Injection molding is a manufacturing process that makes a lot of plastic parts. People use it to make things like toys and medical devices. The main thing in this process is the injection molding machine. It melts plastic and then squirts it into a mold to make the shape you want. In this article, we’ll look at how these machines work and how they make good plastic parts.

Injection Molding Machine

The injection molding machine, also known as an injection molder or injector, is the main molding equipment for shaping plastic products of various shapes using thermoplastic or thermosetting plastic through plastic molds. It is divided into vertical, horizontal, and all-electric types. The injection molding machine can heat plastic, apply high pressure to the melted plastic, and inject it into the mold cavity to fill it.

An injection molding machine works like a syringe. It uses a screw (or plunger) to push the melted plastic, which is like a thick liquid, into a closed mold. The plastic cools and hardens, and the product is made.

Components of Injection Molding Machine

An injection molding machine usually has injection systems, clamping systems, hydraulic transmission systems, electrical control systems, lubrication systems, heating and cooling systems, and safety monitoring systems.

Injection System

The injection system is very important. It has three types: plunger, screw, and screw pre-plasticizing plunger injection. The screw type is the most common. It does three things in one cycle of the injection molding machine. It heats and melts a certain amount of plastic in a certain amount of time. It pushes the melted plastic into the mold cavity with a certain amount of pressure and speed. After it’s pushed in, the melted plastic stays in the shape of the mold cavity.

The injection system is made up of a plasticizing device and a power transmission device.

The plasticizing device of a screw-type injection molding machine mainly consists of a feeding device, a barrel, a screw, a melt assembly, and a nozzle part. The power transmission device includes an injection cylinder, an injection seat moving cylinder, and a screw drive device (melting glue motor).

Clamping System

The clamping system is responsible for closing, opening, and ejecting the mold. It also provides enough clamping force to withstand the cavity pressure created by the molten plastic entering the mold cavity after the mold is closed, preventing the mold from opening and causing defects in the product.

The clamping system is made up of clamping device, machine screw, mold adjusting mechanism, ejection mechanism, front and rear fixed templates, moving template, clamping cylinder, and safety protection mechanism.

Hydraulic Transmission System

The hydraulic transmission system is responsible for providing power for various actions required by the injection molding machine during the process and meeting the requirements of pressure, speed, temperature, etc., of various parts of the injection molding machine. It mainly consists of various hydraulic components and hydraulic auxiliary components, among which the oil pump and motor are the power sources of the injection molding machine. Various valves control the hydraulic pressure and flow, thus meeting the requirements of the plastic injection molding process.

Electrical Control System

The electrical control system, in coordination with the hydraulic system, can meet the process requirements (pressure, temperature, speed, time) and various program actions of the injection machine. It mainly consists of electrical appliances, electronic components, instruments (as shown in the diagram “Instrument”), heaters, sensors, etc. Generally, there are four control modes: manual, semi-automatic, fully automatic, and adjustment.

Lubrication System

The lubrication system makes sure that parts that move against each other, like the moving platen, mold adjustment mechanism, tie bars, and ejector, have enough oil on them. This makes the machine use less energy and makes the parts last longer. You can put oil on the machine by hand or you can use an electric oiler.

Heating/Cooling System

The heating system is used to heat the barrel and nozzle. The barrel of the injection molding machine generally uses electric heating coils as heating devices, installed externally on the barrel and segmented detected by thermocouples. Heat is conducted through the barrel wall to provide a heat source for plastic material plasticization. The cooling system is mainly used to cool the oil temperature. Excessive oil temperature can cause various malfunctions, so the oil temperature must be controlled. Another location requiring cooling is near the material pipe discharge port to prevent material melting at the discharge port, causing abnormal material discharge.

Safety Monitoring System

Injection molding machine safety devices are used to protect people and machines. They include safety doors, safety baffles, hydraulic valves, limit switches, and photoelectric detection. These devices are used to interlock, electrically, mechanically, and hydraulically, for protection.
In addition, the surveillance system monitors oil temperature, material temperature, system overload, and processes and equipment to identify abnormal conditions and alarms.

Working Principle of Injection Molding Machine

The injection molding machine is a device used to make plastic products by melting plastic and injecting it into molds. After the plastic cools and gets hard, the molds are open to get the plastic products. The injection molding machine works by these five steps: feeding, melt the plastic, inject the plastic, cool the plastic and open the molds.

Feeding

To get started with an injection molding machine, you gotta feed it. Feeding is when you dump plastic pellets into the hopper of an injection molding machine. Usually, the feeding mechanism on an injection molding machine is a screw or a plunger. It moves the plastic pellets from the drum to the barrel of the machine.

