DIN 53497 Hot Storage Test of Molds Made from Thermoplastic Molding Materials Without Exposure to External Mechanical Stress

The standard “DIN 53497 Testing of plastics - Hot storage test of molds made of thermoplastic molding materials without exposure to external mechanical stress”, published by the German Institute for Standardization (DIN), describes a test method for evaluating the heat resistance and dimensional stability of molded parts made of thermoplastic materials under high-temperature conditions without any external mechanical load.

Thermoplastic molded parts often contain internal stresses resulting from the injection molding process (e.g., due to uneven cooling, molecular orientation, or shrinkage). When exposed to heat during use (e.g., in automotive interiors, electrical appliances, household goods), these stresses can relax, leading to:

• Impact / damage
• Shrinkage
• Changes in shape or size
• Surface defects (sinking marks, stress bleaching)

Hot storage testing simulates this type of thermal exposure without stress (parts are loosely placed without compression or loading) to reveal the long-term thermal behavior and processing quality of the material/molded part.

This standard includes two main procedures:

• Method A Fixed storage time, variable temperature: Samples are stored at increasing temperatures for a fixed period (typically from a few hours to several days) until visible changes occur or a defined limit is reached.
• Method B: Constant temperature, variable storage time: Samples are exposed to a constant temperature (selected according to the expected operating temperature or material data sheet) and the time elapsed until unacceptable changes occur is determined.

In practice, many testing laboratories use a simplified version with constant temperature levels (e.g., 90 degrees, 100 degrees, 110 degrees, 120 degrees) for a specific period (usually 24 hours, 48 ​​hours, or longer) and then conduct an evaluation.

The basic elements of the test procedure are generally as follows:

• Samples: Molded thermoplastic samples are produced according to defined dimensions and conditioning requirements. Typically, actual molded parts (not standardized test strips) or representative sections are used.
• Conditioning: Parts are tested either as received or after defined conditioning.
• Storage: Samples are placed in a ventilated oven at a specific temperature (depending on the material and application). Loose placement is achieved in a circulating air oven or similar controlled heating chamber (no stacking pressure, no fixing). Samples remain in the oven for a predetermined period, which can vary from a few hours to several days.
• Temperatures: Typically range from 80-150 degrees Celsius depending on the thermoplastic (e.g., PP, ABS, PC, PA, POM).
• Cooling and conditioning: After the exposure period, the samples are cooled under standard laboratory conditions.
• Evaluation: After cooling to room temperature, the samples are examined in the following aspects:
• Visual inspection (warping, deformation, cracks, discoloration, gloss change)
• Dimensional/functional measurements (impact or deformation, dimensional changes, possible changes in mechanical properties)
• Sometimes comparison with reference photos or limit samples (cracking or brittleness, surface defects)
• Classification is possible (e.g., passed, minor changes acceptable, failed)

DIN 53497 testing is used in many industries where thermoplastic parts are subjected to thermal loads during storage or use. Typical application areas of this standard include:

• Automotive industry: Instrument panels, clips, housings, interior parts, interior and under-hood components.
• Electrical and electronics: Electrical/electronic enclosures, connectors, insulation components.
• Consumer products: Appliance housings and plastic casings, household appliances
• Industrial components: Technical molded parts, molded structural or functional parts where dimensional stability under heat is critical.
• Quality control during material/process qualification.
• Addressing complaints related to electric shock.

This test helps engineers ensure that materials do not lose their shape or strength when exposed to heat over time.

This standard does not have a direct international equivalent, but it is conceptually similar to parts of the ISO 188 standard or various automotive original equipment manufacturer specifications (e.g., VW PV 1303, BMW AA-005 standards).

This standard is often used in conjunction with other heat-dependent tests, such as Vicat softening temperature, heat deflection temperature, and ball compression test. These complementary tests provide a broader understanding of the mechanical, thermal, and structural behavior of polymer materials.

In short, the DIN 53497 standard includes a test method for evaluating the behavior of thermoplastic molds when exposed to high temperatures for extended periods. This method is used to determine how thermoplastic components respond to heat aging or hot storage conditions. This can affect their mechanical integrity, dimensional stability, and overall performance. It is particularly important for plastics used in environments where components may be exposed to heat for extended periods, such as automotive interiors, electrical enclosures, and industrial equipment.

The primary purpose of the DIN 53497 standard is to simulate long-term thermal exposure and evaluate how thermoplastic materials change under these conditions. This test helps to determine:

• Resistance of thermoplastic molds to thermal aging.
• Dimensional stability after prolonged exposure to heat.
• Potential deformation or warping
• Changes in mechanical or physical properties

Manufacturers use this test to verify that molded plastic parts retain their functionality and structural integrity when stored or used at high temperatures.

Thermoplastics can soften, deform, or deteriorate when exposed to heat for extended periods. The DIN 53497 standard provides a standardized method for assessing these risks. Through this test, manufacturers can:

• We can compare the heat resistance of different materials.
• It can verify compliance with product specifications.
• It can estimate long-term reliability.
• It can support quality control and material selection.

In conclusion, the DIN 53497 standard defines a hot storage aging test that evaluates the resistance of thermoplastic molds to prolonged exposure to high temperatures. The method is widely used for material qualification, product development, and quality assurance, helping manufacturers ensure the long-term reliability of thermoplastic components in heat-exposed environments.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the DIN 53497 standard.