  New-generation communication and sensing systems are gaining strong interest
in the context of Industry 4.0 e.g., related to mapping techniques,
environmental sensing, automation or hyper-vision. The radio propagation in
confined, cluttered and heavily metalized factory environments is a critical
challenge; thus an evaluation by accurate propagation channel models is
necessary. Site-specific channel emulation can be obtained from Ray-tracing
(RT); but RT validation for factory environments is still an on-going work. For
this purpose, a measurement campaign was performed in a machine room with many
metallic objects and machines, using a mmWave channel sounder. Wideband channel
responses were collected and compared to RT simulations. The RT prediction tool
was calibrated to minimize the error observed on some large scale statistics,
thus reaching a very good agreement between the simulation and the measurement.
Average error in received power, delay spread and azimuth spread is below 1.5
dB, 5 ns and 2{\deg} respectively.
