In this paper we investigate the use of lot streaming in non-permutation flowshop scheduling problems. The objective is to minimize the makespan subject to the standard flowshop constraints, but where it is now permitted to reorder jobs between machines. In addition, the jobs can be divided into manageable sublots, a strategy known as lot streaming. Computational experiments show that lot streaming reduces the makespan up to 43% for a wide range of instances when compared to the case in which no job splitting is applied. The benefits grow as the number of stages in the production process increases but reach a limit. Beyond a certain point, the division of jobs into additional sublots does not improve the solution.

Inspired by the industries such as food and beverage, metal and steel, as well as petroleum and petrochemical ones, the current study addresses a joint order acceptance and scheduling, lot streaming in a flexible flow shop and batch delivery problem. For maximizing a profit objective function with trading off between the revenue of the accepted orders and the costs incurred, a novel mixed integer linear programming is proposed. This paper develops a hybrid metaheuristic algorithm based on the Genetic Algorithm. In the developed algorithm, (1) a heuristic, (2) a local search, and (3) a restart phase is proposed. To set the appropriate parameters of the algorithms, Taguchi experimental design was applied. The obtained results reveal the appropriate performance of the hybrid genetic algorithm.

Lot streaming is a technique of splitting production lots into smaller sublots in a multi-stage
manufacturing systems so that operations of a given lot can be overlapped. This technique can
reduce manufacturing makespan and is an effective tool for time-based manufacturing strategy.
Several research articles appeared in literature to solve this problem and most of these studies
are limited to pure flowshop environments where there is only a single machine in each stage.
On the other hand, because of the applicability of hybrid flowshops in different manufacturing
settings, the scheduling of these types of shops is also extensively studied by several authors.
However, the issue of lot streaming in hybrid flowshop environment is not well studied. In this
paper, we aim to initiate research in bridging the gap between the research efforts in flowshop
lot streaming and hybrid flowshop scheduling. We present a comprehensive mathematical
model for scheduling flexible hybrid flowshop with lot streaming. Numerical example
demonstrated that lot streaming can result in larger makespan reduction in hybrid flowshop
where there is a limited research than in pure flowshop where research is abundant.