Robin Hanson

Kitting and time efficiency in manual assembly

The present paper focuses on parts presentation in manual assembly. Its aim is to determine how kitting affects the time spent by the assembler fetching parts and, more specifically, what is the impact of the proportion of parts included in the kit. The present paper is based on four case studies of automobile assembly, in which parts presentation by kitting is compared with parts presentation in component racks. In the case studies, kitting enabled shorter distances between parts presentation and assembly object and thereby a potential reduction in the time spent fetching parts. However, when only a proportion of parts were kitted, the time spent fetching parts was not always reduced, in spite of this potential. The present paper finds that when deciding which parts should be kitted, attention should be paid to how and in what order assembly operations are performed.

A comparison of kitting and continuous supply in in-plant materials supply

In the context of in-plant materials supply, the materials feeding principle of kitting is often discussed as an alternative to the more common continuous supply (also known as line stocking). However, there are few detailed studies describing the relative effects of kitting and continuous supply. The current paper identifies the relative effects of kitting and continuous supply, and provides insight into how these effects arise. The paper draws on empirical data from two case studies in the Swedish automotive assembly industry. In each of the cases, continuous supply has been replaced by kitting, enabling comparison of kitting and continuous supply in the same production environment. The performance areas studied include man-hour consumption, product quality, flexibility, inventory levels, and space requirements. Interviews with production engineers, assemblers, and operators responsible for kit preparation at each company contribute to a broad yet detailed view of the relative effects of the two materials feeding principles.

Assembly station design: A quantitative comparison of the effects of kitting and continuous supply

Purpose – The purpose of this paper is to determine how kitting, compared to continuous supply, affects the time spent by the assembler fetching parts in manual assembly. Design/methodology/approach – The paper is based on an experimental setup at the Saab Automobile assembly plant in Trollhattan, Sweden. Experienced assemblers were studied as they performed the same assembly operations in ten different configurations. Each configuration consisted of a different arrangement in terms of how parts were presented. The use of kits to present parts was compared to parts presentation through continuous supply, where each part number was presented in a separate container. Findings – The time for fetching parts is significantly shorter when parts are presented through kitting instead of through continuous supply. Furthermore, the shorter fetching time is not just related to a shorter distance between assembly object and parts presentation, which can often be achieved through kitting. The reduction of time spent searching for parts is also considerable. Practical implications – The results of the paper provide valuable input in the design of assembly and materials supply systems, as they enable a better understanding of the relative performance of the materials feeding principles of kitting and continuous supply. Originality/value – Previous studies of kitting and its impact on assembly are mostly conceptual or qualitative, whereas quantitative studies are scarce. The current paper provides a substantial contribution by quantifying the effects that kitting, compared to continuous supply, has on the time spent fetching parts.

Effects of using minomi in in-plant materials supply

Purpose – “Minomi” is a unit load where no container is used. The aim of this paper is to identify the effects of using minomi in the materials supply within an assembly plant. Design/methodology/approach – Based on three case studies within the body shop of Saab Automobile in Trollha¨ttan, Sweden, effects of using minomi are identified. Furthermore, relations are identified between these effects and the different characteristics of each case. Findings – The paper identifies both benefits and drawbacks of using minomi and relates these benefits and drawbacks to different part characteristics, characteristics of the receiving assembly station, and characteristics of handling and storage. Among the benefits is that minomi is associated with space efficient presentation of parts. This can enable the presentation of a large number of part variants and also result in time efficient parts picking in the receiving assembly operations. Practical implications – Through the knowledge gained in the case studies, the potential benefits associated with minomi are more likely to be realised within industry. Originality/value – The paper provides insight into the concept of minomi, which has previously received very little attention in research literature, but which can offer substantial benefits within industry if used under the right conditions. Keywords Materials handling, Materials management, Sweden, Automotive industry Paper type Research paper

Order batching and time efficiency in kit preparation

Purpose – The purpose of this paper is to determine whether man-hour efficiency of picking is affected by the use of batch preparation, compared to preparation of one kit at a time. This paper focuses on small kit preparation areas. Design/methodology/approach – This paper is based on two experiments that were performed at a vehicle assembly plant and then analysed quantitatively. Findings – The results provide a strong indication of the advantages associated with batch preparation, in terms of man-hour efficiency. Practical implications – The fact that the effects identified during the experiments are substantial, over 20 per cent reduction of average time per picked component in Experiment 1 and 7 per cent in Experiment 2, indicates that the option of batch picking holds potentials for large cost reduction and should be considered when kit preparation systems are designed. Originality/value – Limited research has dealt with the design of kit preparation systems, thus leaving considerable knowledge gaps. Previous research dealing with batch picking focuses on other environments than kitting and on large picking areas where batching can reduce walking distances. In contrast, the current paper focuses on small picking areas, which are common in industrial kitting applications. This paper provides a considerable contribution by demonstrating improvements in time efficiency that batch preparation can offer to small picking areas in addition to larger areas. The discussion also provides a basis for future research, which could focus on aspects other than time efficiency, such as the quality of kit preparation, and variables that might moderate the effect of batching.

Augmented reality as a means of conveying picking information in kit preparation for mixed-model assembly

Kitting is a materials feeding principle that is increasingly common in mixed-model assembly. Currently, there is no consensus within industry regarding how picking information should best be conveyed to support kit preparation and research on the topic is scarce. The purpose of this paper is to determine whether information conveyance through augmented reality can be used to support time-efficient kit preparation, considering the two commonly applied approaches of single-kit preparation and batch preparation. The paper presents a novel application of augmented reality and tests it in a realistic laboratory experiment. As a basis for comparison, a traditional printed paper list is also tested. In the experiment, augmented reality is competitive both in terms of time-efficiency and picking accuracy, both for single kit and batch preparation, which indicates that augmented reality can constitute a viable option for conveying picking information in kit preparation. Especially for the batch preparation, where more information needs to be displayed, the augmented reality application is associated with considerably better performance than the paper list. The paper suggests that future research efforts should include studies on augmented reality applied in an actual industrial setting over a longer period.

Time efficiency and physical workload in manual picking from large containers

A common task in both trade and manufacturing, manual picking from large containers often involves considerable physical workload, as well as low efficiency and varying picking times. With quantitative evidence from an industrial setting, the paper provides detailed insights into how physical workload and picking time vary in picking from large containers. Components at a short horizontal distance from the picker and at the top instead of the bottom of the pallet are associated with shorter picking time and lower physical workload. Moreover, pallets tilted 45° towards the picker are associated with picking times that are significantly shorter on average and display smaller variations than horizontal pallets. The effects that the tilting of the pallets has on physical workload differs depending on component characteristics and from which section of the containers picking was performed. In the study, the greatest values of physical workload were observed for the tilted pallets.