In a world where engineered products constantly push the boundaries for performance, tyre moulds are critical in integrating complex tread architectures into tyres to help improve water displacement rates from tyres, grip and durability. The quality of the tyre is not only influenced by the tread design and materials used but also the surface of the mould itself, which can become contaminated and foul from repeated curing.
WHAT are tyre molders doing ABOUT IT?
Kingpin Tyres, a family run tyre re-moulder based in Wem, Shropshire is a forerunner in its industry and have begun investigating laser solutions for cleaning tyre remoulds. They have a vested interest in cutting edge technology to ensure they deliver the highest possible quality re-moulds and best performance tyres for their select clients. To achieve this, Powerlase and Kingpin engaged in a collaborative feasibility project. The study focused on the suitability of high average power nanosecond pulsed lasers to clean the mould surface to a ready-for-use condition by selectively removing curing residue. The results of the investigation showed that custom optics engineered by Powerlase, allows removal of mould fouling by-products in under 30 seconds per mould segment without altering the mould’s metal substrate. The Vulcan 500c and Vulcan 1600e laser systems were tested successfully with the custom optics installed in the handheld Vulcan tool.
Conventional Cleaning and the need for change
Mould fouling is the presence of excessive contaminants on the surface of the mould which can alter the curing process, leaving the final tyre surface denatured consequently compromising performance. This contamination moreover undermines the effectiveness of release agents, worsening the fouling on the mould and increasingly degrading successively moulded tyres, leading to them being scrapped. To avoid wasting resources, tyre moulds are cleaned at frequent intervals so they can continue to be used. However conventional cleaning methods are often off-line and require tyre moulds to be removed and cooled before cleaning can take place, using techniques such as shot blasting or polymer media blasting. This leads to extensive down time, results in an opportunity-cost on the volume of tyres made and curbs productivity. Blasting processes may also risk the integrity of the tyre mould surface when using abrasive shot while struggling to fully remove tough residue when using softer media. Moreover, a considerable volume of non-recyclable waste material is produced from shot or media blasting, deepening the environmental impact of this method.
Subsequently, manufacturers are seeking alternatives which can clean surfaces more quickly and reduce the amount of waste material produced. Alternatives such as dry-ice cleaning are effective for on-line cleaning, that is, when moulds are still hot but quickly fall short when attempting to remove cold residue; contamination built up on moulds from successive that have been removed from the production line and left to cool. However, laser cleaning technologies have been able to provide fast contaminant removal of all grades of cold and hot residue while minimizing the production of waste, thereby omitting the disposal stage entirely. The custom optics fitted in the Vulcan systems ensure any damage to the metallic substrate is prevented by maintaining laser process parameters well below the damage threshold for the mould. Therefore laser cleaning solutions provide an attractive and environmentally conscious alternative to conventional shot and polymer media blasting.