic is finished, it is necessary to add standard parts. The principle of adding standard parts is to focus first and then parts, and try to arrange the balance and symmetry as much as possible. Generally, ejector pins are added first, and the arrangement of waterways must be considered when adding ejector pins.Under normal circumstances, the arrangement of the ejector pins should be given priority, then the waterway should be roughly designed, and then the waterway ejector pins should be adjusted according to the actual situation to achieve a balance between the two. The principle of adding ejectors is to place where the holding force is strong. In addition, it should be added to the place where the strength structure of the product is relatively good, such as the table, the edge, etc., so as to avoid whitening of the ejector or unbalanced ejection.

The principle of drainage is the principle of adding ejection, because generally speaking, the place where the product has a strong grip is the hot spot of the product, and the part that needs to be cooled, this contradiction needs to be adjusted. As for whether to use the ejector rod or the ejector block or push plate, it needs to be analyzed in combination with the structural characteristics of the product. For example, if the product is easy to stick to the front mold, it is necessary to consider whether to add an undercut to the rear mold, or to add an ejector to the front mold. If the product structure is not fully analyzed, and the state of the product during the injection molding process is not actually considered, problems may arise in the mold design work. The ejector pin waterway is added, and the rest are various standard parts. The underlying concept of incorporating standard parts is to prioritize the focus on the whole, followed by its individual components, and strive to achieve a harmonious and symmetrical arrangement.

Check the finished mold design

After the design of the whole set of mold is completed, the following checks must be done. The first is the draft analysis of the insert to see if there is any undercut. The second is the interference check of each part of the mold, which is the most important. The last is the simulation of the mold opening and closing action to ensure the machinability of each mold part and the smooth assembly process of the mold.

At this point, the general plastic injection mold design process is over. In fact, mold design is a matter full of contradictions. If the design is perfect, the cost of the mold will be high. If the design is simple, the product may have to be changed, or the strength and service life of the mold will be affected. Therefore, there is no absolute mold design. As long as the balance between cost and actual needs is found, the mold design service will be successful.