 ALT Design using Field Failure and Usage Profile Azianti Ismail, Faculty of Mechanical Engineering, Universiti Teknologi MARA, Malaysia Won Jung, Department of Industrial and Management Engineering, Daegu University, South Korea Email: azianti106@salam.uitm.edu.my Abstract: Initial reliability prediction done by calculation would be more practical if support by evidence from customer usage profile and field failure data to improve the prediction. Thus, the consistency of the design and the product would be practically validated. In this paper, it will address rationale and method to decide on Acceleration Factor (AF) to be used in Accelerated Life Test (ALT) through usage profile and field failure. The case study of tractor transmission is used to demonstrate the method which data obtained from surveys done on farmers, field visits and field failure data from service center. By considering all the elements, it will determine more relevant AF which indicates the real use conditions of the component. Key words: acceleration factor, usage profile, field failure 1. Introduction Speedier product development, more demanding customer requirements, rapid changing technology and more complex products leads to application of Accelerated Life Test (ALT) in manufacturing for many years. All of these reasons have been forced the manufacturer to get reliability information as soon as possible. ALT offers reduction of time needed to demonstrate the reliability of the product. Nowadays, higher manufacturing costs are due to over-designed, too complex and excessive warranty period. The final product must able to fulfill customer satisfaction in which the manufacturer need to understand the real conditions. Ion et al (2007) discussed that by using field data, the reliability of the product can be checked whether it is at the right level. It gives the opportunity to take immediate actions in case unforeseen reliability problems occurred at customer’s use conditions. Krasich (2006) pointed out that it is significant to have good understanding of the intended use conditions, environmental and operational profile of the product and product design capabilities to effectively design an accelerated test. Early reliability prediction done by calculation would be more realistic if support by evidence from usage profile and field failure data to improve the prediction. Thus, the reliability of the design and the product would be practically verified. Usage profile should include variety of weather, environmental and working conditions such as type of crops, soil state and surroundings temperature. It also covers customer usage patterns to determine possible failure modes such as location, purpose and handling of the tractors to provide exact use conditions.