Injection molding helps in making products for car body parts, phone cases, water bottles, and containers. Lastly, many of the plastic products we use in our daily lives are molded under pressure. This is a quick process of creating identical plastic parts.

Ability to perform different shapes and sizes, achieved by using injection molding. The boundaries of design are consistently expanding, which allows the use of significant alternatives to traditional materials due to the large variety of products and their lightweight.

What is an automatic Injection molding machine?

The automatic injection molding machine is intended to produce polymeric products by injection molding and consists of three main components – the loading barrel, the screw, and the cylinder. Plastic pellets come into the equipment using the barrel.

The plastic that is placed in the hopper usually has a powder or granular shape. Then the material melts due to the frictional action of the piston auger and the operation of the ring or semi-ring electric heaters. The molten plastic is then injected through a nozzle into the cavity of the mold.

Molten plastic vs Injection molding

Molten plastic may seem like a fairly simple process, but injection molding is a very complex type of production. While for injection molding in the cavity of the mold, the material cools and solidifies to the configuration of the cavity. When the part hardens, the movable plate opens.

Problems of injection molding and temperature control of pouring channels of TEN 24 are there. The dimensions of the injection molding machine can vary from 5 tons of clamping force to more than 6000. The larger the tonnage, the larger the machine.

Classification of injection molding

Injection molding machines are classified based on tonnage, or, more precisely, clamping force or pressure. The automatic molding machine is easy to equip with a runner system which in turn is divided into three types: cold-runner, hot-runner, and combined.

 The most complex and high-quality products for injection molding are easy to make using hot-runner systems. Let’s talk about the nuances of working with them. The temperature at which the processing of polymers in the gutters affects the quality of the final product.

Thermal component role in injection molding

Also, the thermal component in the molds during molding will affect the temperature of the molten polymer raw material in the cavity of the mold. This subsequently at the time of curing and the appearance of the finished product.

If the temperature regime of injection molding is violated. A plug of hardened material may form in the intake manifold. Which will stop production. It is important to consider the thermal regime. Heat distribution on the pouring runners, the method of temperature control and regulation when choosing the design of GCS parts, and the temperature control system.

Thermoplastics role injection molding

Thermoplastics are thermally unstable materials, so increasing the thermal values ​​during production, is necessary to reduce the residence time of the melt in such conditions. But here there can be a second problem in the form of a decrease in stability of process and quality of finished goods.

The uneven effect of the temperature of injection molding is on the molten polymer increases the risk of destruction of the material. Especially often such problem arises in the conditions of a long cast cycle which is characteristic of the production of details with thick walls.

Drawbacks of injection molding

Some of the problems of injection molding and temperature control of pouring channels of TEN 24 is the subject matter ahead. Overheating of the molten polymer, which occurs due to too high a temperature effect.

Or increased residence time in the heating zones leads to changes in the characteristics of the polymer product. Overheating may come by an unpleasant odor, and the product will show dark spots, strokes. For injection molding, you can also see the destruction and inconsistency with the stated size.

Drawbacks for injection molding

Considerable problems can arise when changing the color of polymer raw materials. On the walls of the channels of the spout can form fixed layers of polymer of another color. The polymer can also be deposited on some types of nozzles. The process of replacing polymers of different colors should determine by the temperature distribution in the gutters.

What affects the temperature of the polymer in the gutters?

The most important source of heat in the processing of polymers is the dissipation of temperature in the melt. This heat arises from two mechanisms: flow shifts and compression of the material. The rate at which heat q is released in the molten polymer mass in shear flow per unit volume is:

   1-q = η ŷ²  

For injection molding, first, η effective viscosity (depending on the shear rate, temperature, and pressure)

   2- ŷ – shear rate.  

The temperature rise ∆T of the polymer mass under adiabatic compression of indeterminate volume with a simultaneous increase in pressure by the value of P is easy to calculate by the following formula:

   3-∆ T = ∆ P / (Cp)

P is the average density of the molten polymer; Cp is the average specific heat of the molten polymer under constant pressure. Dissipation in the polymer comes by shear flow is a major contribution to the overall heat balance during casting.

