Owing to product proliferation and expanding high customer service provision, firms nowadays face severe competitive challenges in globalisation. The revised process or product design often involves delaying products differentiation until later production stages. Form postponement applying fuzzy theory and mathematical programming is implemented to formulate a multi-period, multistage assembly network model with multi-product under uncertain leadtimes to find a set of optimal alternative for searching optimal differentiation plans. The inherent fuzziness involved in determination of corresponding leadtimes is handled by expected values of fuzzy numbers, and a set of crisp values of leadtimes had executed by centre of gravity defuzzification.
Keywords: product variety, uncertainty, fuzzy sets, leadtime, defuzzification, multistage assembly network, differentiation plans, postponement strategy