Development of a Real-Time Cure Optimization Process Control System and its Use with Low Temperature Cure Elastomers
|Date Published||January 1, 2006|
During moulding, when temperature is applied to uncured rubber compound, it initially softens with increasing temperature, after which the formation of vulcanisation crosslinks stiffens the rubber until it reaches its modulus maximum. If the rubber experiences more heat than is required to cure the part, energy is wasted. Also, the part is left in an over-cured state, often with compromised mechanical properties which may result in rejection or customer returns. The frequency of over-curing can be minimised by ensuring that “exactly” the correct curing schedule is always used. This provides optimised components with the added benefit of reduction in energy costs. To achieve this, a concept is employed of controlling/monitoring the amount of heat applied to the component by identifying units of cure based on actual rubber temperature rather than input temperature. In this work, this approach is described along with its application to processes using processable low temperature cure elastomers (PLTCs), which further improve energy efficiency of the process. PLTC materials have been developed capable of curing at 70C and producing equivalent and in some cases enhanced mechanical properties when compared to the “conventional” compound it replaced; an example is discussed.