Техническое обслуживание и очистка сопла методом холодного вытягивания для H2C

Preface

Ensuring a clean and unobstructed nozzle is crucial during the 3D printing process, as it directly affects print quality and performance. Due to the H2C intelligent extruder motor, we have developed a practical feature that enables users to efficiently clean the nozzle. We strongly recommend incorporating this function into your routine maintenance to effectively extend the nozzle's lifespan.

Here are some scenarios where cold pull maintenance is necessary:

1. Frequent Extruder Motor Overload Errors: If the extruder motor frequently reports overload errors under normal printing flow conditions, it indicates excessive nozzle resistance and requires immediate cleaning.

2. Before Switching to TPU Filament: TPU is highly sensitive to nozzle resistance. If other materials have been previously used, we recommend performing a cold pull before printing with TPU to ensure smooth extrusion.

Note: If the nozzle is completely clogged and cannot be cleaned using the standard flushing procedure, please refer to the Hotend Unclogging Procedure first. After clearing the clog, proceed with the cold pull operation.

Test Criteria for Complete Nozzle Clogging:
After assembling the nozzle on the extruder and heating it steadily to 250°C, perform a feeding test using PLA or PETG filament. If no molten material is extruded from the nozzle tip or the extrusion is significantly lower than normal, the nozzle is considered completely clogged.

Selection of Cold Pull Parameters

Through a series of tests, we have determined that PLA and PETG perform excellently in the cold pull process. Other filaments showed poor performance during cold pulling, as they are prone to tearing, leaving residue inside the nozzle. For cleaning filaments produced by third-party manufacturers, please carefully read the instructions before use and ensure they are used under appropriate conditions. The following is a guide for selecting parameters during the cold pull process:

Extruder Selection

Both left and right extruders support automatic cold pull functions. If you are performing a cold pull on an HF nozzle, we recommend using the right extruder to significantly improve the cold pull success rate.

Nozzle Selection

Here, you need to enter the parameters for the nozzle you wish to cold pull. Due to differences in the geometric parameters of various nozzles, we have preset corresponding parameters for each type of nozzle.

Cold Pull Filament Selection

Cold pull filaments need to fulfill three core functions:

1. Perform flushing based on the flushing temperature to remove any residual filament inside the nozzle.

2. Refill the nozzle chamber based on the filament's printing temperature.

3. Cool down to the cold pull temperature and use cold pulling to remove internal impurities. Different nozzle models may require different cold pull filaments:

• SF Nozzle: PLA or PETG is recommended as the cold pull filament.

• HF Nozzle: PETG is preferred for cold pulling due to its better extensibility.

Flushing Temperature Selection

You can choose the appropriate flushing temperature based on the highest temperature filament the nozzle has previously used:

• 250°C: Suitable for low-temperature filaments such as PLA, PETG, TPU, PVA, etc.

• 290°C: Suitable for high-temperature filaments such as ABS, ASA, PA, PC, PET, etc.

• 320°C: Suitable for ultra-high-temperature filaments such as PPS, PPA, etc.

If you are unsure which temperature to choose, you can base your flushing temperature on the highest usage temperature of the filaments you have.

Cold Pull Temperature Selection

Cold pulling works by precisely controlling the nozzle temperature (recommended to be set 20-30°C above the filament's glass transition temperature) and using the material's viscoelasticity to physically strip contaminants from the nozzle wall. H2D has pre-configured parameter tables for you, but you can adjust them flexibly based on cold pull effectiveness and success rate. The suggested adjustment increment is 5°C. Specific adjustment directions are as follows:

• If you encounter significant resistance and the filament breaks easily during cold pulling, it is recommended to increase the cold pull temperature.

• If the filament breaks with minimal resistance during cold pulling, it is recommended to lower the cold pull temperature.

Cold Pull Process

Step 1. Preparation Before Starting

On the printer touchscreen, follow the path below:

1. Navigate to the “Settings” menu
2. Select the “Toolbox” button

3. In the menu, find and tap “Nozzle Cold Pull Maintenance” to enter the cold pull preparation interface.

Step 2. Cold Pull Parameter Setup and Preparation!

Tap “Next” on the screen to proceed.

Enter the cold pull parameter configuration page. The menu will display the following adjustable options (as shown below):

1. Select Nozzle to Clean: Check “Left” or “Right” according to the nozzle that needs cleaning.
2. Select Cleaning Filament: PLA or PETG is recommended. Choose a filament with a lighter color or higher contrast than the previously used one to help identify any debris or residue removed during cleaning.
3. Specify Nozzle Size: Select the correct nozzle diameter (e.g., 0.4 mm, 0.6 mm) and type currently installed.
4. Select Residual Filament Type: Choose the filament type that was in use during or just before the clog occurred. The system will automatically set an appropriate heating temperature to ensure the residual filament softens completely.

After configuring all parameters, tap “Start” to begin the cold pull cleaning process.

Step 3. Remove the PTFE Tube

Following the on-screen instructions, press and hold the outer ring of the black pneumatic connector, then pull out the upper PTFE tube.

2. Tap “Done, Continue ” to proceed to the next step.

Step 4. Insert the Filament and Start the Automatic Program

1. Following the on-screen instructions, insert the cleaning filament selected in Step 2 (PLA or PETG) into the filament inlet and push it in until it is fully seated.

2. After confirming the filament is properly inserted, tap “Done” to continue.

3. The device will then automatically perform the following steps (no manual operation is required):

• Heat the nozzle to the preset temperature.
• Purge any residual filament from inside the nozzle.
• Cool the nozzle to the optimal temperature for the cold pull process.

Step 5. Remove the Filament and Reinstall the PTFE Tube

1. When prompted, slowly and steadily pull out the filament by hand. (The front end of the filament may carry out debris or residue causing the clog.)

Note: During the cold pull process, pull the filament vertically and slowly upward. Pulling too quickly or at an angle may cause the filament to break.

2. After the filament is completely removed, tap “Done” to continue.

3. The screen will then display a reference example of the cleaned filament for comparison.

• If the removed filament still shows residue, burnt spots, or discoloration, repeat the cold pull process until the filament tip is clean and smooth.
• If the filament tip is smooth and free of debris, the cleaning is complete.

4. Finally, reinstall the PTFE tube and press it firmly into place to ensure a secure fit. Then tap “OK” (Label 1) to complete the cold pull maintenance process.

Check the Cold Pull Results

At the end of the extracted filament (as shown below for the HF nozzle), pay close attention to the following quality indicators:

1. Color Consistency: The extracted filament should not contain any discoloration, impurities, or carbonized deposits.
2. Surface Cleanliness: The surface of the extracted filament should appear uniformly melted and smooth, with no granular residue or sintered material attached.

We strongly recommend repeating the cold pull process several times until the extracted filament shows a clean surface with no abnormal residue, as shown below (example for the HF nozzle).