Earticle

In the manufacturing industry of metallic bellows, accurate cost estimation and quotation generation are crucial because the design dimensions and material specifications vary with each OEM order. This study aims to develop a Microsoft Excel-based software that automatically calculates production costs and generates quotations for single-type and double-type circular bellows based on the EJMA (Expansion Joint Manufacturers Association) 10th Edition design standards. The proposed program integrates the essential cost components — raw materials, forming processes, welding, assembly, inspection, and overhead — into a modular calculation system. Using VBA (Visual Basic for Applications), the system allows users to input design parameters (such as pitch, convolution height, mean diameter, and thickness), after which it automatically computes material consumption, manufacturing time, and total cost, providing an itemized quotation sheet. This automation not only reduces manual calculation errors but also significantly shortens the lead time for quotation preparation. The research demonstrates that the developed system achieves cost estimation accuracy within ±3% of actual production costs and can be easily adapted to different bellows configurations, thereby enhancing productivity and competitiveness in OEM manufacturing environments.