Detailed explanation of the weather resistance test standards for thermal fuses

Detailed explanation of the weather resistance test standards for thermal fuses

In today’s global market, thermal fuses are an important industrial material with a wide range of applications, from textiles to automobile manufacturing, from the construction industry to the electronics field, etc. For international wholesale buyers, it is crucial to ensure that thermal fuses have good weather resistance, as this directly affects the quality and service life of the product. This article will explore the various standards for thermal fuse weather resistance testing in depth to help you fully understand this key area.

1. The importance of weather resistance testing
In actual use, thermal fuses often face various complex natural environmental conditions, such as high temperature, low temperature, humidity, ultraviolet radiation, ozone, etc. These factors may cause the performance of thermal fuses to deteriorate, and problems such as brittleness, discoloration, and reduced strength may occur, thereby affecting their normal use functions. Therefore, through weather resistance testing, the stability and durability of thermal fuses under different environmental conditions can be evaluated in advance, providing an important basis for product quality control and market application.

2. Natural environment exposure test
(I) Outdoor exposure test
Principle: Place the hot melt sample directly in the outdoor natural environment, expose it to natural factors such as sunlight, wind and rain, temperature changes, etc. After a period of time, observe its performance changes. This is the most direct test method that can best reflect the actual situation, but due to the long test cycle, it usually takes months or even years, and is greatly restricted by natural conditions such as geographical location and season.
Standard: ISO 877 “Plastics – Part 1: General Principles”, ASTM G7 “Natural Exposure Test Standard for Non-metallic Materials” and other standards have detailed provisions on the conditions, methods and sample requirements for outdoor exposure tests, such as the size, shape, and quantity of samples, the selection, direction and angle of the exposure site, and the determination of the test cycle.
(II) Natural damp heat test
Principle: Place the hot melt sample in a natural damp heat environment, such as tropical areas or humid coastal areas, to simulate high temperature and high humidity climate conditions, and examine its damp heat resistance. This test method can accelerate the wet heat aging process of the sample and shorten the test cycle, but it still takes a long time to get reliable test results, and it is greatly affected by natural environmental factors.
Standard: GB/T 2423.4 “Environmental testing for electrical and electronic products Part 2: Test methods Test Db: wet heat, alternating wet heat (12h+12h and
24h cycle)”, ISO 6942 “Textiles – Color fastness to wet heat – Simulated climate test” and other relevant standards regulate the conditions and methods of natural wet heat testing, including the setting of temperature and humidity parameters, sample processing and determination of test cycles.

3. Artificial accelerated aging test

(I) UV aging test
Principle: Use a UV aging test chamber to simulate the ultraviolet radiation in sunlight to irradiate the thermal fuse sample, while controlling the temperature and humidity conditions in the test chamber to accelerate the aging process of the thermal fuse. By measuring the performance changes of the sample at different time points, such as tensile strength, elongation at break, color change, etc., its UV resistance is evaluated. UV aging test can obtain relatively accurate test results in a short time, and the test conditions are highly repeatable, which is convenient for quality control and comparative research.
Standards: ASTM G154 “Standard Test Method for Exposure of Nonmetallic Materials with Fluorescent UV Lamps”, ISO 4892-3 “Plastics – Laboratory Light Source Exposure Test – Part 3: Fluorescent UV Lamps” and other standards have detailed provisions for the lamp type, irradiation intensity, temperature, humidity and other parameters of UV aging test to ensure the accuracy and comparability of test results.
(II) Xenon lamp aging test
Principle: The xenon lamp aging test chamber uses a xenon lamp as a light source to simulate the full solar spectrum radiation, including ultraviolet light, visible light and infrared light, which can more realistically simulate the spectral characteristics of natural sunlight. By adjusting the light intensity, temperature, humidity and spraying conditions in the test chamber, the thermal fuse samples are subjected to comprehensive environmental stress to accelerate their aging process. The xenon lamp aging test is suitable for thermal fuses of various colors and different transparencies, and can better predict their weather resistance during actual use.
Standards: ISO 4892-2 “Plastics – Laboratory Light Source Exposure Test – Part 2: Xenon Arc Lamps”, ASTM G155 “Xenon Lamp Light Source Exposure Test Standard” and other standards regulate the equipment requirements, test conditions, sample preparation and performance evaluation of xenon lamp aging tests to ensure the reliability and consistency of test results.
(III) Ozone Aging Test
Principle: Ozone is a strong oxidant that can accelerate the breaking of some chemical bonds in thermal fuses, leading to material aging. The ozone aging test chamber can produce a certain concentration of ozone gas and control the temperature, humidity and gas flow rate in the test chamber to make the thermal fuse samples undergo aging reactions in the ozone environment. The ozone resistance of the sample is evaluated by observing the cracking, discoloration, deformation and other phenomena on the surface of the sample and measuring the changes in its physical properties. The ozone aging test is mainly used to study the resistance of thermal fuses to ozone, which is of great significance for some thermal fuse products used outdoors or exposed to ozone environments for a long time.
Standards: ASTM D1149 “Rubber – Accelerated Ozone Aging Test by Static Tensile Method”, ISO 1431-1 “Rubber – Ozone Cracking – Part 1: Static Tensile Test” and other standards have detailed provisions for parameters such as ozone concentration, temperature, humidity, sample shape and size of ozone aging test to ensure the accuracy and repeatability of test results.

