Exploring Hot Runner vs Cold Runner Injection Molding

Hot vs Cold Runner Injection Molding

Ever wondered about the difference between hot runner and cold runner injection molding? These are the systems used to shape the molten material into products.

A hot runner system keeps the plastic melted as it goes through heated channels, which reduces waste and speeds up the process. A cold runner system lets the plastic cool down, which causes it to harden before molding. 

Industries like automotive, aerospace, and consumer goods use these methods for better efficiency and quality.

At ProleanTech, we provide advanced injection molding solutions to fit your needs, so you can choose the right system for your projects.

In this blog, we will look at the main differences between hot runner and cold runner systems, the pros and cons, and what to consider when choosing the best for your manufacturing needs.

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What is a Hot Runner in Injection Molding?

Hot Runner Injection Molding

A hot runner is a system in injection molding that keeps plastic warm while it flows into the mold. This means that plastic remains liquid and does not become rigid. 

Hot runners help reduce waste because there are no remaining solid pieces. They also speed up production as the process is faster.

Hot Runner Injection Molding Process

Hot runners function to maintain plastic temperature during injection molding operations. The system contains a heating mechanism that maintains plastic in a liquid state until it reaches the mold. The hot runner system prevents runner cooling , which results in faster and more efficient processing.

The system consists of three essential components, which include a heated barrel together with a manifold, and nozzles. 

The barrel maintains the plastic at a warm temperature. The manifold directs plastic material to each nozzle. The nozzles direct the molten plastic directly into the mold. The plastic flows effortlessly through this system while minimizing waste production.

Hot runner injection molding for efficient output eliminates the need for post-molding plastic removal. This saves material and time. The system maintains better heat control, which produces higher quality parts. Hot runners enhance both speed and reliability during the manufacturing process.

What is a Cold Runner in Injection Molding?

Cold Runner in Injection Molding

A cold runner is a different system used in injection molding. The plastic material cools down through the channels before it reaches the mold. 

The cooling process in the runners causes plastic material to become hard, which results in waste production. The production speed decreases when using cold runners because they require a simpler setup and lower initial costs.

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Function of Cold Runners in Injection Molding

Cold runners are simple paths. They carry hot plastic from the machine to the mold. These runners do not get heat. The plastic gets cold as it moves. When plastic gets hard, it takes the mold shape.

The hot plastic goes through a sprue first. Then it goes into the mold. After it gets cold, the plastic part comes out. The cold runner comes out too. Workers take the runner off the part. They do this by hand or use a machine.

Workers can use the leftover runner plastic again. This cuts down waste. Cold runners work in two-plate molds. They also work in three-plate molds. 

These designs change how the runner joins. They change how workers take it out. This setup gives more choices for different molding jobs. It helps control how much material workers use.

Useful Guide: https://proleantech.com/foam-injection-molding/ 

Types of Hot Runners in Injection Molding

Types of Hot Runners

Hot runners heat up in different ways. Each type keeps plastic warm in its own way. This makes molding work better and cuts down waste.

1. Internally Heated

This system heats plastic from the inside. It uses special heaters and sensors to keep the right heat. This way works very well and gives good control over plastic flow. It works great for many plastic types and helps cut waste.

2. Externally Heated

This system puts heaters around the outside parts. This keeps plastic at the right heat as it moves. It works well for plastics that break with too much heat. This way works really good for big setups and keeps plastic moving steadily.

3. Insulated Runners

These runners use the heat from the hot plastic to stay warm. They have big paths that keep the heat inside. This system costs less money and works simply for some jobs. This makes it a good pick for some products. It still gives good flow control.

To know which method fits your production goals, you can check our blog on China Injection Molding, which explores cost, quality, and supplier options.

Types of Cold Runners in Injection Molding

Cold runner systems have two main types. These are two-plate and three-plate systems. Both types work in different ways. Each type works better for different plastic parts.

1. Two-Plate Cold Runner

Two-Plate Cold Runner

This system uses two plates. The first plate holds the sprue and runners, and gates. It also holds the mold holes. Hot plastic flows through the sprue. It goes through the runners into the mold. The plastic gets cold. Both the part and runner come out together. 