The greatest amount of heat for injection molding is released during plasticization and injection because the shear rate is very high. The dissipation that comes by compression will differ in different areas of the ACS. Due to changes in the pressure of the polymer mass during the casting cycle, dissipation will change over time.

What is the process of injection molding?

Through the channels of the spout and in the cavity of the mold, the melt at the loading stage proceeds due to the increase in pressure drops throughout the system. The dissipation that comes by compression at these stages has almost no effect on the temperature of the polymer.

In injection molding because of the pressure in the flow areas close to atmospheric values. Moving away from the flow front, the effect of dissipation increases. The temperature of the polymer in the ACS affects by the temperatures of the material, which are still in the material cylinder.

An overview of heat balance

The total heat balance includes the heat produced by the heating elements placed in the GCS and the collector. Electric heaters are common for hot-runner casting in modern equipment. Heat losses in the forms of hot-runner casting can occur for various reasons.

• First, thermal conductivity
• Second, convection
• Third, heat radiation

Cooling of the molten mass can occur due to its expansion due to reduced pressure.

Investing in injection tool
Generally, much of the product cost goes to making the mold for the injection tool. If the product has a short life cycle or low demand, investing in a durable form can be more expensive than using a 3D printer.

Limitations in making changes to the design of the part
After the manufacture of the mold, it is difficult to make changes in the design of the part without significant costs to change the design of the mold and increase the time to manufacture the latter. If you have not yet decided on the design of the product (Injection tool) then it is better to use 3D modeling until the design is finally approved.

Features of injection mold

Some of the most common features of injection molding include:

• First, production of large volumes of products.
• Second, quality plastic products require precision and consistency.
• Moreover, projects with a long implementation time.
• Lastly, production of any details, from the smallest and small to difficult and large.

3D printing working

3D printing uses computer-aided design (CAD) files to build three-dimensional details layer by layer. The 3D printer uses a heated thread to create vertical layers that overlap; this creates a single product at a time.

Benefits of using 3D printing

1-Low initial cost
No special stamps or molds are common for 3D printing of the Injection tool. Once the product design is complete, the printer can create one or hundreds of finished parts at the same unit cost.

2-Ability to make changes to the configuration of part
Since a computer file is common instead of a mold, 3D printers can easily apply product changes to the design. This is ideal for prototyping when your team is testing different designs and different stages.

Disadvantages of the 3D printing

1-Technical nuances in tools
3D printing is an evolving science. Software and hardware sometimes fail, which can lead to errors and poor quality of the structure.

2-Speed of 3D printing
3D printing creates layer by layer, one product at a time. This is the most efficient way to make orders of up to 100 units. If you need to make more parts of the Injection tool, then this method becomes economically costly.

3-Product quality by 3D printer
3D printing can create structural defects during manufacture, which usually do not occur when casting plastics under pressure.

Features of injection mold

3D printing is common for:

• Firstly, prototyping and testing
• Second, with a small production volume
• Moreover, testing of the individually designed product
• Manufacture of products, the structure of which is often changed or updated

An overview of injection molding implementation

When injection molding, each error is usually very expensive. Quality problems in cast products are reflected in the form of minor surface defects. Or more serious damage to the Injection tool that can affect the safety, performance, and functionality of the product. 

They can be common by problems related to the casting process, the use of materials, the design of the tools, or a combination of all three factors. But like any quality problem, knowing how casting defects occur is a partially won battle. 

Recommendations for injection molding

Individual recommendations and knowledge about common casting defects and how to avoid them can help you reduce the costs associated with the goods. Consider the most common defects that occur during injection molding, as well as determine what causes them and what can be done to avoid them.