4. Climate Cycle Test
(I) Temperature Cycle Test
Principle: Place the thermal fuse sample in a temperature cycle test chamber to subject it to rapid changes between high and low temperatures, simulating the temperature drastic changes that the thermal fuse may encounter during actual use, such as in areas with large temperature differences between day and night or in an environment with frequent indoor and outdoor conversions. This temperature cycle change will cause thermal stress to the thermal fuse, causing changes in its internal structure, thereby affecting its performance. Through the temperature cycle test, the stability and reliability of the thermal fuse under temperature changes can be evaluated.
Standard: GB/T 2423.22 “Environmental testing for electrical and electronic products Part 2: Test methods Test N: Temperature change”, ISO
105-10 “Textiles – Tests for color fastness – Part 10: Color fastness to moisture and heat: Temperature change (washing resistance, water extraction resistance)” and other relevant standards stipulate the temperature range, change rate, number of cycles and other parameters of the temperature cycle test to meet the test requirements of different types of thermal fuses.
(II) Wet heat cycle test
Principle: The wet heat cycle test combines the factors of temperature cycle and humidity cycle, and exposes the thermal fuse samples to an environment with alternating high temperature and high humidity and low temperature and low humidity, simulating various complex climatic conditions that may be encountered in actual use, such as the alternation of hot and humid rainy seasons and hot and dry dry seasons in tropical areas, and the alternation of wet and dry seasons in coastal areas. This test method can more comprehensively evaluate the weather resistance of thermal fuses under different climatic conditions, especially for some humidity-sensitive thermal fuse products, wet heat cycle test is an important quality inspection method.
Standards: ASTM D2247 “Standard Test Method for Resistance of Plastics to Moisture and Heat (Tested by Cyclic Immersion)”, ISO
6942 “Textiles – Color Fastness to Moisture and Heat – Simulated Climate Test” and other standards have detailed provisions for parameters such as temperature, humidity, and cycle period of the moisture and heat cycle test to ensure the accuracy and repeatability of the test results.

