The Complete Guide to Mold Temperature Controller

Table of Contents

The mold temperature plays a crucial role in determining the cycle duration and part quality while producing plastic injection-molded parts. Thus, maintaining ideal temperature control during thermoplastics processing directly affects production efficiency.

Mold temperature controllers are essential tools for controlling mold temperature and creating ideal conditions for producing high-grade plastic components. In this article, we will explore every aspect of mold temperature controllers, including kinds, benefits, and best practices. 

Mold Temperature Controller 2

Mold Temperature Controller (Image Source: Pinterest)

What is a Mold Temperature Controller?

A mold temperature controller is an indispensable device that regulates and maintains mold temperatures at precise levels. This device works for both heating and cooling purposes and produces high-quality and precise products.

Mostly used in plastic or metal molding, a mold temperature controller regulates the cold or hot temperature of a mold by circulating a heated or cooled fluid through the mold. Whether you’re manufacturing automotive components, consumer electronics, or aerospace parts, this method ensures consistent product quality and performance.

A mold temperature controller has a heating and a cooling unit. These units are filled with a heated or cooled fluid, which regulates the temperature of the mold at the desired set point. The unit has a temperature sensor inside it. 

When it sends a signal to the controller, the mold temperature is compared with the set point temperature. If there is a temperature difference, the controller activates the heating or cooling element (whichever is required) to optimize the temperature. While the heating unit circulates hot oil or water to raise the temperature, the cooling unit cools the mold down by circulating cold water or oil.

Types of Mold Temperature Controllers

There are two types of mold temperature controllers: 

  • Water mold temperature controllers
  • Oil mold temperature controllers

In regards to injection molding, both water and oil mold temperature controllers are known to be effective at reducing machine costs for injection molding. However, they bear some basic differences. Let’s take a look at them!

Water Mold Temperature Controller

As is obvious from the name, the water mold temperature controllers utilize water as a heat transfer medium. This mold temperature controller system is equipped with stainless steel piping and comes with a direct or indirect cooling option. 

Mostly used for plastic and metal molding processes, it is best suited for products that require lower to moderate temperatures. As high-temperature water is moved back and forth between the mold and the controller, energy efficiency is improved.

Characteristics of Water Mold Temperature Controller 

  • Maximum use temperature – 40°C-120°C
  • Easy microcomputer touch control operation
  • Automatic boot exhaust

Oil Mold Temperature Controller 

The oil mold temperature controller finds utility in a number of industries. It uses oil or synthetic oil as the medium and a heat transfer fluid. With an indirect cooling design, they are ideal for products that require higher temperature controllers.

In this process, the heat transfer oil enters the system from the oil storage tank. It is then directed to the temperature-controlled mold through a circulation pump.

Characteristics of Oil Mold Temperature Controller

  • A touch-sensitive display for internal storage, automatic calculation, and precise and reliable temperature control within ±2 °C
  • Faster heating and cooling time and relatively stable temperature
  • High-quality, long-lasting imported components

How Mold Temperature Controllers Work

Mold temperature controllers play a crucial role in the injection molding process by maintaining precise temperatures within the mold cavity. The operational mechanism involves several key components working together seamlessly. Let’s look at these components and how they work!

Heating and Cooling Units

Heating and cooling units are integral to mold temperature controllers. Heating elements, often electric or oil-based, raise the temperature of the mold to the desired level before the injection of molten material. On the other hand, cooling systems, typically using water or oil, lower the temperature of the mold after injection to facilitate the solidification of the material.


The thermostat serves as the control center, monitoring and regulating the temperature within the mold cavity. It receives feedback from temperature sensors embedded in the mold and adjusts the heating or cooling units accordingly to maintain optimal temperatures for the specific material being molded.

Flow Regulator

Flow regulation systems ensure a consistent flow of heating or cooling medium to the mold. This may involve pumps, valves, and piping networks that distribute the heat transfer fluid throughout the mold cavity efficiently.

