Planning Process Families with PROGRES

Introduction

To survive, manufacturing companies strive to timely offer a large number of customized products at affordable costs. Developing product families, instead of single products, has been well accepted as an effective means to accommodate the increasingly individualized customer expectations while leveraging cost of delivering the resulting variety (Meyer and Utterback, 1993). A product family refers to a set of customized products that assume some common structures and yet possess specific features and functionalities to meet particular customer requirements. Many approaches and methodologies have been introduced to accommodate product family development (e.g. Agard and Kusiak, 2004; Anderson, 1997; Hsiao and Liu, 2005). With focus on design, these methods can help companies reduce design costs and time and reuse proven design knowledge, as evidenced by some successful industrial cases, including Sony Walkmans (Sanderson and Uzumeri, 1997), Compaq personal computers (Meyer, 1997) and Lutron lighting systems (Pessina and Renner, 1998). However, they are not able to facilitate other issues of product family development (e.g., production). Authors have pointed out successfully developing product families hinges on efficiency of both design and production (do Carmo-Silva and Alves, 2006; Wiendahi et al., 2007)

Due to the finite manufacturing resources existing on shop floors and the short delivery lead times, product families lead to difficulties in production process planning, and further in production (Wortmann et al., 1997). This is because the production optimality of single products may conflict that of a product family (Jiao et al., 2007). In response to the inefficiency of the traditional approaches to planning, planning production processes for product families rather than single products (i.e., process family planning) has been put forward as an effective means for companies to obtain production efficiency of product families (Martinez et al., 2000; Schierholt, 2001; Zhang and Rodrigues, 2009). This is accomplished by exploiting process reuse and near mass production efficiency underlying product families. The rationale of process family planning lies in anchoring the planning of production processes for product family members to a common platform so as to reconfigure the existing processes and capitals (Azab et al., 2008).

A process family refers to the set of production processes to produce the set of product variants in a family. In this regard, a production process is to produce a complete product, which consists of both component parts and component assemblies. It is formed by a number of operations, operations precedence and manufacturing resources. Further, in accordance with the hierarchy of a product in consideration, operations and other associated process elements in a production process can be grouped as several subprocesses. Each such subprocess is to produce the corresponding component part or assembly in the product hierarchy. In this regard, dealing with part manufacturing, cellular manufacturing compliments process family planning. With operations and manufacturing resources determined in process family planning, the appropriate methods reported in cellular manufacturing can be used to, e.g., group parts with similar routings.