Production data from a small bakery manufacturing line

Finding an optimal production schedule is a crucial part in improving manufacturing efficiency. Data collected from a real production line serves as the process's starting point. It provides details on the products, the processing procedures, how long they take, and the machines needed to carry out these steps. The production schedule is simulated using a flow shop model. The manufacturing environment determines the sort of flow shop model. The simplest model is a permutation flow shop, where all products are processed by machines in the same order. The majority of production systems in practice contain numerous distinctive constraints that make models quite complex. The "no-wait" flow shop model refers to a particular type of flow shop model where no waiting period is permitted between two successive stages of a product. A hybrid no-wait flow shop scheduling model can be used to explain the production environment in bakeries. Multiple machines are accessible here for a single processing stage, such as oven A or oven B for baking a product. Products' processing stages may not be organized in the same order depending on the recipe. Occasionally, the same dough is used to make several different bakery products. In these situations, bakers divide the dough after a few preliminary processing steps and carry out the remaining steps independently in accordance with the product recipes. Baking ovens need a lot of energy, and using them even when only partially occupied wastes energy. Therefore, in order to conserve energy, baking of a number of products may occasionally be conducted together that followed separate processing paths. The products are arranged into groups based on their inherent interdependence, such as baking or beginning steps being performed concurrently. At any stage of the production process, one product from this group may be processed. However, it influences the start time for the remaining products in the same group. Small and medium-sized bakeries rely on manual operation for many processing tasks. Therefore, manual tasks must be distributed among staff in order to continue the production without interruption. Some processing tasks need the use of two machines, or one machine and one employee at the same time. To prevent ingredient mixing, a machine may need to be cleaned after processing a product. For instance, after kneading dough containing oil seeds, a kneader is cleaned.寻求最优生产调度方案是提升制造效率的关键环节。从真实生产线采集的数据是该研究流程的起点，其涵盖了产品信息、加工工序、作业时长以及执行各工序所需的设备详情。本研究采用流水车间模型（flow shop model）对生产调度方案进行仿真，而制造环境决定了流水车间模型的具体类型。最简单的模型为置换流水车间（permutation flow shop），即所有产品均按照相同的工序顺序由设备完成加工。实际生产中的多数系统存在诸多差异化约束，导致模型复杂度显著提升。无等待流水车间模型（no-wait flow shop model）特指一类流水车间模型，其中产品在相邻两道工序之间不允许存在等待时长。 混合无等待流水车间调度模型（hybrid no-wait flow shop scheduling model）可用于阐释面包店的生产环境：单个加工工序可配备多台设备，例如用于产品烘焙的烤箱A与烤箱B。根据产品配方的不同，各产品的加工工序顺序可能并不统一。部分烘焙产品可使用相同的面团原料制作，在此类场景下，操作人员需在完成若干预处理工序后对面团进行分切，并依据不同产品的配方独立完成后续工序。烘焙烤箱能耗较高，即便处于半负载状态开机也会造成能源浪费，因此为节约能源，有时会将多条加工路径不同的产品集中在一起进行烘焙。此时需根据产品间的内在关联性（例如可同步进行烘焙或起始工序的产品）将其划分为若干批次，同一批次内的产品可在任意加工工序中依次开展作业，但该批次内其余产品的开工时间会受到当前产品加工进度的影响。中小型面包厂的多数加工工序依赖人工操作，因此需将人工任务合理分配至各操作人员，以保障生产连续不间断。部分加工工序需同时使用两台设备，或是一台设备与一名操作人员方可完成。为避免原料串味，设备在完成某一产品的加工后需进行清洁作业，例如在处理含油料种子的面团后，需对揉面机进行清理。