Operation Procedure for Replacing the Mold of Extrusion Blow Molding Machine

Step-by-Step Guide to Changing Molds on Extrusion Blow Molding Machines

Pre-Mold Change Preparation

1. Safety Protocols

Begin by shutting down the machine using the standard procedure, ensuring the extruder screw stops rotating and the clamping unit is fully open. Disconnect power at the main switch to prevent accidental activation during mold handling. Equip operators with heat-resistant gloves, safety glasses, and steel-toed boots to protect against hot surfaces and heavy components.

2. Workspace Organization

Clear the area around the machine of tools, debris, and excess material to create a safe workspace. Position a sturdy lifting device, such as a hoist or forklift, near the mold area if the mold is heavy. Lay down protective mats or cardboard to catch any residual polymer or lubricant that may drip during removal.

3. Tool and Equipment Readiness

Gather necessary tools, including wrenches, Allen keys, and mold release agents. Verify that the new mold is compatible with the machine’s specifications, such as clamping force and tie-bar spacing. Inspect the mold for visible damage, such as cracks or worn alignment pins, before installation.

Mold Removal Process

1. Disconnecting Utilities

Shut off hydraulic pressure to the mold clamping system by closing the relevant valves or switches. Disconnect any cooling water lines, air hoses, or electrical connections attached to the mold. Label each connection with tape or markers to simplify reinstallation later.

2. Loosening Fasteners

Use the appropriate tools to remove bolts securing the mold to the clamping plates. Start with the corner bolts to relieve pressure evenly, then proceed to the center bolts. If bolts are stuck, apply penetrating oil and allow it to sit for several minutes before attempting removal again.

3. Lifting and Storing the Old Mold

Attach lifting straps or chains to the mold’s designated lifting points, ensuring the load is balanced. Slowly raise the mold using the hoist or forklift, keeping hands and body clear of the mold’s path. Move the old mold to a designated storage area, placing it on wooden blocks or pallets to avoid direct contact with the floor.

New Mold Installation Steps

1. Aligning the Mold

Position the new mold between the clamping plates, ensuring alignment pins fit into the corresponding holes. Use a straightedge or laser alignment tool to verify that the mold halves are parallel to the clamping plates. Adjust the mold’s position as needed to prevent uneven clamping pressure during operation.

2. Securing Fasteners

Hand-tighten the mold bolts in a crisscross pattern to distribute pressure evenly. Gradually tighten each bolt to the manufacturer’s recommended torque using a torque wrench. Double-check all bolts after initial tightening to ensure none were missed or loosened during adjustment.

3. Reconnecting Utilities

Attach cooling water lines, air hoses, and electrical connections to the new mold, following the labels created during removal. Open hydraulic valves to restore pressure to the clamping system, then cycle the clamping unit several times to check for leaks or unusual noises.

Post-Installation Checks

1. Testing Clamping Force

Close the mold halves and verify that the clamping force matches the material’s requirements, as specified in the machine’s manual. Adjust hydraulic pressure settings if the mold does not close fully or exhibits excessive flexing.

2. Running a Test Cycle

Initiate a low-speed test cycle with no material to confirm the mold opens and closes smoothly. Check for proper alignment by observing the parting line on the mold halves. If misalignment is detected, stop the machine and re-tighten bolts or adjust the mold’s position.

3. First Production Run

After successful testing, run a short production cycle with material to produce sample parts. Inspect the parts for defects like flash, warping, or uneven wall thickness, which may indicate issues with mold temperature or clamping pressure. Make incremental adjustments to cooling settings or hydraulic pressure until consistent quality is achieved.

By following these steps, operators can ensure safe and efficient mold changes, minimizing downtime and maintaining product quality in extrusion blow molding operations.