253 14 th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology” TMT 2010, Mediterranean Cruise, 11-18 September 2010 DESIGNING A SIMPLE U-SHAPED PRODUCTION LINE AND ANALYSIS OF EFFECTIVENESS Şenim Özgürler Yildiz Technical University Beşiktaş Yerleşkesi Endüstri Mühendisliği Bölümü 34349 Beşiktaş, Istanbul Turkey Bahadır Gülsün Yildiz Technical University Beşiktaş Yerleşkesi Endüstri Mühendisliği Bölümü 34349 Beşiktaş, Istanbul Turkey Ali F. Güneri Yildiz Technical University Beşiktaş Yerleşkesi Endüstri Mühendisliği Bölümü 34349 Beşiktaş, Istanbul Turkey Onur Yılmaz Yildiz Technical University Beşiktaş Yerleşkesi Endüstri Mühendisliği Bölümü 34349 Beşiktaş, Istanbul Turkey ABSTRACT U-shaped production lines are special type of cellular manufacturing used in Just-In-Time (JIT) and Lean manufacturing. The U-line arranges machines around a U-shaped line in the order in which production operations are performed. Operators work inside of the U-shaped layout. In this study, first of all, U- shaped assembly lines and the layout options are explained, and then a heuristic technique applied to a Turkish company. In the company where the application took place, the cells involving the production of axis in two different types (central axis UK, central axis DXE) and dimensions are analyzed. The new system which was designed considering new demand levels is investigated depending on various criteria, viz., cycle time, manpower, number of shifts, overtime durations, security buffers, labor and cell efficiencies, average efficiency and profit. This is followed by the balancing of the new design for various demand levels and evaluation of these alternatives depending on the pre-said criteria. Keywords: U-shaped production lines, cellular manufacturing, assembly line balancing 1. INTRODUCTION In recent years, many manufacturers have adopted a Just-in-Time (JIT) approach to manufacturing, finding that it improves their productivity, profits, and product quality. JIT is beneficial for companies engaged in repetitive, job shop, or process manufacturing. One of the important changes resulting from JIT implementation is the replacement of the traditional straight lines with U-shaped production lines [1]. U-shaped production line can be described as a special type of cellular manufacturing used in just-in-time (JIT) and Lean Manufacturing [2]. Machines are arranged around a U-shaped line, in the order in which production operations are performed. Operators work inside the U-line. One operator supervises both the entrance and the exit of the line [3]. In the U-line, tasks are organized into stations that can cross from one side of the line to the other [4]. The assignment of tasks to stations on a U-line exploits the geometry of the line to keep the return and crossover distances as small as possible. Consequently, total travel distance and, hence, travel time is less on a U-line [5].