113 DEVELOPING PROPOSED LAYOUT FOR INCREASING LINE EFFICIENCY ON BODYSHOP Johan Oscar Ong and Cornellia Faculty of Technology, Industrial Engineering Department, President University Jl. Ki Hajar Dewantara Kota Jababeka,Cikarang, Bekasi - Indonesia 17550 Email: johanoscarong@gmail.com ABSTRACT Recently, an imbalance workstation in the assembly line is one of the critical problem that many companies face. Many researches have done to solve this problem with the various designs of assembly line balancing. This research presents the comparison between straight line balancing and u-shaped line balancing. Both straight line balancing and u-shaped line balancing have the same goal; minimizing the workstations. The result of this research shows that u-shaped line balancing gives a better solution than the straight line balancing in term of number of workstation. Straight line balancing is using Rank Positional Weight (RPW) whereas u-shaped line balancing is using Critical Task Method (CTM). Significantly, u-shaped line balancing is more efficient than straight line balancing. Keywords : assembly line balancing, straight line balancing, u-shaped line balancing, Rank Positional Weight, Critical Task Method I. INTRODUCTION Recently the automotive industry is growing rapidly. It leads the bodyshop’s factory be a promising business because the automotive company could not stand itself without the bodyshop’s activities. There are three kinds of bodyshop’s activities; light repair, medium repair, and heavy repair. The standard time for light damage (1-3 panels) is 1 day or more and less than 3 days. For medium damage (4-6 panels) is 3 days or more and less than 5 days and for the heavy damage (≥ 7 panels) is more than 5 days or around 2 weeks. Form the observation, it is found that the actual repair time of light damage is 4.44 working-days (more than 3 working-days) and the repair time of medium damage is 7.02 working-days (more than 5 working-days). Based on the observation data above, the line efficiency of bodyshop is still low. The line of bodyshop is not balance, it makes many vehicles got stuck when entering the stalls. There are two types of assembly line balancing that matches for the condition of bodyshop; straight line balancing and u-shaped line balancing. Straight line balancing means a balance production line in which stations are arranged consecutively in a line by grouping tasks into stations while moving forward through a precedence diagram by using Rank Positional Weight. On the other hand, u-shaped line balancing is a balance production line is arranged by assigning tasks into stations while moving forward, backward, or simultaneously in both directions through the precedence diagram by using Critical Task Method. II. LITERATURE STUDY A. Standard Time (Time Study) 1. Validity Test There are three kind of test to prove the observation’s data is valid: a. Normality Test While confidence interval construction is about unknown population mean μ based upon the calculation of a point estimate and level of confidence, hypothesis testing allows an experimenter to assess the plausibility and credibility of a specific statement (Hayter, 2000). Actually, the state of H 0 and H A could be explained below. H 0 : The data is normally distributed