The perennial challenge for the industry is to make parts, assemblies and machinery lighter and more efficient. This has led to progressively wider application of composites due to their excellent strength, stiffness and corrosion resistance properties. Composite components are assembled predominantly by fastening, which makes drilling a common machining process for such components. Delamination of the component surface at entry and exit of the drill is a drilling defect frequently encountered. Assessment of the severity of the delamination is necessary for correction and improvement of the performance of the parts and assemblies. Over a period of time, several factors have been suggested as the index of delamination for comparison and control. Also, various techniques are being adopted to measure the extent and severity of delamination so as to calculate the assessment factor. This study aims to present and review the different means and methods for the assessment of delamination.

Composites are cutting edge engineering materials for modern high-technology products. Their heterogeneous structure entails processing defects uncommon with metallic parts. Drilling is a crucial manufacturing process to facilitate fastening and assembly of composite components. High-speed drilling especially is a promising technique to increase the productivity as well as the quality of the drilled hole. The severity of delamination damage around the drilled hole is a critical factor in the error-free performance of these parts in service. A new method to characterize the delamination induced by drilling with a comprehensive assessment factor called effective equivalent delamination factor is developed to overcome the limitations of other measures being used hitherto. The capability and appropriateness of effective equivalent delamination factor as a delamination assessment factor are verified from experimental results.