* Corresponding author. Tel.: 001 319 335 5934; fax: 001 319 335 5424; e-mail: ankusiak@icaen.uiowa.edu Robotics and Computer-Integrated Manufacturing 14 (1998) 415 — 427 Design for agility: a scheduling perspective Andrew Kusiak,* David W. He Intelligent System Laboratory, Department of Industrial Engineering, The University of Iowa, Iowa City, IA 52242 - 1527, USA Abstract Agility is the ability of a company to produce a variety of products in a short time and at a low cost. This demands that products and manufacturing systems be simple, robust, and flexible to allow for quick response to the changing market. Scheduling of manufacturing systems in a changing environment is complex. This paper attempts to simplify scheduling of manufacturing systems through appropriate design of products and manufacturing systems. An attempt has been made to generate rules that allow to design products and systems for easy scheduling. Four design for agility rules are proposed in the paper. The first rule deals with decomposition of a manufacturing system. The rule simplifies the scheduling problem and reduces the total changeover cost. The second rule is concerned with design of products with robust scheduling characteristics. Product designs with robust scheduling characteristics can improve the response of a manufacturing system to the changes in the product demand and mix and reconfigura- bility of the system. The third rule results in a streamlined assembly line which has the type of product flow that simplifies scheduling. The fourth rule emphasizes the reduction of the number of stations in an assembly line. Examples are provided to demonstrate the benefits from using these rules. The implemention of the four rules is also discussed.  1998 Elsevier Science Ltd. All rights reserved. Keywords: Agile manufacturing; Scheduling; Design for manufacturing; Decomposition 1. Introduction Agile manufacturing is an emerging concept in indus- try that aims at achieving manufacturing flexibility, speed, and responsiveness. According to the definition provided by the Agile Manufacturing Enterprise Forum (AMEF), agile manufacturing has at least the following four characteristics [1]: (1) Greater product customization — manufacturing to order, but at a relatively low unit cost. (2) Rapid introduction of new or modified products. (3) Upgradable products — designed for disassembly, re- cyclability, and reconfigurability. (4) Dynamic reconfiguration of production processes — to accommodate swift changes in product designs or entire new product lines. Although the definition of agility has not been univer- sally agreeded on, some of its elements have been accep- ted throughout industry. The basic concept of agility is reflected in the description given in [2]: ‘‘In an ‘agile’ enterprise, products will be built quickly and cheaply for a customer based on detailed date received at the point of sale’’. The above definition of agility has been accepted in this paper. To be agile, products and manufacturing systems must be designed to be flexible and simple enough to allow easy reconfiguration and quick response to the changes in product designs. The agility concept has an impact on design of products and manufacturing systems. The complexity of scheduling in manufacturing sys- tems is an obstacle for achieving agility. Effective manu- facturing scheduling reduces the manufacturing cost and accelerate the response to the changing market. From a computational point of view, many manufacturing scheduling problems are NP-hard. The practical conse- quence of NP-hardness has been discussed in [3]. The time required to solve an NP-hard problem of reasonable size can be unrealistically long. For example, consider a problem that in the worst case requires 2 microseconds to solve it, where n is the size of the problem. The problem of size of 10 will require no more than 0.001 s to solve it. A problem of size 40 could take as long as 12.7 0736-5845/98/$19.00  1998 Elsevier Science Ltd. All rights reserved. PII: S0736-5845(98)00017-9