What is the function of a polyurethane high-pressure foaming injection machine?

A polyurethane high-pressure foaming injection machine is an industrial device specifically designed for mixing, metering, and high-pressure injection molding of polyurethane (PU) raw materials. It is widely used in the automotive, construction, home appliance, and cold chain industries. Its core function is to achieve efficient molding of polyurethane foam through high-pressure mixing and precise control.

1. Functions of a Polyurethane High-Pressure Foaming Injection Machine

High-Pressure Mixing and Foaming

Raw Material Mixing: The two main components of polyurethane (isocyanate (material A) and polyol (material B)) are precisely mixed under high pressure (typically 10-200 bar) to ensure a thorough chemical reaction.

Uniform Foaming: High-pressure impingement mixing technology fully atomizes the raw materials, forming a fine bubble structure, avoiding the uneven mixing problems of traditional low-pressure machines.

Precise Metering and Proportioning

Ratio Control: High-precision metering pumps (error ≤ ±1%) ensure the A/B material ratio meets process requirements (e.g., 1:1 or 1:1.2).

Temperature Control: A heating system maintains the raw materials at 20-50°C (depending on the formulation) to ensure fluidity and reactivity.

Complex Molding and Filling

Mold Filling: High-pressure injection allows for rapid filling of complex molds (e.g., car seats, refrigerator insulation), preventing air bubbles or cavities.

Fast Curing: Adjusting the catalyst ratio allows for controlled curing time (typically 5-60 seconds) to improve production efficiency.

Diversified Product Production

Soft Foam: For example, car seats and sofa cushions (density 30-80 kg/m³).

Rigid Foam: For example, building insulation boards and cold chain containers (density 30-300 kg/m³).

Semi-rigid Foam/Integral Skin Foam: For example, steering wheels and shoe soles (combining elasticity and a smooth surface finish).

Advantages of High-Pressure Foaming Injection Machines

2. Precautions for Using the Polyurethane High-Pressure Foaming Injection Machine

Pre-Startup Inspection

Raw Material Preparation

Material A (isocyanate) and Material B (polyol): Ensure they are free of impurities and moisture, and stored at the required temperature (usually 20-30°C).

Filtration System: Check that the filters for Material A and Material B are clean to prevent clogging of the mixing head.

Equipment Condition Inspection

Hydraulic System: Check the hydraulic oil level (ISO VG46) to ensure there are no leaks.

Air System: Confirm that the compressed air pressure is stable (0.6-0.8 MPa).

Electrical System: Check that the PLC, temperature control instrument, and motor are functioning properly.

Mold Inspection

Preheating: The mold must be preheated to 40-80°C (depending on product requirements) to prevent shrinkage or cracking of the foam due to a cold mold.

Release Agent: Evenly spray a release agent (such as silicone oil) to prevent sticking.

Operation Procedure

Starting the Equipment:

First, turn on the hydraulic system, then start the metering pump and mixing head.

Run the machine at no load for 1-2 minutes to observe whether the pressure stabilizes.

Test Injection:

Perform a small-batch trial run to check the foam quality (density and bubble uniformity).

Full Production:

During continuous production, regularly check the remaining raw material to avoid material shortages.

Safe Operation

Protective Equipment:

Operators must wear a gas mask (to protect against isocyanate volatilization), goggles, and chemical-resistant gloves.

Emergency Stop:

Be familiar with the location of the emergency stop button and immediately stop the machine if any abnormalities (such as leakage or unusual noise) are detected.

3. Polyurethane High-Pressure Foaming Injection Machine Maintenance and Care Guide

1. Daily Maintenance (Every Shift/Daily)

Cleaning and Inspection

Mix Head Cleaning:

Use a dedicated solvent (such as acetone or polyurethane cleaning agent) to thoroughly rinse the mix head to prevent residual material from solidifying and clogging.

Inspect the mix head seal for wear and replace immediately if damaged.

Filter Cleaning:

Remove the A/B material filter and ultrasonically clean or soak it in a solvent, then blow dry to ensure it is free of impurities and clogging.

Equipment Surface Cleaning:

Remove material splashes, dust, and oil from the equipment surface and surrounding area, and maintain a clean working environment.

Operation Status Inspection

Pressure and Temperature Monitoring:

Confirm that the injection pressure (80-200 bar) and material temperature (20-50°C) are within the set range.

Check that the hydraulic system pressure is stable (usually 10-15 MPa).

Leak Check:

Check the A/B material pipelines, hydraulic oil pipes, and air lines for leaks, and tighten any loose joints.

2. Weekly Maintenance

Lubrication of Key Components

Guide Rails and Sliders: Apply high-temperature resistant grease (such as lithium-based grease) to ensure smooth operation of mechanical components.

Chains and Drive Mechanisms: Spray with anti-rust lubricant to prevent rust and seizure.

Electrical System Inspection

PLC and Sensors: Clean dust from the control cabinet and check for loose terminals.

Heating Elements: Test the resistance of the feed pipe and mold heater to ensure proper heating.

Hydraulic System Maintenance

Hydraulic Oil Inspection: Observe the oil color (transparent or light yellow). Replace if cloudy or black.

Tank Venting: Open the tank vent valve to remove air and prevent cavitation in the hydraulic pump.

3. Monthly Maintenance

Replacement of Seals and Wear Parts

Mix Head Seals: They are prone to aging in high-pressure environments and should be inspected and replaced monthly.

Pump Seals: Check the tightness of the metering pump (gear pump/plunger pump) to prevent material leakage.

System Performance Calibration

Metering Accuracy Calibration:

Verify the A/B material ratio error by weighing (standard ≤ ±1%) and adjust metering pump parameters.

Pressure Sensor Calibration:

Compare the device's displayed value with a standard pressure gauge. Recalibration is required if the error exceeds 5%.

Deep Cleaning

Raw Material Tanks and Pipelines: Empty any remaining raw material and flush the pipes with a dedicated cleaning agent.

Mold Maintenance: Remove any residual foam from the mold and spray with a rust inhibitor to prevent oxidation.