Digitalization of production environment, also called Industry 4.0, the term invented by Prof. Wahlster in Germany, is now one of the hottest topics in the software/hardware engineering departments at universities and companies. It splits to many subtopics and technologies. One of the most interesting concerns Augmented Reality glasses – giving a very natural human-machine interface – possibility to present the needed information right in front of user’s eyes and ability to communicate with the system by simple gestures and voice. To show the long lasting need of convenient presentation of information, authors show different examples in different markets, but then, concentrate on one example around the production maintenance team. The point of this paper is the AR system usability evaluation – as noted by scientists around the world note, in-depth studies about the effects of AR applications are sparse. In the first part of this paper, authors recall the concept presented in 2018 about the new method of monitoring the production line with the AR glasses. In the second part, there is a description of conducted study for this concept, carried out in the real production environment on the real production process. Finally, authors deliberate about conclusions, technology imperfections, limitations and future development.