You can determine the grade of silicone foam products from two aspects: "subjective experience judgment" and "objective data detection"
1. Subjective Experience Judgment (Preliminary and rapid screening).
This method is applicable to scenarios such as procurement selection and initial inspection of incoming materials. It does not require precision instruments but demands certain experience.
Appearance and Color: High-grade products have uniform and consistent colors, without obvious color differences, stains or impurities. Low-grade products may be dark in color, uneven or have spots.
Surface: The surface cell structure should be fine, uniform, and free of major defects. When touched by hand, it should feel smooth and flat, without any obvious grainy or tearing sensation. Poor-quality products may have rough surfaces, cracks or holes.
Shape: The cutting process is excellent, with neat edges, no burrs, flash or deformation. Hand Feel and Elasticity: After being pressed by hand, high-grade silicone foam can quickly rebound and return to its original shape, with almost no permanent deformation. Low-grade products have a slow rebound and may even leave indentations.
Softness (Softness) : Soft to the touch, comfortable to compress, and the softness of different batches should be consistent. Both being too hard and too soft may be signs of non-compliance.
Texture: The overall texture is uniform. When torn by hand, you can feel good toughness and strength, and it will not be easily torn apart. Inferior products may become brittle or stiff.
High-quality silicone foam products usually have no Odor or only a very faint smell of silicone material. If a pungent chemical smell or strange odor is detected, it indicates that inferior additives (such as inferior vulcanizing agents or foaming agents) may have been used in the production process, or there may be residual solvents. It is a low-grade product and may even not be environmentally friendly.
Second, objective data testing (precise and authoritative grading)
This is the authoritative method for ultimately determining the quality grade of products, which relies on professional testing equipment and standardized testing methods.
The following performance indicators are mainly referred to:
What is Apparent Density? It is the mass per unit volume (g/cm³). Why important: Density directly affects the weight, softness and hardness, buffering performance and cost of the product. Different application scenarios have different requirements for density (for example, high density is needed for sealing, while low density may be required for shock absorption). The density value of high-grade products is stable and deviates very little from the design target value.
What is Compression Set: The ability of a sample to recover its height after being compressed to a certain deformation at a specified temperature and time. It is a key indicator for measuring elastic recovery performance. Why important: This indicator is of vital importance as it directly determines whether the seal will fail after long-term pressure. The lower the value, the better the resilience and creep resistance, and the longer the product's lifespan. For instance, when tested at high temperatures (such as 125°C/150°C) for 22 hours with a compression rate of 30%, the deformation of low-grade products may exceed 20%, while that of high-grade products can be controlled within less than 5%.
What is Temperature Resistance & Thermal Stability: It examines the changes in the performance of a product under high-temperature (such as 200°C) and low-temperature (such as -40°C) environments. Why important: The core advantage of silicone is its wide temperature range. High-grade products can still maintain good elasticity and physical properties after experiencing high and low temperature cycles, without becoming brittle, melting or cracking.