“…This occurs at any time after pre-processing (Demir & Previtali, 2017), causing a longer processing time when the process begins at a later time (Cheng, Kang & Ng, 2004). A linear deterioration, i.e., the increase of part processing time at a constant proportion δ of the initial processing time, was assumed in this research (Mor & Mosheiov, 2021), leading to deterioration function D(x) in Equation ( 12), ( 12) where t = initial processing time (before deterioration), x = part sequence, and δ = deterioration rate of 0 or more (a higher δ means a faster deterioration, δ = 0 means no deterioration).…”