Hot Runner VS Cold Runner

What is the difference between Hot Runner VS Cold Runner?

The Hot Runner VS Cold Runner is that the hot runner has a nozzle material, also known as waste. The Hot Runner has a form, a needle valve type, and an open tip.

For the Hot Runner VS Cold Runner. A hot runner system keeps material in a molten state during the duration of the runner process until it flows into the mold cavity. In a cold runner system, the runners and the molds are maintained at the same temperature.

Hot Runner

As a common part of the injection mold system, the plastic in the runner and gate is kept in a molten state by heating. Since there are heating rods and heating rings near or in the center of the runner, the entire runner from the nozzle outlet of the injection molding machine to the gate is in a high-temperature state, so the plastic in the runner is kept molten.

After shutdown, it is generally not necessary to open the runner to take out the condensate, and only need to heat the hot runner to the required temperature when restarting. Therefore, the hot runner process is sometimes called a hot header system or a runner mold, and we can understand that the hot runner is the extension of the injection molding machine nozzle (barrel nozzle).

Cold Runner

Refers to the part between the mold inlet and the product gate. The plastic is kept flowing in the runner by the injection pressure and its heat. The runner is a part of the molding material, but it does not belong to the product. Therefore, when we design the mold, we must consider not only the filling effect but also how to save material by shortening and narrowing the runner.

What are the Advantages and Disadvantages of the Hot Runner VS Cold Runner?

The Advantages of Hot Runner

1. Saving raw materials and reducing manufacturing costs.

2. Shorten molding cycle time and improve machine efficiency.

3. Improve product surface quality and mechanical properties.

4. Spot gates can be used without the need for a three-plate mold.

5. Economical molding of a single product with a side gate.

6. Increase automation.

7. Needle valve gate can be used to control gate freezing.

8. The quality of the injection parts of the multi-cavity mold is consistent.

9. Improve the surface aesthetics of injection-molded products.

The Disadvantages of Hot Runner

1. The mold structure is complex, the cost is high, and the maintenance cost is high.

2. Boot need.

The Advantages of Cold Runner

1. Easy to use, but also good for some aesthetic needs.

2. It can reduce the parts of acrylic or polycarbonate used for light transmission in the injection molding channel, and avoid the visible band effect caused by injection in some parts.

The Disadvantages of Cold Runner

1. More waste of raw materials.

2. Add steps to the entire production process.

3. Not suitable for the multi-cavity system.

Inspection before the Hot Runner System is Installed

1. The hot runner system is composed of hot nozzles, manifolds, and heating components. The heating components of the hot runner system are the most easily damaged parts. Please ensure that the heating insulation value of the hot runner is greater than 0.5MΩ before use.

2. Before the mold is installed on the injection molding machine, please check whether the wiring method and joint of the hot runner are consistent with the wiring method and joint of the thermostat and whether all the wiring is complete.

3. The electrical parts of the hot runner system are different from general mold parts, and electrical inspection is necessary, especially in terms of electrical safety and power.

4. Check whether the resistance of the heater is in line with that marked in the material table.

5. The temperature sensing wire is divided into grounding, non-grounding, and the commonly used K and J types. The general hot nozzle is the ungrounded type, and the plate temperature sensing wire on the shunt board is the grounding type.

6. The J-type temperature sensing line is commonly used, and the heat constant is identified by a light yellow bundle. The white line is +, and the red line is -. The red line of the panel temperature sensor is +, and the blue line is -.

7. Check whether the outer skin of the wire is damaged, crushed, etc, and whether the mold has water leakage, oil leakage, etc., which may cause damage to the heating element. If it is found, it needs to be dealt with in time.

8. Install the mold on the machine table, and connect all cooling circuits and air circuits.

9. Determine the plug to connect the hot runner system.

10. Turn on the power of the controller, then turn on each control panel one by one, start the dehumidification function, and observe the temperature change of each control panel.