7.2.1 Focusing on the order picking process
De Koster et al. (2007) argued that researchers should focus on applying methods that can be generally drawn instead of only focusing on a specific situation or problem. Although the focus within this study was on specific problems within the order picking process, it should be stated that factors causing non-value-adding activities also affect the overall management of material at the facility. Low accessibility and packages that are non-standard volume and non-standard- lengths also affect the truck operators responsible for production, since they also must prepare packages before production starts. Thus, decreasing productivity. The exploration of the order picking process has certainly led to suggestions that will make the overall material handling more efficient. The statement made by de Koster et al. (2007) is agreeable, but in this study, it appears by focusing on a specific situation also can lead to methods that can be generally drawn. Such as decreasing the number of packages that have been moved many times by correcting the packages that are non-standard-lengths due to production faults such as increasing the sales of non-standard volume packages. The authors further claimed that storage assignments seem to have been neglected during their literature review, although it impacts the performance of routing (ibid.). As been mentioned the focus was on the actual order picking process and not so much on the activities around it such as the inventory layout. However, many of the activities identified are caused by the inventory layout which was settled by conducting an ABC analysis analysing the compartment content.
7.2.2 Collection of data through interviews, time studies, and observations
The initial thought was to conduct time studies and time each activity within the order picking process such as the dialogue with the office, changing reserved packages to another one, communicating with other truck operators, etc. However, a lot of different activities are carried out and there are no distinct lines between the activities that occur. That made it difficult to measure since it was shown to be great complexity. The cycle time for picking individuals orders and belonging order lines was still measured but without deriving it to specific motions. Except for empty travels and unnecessary movements of packages and transportation of reserved packages to loading spot. Instead, the observations became more valuable in terms of identifying both motions and factors that affect the process. Both negatively and positively. The observations contributed to the analysis of the process to a great extent since many of the activities were not heard during the interviews. It cannot be precluded that the amount of time each motion take would have been both interesting and valuable within this study, as well as measurable and comparable if suggestions were implemented. However, the cycle time of the order picking process, as well as inputs from observations and interviews, still made it possible to analyse the process.
Since the order picking process showed great complexity, in combination with that the inventory layout and storage areas are scattered, the time studies, observations, and interviews were felt to be the right approach. Especially since the order picking process has remained somewhat a non-investigated area at the company. Theys et al. (2010), Yu & de Koster (2010), Ene & Öztürk (2012), Chen et al. (2015), and Altarazi & Ammouri (2018) have been developing mathematical models, algorithms, and simulations to rationalise the order picking
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process. Although they are popular research methods to analyse problems within order picking planning (van Gils et al. 2018), it was felt to not suit the aim of this study since the current state of the order picking process and influencing factors had not been identified in depth before. The choice to not adopt or create a mathematical model, algorithm, or simulation was strengthen during the literature review. Shqair et al. (2014) claimed that it is difficult because of the randomness in operations and the variety of parameters affecting them which certainly was the case within the studied organisation.
7.2.3 Performing a VSM
Creating a value stream map is common within operations management and when optimising processes in organisations. Both Bild & Svensson (2019) and Purba & Aisyah (2018 performed a VSM in their studies when identifying non-value-added activities and improving value-adding ones. Value stream maps are often detailed, and the lead time is derived from each activity that occurs. As previously was mentioned, a lot of different activities were carried out and there were no distinct lines between the activities that occurred. That made it quite tricky to perform a detailed VSM accordingly to the maps that the authors did. Instead, the order picking process was mapped out more simply and the summary of the lead times acted as a complement to the model. However, the order picking process was mapped out and gave an overview of which activities that occur and which ones that are value-adding, non-value-adding but necessary, and completely non-value-adding. In that sense, business modelling or value stream mapping has proven to be a good and useful tool to eliminate waste in a cycle and identify more waste to eliminate in the next cycle, which was stated by Chen & Meng (2010).
7.2.4 Parameters used in the ABC analysis
Two ABC singles analyses could have been conducted and then merged to attain the traditional way of conducting an ABC cross-analysis as De Felice et al. (2014), Arnesson & Bergqvist (2018), and Kevine (2018) exemplifies. In this study, a weighted volume was retrieved by multiplying demand and order frequency which fills the same purpose. Kevine (2018) found that although certain products are of high sales value, they are not always highly requested in terms of order frequency. Within this study, the demand in quantity was used instead of sales value. However, the authors´ conclusion is found to be the same in this study. Although the demand for one product was higher than another, the order frequency leads to a higher weighted volume in comparison, leading to an increase in importance from an ABC-classification perspective. This strengthens the fact that a single ABC analysis, accounting for only one criterion, becomes limited as also been claimed by De Felice et al. (2014). In this study two criteria were chosen, however, De Felice et al. (2014) argue that many factors could be considered, for example, the risk of damage. The truck operators mentioned that defects on packages can arise if heavier dimensions are placed on products with thinner dimensions. With that said, damage risk could perhaps be included to identify if products with a higher risk are currently placed in mixed compartments containing heavier dimensions to decrease obsolescence. Arnesson & Bergqvist (2018) performed an ABC analysis based on order frequency and weight as weight often tended to stop the order picking process according to the employees. With that said, the ABC analysis could be used in a variety of ways. Based on Arnesson & Bergqvist (2018) analysis, their suggestion was to place the most important products near the entrance to achieve cost savings. This study was delimited to not focus on inventory layout more than the ABC analysis and compartment content. However, besides increasing the number of SL compartments the important products shall be placed near the entrances but another factor must be included within this company and the facility layout. The inventory layout shall also be based on which products that often are requested together. Placing important products near the entrances is a start, but transportation might not become less.
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8 Conclusions
In this section, the conclusions are presented that refers to address the aim of the study and associated research questions. The section concludes with suggestions for further studies.