Complete Guide to Tool Change and Safe Parking for Large Plastic Extruders

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Contents hide
1 Prepare for Shutdown
1.1 Slow Down Production
1.2 Empty the Barrel
1.3 Turn Off Heating System
2 Park the Extruder
2.1 Stop the Screw
2.2 Release Pressure
2.3 Move the Die Head
2.4 Lock the Machine
3 Change Tools
3.1 Remove Old Tools
3.2 Install New Tools
4 Restart Production
4.1 Preheat the Machine
4.2 Check for Leaks
4.3 Adjust Settings
5 Safety Rules
6 Maintenance Tips
6.1 Daily Checks:
6.2 Scheduled Repairs:
6.3 Lubrication:
7 Fix Common Issues
8 Eco-Friendly Practices

“How to Park Extruder on Pause Tool Change? Tool changes are critical for maintaining large plastic extruders, but improper handling can lead to equipment damage or downtime. This step-by-step guide covers shutdown preparation, pressure release, mold replacement, and safe restart procedures to help you park the extruder and switch tools efficiently while following industry standards.”

Prepare for Shutdown

Slow Down Production

  1. Step-by-Step Slowdown:
    • First, slowly reduce the screw speed to 20-30% of normal speed over 10-15 minutes.
    • At the same time, reduce the feeding rate to avoid material buildup.
    • Keep checking the pressure sensor until it drops to 10-15% of normal.
  2. Important Notes:
    • Never stop the machine suddenly—this can burn the material or damage the screw.
    • Write down current settings (temperature, pressure, speed) for later reference.

Empty the Barrel

  1. Steps:
    • Switch to a cleaning material (like LDPE or special resin) and keep extruding until old material is gone.
    • Watch the color of the extruded material to confirm it’s clean.
    • If possible, reverse the screw briefly to clear stuck material.
  2. Tools Needed:
    • Use copper brushes or high-temperature lubricant to clean the screw and barrel.

Turn Off Heating System

  1. Cooling Steps:
    • Lower the temperature by 50°C every 30 minutes until it’s below 100°C.
    • Turn off heaters but let cooling fans run until the machine is fully cool.
  2. Focus Areas:
    • Cool high-temperature zones (like the die head) first to prevent damage.

Park the Extruder

Stop the Screw

  • Action: Turn off the main motor and use the brake (if available) to stop the screw.
  • Safety: Hang a “Do Not Start” sign and lock the power source (LOTO procedure).

Release Pressure

  • Manual Method: Open the pressure relief valve slowly and check the pressure gauge until it reads zero.
  • Automatic Method: Use the control panel’s “Emergency Pressure Release” mode.

Move the Die Head

  1. Steps:
    • Use a hydraulic system to move the die head to a parking stand.
    • Check alignment with a laser level (error should be ≤ 0.5mm/m).
  2. Tools: Heavy-duty slings and laser level.

Lock the Machine

  • Secure the die head with safety pins.
  • Install anti-backlash clamps on the screw.

Change Tools

Remove Old Tools

  1. Steps:
    • Heat bolts to 80-100°C before loosening them.
    • Loosen bolts in a diagonal order to avoid uneven force.
    • Use a lifting beam to remove the old mold horizontally.
  2. Clean Residue: Soak the mold in solvent or use sandblasting.

Install New Tools

  1. Calibration:
    • Use a laser aligner to center the mold with the screw (tolerance ≤ 0.05mm).
    • Tighten bolts in three stages: 30% → 50% → 100% of required torque.
  2. Test Run:
    • Run the screw at 5-10 RPM to check for vibrations.
    • Adjust die gaps with a feeler gauge (e.g., ±0.01mm).

Restart Production

Preheat the Machine

  • Heat the machine gradually (20°C per hour) to avoid stress.
  • Monitor temperature differences at connections (keep ≤ 15°C).

Check for Leaks

  • Test seals at 0.5MPa for 30 minutes—pressure drop should be ≤ 5%.

Adjust Settings

  1. Start Slowly:
    • Begin at 10% of normal speed, then increase by 5% every 5 minutes.
    • Watch for stable melt pressure (fluctuations < ±2%).
  2. Quality Checks:
    • Measure product dimensions and melt index (MI) of the first samples.

Safety Rules

  • Lock Out Power: Use personal locks on electrical panels and isolate pipes.
  • Wear PPE: Heat-resistant gloves (500°C+), face shields, and safety boots.

Maintenance Tips

Daily Checks:

  • Measure screw wear monthly (replace if worn by > 0.5mm).
  • Check heater resistance and gearbox oil levels.

Scheduled Repairs:

  • Yearly: Replace thrust bearings and calibrate sensors.
  • Every 3 years: Replace screw/barrel assembly.

Lubrication:

  • Screw bearings: Add high-temperature grease every 500 hours.
  • Gearbox: Change oil every 2000 hours.

Fix Common Issues

Problem Cause Solution
High melt pressure Clogged filter Switch to backup filter and clean.
Die head leaks Uneven bolt tightening Retighten bolts diagonally.
Motor overload Jammed screw Reverse screw and check for blockages.

Eco-Friendly Practices

  • Recycle waste into labeled bins (cleaning material, scraps, etc.).
  • Use biodegradable solvents for cleaning.

By following these steps on how to park the extruder during a pause for tool change, operators can maintain safety, efficiency, and product quality in large plastic extruder operations.In actual operation, the technical manual provided by the equipment manufacturer must be strictly followed, and operators must be regularly trained in IATF 16949 standards. It is recommended to fill out the “Equipment Health Status Report” after each shutdown maintenance and include it in the enterprise ERP system for life cycle management.

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