1. Improper selection of glue

Solution: choose the right adhesive

2. The metal surface treatment fails, so that when the primer is vulcanized, it cannot achieve physical adsorption with the metal surface well.

（1） Roughen the metal surface to ensure that when the primer is vulcanized, it can smoothly and tightly adhere to the metal surface. The commonly used treatment methods are: sandblasting and shot blasting of metal inserts in products;

（2） The metal surface should not be rusted, and should not be stuck with impurities such as oil, dust, water droplets, etc.;


3. The stability of the glue coating process is poor, the glue is too thin, the coating is missed, and the residual solvent is left.

（1） Pay attention to the surface coating operation to prevent the glue from leaking and coating less; the importance and influence of the top coating (the surface film formation of the coating is related to the surface tension of the coating, gravity, construction mechanical force, material intermolecular force and chemical reaction force) Therefore, the quality of the topcoat is affected by the comprehensive influence of these forces, so it is extremely important to use different processes, superb skills, and skilled craftsmanship.)

（2） The metal parts coated with glue should be fully dried to allow the solvent to fully volatilize to prevent the residual solvent from volatilizing during vulcanization, resulting in bond failure;

（3） To ensure a certain thickness of glue on the metal surface. In this way, on the one hand, it can ensure that there is sufficient glue on the metal surface and the rubber entering the mold cavity and the mutual diffusion and co-crosslinking effect are fully carried out, so that the metal surface and the vulcanized rubber are fully bonded; on the other hand, the metal surface to the surface of the product A certain modulus gradient layer can also be achieved, so that there is a gradual transition from soft to hard between the rubber surface of the product and the metal insert. (stiffness gradients Beneficial gradients in the ratio of elasticity to stiffness of rubber section);

4, the formula is unreasonable, and the vulcanization speed of the rubber compound is inconsistent with the vulcanization speed of the glue (the formula generally refers to the rubber compound formula and the glue formula)

（1）Improve the formula to ensure sufficient scorch time;

（2） Improve the product mold and formula to ensure that the rubber material reaches the bonding part of the metal insert at the fastest speed;

（3） Try to use ordinary and semi-effective vulcanization systems (the fatigue resistance and thermal oxygen aging properties of different vulcanization systems are significantly different. In general vulcanization systems, as the ratio of accelerator to sulfur changes from small to large, the vulcanization system changes from ordinary to ordinary. The vulcanization system transitions to a semi-effective vulcanization system, and then to an effective vulcanization system. The vulcanized rubber network structure changes from polysulfide cross-linked bonds to the coexistence of polysulfide bonds, disulfide bonds and monosulfide bonds. Finally, the full vulcanization system becomes Brittle structure dominated by mono- and di-sulfide bonds. The physical and chemical properties of general rubber products can be better adapted to production and use in the first two vulcanization systems.), increase the amount of sulfur (relatively speaking, not more the better) to achieve polysulfide crosslinks;

（4） Improve vulcanization conditions (temperature, time and pressure);

（5） Reduce the use of frost-prone substances and plasticizers to prevent them from migrating to the rubber surface during vulcanization, thereby affecting bonding;

（6） If the rubber compound is parked for too long, a certain physical and chemical reaction will occur in contact with the air, resulting in the failure of the rubber compound vulcanization. Use fresh rubber instead.

5. Insufficient pressure

solution:

（1）Increase the clamping pressure during vulcanization

（2） Pay attention to the position and size design of the overflow port and the vacuum tank to prevent the pressure in the mold cavity from being released through them, resulting in insufficient pressure when the product is vulcanized;

（3） Ensure that the mold is closely matched to prevent excessive local pressure loss;

6. Volatilization or curing of the active ingredients of the glue

solution:

（1） For metal parts that need to be pre-baked before vulcanization, attention should be paid to the time and temperature control of pre-baking. Excessive pre-baking will cause the volatilization of reactive substances and the scorching (or curing) of the glue; (baking: heating and drying)

（2） Pay attention to prevent the metal parts from staying in the mold for too long during operation;

7. Foreign matter such as vulcanized rubber and rubber chips is mixed into the rubber compound and vulcanized together with the rubber compound, causing the bonding part of the metal insert and the rubber compound to be degummed in a small area during vulcanization, which in turn causes the product to peel off in a large area.

Solution: Strengthen material management