Rapidly increasing, global competition has led many companies to pay more attention to each singular requirement of their customers and, therefore, caused the tendency to small batch sizes and a greater variety of products. Assembly workload and human labor is the prime expense factor during the assembly of products. Here the hours of work by workmen multiplied with a company-specific factor equal the occurring costs. Based on the frequent use of variant-oriented product modelling, the efficiency of preparation processes has been improved. However, the assembly planning of single productions or short runs is often based on experience or the method of compare and estimate. Most production planning systems used in practice have an essential weakness in that they do not support hierarchical planning based on assembly constraints and do not observe resource constraints at all production levels. Therefore, tight synchronisation between design and production structures is necessary in early stage of the preparation and planning process in parallel to the design process. In this paper a project is presented, in which the assembly planning is put into practice based on engineering 3D CAD models in 3D PDF and a preplanned library of work steps. Through connected time values multiplied by frequency and under consideration of assembly difficulties, transparent assembly basetimes can be calculated and expectable costs can be estimated. Though connected resources the needed tooluse per workstation can be determined. Furthermore a connection of product, assembly process and resource is implicitly created by the planning process itself, which machine-readable will provide a lot of potential for future automatisms.