Abstract
BIW holes are one of the crucial and inevitable design requirements for various functions like draining excess cathodic electro deposition (CED), paint and anti-corrosion coating, providing access to components during assembly, facilitating body transportation during production, etc. But closing these holes properly is also an equally important factor. Otherwise, severe impact on noise, vibration and harshness (NVH) performance, aesthetics and durability can be caused due to humidity penetration along with engine noise, dust entry, etc. This paper describes an innovative solution called “Flexiseal Hole Cover”, introduced first time in automotive industry that overcomes all barriers present in existing technologies with improved performance, applicability, and reduced component cost. It is a five-layer laminate structure where silicone liner gives handling ability of uncured material. Based on real world vehicle usage pattern and field issues faced with existing options, a thorough validation plan was designed. Primary requirements were adhesive strength, high temperature aging resistance, humidity resistance, water leakage, stone chip resistance, weatherability, poly vinyl chloride (PVC) and paint compatibility, acoustic solution etc. Proposed technology hole cover met all technical requirements and acceptance criteria specified as per design validation plan or surpassed the requirements. They were found compatible with sealer, paint materials and processes. Hence can be applied in any stage like body in white (BIW) build or paint shop. Overall test results met or surpassed performance requirements. Proposed technology was also found to be cost efficient as compared to existing options for hole cover. As for example, for plugs, every hole size needs different hole plug and each plug needs separate tool to manufacture. Whereas, proposed technology can be die cut into any shape. In addition to this, new hole covers were found to be significantly economic with respect to storage, logistics cost, investment costs involved for new molding tools for every new dimension, process miss-outs, etc. A rough estimation shows 60% cost and 70% weight can be reduced with ease of application in body shop and compatible with paint material and process.