A Fiber thermal shrinkage tester, also known as a heat shrinkage tester, is generally used to test the heat shrinkage performance and dimensional stability of materials such as films, sheets, heat shrink tubing, pharmaceutical PVC rigid sheets, shrink films, and cling film within the range of 80-150 degrees Celsius. The heat shrinkage tester is an instrument for determining the deformation recovery performance of frozen samples as the temperature rises by L. It consists of a temperature control unit, air supply, sample sampling, force measuring mechanism, and deformation measurement system. A fiber heat shrinkage tester is used to measure the heat shrinkage rate of chemical and natural fibers after treatment with dry heat, high-temperature steam, or boiling water. These instruments typically employ automatic control and data processing technology, enabling automated testing and providing high-precision and high-stability test results.

This instrument uses automatic control and data processing technology. The entire testing process is automated, and a maximum of two sample tubes can be tested at a time, with each sample tube holding up to 30 samples. The number of sample tubes and the number of samples per tube can be freely set. The instrument automatically identifies the tube number, ensuring data correspondence between before and after baking, and can also determine breakage after baking. The instrument automatically counts and processes data. It can display and print statistical data such as individual and average shrinkage rates, extreme values, CV values, and the number of valid test specimens. The instrument boasts high resolution, stable performance, a high degree of automation, and simple operation.

Principle:

The fiber heat shrink apparatus utilizes the memory effect of heat-shrinkable materials when the temperature exceeds a specific transition point, driving the covering layer, protective sleeve, or encapsulation structure to shrink and achieve a tight fit. The shrinkage behavior of different materials is influenced by parameters such as polymer molecular chain orientation, glass transition temperature (Tg), and softening point. Therefore, process design must consider the material's shrinkage temperature range and stress release characteristics to ensure uniform shrinkage and mechanical matching within the controlled temperature range.

Temperature Control and Process Control: The heat shrinking process is a high-precision process requiring closed-loop temperature control and process monitoring. Common control strategies include PID or more advanced model predictive control to ensure smooth temperature rise and fall within the target range and avoid overheating. The uniformity of shrinkage depends on the temperature field, residence time, and part diameter consistency. Therefore, process parameters typically need to be optimized based on sample diameter, wall thickness, and material thermal properties, supplemented by a cooling step to fix the formed shape.

Complete Operation Flow:

Preparation Before Use:

Sample and Fixture Selection: Select fixtures that match the material, ensuring the fixture surface is clean and free of foreign matter, and that the sample is securely fixed without excessive compression.

Environmental and Instrument Checks: Confirm that the equipment power supply, gas supply, and insulation layer are intact. Check the condition of seals and sensors to ensure the instrument operates in a good working environment.

Initial Parameter Setting and Calibration: Perform temperature calibration and no-load test runs before formal testing. Record initial parameters and retain control data for comparison.

Operating Procedures:

Step 1: Place the sample in the fixture, ensuring the heated area covers the core fiber region and the sample edges are not excessively stretched or warped.

Step 2: Set the target temperature, heating rate, and holding time. Optimal parameters should be verified based on the material specifications and a small sample.

Step 3: Start the heat shrink apparatus, slowly heating and observing the sample shrinkage process to avoid localized overheating caused by rapid heating.

Step 4: After reaching the set conditions, enter the holding stage, followed by controlled cooling to avoid stress concentration caused by rapid cooling.

Step 5: Remove the sample and record the dimensional changes after shrinkage. Repeat the test if necessary to evaluate repeatability and stability.

Parameter Settings and Material Matching

Parameter selection should be based on material characteristics: different fiber types, coating thicknesses, and initial dimensions have different requirements for temperature, time, and heating/cooling rates.

Refer to the manufacturer's manual and combine it with your own small-scale tests to create a reusable parameter table for rapid application across similar materials or batches.

Precautions During Use

Safety First: Wear protective equipment to avoid burns; keep the area around the heat source clean and keep away from flammable materials.

Sample Distance from Heat Source: Ensure uniform heating of the sample to avoid localized hot spots that could cause deformation deviations.

Process Monitoring: If abnormal vibrations, odors, or abnormal equipment display are detected, immediately stop the test and investigate.

Cleaning and Sealing: After the test, clean the fixture and hot plate surface to prevent residual contamination from affecting subsequent tests.

Maintenance and Care

Daily Cleaning and Dust Removal

Regular Cleaning: After turning off the power and ensuring the equipment has completely cooled down, gently clean the surface and interior of the equipment with a clean, soft cloth or brush to remove dust and fiber residue. Avoid using excessively hard tools to prevent scratching and damaging the equipment.

Environmental Control: Keep the environment in which the equipment is located clean to reduce the accumulation of dust and fibers.

Lubrication and Maintenance

Lubrication System Inspection: Ensure the equipment's lubrication system has an adequate supply. Add lubricating oil or grease as needed.

Transmission Component Inspection: Regularly inspect the equipment's transmission components and bearings to ensure they operate smoothly and without abnormal wear. Repair or replace any problematic components promptly.

Lubricating Oil Replacement: Regularly change the lubricating oil and grease to maintain their performance and quality.

Parameter Check and Adjustment

Understanding Equipment Parameters: Carefully consult the equipment's instruction manual and operation manual to understand the function and range of each parameter.

Parameter Testing and Adjustment: Use professional testing instruments and tools to test various parameters of the equipment, such as temperature, speed, and tension, and make corresponding adjustments to ensure they meet processing requirements.

Professional Consultation: If necessary, consult the equipment supplier or professional technicians for more detailed and accurate guidance and advice.

Regular Inspection and Maintenance

Planning: Develop corresponding inspection and maintenance plans based on the equipment's usage frequency and operating status.

Replacement of Wear Parts: Regularly inspect and replace wear parts such as the equipment's thermoforming plates, heating elements, and drive belts to ensure their normal working performance.

Fault Repair: Promptly repair equipment faults and problems to reduce downtime and production losses.

Other Precautions

Operating Environment: Ensure the equipment operates in an environment with suitable temperature, humidity, and air quality, avoiding environments with corrosive gases, dust, and explosion hazards.

Professional Operation: Train qualified personnel to operate the equipment to avoid damage caused by misoperation.

Maintenance Log Recording: Record the equipment's operating status and maintenance records to facilitate timely problem identification and resolution.

Instruments for testing heat shrinkage properties play an indispensable role in materials research and application. From thorough preparation, standardized operating procedures, and precise parameter settings, to meticulous precautions during use, and comprehensive and regular maintenance, every step is closely linked and crucial. Strictly adhering to these points not only ensures the accuracy and reliability of test results, providing a solid basis for material performance evaluation, but also effectively extends equipment lifespan, reduces operating costs, and propels related industries to new heights in materials research and quality control.