The increased availability of computer aided processing has enhanced the usefulness of simulation. It has now found uses in almost every sphere of industry and business. At the Molins Advanced Technology Unit we are developing the use of simulations to assist us in the design of our machinery. Areas of application are : _ Modelling the process within a cigarette making machine. _ Optimising machine grouping efficiencies. _ Selecting drive mechanisms. The presentation illustrates the techniques we have used to construct the simulation, the software and hardware employed and typical results obtained. Also how the simulation was validated using experimental data.