5. Single Climate Condition Test
(I) High Temperature Test
Principle: Place the hot melt sample in a high temperature environment for a certain period of time to observe its appearance changes, physical property changes, and whether it softens, melts, decomposes, etc. at high temperature. High temperature testing can evaluate the stability and heat resistance of hot melts under high temperature conditions. For some hot melt products used or stored in high temperature environments, such as hot melts in automobile engine compartments and hot melts in industrial equipment, it has important quality inspection significance.
Standard: GB/T 2423.2 “Environmental testing for electrical and electronic products Part 2: Test methods Test B: High temperature”, ISO 870 “Plastics – Determination of density” and other related standards stipulate the temperature range, test time and other parameters of high temperature test to meet the test requirements of different types of thermal fuses.
(II) Low temperature test
Principle: Place the thermal fuse sample in a low temperature environment, and after a certain period of time, observe its appearance changes, physical property changes, and whether there are brittle cracks, fractures, etc. at low temperatures. Low temperature testing can evaluate the toughness and cold resistance of thermal fuses under low temperature conditions. For some thermal fuse products used in cold areas or low temperature environments, such as thermal fuses used outdoors in winter and thermal fuses in refrigeration equipment, low temperature testing is an important means to ensure product quality and performance.
Standard: GB/T 2423.1 “Environmental testing for electrical and electronic products Part 2: Test methods Test A: Low temperature”, ASTM D648 “Standard test method for determination of stress cracking index at bending temperature of plastics” and other standards have detailed provisions on the temperature range, test time and other parameters of low temperature testing to ensure the accuracy and comparability of test results.
(III) Humidity test
Principle: Expose the hot melt sample to a high humidity environment, maintain a certain temperature and humidity conditions, and after a certain period of time, measure its water absorption rate, dimensional change, mass change, and physical property change. Humidity testing can evaluate the water absorption and moisture resistance of hot melts in humid environments. For some hot melt products used in humid environments, such as hot melts in textiles and hot melts in building sealing materials, humidity testing helps to understand their performance stability and service life in actual use.
Standard: GB/T 2423.3 “Environmental testing for electrical and electronic products Part 2: Test methods Test Ca: Constant humidity and heat”, ISO 62 “Plastics – Determination of water absorption” and other relevant standards stipulate the humidity range, temperature range, test time and other parameters of humidity testing to meet the test requirements of different types of thermal fuses.

6. Comprehensive environmental stress screening test
(I) Principle
The comprehensive environmental stress screening test is a test method that subjects thermal fuse samples to the combined effects of multiple environmental stress factors, including temperature, humidity, vibration, voltage, etc. By applying a series of harsh environmental stress conditions to the samples, potential defects and failures in the samples are quickly induced, thereby screening out unqualified products. This test method can not only evaluate the weather resistance of the thermal fuse, but also comprehensively examine its reliability and stability under complex environmental conditions, which is of great significance for improving product quality and consistency.
(II) Standards
Temperature, humidity and vibration comprehensive test: GB/T 2423.36 “Environmental testing for electrical and electronic products Part 2: Test methods Test L: Temperature/humidity/vibration (comprehensive)”, GJB 150.9A-2009 “Environmental test methods for military equipment Part 9: Damp heat test” and other standards have detailed provisions on the conditions, methods and sample requirements for the temperature, humidity and vibration comprehensive test, including the setting of parameters such as temperature range, humidity range, vibration frequency, vibration acceleration, test cycle, as well as sample installation methods, test items and judgment criteria.
Temperature cycle and vibration comprehensive test: ASTM D4499-07 (2015) “Standard test method for thermal stability of hot melt adhesives” is mainly aimed at the thermal stability test of hot melt adhesives, but it also involves some related contents of temperature cycle and vibration comprehensive test, which provides a reference for the comprehensive environmental stress screening test of hot melt wires. In addition, some industry standards and enterprise standards will also formulate corresponding comprehensive environmental stress screening test methods and standards according to the characteristics and usage requirements of their own products.

