A pump used in a mold temperature controller must circulate water or thermal oil continuously through the heating or cooling system. Correct pump selection helps maintain stable mold temperature, reliable circulation and consistent production.

The pump should not be selected only according to motor power or connection size. The heat-transfer medium, operating temperature, required flow rate, total head, system pressure and material compatibility must all be confirmed before choosing a model.

What Does a Mold Temperature Controller Pump Do?

A mold temperature controller circulates a heat-transfer medium between the temperature control unit and the mold or production equipment. The circulating liquid absorbs or delivers heat to keep the process temperature within the required range.

These systems are commonly used with:

• Plastic injection molding machines
• Extrusion equipment
• Rubber processing machinery
• Die-casting equipment
• Roller and plate temperature control systems
• Industrial heating and cooling equipment
• Food and pharmaceutical processing machinery

Stable circulation is important because insufficient flow can cause uneven temperature, slow heating, unstable production or excessive temperature differences within the system.

1. Confirm the Heat-Transfer Medium

The first step is to identify the liquid being circulated.

Water-Type Systems

Water offers efficient heat transfer and is commonly used in low- and medium-temperature applications. The pump materials and sealing arrangement should be compatible with the water quality and any additives used in the system.

Thermal Oil Systems

Thermal oil is used when the required operating temperature is higher than the practical range of a water system. Oil viscosity changes with temperature, so the pump must provide sufficient circulation during both startup and normal operation.

The exact name and specification of the thermal oil should be provided to the pump supplier whenever possible.

Chemical or Special Fluids

If the medium is corrosive, toxic, flammable or chemically aggressive, its full composition and concentration should be confirmed. Material compatibility must be checked before selecting the pump.

Never assume that one pump material is suitable for every liquid.

2. Confirm the Operating Temperature

The buyer should provide both the normal operating temperature and the maximum possible temperature.

For example, a system may normally operate at 160°C but experience a higher temperature during startup, shutdown or abnormal conditions. The pump should be selected according to the actual maximum working condition rather than only the normal temperature setting.

Temperature can affect:

• Pump materials
• Bearings and internal components
• Magnet selection
• Seal selection
• Motor protection
• Thermal expansion
• Fluid viscosity

For high-temperature service, the complete pump configuration must be evaluated according to the specified medium and operating temperature.

3. Determine the Required Flow Rate

Flow rate indicates how much liquid the pump must circulate within a given time. It is usually expressed in liters per minute, cubic meters per hour or gallons per minute.

The required flow depends on:

• Heating or cooling capacity
• Temperature difference between supply and return
• Heat-transfer medium
• Mold or equipment design
• Pipe diameter and length
• Number of circulation channels
• Required process stability

Selecting a pump only by comparing its maximum flow rate can be misleading. Maximum flow is normally measured under very low-head conditions and may not represent the actual operating point.

The required flow must be evaluated together with the required head.

4. Calculate the Required Pump Head

Pump head represents the resistance that the pump must overcome to circulate the liquid through the complete system.

The calculation should consider:

• Pipe length
• Pipe diameter
• Number of bends and fittings
• Valves and filters
• Heat exchangers
• Internal channels in the mold
• Height difference
• Pressure loss caused by liquid viscosity

A longer or more complex circulation circuit normally requires higher pump head. If the selected head is too low, the actual flow may be insufficient. If the pump is significantly oversized, it may create unnecessary pressure, energy consumption and system wear.

The final selection should be based on the pump performance curve and the expected operating point.

5. Check the System Pressure

Operating pressure and pump head are related, but they are not the same specification.

The supplier should know:

• Normal system pressure
• Maximum allowable pressure
• Whether the system is open or closed
• Whether pressure changes during heating
• Whether valves may restrict the circuit

This information helps determine whether the pump casing, connections and other components are suitable for the system.

6. Select Suitable Pump Materials

Pump materials should be selected according to the liquid, temperature and operating environment.

Common considerations include:

• Corrosion resistance
• High-temperature strength
• Wear resistance
• Compatibility with water, thermal oil or chemicals
• Required cleanliness
• Risk of contamination

Stainless steel may be suitable for many industrial liquids, but the exact grade and internal component materials still need to be confirmed. Material selection should be based on the actual operating conditions.

7. Consider the Pump Drive and Sealing Structure

Traditional pumps may use a mechanical shaft seal. The suitability of the seal depends on temperature, pressure, liquid properties and operating conditions.

A magnetic drive pump uses magnetic coupling to transmit motor power without a conventional shaft seal. This structure can help reduce the risk of leakage from the shaft-seal area and may be considered for clean, corrosive, high-temperature or hazardous liquids.

However, magnetic drive pumps also require correct operating conditions. Dry running, poor cooling, solid particles or incorrect material selection may damage internal components.

The final choice between a magnetic drive pump and a mechanically sealed pump should be based on the application rather than on one feature alone.

8. Confirm the Electrical Requirements

Before ordering, confirm:

• Single-phase or three-phase power
• Rated voltage
• Frequency
• Motor power
• Required protection level
• Installation environment
• Local electrical standard

Voltage and frequency vary between countries. Providing this information at the inquiry stage reduces the risk of receiving an incompatible motor configuration.

9. Review the Pump Performance Curve

A pump should normally operate within an efficient and stable section of its performance curve.

1. Locate the required flow rate.
2. Confirm that the pump can provide the required head at that flow.
3. Check the motor power requirement.
4. Allow a reasonable operating margin.
5. Avoid selecting the pump only from its maximum flow or maximum head.

Maximum flow and maximum head usually occur at different operating points and should not be treated as simultaneous performance values.

Information Required for Pump Selection

To receive a suitable pump recommendation, provide the following operating information:

If the required flow and head are unknown, provide the equipment capacity, pipe dimensions, circulation distance and application details so that the supplier can assist with a preliminary selection.

Common Pump Selection Mistakes

• Selecting only by motor power
• Comparing only maximum flow
• Ignoring the required head
• Failing to provide the maximum temperature
• Using water-pump specifications for thermal oil service
• Ignoring liquid viscosity
• Choosing materials without checking chemical compatibility
• Ordering the wrong voltage or frequency
• Operating the pump without liquid
• Installing pipework that restricts the inlet

Need help selecting the right pump? Contact FENGHE for pump selection support and quotation.