Mold temperature controllers operate by precisely controlling the temperature of the mold during the injection molding process, thus ensuring quality, consistency, and efficiency in production.

Importance of Mold Temperature Control

Mold temperature control is very important. Below are some of its benefits in injection molding: 

1. Enhances the Quality of the Product

Mold temperature controls can help to ensure that all areas of a mold are at the same temperature. It guarantees a high yield of finished goods with minimal to no flaws such as shrinkage and porosity.

2. Cuts Down on Cycle Time

Mold temperature controllers allow for speedier cooling by precisely adjusting the temperature of the mold. Your molding activities run faster and with shorter cycle times thanks to the expedited cooling process. It increases your aluminum die-casting process’ total production efficiency while conserving energy, money, and other resources.

3. Boosts Energy Efficiency

Using conventional aluminum die-casting techniques may result in less accurate temperature control. It could result in overheating, which uses more energy than necessary. Mold temperature controllers provide you with accurate temperature control. Therefore, there is no overheating hence preventing energy wastage. 

Furthermore, the mold temperature controller reduces the duration needed for preheating or after-cooling. This maximizes energy and time efficiency because there is little to no idle time between two manufacturing operations.

4. Improves Mold Life

Mold is subject to thermal stress due to temperature variations. This may cause cracks, deterioration, and other kinds of harm. Because mold temperature controllers are consistent at temperatures, they eliminate the risk of such damage. Additionally, it aids in maintaining the mold’s structural integrity thus helping you save money on mold removal and maintenance expenses.

Selecting a Mold Temperature Controller

Selecting a mold temperature controller should be based on various factors like type of material, size and complexity of mold, and of course, size of your injection molding project. 

Mold Temperature Controller 3

Oil Mold Temperature Controller (Image Source: Pinterest) 

Type of Material

The type of molding material significantly affects temperature control requirements. Different materials have specific temperature requirements for proper flow, solidification, and final product quality. Therefore, knowing the precise temperature required to process the material before selecting it is essential. 

Size and Complexity of Mold

The size and complexity of the mold play a key role in determining the capacity and capabilities required of the temperature controller. Large molds or molds with complex designs may require a more powerful temperature control system with higher heating and cooling capabilities to ensure uniform temperature distribution throughout the mold cavity.

Size of the Project

The size of your injection molding project dictates the type of mold temperature controller needed. For smaller projects with limited production, a compact and cost-effective controller suffices. 

Larger projects with high production volumes require robust, high-capacity controllers to ensure efficiency and consistency throughout extended runs. Matching the controller’s capacity to the project’s scale ensures optimal performance and quality.

Calculating Heating and Cooling Capacity in Injection Molding

Assuming that all electrical energy entering a process is transformed to heat is a simple and rapid way to estimate heat load. The quantity of energy entering a system can never be larger than the amount of energy leaving it, according to the First Law of Thermodynamics. If the only energy entering a system is electricity, then the heat load can be roughly estimated to be equal to the amount of electricity consumed.

The Specific Heat Formula

Use the heat transfer equation to determine the heat load with greater accuracy: Where: 

  • Q = m x Cp x ΔT
  • Heat load (Q) = W [BTU/hr
  • Mass flow rate (kg/s [lb/hr]) equals m.
  • Specific heat (J/g-K [BTU/lb °F]) equals Cp.
  • ΔT is equal to temperature change (°C [°F]).

Setting Up and Operating Mold Temperature Controllers

To optimize your injection molding temperature control, you need to follow a few vital steps to achieve this. These steps include: 

1. Determine Barrel Temperature

Understand the plastic being used and its flow temperature. Set the barrel temperature accordingly, considering both plasticization and flow requirements. Adjust temperatures based on the specific characteristics of the plastic, such as molecular weight and distribution.

2. Set Nozzle Temperature

Ensure the nozzle temperature is slightly lower than the maximum barrel temperature to prevent the “flowing phenomenon” of melt in the straight-through nozzle. Avoid setting the nozzle temperature too low to prevent early condensation of the melt, which can block the nozzle or affect product performance.

