  The digital twin has emerged as a technology to predict the undesirables, and
ensure desired performance of complex systems. Although digital twins have got
attention in the manufacturing research spectrum, yet their industrial
application has been limited. Virtual simulations are considered an integral
part of a digital twin, but a challenge is the lack of structured approaches to
creating simulation models that can be extended as a digital twin. At the same
time, the virtual models need to be accurate and flexible enough to be updated
along the life cycle of the factory as desired in a digital twin. This paper
presents a framework for virtual modeling of factories that can be extended as
a digital twin. The case of a manufacturing company is presented to model and
simulate a manufacturing system in a structured yet flexible way.