Plastic Melting

The injection molding machine starts by heating up and melting the plastic materials. Generally, plastics are used in the form of granules or powder. These plastic materials get poured into the hopper of the injection molding machine. Once in the heating barrel of the machine, the plastic materials get warmed up and melted by electric heaters in stages. It gradually melts into the molten plastic, which then gets injected. The screw is the molten plastic injection process’s forward movement, driven by rotation, as well as the plastic’s mixing action.

Injection

When the plastic raw materials are completely melted, the plastic injection molding machine begins the injection process. During the injection process, the molten plastic is pushed from the heating barrel into the mold cavity by the screw in the injection cylinder. The screw movement sends molten plastic into the mold cavity – filling up the entire mold cavity. The injection process consists of the injection cylinder, injection piston, and injection nozzle. Molten plastic in the injection cylinder is pushed by the injection piston into the mold cavity through the injection nozzle. Adjust the injection speed and pressure as needed to ensure the injection process is accurate and stable.

Cooling

After injection, the injection molding machine enters the cooling stage. The plastic melts into the mold and then quickly cools. It sticks with the mold. The cooling time varies, according to different plastics and what people want. After cooling, the new plastic piece is done. You can change the cooling time and temperature according to different plastic and what you want as well. Usually we got a cooling system with a mold machine, like water or gas.

Mold Opening

After cooling and solidifying, the injection molding machine begins the mold opening operation. During mold opening, the mold clamping mechanism opens to remove the formed plastic product from the mold cavity. The mold opening mechanism consists of a clamping device, mold opening cylinder, and mold opening mechanism. After the plastic product is removed from the mold cavity, the mold closes, and the injection molding machine enters the next injection molding cycle of operation.

Alright fools. The stuff up here is how the damn machine works. The machines all herd the plastic goop into it from this way, it melts it all up, then it squirts the molten plastic material into the molds, and then you just let the stuff harden and you open the molds and boom skippity bop you got a fancy plastic thingy. These machines are super popular in the biz world and they blow off stuff like cups, parts, and toys. The more you know how they work, the better you are at making them not totally suck and making your crap as quickly as possible.

Injection Molding Machine Operation Process

When operating an injection molding machine, which is a plastic processing device that’s used a lot, you need to do these things:

1. Weigh and Prepare Raw Materials: Weigh and prepare plastic pellets or granules according to your product needs to get a balance between quality and costs. Make sure to check for unwanted stuff in your raw materials and do some screening and cleaning if you need to.

2. Clean the Mold: The injection molding machine uses a mold to shape the product, so you will need to clean the mold to give your product a smooth surface and a high-quality finish. Cleaning a mold really depends on the mold material and the requirements for the mold, but usually involves things like buffing, polishing, and maybe spraying a release agent on the mold.

3. Installing the Mold: The cleaned mold is installed on the injection molding machine and adjusted as needed for the product. We make sure it’s in the right position and locked in place, and we also adjust how it opens and closes.

4. Adjusting Injection Process: When the mold has been built and mounted in the injection mold machine, it’s time to run the molding process. Set the molding parameters — injection speed, holding pressure time, melt temperature and injection pressure — based on the results you obtained during the mold trials to achieve the best part possible.

5. Begin Injecting Stuff: Turn on the injection molding machine by following the instructions onscreen to get it started. This includes turning on the machine, setting the heating temperature and pressure, and so on.

6. Injection Process: When you inject stuff into a mold, you use the machine’s gears and liquid machinery. Before you start making products, put some plastic pellets in the hopper on the injection machine. Then, the stuff in the hopper goes through the brainscrew, and the barrel gets heated up. The molten plastic goes into a mold through the straw. Be careful with how fast you inject stuff and how hard you do it so the thing you’re making turns out good.

7. Injection Completion: After the injection is done, open the mold and get the product out. This should be done carefully so that you don’t damage it or the mold.

8. Clean the Injection Molding Machine: After you use the thing, you gotta clean the plastic thing. You gotta clean the plastic thing by getting rid of the plastic residue, washing nozzles and screws, and letting go of the air pressure inside the plastic thing.

9. Mold Adjustment and Repeat of the Above Operation: If you want to make another thing you have to take the old mold out and put in a new one. Then you need to change the settings and make a new thing using the same process as before.

Common Faults and Solutions of Injection Molding Machines

The injection molding machine is widely used to produce plastic products. Stable operation is very important for the production process to go smoothly. However, due to improper operation, equipment aging, or other reasons, injection molding machines may have some common faults during use. This article introduces some common faults of injection molding machines and provides corresponding solutions, hoping to help users of injection molding machines.

