Purpose - For companies in the process industry, capacity utilization and bottleneck analysis are central parts. To ensure that improvement proposals have an effect, companies need to identify which process is the system’s bottleneck and which aspects affect its capacity utilization. Despite established frameworks, practical methods for identifying causes of capacity losses and proposing improvement measures are often lacking. The purpose of the study is therefore: “The purpose of the study is to analyze capacity utilization in a bottleneck process within the sawmill industry, identify aspects that reduce capacity utilization, and propose measures to reduce the gap between nominal and net capacity”. Based on the purpose, the following two research questions were formulated:

[1] Which aspects reduce capacity utilization in a bottleneck process?

[2] How can the gap between nominal and net capacity be reduced and thereby increase capacity utilization in the bottleneck process?

Method - The study was conducted as a single-case study with a mixed-methods approach. To answer the study’s questions, triangulation was applied through interviews, observations, and document studies. First, a preliminary study was conducted to create an overview of the process. Thereafter, quantitative data were collected through observations, while qualitative data were collected through interviews. The interview data were analysed through an inductive thematic analysis, where four themes were identified. These themes were then used together with the quantitative empirical data to analyse which aspects reduce capacity utilization.

Findings - The findings show that capacity utilization in the stacker is reduced by four overarching aspects: technical disturbances and system errors, flow-related disturbances, insufficient staffing and variation in working methods. The largest interruption categories were waiting time, the lath layer, and labeling, which together accounted for the majority of the total interruption time. The study also shows that the gap between nominal and net capacity can be reduced through measures such as automated labeling, improved lath handling, systematic follow-up of causes of interruptions, and standardization of working methods.

Implications - The study contributes theoretically by showing how capacity theory, Lean, TOC, and standardized working methods can be combined to analyze capacity losses in a bottleneck process within the sawmill industry. The study contributes practically by providing the case company with a basis for which interruptions should be prioritized in improvement work, and which measures can reduce the gap between nominal and net capacity.

Limitations - The study is limited to the stacker as the identified bottleneck process. Surrounding processes are only considered when they directly affect the stacker’s capacity utilization but are not analyzed in detail. The improvement proposals only concern the stacker. Breaks and shift changes are excluded.