Reasons for injection molding defects

Some casting (Injection tool) defects can be difficult or expensive to repair. Others can be prevented by regulating the casting process, without the need to recycle the mold or replace other production equipment. You can usually avoid these defects relatively easily by simply adjusting the material consumption, temperature, or pressure of your mold.

 Separation due to injection tool

Separation often looks like wavy patterns, slightly different in color than the general area, and usually on narrower areas of the molded component. They can also be annular strips on the surface of the product near the injection points of the mold or “gate” of the gutter system.

Through which flow the molten material, Injection tool. Separation lines usually do not affect the integrity of the part. However, they have an unaesthetic appearance and maybe unacceptable if they can be seen on the finished product, such as sunglasses.

Causes and means of eliminating divorces and lines 

Divorces and flow lines most often occur because of fluctuations in the cooling rate of the material, because it flows in different directions throughout the form. Differences in wall thickness can also cause the material to cool at different speeds, leaving flow lines.

 For example, the Injection tool cools very quickly during the injection process, and traces of flow are visible when the rate of introduction of the material is too slow. The plastic becomes partially hard and sticky while filling the mold, causing a wavy pattern.

Here are some common ways to fix stains and streams:

 

1. First, increase the injection rate, pressure, and temperature of the material so that the material fills the mold before cooling
2. Second, round the corners of the mold where the wall thickness increases to ensure a constant flow of material and prevent stains
3. Third, move the mold inlets/openings to create a greater distance between them and the cooling to prevent premature cooling of the material during casting
4. Above all, increase the injection diameter to increase the feed rate and prevent premature cooling.

2. Traces of burning

Traces of burns (Injection tool) usually appear in the form of black spots or the form of traces of rust on the edge or the surface of the molded plastic part. Combustion marks usually do not affect the integrity of the parts if the plastic is not burned to the point of decomposition.

Causes and prevention of burn marks

Excessive injection or heating of the material often leads to overheating, which is the cause of combustion marks. We recommend the following prevention measures to avoid burn marks in the molded components:

1. First, lower the melt temperature and mold to prevent overheating
2. Second, reduce the injection rate to reduce the risk of air entering the mold
3. Moreover, increase the exhaust vents and inlets so that the trapped air leaves the mold
4. Above all, shorten the molding cycle so any trapped air and polymer do not have a chance to overheat

3. Deformation (twisting) in injection molding

Bending/twisting in an Injection tool is a deformation that can occur in injection molding products when different parts of the component are compressed unevenly. Just as wood can warp when it dries unevenly, plastic, and other materials can warp during the cooling process.

It is when uneven immersion creates excessive stress on different parts of the molded part. This excessive stress causes the finished part to bend or twist during cooling. This is visible in the part that should lie flat but leaves a gap when placed on a flat surface.

Causes and prevention of distortions in cast parts

One of the main reasons for the distortion of the Injection tool and similar casting materials is that the cooling is too fast. Often, excessive temperature or low thermal conductivity of the molten material can exacerbate the problem. 

On the other hand, the design of the mold can contribute to the curvature when the walls of the mold do not have the same thickness – the shrinkage increases with the thickness of the walls. Here are some common ways to avoid distortions in your details:

1. Make sure that the cooling process is gradual and long enough to prevent uneven stress on the material
2. In addition, lower the temperature of the material or mold
3. Moreover, try switching to a material that shrinks less during cooling
4. Lastly, redesign the mold so that it has a uniform wall thickness and symmetry

5. Vacuum voids/air pockets in injection tool

 

Vacuum voids or air pockets are trapped air bubbles that appear in the finished cast component of the Injection tool. Quality control professionals usually consider voids a “minor” defect. But larger or more voids can weaken the cast component in some cases because the air is below the surface of the product where the cast material should be.

Multi-Drop Hot Runner Injection Mold    

Why is a multi-drop hot runner injection mold system called that? The term hot runner is used because some parts of this system are physically heated so that it is easier to transfer plastic in a molten state from the machine into the mold cavities. If we compare this to the cold runner system, then the main difference between the two is simply that the cold runner system is not physically heated that is the hot runner system is in fact physically heated.

