Purpose – The purpose with this study is to investigate how an assembly line for products with long cycle time, high product variation and operators who follow the products through the flow can be planned for a high resource utilization as well as the challenges that can arise when planning an assembly line with an increasing demand and how these can be handled. Method – To fulfill the purpose of this study a case study was conducted at Mastec Components AB in Vaggeryd. The empirical data gathered from the case study was obtained through interviews, observations and document studies. The empirical data was then analysed against theory, which means that pattern matching was used and the analyse led to the studies results. Findings – This study illustrates how an assembly line with special demands can be planned to gain high resource utilization. When the products cycle times are multiple they can be sorted into product families to simplify the planning and it also enables a tacted planning method to be used. The study also presents how the usage of time buffers can facilitate the planning of an assembly line. Moreover the study illuminates the importance of controlling tact, both from the customer and the own production. When demand increases it is important that the production line is capable to keep up, therefore some arrangements can be done to reduce waste and increase capacity. Possible alternatives can be buffers, allocating resources and parallel assembly lines. Implications – The study investigates a type of assembly line where the operators follow the products through the flow. This type of assembly line is unexplored in theory and thereby a knowledge gap has been identified which partly have been covered by this study. Further on, the study contributed to an increased understanding of the consequences that occur when operators follow the flow and when products have long varying cycle times. The study also shows the value of calculating tact and use the advantages from it to easier handle variation in demand. Limitations – The case study was performed as one case study which means that only one unit has been analysed. This was due to the lack of resources to do several case studies, both regarding time and ability to find more facilities with similar conditions. If it were possible to conduct more case studies the results could have been more general. Keywords – Tact, tact time, tacted planning, assembly line, planning, operators, buffer.

På Scanias chassimontering används mjukvaran AVIX för att skapa elementblad, positionsstandarder och balansera monteringslinorna. Tidssättningen sker för närvarande med stoppurmetoden, men en övergång till Scania Time Block (STB) är pågående. STB är en metod som redan har standardiserade tider för olika moment och används i stället för manuell tidtagning. Målet är att förstå hur Scania arbetar med AVIX och ES, analysera kompetenserna i AVIX och STB, samt tidssätta fler positioner med STB och förbättra processer och rutiner. STB bygger på MTM-SAM metoden och använder standardiserade koder för olika moment på ES. En utredning genomfördes på trycktanksförmonteringen för att undersöka tidsdifferensen mellan de olika metoderna och tidspress hos montörerna. Genom att använda STB kunde man få en objektiv och standardiserad tidsuppskattning för att producera en specifik variant. En intressant observation var att det fanns en tydlig avvikelse mellan de manuellt klockade tiderna och STB-tiderna. De manuella tiderna verkar inte ta hänsyn till specifika steg som operatörerna måste utföra. Baserat på analysen rekommenderas Scania att införa STB på alla produktionsanläggningar, särskilt för chassi, för att säkerställa att montörerna får en rättvis takttid som tar hänsyn till den faktiska tiden för varje moment. Detta skulle bidra till förbättrade processer och rutiner i produktionen. / Scania's chassis assembly utilizes the software AVIX to create bill of materials, position standards, and balance assembly lines. Currently, time measurement is done manually using stopwatch, but a transition to Scania Time Block (STB) is underway. STB is a method that already has standardized times for different tasks and replaces manual timing. The goal is to understand Scania's utilization of AVIX and ES, analyze the competencies in AVIX and STB, time more positions using STB, and improve processes and routines. STB is based on the MTM-SAM method and employs standardized codes for various tasks on the assembly line. An investigation was conducted on the pre-assembly of pressurized tanks to examine the time differences between the methods and the time pressure experienced by the assemblers. By utilizing STB, an objective and standardized time estimation for producing a specific variant could be obtained. An interesting observation was a clear deviation between the manually timed durations and the STB times. The manual timings seemed to overlook specific steps that operators must perform. Based on the analysis, it is recommended that Scania implement STB across all production facilities, particularly for chassis, to ensure fair cycle times that consider the actual time required for each task. This would contribute to improved processes and routines in the production line.