How to replace the gear of the melt pump?

The replacement of the gears in a melt pump is a meticulous process. Below are the detailed steps compiled based on reference articles:

I. Preparation

Shut Down the Melt Pump: Ensure that the melt pump has completely stopped working and cut off the power supply to prevent accidents during the replacement process.

Prepare Tools: Gather the necessary tools, such as wrenches, screwdrivers, plastic or copper hammers (avoid using iron hammers to prevent damaging the gears and bearings), sandpaper (e.g., 600-grit for light grinding), etc.

Clean the Work Area: Ensure the work area is clean and tidy, with sufficient space for replacing the gears and storing components.

II. Disassembling the Gears

Remove the End Cover Plate: First, loosen and remove all bolts from the end cover plate, then take off the cover plate. During this process, pay attention to the grooves on each bearing, which correspond to the orientation of the pump's inlet and outlet, to ensure correct repositioning during assembly.

Extract the Gear Shaft: Remove the gear shaft and bearings from the middle plate. Due to residual viscous material inside the pump, the gear shaft and bearings may be difficult to extract. At this point, be extra careful not to hit or damage the teeth or bearing edges. Use a plastic or copper hammer to gently tap and dislodge them.

Separate the Bearings from the Gears: Remove the bearings from the gear shaft. Again, avoid damaging the teeth, bearing edges, or shaft. If separation is difficult, gently tap the bearings with a plastic or copper hammer to loosen them, but never use an iron hammer or screwdriver to pry them apart, as this could damage the gears.

III. Inspection and Cleaning

Inspect the Gears and Bearings: Carefully examine the removed gears and bearings for signs of wear, cracks, burrs, scratches, etc. If necessary, use sandpaper to lightly grind off surface contaminants, but avoid removing metal or performing any grinding that could affect their metering function.

Clean the Components: Use compressed air or clean cotton cloths to remove residual material and impurities from the components. Then, clean them with trichloroethane or vinyl chloride solvent and wipe them dry with cotton cloths. Avoid using paper towels or other materials that may leave lint or impurities.

IV. Installing the New Gears

Prepare the New Gears: Ensure that the new gears match the model, specifications, and quality of the original gears.

Install the Bearings: Mount the new bearings onto the gear shaft, paying attention to their orientation and position to avoid installation errors.

Assemble the Gear Shaft: Replace the gear shaft with the new bearings back into the middle plate, ensuring its correct position.

Install the End Cover Plate: Return the end cover plate to its original position and secure it with bolts. When tightening the bolts, apply high-temperature-resistant grease to the threaded portions and tighten them diagonally in sequence to maintain pump stability.

V. Inspection and Testing

Check the Installation: Verify that all components are properly installed, bolts are tightened, and seals are intact.

Perform Testing: After confirming everything is in order, start the melt pump for testing. During the test, observe the pump's operation and check for abnormal noises, leaks, or other issues. If any abnormalities are detected, immediately shut down the pump, inspect, and address the issues.

By following these steps, you can successfully replace the gears in a melt pump. Throughout the process, pay close attention to details and adhere to operational norms to ensure safety and reliable gear operation.

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