A Digital Human Model (DHM) enables computer-aided analysis of production processes and supports the ergonomic design of workflows. In particular, DHMs are often used to analyze manual work and evaluate ergonomic parameters. Previous studies show that the hand models for ergonomic evaluation are still limited due to inaccurate movement patterns. This study focuses on the simulation of manual assembly work using an anthropometric model. It illustrates with motion measurements how large the angular deviation of the hand postures is. To investigate ergonomic parameters, a cordless screwdriver was used to assemble screws on differently angled mounting plates, which caused different hand-arm postures. The motion capture was done with IMU sensors. Fifteen male subjects aged between 20 and 30 took part in these motion measurements. The results show the effect of the inclined position of the mounting plate on the wrist angles of the respective test subjects. Finally, the deviations between simulation and measurement are discussed and the limitations are shown.