مدلسازی رابطه ای داخلی و بهینه سازی برنامه ریزی تولید برای مسکن پیش ساخته

The ‘manufacturer-internal relationship optimization model (MIROM)’, a schematic framework for internal relationship, is proposed for the manufactured housing (MH) factory. This model emphasizes the relationship between customer order from retailers (i.e., customized MH) and the production process, indicating that these elements are not mutually exclusive. In particular, through surveys and site visits, the planning of the product mix and sequence in the MH factory is considered the most critical area of the MIROM framework. This paper aims to convey how these areas can be elevated to the planning level with innovative changes and optimization. A product mix optimization model with linear programming was developed and a sequence optimization model was created by incorporating just-in-time (JIT) approaches. The proposed strategic MIROM framework and the specific optimization models can contribute to achieving significant improvement in the internal MH production planning. It can be applied for the site-built housing industry with similar industrialized environments depending on the scale of the operation.

From the point of view of a manufacturer producing manufactured housing (MH), all supply chain activities belong to one of three macro processes — customer relationship management (CRM), internal supply chain management (ISCM), and supplier relationship management (SRM). For a supply chain to be successful it is crucial that the three macro processes are well integrated. However, for many MH manufacturers, CRM, ISCM, and SRM processes have little communication and the lack of integration hurts the supply chain's ability to match supply and demand effectively, leading to dissatisfied customers and high production costs [6]. In particular, the ISCM process aims to fulfill the demand generated by the CRM process in a timely manner and at the lowest possible cost. ISCM processes include the planning of internal production and storage capacity, preparations of demand and supply plans, and internal fulfillment of actual orders [4]. However, in terms of ISCM of MH industry, it was found through survey and site visits that production planning procedure is not standardized in a systematic way and the insufficient use of modern analysis tools are preventing smooth production flow in the facility. Specifically, there was difficulty in controlling the house order demand. The production level was different each month fluctuating seasonal backlog so that it was difficult to estimate actual delivery time exactly when the retailer makes a house order. Also, it was observed that in spite of producing various sizes of house models, there was no standardized sequence scheduling rule considering mixed model assembly. Many production managers used ‘rules of thumb’ to select actual production sequence and tried to sequence larger house models spaced out between smaller house models if possible. Under such an environment, it is necessary to develop a new capacity planning and new production scheduling method. Therefore, this paper describes the framework of an industry-specific internal relationship management solution for the MH industry and suggests a new paradigm for the MH production planning process. The main objectives of this paper are to (i) propose an MH industry — specific framework of internal relationship management at a macro level and (ii) develop an optimal product mix and sequence model for an operational level of production planning at a micro level. The proposed strategic MIROM framework and the specific optimization models will contribute to achieve significant improvement in the internal MH production planning and it will contribute to improve overall efficiency and cost-effectiveness of all types of site-built housing as well.

In order to solve the current needs of manufactured housing (MH) industry, new framework of internal supply chain management called ‘manufacturer internal relationship optimization model (MIROM)’ was proposed. This model emphasized the interrelationship between customer order from retailers (i.e., customized MH) and production process, indicating that these elements are not mutually exclusive. In particular, within the MIROM framework, product mix and product sequence in the MH factory were identified as the key constraints of the efficient supply chain performance, as a result, linear programming optimization model for product mix was developed and optimal sequence model was created by incorporating JIT concepts. The suggested optimal product mix model showed the direct savings in terms of space utilization, labor utilization and contribution profit per day. The suggested optimal product sequence model showed the indirect savings by reducing management cost due to constant speed of material consumption. In addition, depending on the scale of the operations, the proposed strategic MIROM frameworks and specific optimization models can be applied directly to the site-built housing industry with the similar industrialized environments.