7. Development Trends of Test Standards and Industry Application Cases
(I) Development Trends
Internationalization and Coordination of Standards: With the accelerated development of globalization, trade between countries is becoming more and more frequent, and the international trade of thermal fuse products also needs unified standards to regulate. Therefore, international standard-setting organizations such as the International Organization for Standardization (ISO) and the American Society for Testing and Materials (ASTM) are playing an increasingly important role in the formulation of thermal fuse weathering test standards. The standards of various countries are also gradually moving closer to international standards to improve the compatibility and mutual recognition of standards and promote the facilitation of international trade.
Innovation and Improvement of Test Methods: With the continuous advancement of science and technology, new test technologies and methods are constantly emerging, such as the application of spectral analysis technology, chromatographic analysis technology, and electron microscopy technology in thermal fuse weathering test, which can more deeply analyze the aging mechanism and performance changes of thermal fuses under different environmental conditions. At the same time, traditional test methods are also constantly improving and perfecting to improve the accuracy and reliability of test results and adapt to the test needs of different types of thermal fuse products.
Comprehensive consideration of environmental factors: In actual use, thermal fuses are often affected by multiple environmental factors at the same time, and a single environmental factor test may not be able to fully reflect their weather resistance. Therefore, future test standards will pay more attention to the comprehensive consideration of multiple environmental factors, and develop more complex and realistic environmental simulation test methods to more accurately evaluate the performance stability and service life of thermal fuses in actual use environments.
Enhanced correlation with actual use performance: The test standards will be more closely combined with the actual use performance of thermal fuses, not only testing the performance of the material itself, but also focusing on its performance in different application fields. For example, for thermal fuses used in the automotive industry, the test standards will pay more attention to its bonding performance, sealing performance and aging resistance in complex environments such as high temperature, high humidity, and vibration in the engine compartment of the car; for thermal fuses used in textiles, more attention will be paid to its resistance to hot water, friction, and UV rays during washing, drying, ironing, etc.
(II) Industry application cases
Automotive industry: Automakers have extremely high requirements for the weather resistance of thermal fuses, because cars need to operate in various harsh environmental conditions, such as high-temperature desert areas, cold Arctic areas, humid tropical areas, etc. Automakers usually use a series of strict weather resistance test standards to screen and evaluate thermal fuse products, including UV aging test, xenon lamp aging test, temperature cycle test, wet heat cycle test, etc. For example, when a certain automaker tested a new type of thermal fuse, it used the ASTM G154 standard for UV aging test. After 1000 hours of testing, it was found that the tensile strength of the thermal fuse only decreased by 5%, and the elongation at break decreased by 8%, indicating that it has good UV resistance and can meet the requirements of long-term outdoor use of automobiles.
Construction industry: Thermal fuses are also widely used in the fields of building sealing materials, thermal insulation materials, etc. Since the construction industry has high requirements for the weather resistance and durability of materials, the relevant weather resistance test standards are also very important. For example, a manufacturer of building sealants used the ISO 4892-3 standard for xenon arc aging testing to test a thermal fuse.The product was tested for 500 hours. The test results showed that the color of the thermal fuse changed little and the physical properties remained basically unchanged, proving that it has good weather resistance and is suitable for the application of building sealing materials.Electronic and electrical industry: In electronic and electrical products, thermal fuses are often used to fix electronic components and protect circuit boards. Since electronic and electrical products may be affected by various environmental factors such as temperature, humidity, and vibration during use, weather resistance testing of thermal fuses is also very important. For example, an electronics manufacturer used the IEC 68-2-30 standard for temperature change testing and tested a thermal fuse for 10 cycles, each cycle including high temperature storage (70°C, 4 hours) and low temperature storage (-40°C, 4 hours). The test results showed that the thermal fuse had no significant decrease in bonding strength and insulation performance after the temperature change, and could meet the use requirements of electronic and electrical products in complex environments.

8. Conclusion
The weather resistance test standard of thermal fuse is the key basis for ensuring its quality and performance stability, covering a variety of methods such as natural environment exposure test, artificial accelerated aging test, single climate condition test, climate cycle test and comprehensive environmental stress screening test. In the process of continuous development and improvement, these test standards are increasingly related to actual performance, and can better meet the quality requirements of thermal fuse products in different industries. As a supplier or purchaser of thermal fuse, in-depth understanding and mastery of these test standards will help to select suitable products, improve the market competitiveness of products, and promote the healthy development of the industry. At the same time, we also expect that future test standards will provide stronger support for the sustainable development of the thermal fuse industry driven by technological innovation and international cooperation.