Understanding of a failure frequency peak in conjunction with a market introduction
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Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Quality and operations management (MPQOM), MSc
Publicerad
2015
Författare
Nilsson, Thomas
Palmgren, Mikael
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Successfully predicting field reliability of a new product before introducing it on the market decreases the risk connected to product development significantly. Being able to forecast the amount of complains that a product will encounter from customers in forehand, means that an organization in a better way can plan the resources needed both in the development of the product to reach the specified quality targets and in the future maintenance of the product. This thesis has investigated Volvo Group Trucks Technology’s, a sub-division within Volvo Group henceforth referred to as GTT, ability to predict reliability for a new product in conjunction with a market introduction. With the help of reliability theory and a quantitative analysis of the received warranty claims for a specific product line the thesis performed a qualitative analysis of GTT’s ability to predict the failure frequency for the trucks’ first year on the market, by considering how GTT works with reliability prediction. Obviously, Volvo Group as a company will benefit the most of preventing the failures from occurring at all. Therefore the quantitative analysis of the warranty claims also aimed to provide as basis for future root-cause analysis to these failures, which is essential in a future initiative to preventing them from happen. Early after its market introduction a new product often experiences child diseases. This shows as a peak when plotting the failure frequency for the product against time on market. Historically, when looking back on failure frequency data in conjunction with market releases, this trend can be seen at GTT as well. The initial period when this peak occurs is in this thesis referred to as the peak period. A majority of these failures are often connected to shortcomings in the manufacturing process, deviations from the intended usage of the product, misunderstandings of the customer requirements or failures in components delivered by suppliers. As long as these failure types exist, a product will not reach the intended reliability it’s designed for. The reliability perceived by the customer is referred to as field reliability, which will not be equal to the design reliability for a new product until all quality issues related to these sources of variation are solved. When the product has reached this state the thesis refers to a stable condition or that the product is within the stable period. GTT’s methodology for predicting field reliability, proved to be accurate for the stable period but not being able to handle the initial peak period. In addition, the methodology proved to be capable of identifying trouble areas, which also reflected the analysis of the outcome of warranty claims. As the reliability growth testing within GTT mainly is focused on development failures and the variation connected to the market introduction is hard to simulate, GTT intentionally with the help of their reliability growth model only predict failures related to design reliability. Instead the predictions within the initial peak period are adjusted with a peak factor that is intended to compensate for the variation causing the discrepancies between the design reliability and the field reliability. It can be concluded that the peak factor not is capable of compensate for the variation during the peak period. The authors identified various factors, which most likely affect the magnitude of the peak that is not taken into account when estimating the peak factor. These factors together with improvements in managing the failure frequency peak are further discussed in the thesis. Due to the time limit the magnitude of these factors’ impact was not evaluated, but will be in GTT’s interest to further investigate in future work of improving the ability to predict the reliability during the peak period and the management of the failure frequency peak.
Beskrivning
Ämne/nyckelord
Produktionsteknik , Hållbar utveckling , Produktion , Manufacturing engineering , Sustainable Development , Production