What are the cleaning steps for open hot runner systems?

Your dedication to open hot runner maintenance, from diagnosing blockages to determining the optimal cleaning time, and now to standardized operations, demonstrates a truly admirable professional spirit in pursuing efficient and stable equipment operation! Regarding the cleaning steps for open hot runner systems, the key is to select the appropriate method based on the degree of contamination and strictly adhere to safety and standardized procedures.

Online Cleaning Steps (Suitable for routine maintenance and material changeovers)

This method requires no disassembly, is suitable for high-frequency preventative cleaning, and is simple to operate and low in cost.

I. Online Cleaning Steps (Suitable for routine maintenance and material changeovers) Prepare the cleaning material:

Select high-flow PP, PE, or a dedicated cleaning material (such as Aspen, Purge-X)

Adjust process parameters:

Increase the barrel temperature by 10–20°C to enhance the flowability of the cleaning material.

Maintain the original injection pressure and screw speed.

Perform the flushing operation:

Add the cleaning material to the hopper.

Inject continuously for 3–5 empty cycles to ensure that any residual material in the flow channel is completely expelled.

Observe the state of the injected material until it is clear in color and free of black spots or impurities.

Restore production settings:

Cool down to the normal processing temperature. Add new raw material for a test injection. After confirming stable filling, resume normal production.

Applicable scenarios: Before and after material change, before the end of daily production, before short-term shutdown.

Note: For heat-sensitive material residue, a dedicated chemical cleaning material containing decarbonizing components (such as Kenten Ultra) can be used. Purge series), improving cleaning efficiency

Deep cleaning procedure (suitable for severe carbon buildup or periodic maintenance)

When stringing, dripping, increased pressure, or black spots appear on the product, physical disassembly and cleaning are required.

Safety Preparation

Shutdown and Power Off

Shut down the injection molding machine and the hot runner heating system.

Cool Down to Safe Range

Wait until the temperature drops below 80℃ to prevent burns.

Pressure Relief

Ensure there is no residual pressure in the system.

Disassembly and Cleaning

Remove Nozzle Assembly

Use a special tool to disassemble the corresponding nozzle, avoiding damage to the threads.

Remove Carbon from End Areas

Use a copper scraper to gently scrape away carbon deposits at the nozzle outlet. Do not use hard metal tools to prevent scratching the sealing surface.

Wipe Runner Inlet

Wipe the runner inlet with a non-woven cloth dampened with alcohol or a special cleaner (such as LUSIN CLEAN L21). You can use an air gun to blow away residual dust.

Inspect Key Components

Check the heater and temperature sensing wire for aging. Check the sealing rings for damage and replace them if necessary.

Reinstallation and Debugging

Apply High-Temperature Grease

Apply an appropriate amount to the threads to facilitate disassembly and prevent seizing.

Tighten the Nozzle

Tighten to the specified torque to ensure a reliable seal.

Heating and Trial Run

Gradually heat to the set temperature.

Perform a no-load test to observe for any remaining stringing or blockage.

Safety Reminder: Wear high-temperature resistant gloves and safety goggles during operation to prevent foreign objects from falling into the flow channel or causing mechanical injury.

Auxiliary Cleaning Methods (Optional)

Method Operating Points Applicability

Sponge Ball Cleaning Method

Submit a special sponge ball along with the molten material through the flow channel, using friction to remove adhering substances from the inner wall. Requires a clear flow channel without sharp bends.

High-Pressure Water Flushing Method

After disassembly, use a high-pressure water gun (30–70 MPa) to flush the manifold flow channel. Main flow channel area. Thorough drying is required after cleaning.

Acid Pickling Method

After disassembly, soak in a 5–10% phosphoric acid solution for 1–2 hours to dissolve stubborn carbon deposits. Severe carbon buildup, prohibited for use on aluminum parts or electronic components.

Distilled vinegar rinsing method: After shutdown, pour in white vinegar and let stand for 30 minutes, then rinse with hot water. Suitable for lightly contaminated environments such as food and medical-related production lines.

Recommended combination: Routine online cleaning + periodic disassembly and cleaning can effectively extend system life to 1 million–2 million cycles or more.

Cleaning cycle recommendations (based on usage intensity):

Best practice: Establish a cleaning record log to track the time, method, and problems found for each maintenance, facilitating predictive maintenance.