Temperature Control System Failure

Temperature control system is an essential part of injection molding machine, which is responsible for controlling the melting temperature and mold temperature to ensure product quality and production efficiency. However, sometimes the temperature control system will fail, causing temperature instability or even unable to reach the set value. The common causes of failure are damage of thermocouple, failure of controller, failure of temperature sensor, etc. The solutions are to replace the thermocouple or the sensor, repair or replace the controller, etc.

Lubrication System Failure

The lubrication system of an injection molding machine is there to protect the machine by reducing friction and wear. If the lubrication system isn’t working, the machine won’t last as long. Maybe there’s not enough oil getting to the right places, or maybe the pipes are blocked, or maybe the pump isn’t working. We can fix those things by inspecting and cleaning the pipes, putting in new oil, or getting the pump fixed.

Pressure Control System Failure

The pressure control system of the injection molding machine is very important for the stability of product quality. If the pressure control system fails, it may cause inconsistent product dimensions or incomplete molding. The common causes of failure are the failure of the pressure sensor, the blockage of the hydraulic valve, and the damage of the hydraulic pump. The solutions are to replace the pressure sensor, clean the hydraulic valve, and repair the hydraulic pump.

Hopper Blockage

Hopper choke is a common issue when using an injection molding machine. Hopper choke may result in not getting enough raw material, affecting your production. Reasons for a choke are material sticking together, too much leftover in the hopper, or the feeding system not working correctly. Solutions may be using vibration or hopper agitators to clear the choke or checking and cleaning inside the hopper.

Mechanical Failure

After using the injection molding machine for a long time, some parts may wear or become loose, which will make the machine unstable. Common mechanical failures include difficulty in opening and closing the mold, blockage of the injection device, and loosening of mechanical transmission parts. We can solve these problems by repairing or replacing the damaged parts and adjusting the tightness of the mechanical transmission parts.

To sum up, there are several common problems with injection molding machines: temperature control failure, lubrication system failure, pressure control failure, hopper blockage, and mechanical failure. To fix these problems, you can use different methods to repair them based on the actual situation. In daily use, you should maintain your injection molding machine regularly and handle problems in a timely manner. This can improve the stability and lifespan of your equipment, ensuring smooth production.

Future Trends of Injection Molding Machines

Injection molding machines are a common type of plastic processing equipment that is widely used in the plastic products manufacturing industry. With the continuous advancement of technology and changes in market demand, injection molding machines are also constantly developing and innovating.

1. Green Environmental Protection: With more and more global environmental problems, the future development of injection molding machines should pay more attention to green environmental protection. On the one hand, the manufacturers of injection molding machines should use more environmentally friendly materials and processes to reduce environmental impact. On the other hand, the design and use of injection molding machines should also be more energy-efficient to reduce energy consumption and waste generation.

2. Intelligence: In the future, injection molding machines will be smarter. They will use fancy control systems and sensors to make things automatically. With good sensors and control systems, injection molding machines can watch and change things like temperature and pressure during making things. This will make things faster and better.

3. Rapid Response: With the increasing competition in the market and the different needs of customers, injection molding machines will need to respond more quickly to market needs in the future. Future injection molding machines will be more flexible and capable of quickly adjusting production and switching products. At the same time, manufacturers of injection molding machines should communicate and cooperate more with customers to better meet their individual needs.

4. Composite Injection Molding Machine: With the continued advancement of material technology, future injection molding machines will be more widely used in the production of composite materials. Composite materials have advantages such as being lightweight, high strength, and corrosion resistance and will be widely used in fields such as automobiles and aerospace. The manufacturers of injection molding machines should provide equipment and technical support that meet the processing requirements of composite materials.

5. Adaptive Control: In the future, there will be injection molding machines that have adaptive control. What that means is the machines will automatically adjust themselves and select the best way to make parts based on what’s happening in real time. This is going to be a big deal because the machines will be able to change their own settings and make the best parts possible. This will make the machines more stable and make better parts.

6. Integration with 3D Printing Technology: As 3D printing technology continues to mature and expand, injection molding machines will be deeply integrated with 3D printing technology. Injection molding machines can use 3D printing technology to customize molds and parts, which can improve production efficiency and product quality. At the same time, plastic injection molding machines can also combine with 3D printing technology to achieve the production of injection molded products with special shapes and structures.

Conclusion

So, injection molding machines are like super versatile tools used in the manufacturing industry to create all kinds of plastic parts. By understanding how injection molding machines work and what they’re made up of, manufacturers can make their production process better, make their products better, and be more efficient. Injection molding machines are super important for making plastic stuff in different industries and they’re getting better all the time.