As mentioned above there is a cold runner system as well for the injection molding, so why do we need a hot runner system? The multi-drop hot runner injection mold system uses a heated manifold and runners which ensures a higher quality product to be manufactured.

And this is the main theme of the article, to understand how the hot runner system ensures high-quality product manufacturing. what exactly is a multi-drop hot runner injection mold system? How does it work and what are its advantages that ensure high-quality products?

What is a Multi-Drop Hot Runner Injection Mold System?

A multi drop hot runner injection mold system uses a heated manifold two-turn plastic into a molten state and keeps it Molten throughout the process. this is a type of injection molding system. In this system The molten plastic is injected into a number of mold cavities at the same time, to produce The plastic product. the molten plastic travels through the machine through internal channels that are called runners. Hence, the whole system is called the hot runner injection mode system.

The two main factors that a very important in the system are the temperature flow and the molten plastic flow pressure control. The temperature controller is very important. It maintains the temperature of all the components in the machinery to the desired temperature.

The temperature has a direct effect on the flow of the molten plastic as well as the degree of molten in the plastic. Therefore, maintaining the right temperature is very important in a multi-drop hot runner injection mold system.

The degree of pressure with which the molten plastic flows is related to the channels it flows through. Any variation in the pressure will cause damage to the product, therefore it is very important to maintain the pressure.

Features and Advantages of a Multi-Drop hot runner Injection Mold System

Now, we will look at the features of a Multi-Drop hot runner Injection Mold System. It serves as an advantage for manufacturers and ensures higher quality products.

Time-saving

It has smaller channels and therefore, it takes less time to run each cycle. You get your ready-made product from the machine. Thus, you don’t need to do the extra manual work of making the surface smooth cutting excess, or other stuff. The cycle itself is also shorter compared to the cold runner system which further decreases the cycle time.

No waste produced

Further, hot runners can be beneficial in reducing wasted plastic during high-volume shoots. Because cold runners are unheated, the channel needs to be larger. Thus more plastic needs to be shot during each cycle. If you are producing a large number of parts while iterating to get the design correct you could easily run up the cost of plastic above the cost of a hot runner assembly.

In a multi-drop hot runner injection mold system, a great benefit is that there is little to no waste. Manufacturers who manufacture large volumes of products will greatly benefit from this. In the cold runner systems where there is no heating, the channels or runners are much bigger. Bigger channels mean that larger amounts of plastic are used during each cycle. Making large amounts of different products will easily cost you a lot on the amount of plastic you use. However, in the hot runner Injection Mold System, there is a lot less waste done, close to non.

Precise and good looking products

The multi-drop hot runner injection mold system has a lot of advantages to offer when it comes to very challenging detailed geometry in the products. These types of products require very less error because there is a lot of detailing in them.

For such a product A very undisturbed even flow of the molten proper plastic is required. Therefore, the hot runner system is the best option. As it heats up the plastic throughout the process. A very even flow of molten plastic is produced that enters the mold cavity. Thus, resulting in the production of very good quality products.

If we compare this to the cold runner system, we will get a very uneven flow of molten plastic and the detailing on the product will not be visible. Therefore, a very low-quality product will be produced.

Automation in process of injection molding

There is an increase in the demand for automatic systems in the industries, including injection molding systems as well. As we go in the future, newer and more advanced technologies are being used in every industry.

Likewise, in the injection molding industry, the Multi-Drop hot runner Injection Mold System allows you to atomize your molding process. This system is very flexible and there is no danger of uncoordinated machinery.

The multi-drop hot runner injection mold system can be used to manufacture parts like, phone cases, Bottle caps, and any type of projects that require the manufacturing of large volumes of inexpensive plastic parts.

It is a much better manufacturing plastic products process compared to the cold runner system. Many industries are upgrading to this technology to improve the quality of their products and work efficiently.