The root cause of the ineffective seal

Vulcanized rubber seals are widely used in various fields. Once the seal is invalid, the machinery and equipment cannot be in normal operation, resulting in small property losses, and the actual operating staff lives are high in the safety accident dilemma. Therefore, you must cultivate good inspection habits when actually operating machinery and equipment, and carry out actual operations in strict accordance with the safety and security operating procedures of machinery and equipment. If the problem is found, handle it properly. Carry out careful analysis of many difficult problems, which will help everyone find the problem, and it will be convenient to take effective preventive solutions in the actual operation afterwards, and reduce the occurrence of all accidents.

The ineffectiveness of the seal may be caused by many aspects, such as unqualified quality and embrittlement of materials. Today’s key is to analyze the common ineffectiveness of machinery and equipment in the usual actual operation.

1. Invalidation caused by poor selection of materials

*First, everyone thinks that the selection of materials is a very critical stage in the production of machinery and equipment. The selection of appropriate and cost-effective materials is the basic standard to ensure the long-lasting * of the seal.

Common gasket materials include EPDM, NBR, VMQ, FKM or FPM, CR, etc. The characteristics of this vulcanized rubber are different, and the application is also different. The selection of materials must be considered from various aspects, such as the application temperature, whether the material can withstand the substance, the strength of the material, the reduction of long-term deformation, and the wear resistance.

The selection of materials is not correct. It seems that the simplicity is actually very complicated. It is not easy to select materials based on the main purpose. It is also necessary to learn to fit the natural environment of the application. For example, a customer hates the O-ring that has been applied. An O circle is very easy to break. Everyone checked the disassembled test product and found that the surface of the test product was cracked, and the texture was very similar to oxygen embrittlement. Everyone also learned about the natural environment of the O-ring application and found that there are many industrial equipment and motors around. This is the answer: the flames of the motor can cause safe oxygen, leading to a higher concentration of carbon dioxide in some small natural environments; and the customer selected the material as *nitrile rubber, which is not resistant to safe oxygen. In order to better certify the results, we conducted tests in the laboratory's oxygen aging box. As a result, similar cracks appeared on the surface of the new O-ring presented by the customer. Since the seal is only in contact with gas for a long time, and there is no other chemical substances such as mineral oil, we strongly recommend EPDM to replace customers' current products.

Sometimes the application of the natural environment is very complicated, or it is a brand new and upgraded design scheme, and the selection of materials is not very easy. In addition to careful identification of various influencing factors, system testing must also be carried out.

2. The quality of the seal product causes the seal to be invalid

The manufacturing quality of the seal is closely related to the credibility of the final product. Common problems include: unstable quality of raw materials, wrong raw materials when mixing vulcanized rubber, poor storage of raw materials or mixed rubber (cross-environmental pollution), uneven mixing of plastic pellets, and vulcanized rubber standards (temperature, time, Working pressure, etc.) improper place, improper storage of seal products, improper use of mold shells, etc. This problem usually involves quality management during processing. When placing an order when selecting a seal manufacturer, it should go through several investigations, investigations and product testing. In the whole process of supply, manufacturers of seals can also be required to produce accurate and precise inspection reports.

3. The design plan is incorrect

The incorrect design plan is generally caused by the lack of knowledge of the design plan staff. For example, underestimation of the working pressure of the seal, incorrect understanding of the contact pressure on the raised surface, and unscientific design of the trench for placing the seal, etc.

Finite element (FEA) is often used to assist in the design of seals and failure descriptions. Everyone once made a seal for a US customer. The seal was mainly made of plastic and partly covered with vulcanized rubber. During the whole process of inspecting the parts, the customer found that a part of the plastic was very easy to crack during the inspection, and then concluded that the plastic part was destroyed during the secondary molding (the vulcanized rubber was coated on the plastic part). After analysis, everyone found that the plastic parts were all cracked in one area. According to the finite element method, everyone finds that the damaged location of the plastic part is in fact the area where the seal is subjected to greater ground stress, and the ground stress here is far beyond what the plastic can bear.

If the customer has used the finite element method to analyze the product in the case of the design plan, it will not only prevent similar errors, but also save its time and money. Naturally, in order to successfully predict and analyze the characteristics of vulcanized rubber seals, it is necessary not only to have suitable finite element mobile phone software, but also to have rich and colorful material work experience, model work experience and long-term data accumulation.

4. Seals are invalid due to improper use of seals

A good seal, if used improperly, will also cause all products to be invalid, such as incorrect application of grease.

A certain customer feedback from everyone said that the specifications and regulations of O-ring parts are very different. When we analyzed the sample, we discovered that the customer used the wrong grease. The O-ring is made of EPDM rubber, and the material itself is not resistant to mineral oil grease. Customers applying this type of grease will cause the volume of the product to solubilize. Later, if the customer changed to methyl silicone oil, there was no problem.

Another common problem is incorrect installation. For example, distortion was caused during the whole process of O-ring installation; uneven force of seals was caused due to improper installation; errors such as insufficient lubrication of seals. If this kind of error is caused by the manufacturer of the seal, then it falls within the scope of manufacturing quality manipulation. If it is caused by the ordering party or a third party, it is improper use.

*Efficient design scheme is one of the key elements to ensure the reasonable application of seals.

Nowadays, high-tech technologies are developing rapidly, and many new sealing materials and construction engineering designs have appeared in the market to consider various strict application regulations. In addition, most of the seal manufacturers have also selected scientific research quality system management. Unfortunately, no such diligence can prevent the seal from being ineffective. Therefore, the failure description seems to be particularly critical.