3. Adjust Mold Temperature

Mold temperature greatly influences the intrinsic properties and apparent quality of the product. Consider factors such as the presence of crystallinity in the plastic, the size and structure of the product, performance requirements, and other molding process conditions. Set the mold temperature accordingly to achieve the desired quality and properties in the final product.

4. Monitor and Fine-Tune

Continuously monitor the temperature settings during the molding process and make adjustments as needed. Fine-tune the temperature controllers based on feedback from the molding process, ensuring optimal plasticization, flow, and cooling throughout the production cycle.

Following the above steps and carefully adjusting the temperature controllers, can help you optimize the injection molding process to achieve consistent and high-quality parts. 

Maintenance and Troubleshooting

To ensure the longevity and efficiency of mold temperature controllers, implementing recommended maintenance routines is essential. Regular maintenance helps prevent breakdowns and ensures consistent performance. Here are some key maintenance practices: 

Clean Regularly

Periodically clean the mold temperature controller to remove dust, debris, and buildup that can impede airflow and heat transfer. Use compressed air or a soft brush to clean the exterior and interior components.


Lubricate moving parts such as fans, motors, and valves to reduce friction and prolong their lifespan. Use manufacturer-recommended lubricants and follow the recommended lubrication schedule.

Inspect Electrical Components

Check electrical connections, wires, and components for signs of wear, damage, or corrosion. Tighten loose connections and replace any damaged parts promptly to prevent electrical issues.


Calibrate temperature sensors and controllers often to ensure accurate temperature readings and precise control. Follow the manufacturer’s guidelines for calibration frequency and procedures.

Common Issues in Mold Temperature Controllers

Various issues may occur in injection molding temperature controllers. These include: 

Temperature Fluctuations

If the temperature fluctuates unexpectedly, check for issues such as clogged filters, faulty sensors, or improper calibration. Clean or replace filters, recalibrate sensors, and inspect for any obstructions that may affect temperature control.


Inspect for leaks in the cooling or heating systems, including hoses, pipes, and connections. Tighten connections or replace damaged components to prevent coolant or heating fluid leaks.

Error Messages

Pay attention to error messages displayed on the controller’s interface. Consult the user manual or contact the manufacturer for troubleshooting guidance specific to the error code displayed.

Reduced Efficiency

If the mold temperature controller is operating less efficiently than usual, check for factors such as improper settings, worn-out components, or inadequate maintenance. Adjust settings, replace worn parts, and perform routine maintenance to restore efficiency.

Advanced Features and Technologies

Modern mold temperature controllers have evolved to incorporate advanced features and functions aimed at enhancing performance and productivity in injection molding processes. These include:

  • Precision Temperature Control: Precision temperature control is a key feature in modern temperature controllers. These controllers offer precise temperature regulation with minimal deviation from the set point, ensuring optimal conditions for the molding process. 
  • Automated Sensors: Sophisticated algorithms and sensor technology are used in modern temperature controllers to maintain temperatures within tight tolerances. This guarantees consistent product quality and process repeatability.
  • Advance Interface: Most modern mold temperature controllers are equipped with dedicated touchscreen interfaces. These interfaces provide operators with centralized access to monitor process parameters, adjust settings, and diagnose issues efficiently. 

With these advancements, modern mold temperature controllers not only optimize thermal management but also streamline operation and maintenance processes, making them indispensable tools in the injection molding industry.

Mold Temperature Controller 1

Water Mold Temperature Controller (Image Source: Youtube)


Mold temperature controllers offer various benefits in injection molding. These benefits include precise temperature regulation, which in turn results in improved product quality and productivity. 

That said, understanding the key components, types, benefits, and best practices in mold temperature controllers is vital for you to optimize your molding process and achieve high-quality products. 


Steven Paul

Steven Paul

Steven Paul is the Technical Director in TDL, he has more than 15 years experience in Injection molding design.

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