Rubber Bushing Dynamic Functional & Durability

Rubber Bonding Quality & Structural Strength

Structure strength is the maximum external force an object can withstand before it collapses. Typically, rubber bushing is made of two or three metal sleeves which are securely bonded to rubber compound by a special adhesive.

The strength of rubber compound is much lower than metal sleeves, therefore it is the weakest part of the bushing structure. As a result, the formula design is one of the important keys to determine the structural strength of the bushing.

The bonding strength between rubber compound and metal sleeves is another key to determine the structural strength. If a rubber bushing with poor bonding strength is installed to the vehicle, separation between rubber compound and metal sleeves may occur in a short period of time, resulting in loss of control arm function.

Superior "structural strength" of rubber bushing depends on good formula design for the rubber compound and a very rigorous management and monitoring in the production process of bushings.

Under dynamic stressed and strained condition, the stiffness of rubber compound will attenuate gradually due to elastic fatigue. Besides, the rubber bushing will collapse because of cracked and broken rubber compound or poor bonding between rubber and metal sleeves. When this happens, the wheel alignment fails immediately.

The breakage of the rubber bushing is a gradual process. A fine crack appears in the beginning, and progress over time, the crack will grow and become larger and longer gradually, until it breaks completely and loses its function.

Another situation of bushing breakage happens to the separation of rubber compound from metal sleeves because of very poor bonding quality between rubber and metal sleeves. Such kind of quality problem always lead to a sudden collapse of bushing structure and loses its function.

Under dynamic stressed and strained condition, the mechanical stiffness of rubber material attenuates and deviates away continuously from the original standards. Eventually, the handling and riding comfort of vehicle becomes worse and worse.

The rubber compound used for control arm bushing must be both heat resistant and dynamic elastic fatigue resistant so as to slow down the speed of attenuation and maintaining good handling and riding comfort of vehicle for longer time.

Under high speed driving, the vehicle will float left and right if the mechanical stiffness is too low (too soft), this is particularly obvious while changing lanes at high speed. Or the car nods and shifts the lane while emergency brake. On the other hand, if the mechanical stiffness is too high (too hard), the road feeling becomes strong and obvious. As a result, the vibration and noise become stronger and louder, resulting in poor riding comfort.

Compared with the original OE parts made by Tier 1 suppliers of car manufacturers, those so called "Non-OE brand" control arm bushings available in the after-service market generally lack of this "dynamic stiffness" quality specifications.