Analytical Investigation of Colour Management Systems for Achieving Consistent Colour Quality in Automotive Plastic Components Manufactured in Nigeria

Colour consistency across automotive plastic components produced in different facilities or at different times is a critical quality requirement for vehicle assembly operations, where colour mismatch of exterior panels and interior trim is commercially unacceptable. This study analytically investigates colour management systems applied to coloured thermoplastic components manufactured for automotive assembly at production facilities in Lagos State, South West Nigeria. The study examines the sources of colour variation across the polymer compounding, injection moulding, and assembly chain, employing spectrophotometric measurement in the CIELAB colour space at multiple production stages. Colour tolerance specification, pigment batch variability, melt temperature effects on pigment performance, and metamerism under standard automotive colour assessment illuminants were analysed. A colour management workflow was developed and tested against production data from a six-month period. Results identify pigment batch-to-batch variability as the dominant source of colour deviation, accounting for 52 percent of total colour variation as assessed by analysis of variance. Melt temperature variation of plus or minus 10 degrees Celsius contributed 23 percent of colour variation for thermally sensitive pigment systems. Metamerism assessment revealed significant colour mismatch under D65 versus A illuminant for three pigment combinations used in interior trim components, requiring reformulation. Implementation of a standardised colour approval protocol reduced out-of-specification colour incidence from 8.4 to 2.1 percent over the monitoring period. The study provides a practical framework for colour management system implementation in Nigerian automotive plastics manufacturing, enabling systematic colour quality improvement across the supply chain. Keywords: colour management, automotive plastics, spectrophotometry, CIELAB, colour consistency