This system works in a simple way. It costs less money to make. But the runner stays on the part. You must cut it off later. This takes more time. It makes more waste too.

2. Three-Plate Cold Runner

Three-Plate Cold Runner

This system uses three plates. It has one extra plate for the runner. This lets the runner come off the part. The runner splits from the part when it comes out. 

You do not need to cut off the runner by hand. This system works well for hard shapes. It saves time when you trim parts. But it may take more time to finish each cycle. It uses more material, too.

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What Are the Advantages & Disadvantages of Hot Runner Mold? 

Hot runners work in many plastic-making machines. Here are some advantages & disadvantages that you must consider.

Advantages:

• No need to cut off extra plastic parts. 
• Plastic fills the mold much faster than before. 
• Heat stays the same all the time. This helps make parts with fewer problems.
• It uses less power to keep the system warm. 
• Machines take off extra plastic by themselves. Fewer people are needed for this job.

 Disadvantages:  It costs more money to fix, too.

• The system has many complex parts inside. Fixing or changing it can be very hard.
• Hot runner systems cannot use all plastics.
• The system needs cleaning and checking often. It must run well all the time.
• If heat control goes wrong, plastic gets ruined. 

Advantages and Disadvantages of Cold Runners

Cold Runner Advantages & Disadvantages

Cold runners are much simpler than hot ones. Many basic molding jobs use cold runner systems. They give some good things and some bad things.

Advantages:

• They cost less money to put in. 
• The design is very simple and easy. 
• Can work with many kinds of plastic. 
• Can make many different part shapes too.
• No heating parts are needed at all. 
• It uses much less electricity than hot systems.
• Best choice for easy plastic part designs. 

Limitations:

• Extra plastic must be cut off after molding. 
• Cooling down takes much more time than heating. 
• Workers must remove extra plastic by hand. 
• Cooling may cause small problems in parts. 
• Hot runner systems control temperature much better.

Things to Consider for Hot Runners

When you pick a hot runner system, you need to look at some big things. You must know these to make a good choice.

Material Works Well: Some plastics work well with hot runners. You should use stuff that will not break when it gets very hot.

Part Shape Hard to Make: Hot runners are good for hard shapes. You should think if your shape needs exact heat control.

How Many Parts You Make: Hot runners are great for making lots of parts fast. You should check how many parts you want to make to see if it pays off.

Money You Pay First: Hot runners cost more when you start. But they save money later by cutting waste and making work faster.

Heat Control: You must keep the right heat. You should make sure the system controls heat well for your product.

Things to Consider for Cold Runners

Cold runner systems also need good thinking. You should know the points below to help you pick the right one.

What Plastic You Use: Cold runners work with many kinds of plastic. You should make sure your plastic is okay to use in this system.

Part Shape Easy to Make: These systems work best with easy shapes. You should check if your shape is not too hard for cold runners.

Money You Have: Cold runners cost less to set up. If you do not have much money, this may work better for you.

Extra Plastic Left: Extra plastic stays after each cycle. You should plan how you will use the waste again or recycle it not to hurt the earth.

Time Each Part Takes: Cold runners take more time for each part. You should make sure the slow speed still works for your project goals.

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Quick Comparison Table: What is the Difference Between Hot Runner and Cold Runner Injection Molding?

Hot vs Cold Runner Molds

Hot runners and cold runners are two systems used in injection molding to shape plastic products. Each system has its unique features and benefits. 

Let’s have a quick comparison between hot runner vs cold runner injection molding.

Must Check this one: https://proleantech.com/top-9-metal-injection-molding-companies/

Conclusion 

Picking hot runners or cold runners is a very big choice in injection molding. Hot runners help cut waste and save time. They also keep plastic at a good heat. This makes them great for big and hard jobs. But hot runner injection molding cost more and needs more care and cleaning.

Cold runners are easy to use and cost less money. They work well for simple designs. They make more waste and take more time. But they can use many types of materials. That makes them useful in many cases.

In the end, the right choice depends on things like material type and how many parts you need. ProleanTech can help you choose the right one and make the process better and cheaper, and greener. 

If you’re looking for a reliable hot runner and cold runner injection molding manufacturer or need expert guidance, explore our injection molding services today!