Complete Guide to Magnet Environmental Testing｜Introduction to HAST, PCT, Salt Spray, and Thermal Aging Tests

Understand the key factors of heat resistance, moisture protection, and corrosion resistance in magnets—accelerated aging tests help validate product reliability.

This article is written by New Favor Industry Co., Ltd.
New Favor specializes in the manufacturing and application solutions of high-performance rare earth magnets such as Neodymium Iron Boron (NdFeB), dedicated to providing stable and reliable magnetic component support to clients worldwide.
Whether you are in the electronics, energy, or automation industries, our expertise ensures efficient and precise magnetic solutions tailored to your needs.

Why do magnets need to undergo environmental testing？

The magnetic performance and structural stability of magnets can be affected by real-world operating conditions such as high temperatures, humidity, salt in the air, and repeated mechanical impacts.

These external factors may cause magnetic degradation, surface corrosion, or even structural damage, thereby reducing overall product performance and lifespan.

Therefore, conducting environmental simulation testing and accelerated aging verification before product development or mass production is a critical part of magnet quality control.

What is Accelerated Aging Testing for Magnets？

Environmental testing is a method used to assess the long-term stability and reliability of magnets by simulating extreme conditions (e.g., high temperature, high humidity, corrosion) that may occur in actual working environments.

These tests are often categorized as Accelerated Aging Tests, which help identify changes and potential risks in a short period of time. This approach shortens testing durations and ensures that magnets can operate reliably within defined timeframes and environments.

Four Common Accelerated Aging and Environmental Testing Methods for Magnets

	Test Type	Environmental Parameters	Focus
1.	HAST Highly Accelerated Temperature and Humidity Stress Test	Temperature, Humidity, Pressure	Magnet Body Anti-corrosion
2.	PCT Pressure Cooker Test	Temperature, Humidity, Pressure	Coating Anti-corrosion
3.	SST Salt Spray Test	Exposure	Coating Anti-corrosion
4.	TAT Thermal Aging Test	Temperature	受熱後磁性能

1. HAST Test
Highly Accelerated Temperature and Humidity Stress Test

HAST 試驗，有時被稱為非飽和蒸汽試驗，主要用於評估磁鐵對於濕氣的抵抗能力，亦與抗腐蝕能力高度相關。

此試驗依產品需求，將環境條件設定在較高的溫度、(未飽和)濕度以及氣壓，藉由加高之氣壓使濕氣更快速從磁體表面滲入內部，因此磁體結構和表面的緻密程度成為影響結果之關鍵因素。

Standard reference：JEDEC22-A118

Extended Testing: Low Weight Loss Test
With the growth of wind power and electric motor applications, the demand for uncoated magnets has increased. The Low Weight Loss Test, derived from HAST (Highly Accelerated Stress Testing), is widely used to verify the corrosion resistance of bare magnets, especially in high-stress environments. Magnets that pass specified test standards are referred to as low weight loss magnets.The environmental conditions and test parameters are as follows ：

	Temperature	Humidity	Pressure	Duration	Weight Loss Standard
U.S. Standard	120℃	95% RH	2 atm	96 hrs	<5-10 mg/ cm²
Europe Standard	130℃	95% RH	3 atm	168 hrs	<2-5 mg/ cm²
New Favor can meet stricter requirements (e.g., <1.0 mg/cm² under European conditions) upon request.

2. PCT Test
Pressure Cooker Test

This test simulates long-term corrosion under high pressure, temperature, and saturated steam conditions.
It mainly assesses coating durability under harsh environments.
Typical condition: 120°C, 2 atm, 100% RH, 24 hours or longer.

Standard reference： JESD22-A102-C

3. SST Test
Salt Spray Test

SST is used to evaluate the corrosion or rust resistance of magnets.

During testing, magnets are exposed to a continuous spray of 5% sodium chloride (NaCl) solution at 35°C. The corrosion condition is then observed. Depending on product requirements, the test temperature and duration can be adjusted. Time is typically measured in 24-hour increments. The controlled environment primarily simulates exposure to real-world conditions through material contact.

This test is widely applied to magnets used in wind turbines, motors, and transportation—where weather resistance is critical.

Reference standard：ASTM B-117

4. TAT Test
Thermal Aging Test

與前述以耐蝕性為主的測試不同，熱老化測試主要針對磁鐵在高溫長時間暴露後，磁性能的穩定性。

試驗中，將成品置於特定溫度烘烤1~2 小時，再量測其磁通量下降的程度。下降百分比越低，代表磁鐵耐熱程度越佳。

The Value of Environmental Testing

These testing methods allow manufacturers and engineers to:

• Predict magnet lifespan and failure risks

• Evaluate coating performance and bonding

• Choose suitable coatings or materials based on end-use conditions

• Ensure product quality and customer trust

Applicable across industries such as renewable energy, EV motors, automation, and consumer electronics.

Need tailored magnet testing solutions？

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If you're looking for a high-performance and reliable magnet solution, feel free to contact the New Favor team. We provide design consultation and processing services tailored to your application needs.

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