  As Machine Learning (ML) becomes more prevalent in Industry 4.0, there is a
growing need to understand how systematic approaches to bringing ML into
production can be practically implemented in industrial environments. Here,
MLOps comes into play. MLOps refers to the processes, tools, and organizational
structures used to develop, test, deploy, and manage ML models reliably and
efficiently. However, there is currently a lack of information on the practical
implementation of MLOps in industrial enterprises. To address this issue, we
conducted a multiple case study on MLOps in three large companies with
dedicated MLOps teams, using established tools and well-defined model
deployment processes in the Industry 4.0 environment. This study describes four
of the companies' Industry 4.0 scenarios and provides relevant insights into
their implementation and the challenges they faced in numerous projects.
Further, we discuss MLOps processes, procedures, technologies, as well as
contextual variations among companies.
