Deep Modeling and Dynamic Constraints
The results of any planning engine are only as good as how the engine models the environment. There are many “excel-based” planning engines that treat capacity simply as a Rate of output in a bucket of time. There are two major problems with this approach: 1) It automatically implies static and fixed lead-times, and 2) it assumes any mix of products takes the same amount of capacity! We know that by building different mix of products you could generate plans that can underutilize the capacity by as much as 40% or overschedule production by the same amount. Lets look at a simple example. Assume you have two machines A and B and two Products Pa and Pb that can be made in any of the machines except that Pb takes twice as long as Pa to be manufactured. Furthermore, let’s assume that we have enough demand for both products. By not considering the mix, we can schedule all Pb’s or All Pa’s or a mix of the two. By simply looking at the rate or production per bucket in the factory, it is Easy to see how ineffective the plan might be. This is not a surprise since this is how spreadsheets are used for planning and planners have expressed their frustrations with their Inaccuracy and constant readjustments of the plan to match the reality of the production.
Adexa applications have 3 modes of operation: White box, Grey box and Black box. The latter is used when the capacity is not mix-dependent and the lines are dedicated. The Grey box model is used when mix is critical and details of equipment are not as critical or not available. The White box model takes into account all the details of equipment including batching, setup, process and machine alternatives and even time spent between two critical processes as a constraint.
Adexa has by far the most comprehensive capacity and material modeling Available in the market today. The modeling is so accurate that the model can even go to the level of real-time sequencing of the WIP on the shop floor, if this is what is desired.