When products undergo airtightness testing, if leaks are found or the test fails, many manufacturers' first reaction is to "apply some grease" to the sealing rings. While this seems simple and crude, is it truly effective?
The answer is: grease can indeed improve sealing performance to some extent, but only if you choose the right grease. If you choose the wrong grease, it will not only fail to improve leakage, but may also cause the seal to be damaged faster.
Why does this happen? Because most sealing ring materials (such as rubber, TPU, silicone, TPV, etc.) have varying degrees of "oil absorption" and "swelling" properties. Many greases on the market contain mineral oil, esters, or certain polar components, which can react chemically with the sealing material, causing the sealing ring to soften, swell, become sticky, or even crack. This phenomenon is called "material incompatibility."
If they are incompatible, changes in the size of the sealing ring will exacerbate the leakage. The original 0.1 mm sealing gap will be further amplified, and the airtightness test will naturally fail.
Therefore, simply adding some grease won't solve the problem; three key points need to be considered:
First, check if the grease is compatible with the seal material. Different rubbers have different tolerances to oils; for example, NBR is sensitive to esters, EPDM to mineral oils, and PC to silicone oils. Choosing the wrong oil often leads to the failure of the seal.
Secondly, check if the grease has the right consistency and filling properties. If it is too thin, it will penetrate into the material and cause softening; if it is too thick, it will not be able to form a uniform oil film, will not be able to fill the micropores, and will not improve the sealing performance.
Third, check whether the grease has water resistance, temperature resistance, and aging resistance. Since the seal is constantly exposed to changes in temperature, humidity, and pressure, the worse the grease's stability, the more obvious the sealing problem will be.
The correct approach is to first determine the cause of the leak, and then select the appropriate grease based on the material, structure, and operating conditions, rather than blindly applying grease. For many manufacturers, this step is often far more important than they realize.
Baoxing can customize specialized greases for various sealing rings in the manufacturing industry. These greases have excellent plastic compatibility, complete certifications, and are suitable for export. Free sample testing is available; please feel free to message us to request a sample.
