Kit preparation for mixed model assembly – efficiency impact of the picking information system

Artikel i vetenskaplig tidskrift, 2019

Kitting is an increasingly common materials supply principle in mixed-model assembly. Several types of picking information systems are available for supporting kit preparation, but there is no consensus in the literature or in the industry about which type should be used. Furthermore, to prevent errors, industrial applications typically require a confirmation when components are picked from storage and placed in kits, but previous research that considers confirmations is scarce. The purpose of this paper is to establish the extent to which the type of picking information system impacts the time-efficiency of kit preparation when confirmations are required, considering the two cases of single-kit and batch preparation as well as the picking density of the picking area. In the paper, a realistic laboratory experiment is used to compare the time-efficiency associated with four types of picking information systems – pick-by-paper, pick-by-light, pick-by-voice and pick-by-HUD (Head-Up Display) – when applied in kit preparation. In the comparison, the type of picking information system used is found crucial for the time-efficiency of both single-kit and batch preparation. Pick-by-light and pick-by-HUD applied with single-kit preparation show to be more efficient than when applied with batch preparation, likely owing to the extra time for performing placement confirmations with batching. The visually intuitive information provided by pick-by-light and pick-HUD show to be efficient when applied with single-kit preparation. Applying pick-by-paper – with which one confirmation is made for every order line – with batch preparation gives superior efficiency over the other systems for which each storage location and kit-container is confirmed. Pick-by-HUD seems to benefit more than the other systems from higher picking density, while pick-by-light seems to benefit more from the improved overview associated with lower picking density. Pick-by-voice is found associated with low efficiency overall, likely owing to the short walking distances – and hence less time in between picks to administer the voice dialogue – normally associated with kit preparation. The paper suggests further research to study how the graphical interface in pick-by-HUD systems should be designed. Moreover, combinations of information conveyance and confirmation methods other than those typically used in industry should be studied.