appendix_c1_2011.doc-FormulaSAE.docVIP

APPENDIX C-1 Cost Models and Cost Methodology 1 Cost Models Costing Methodology The cost models are the underlying methodology and equations that relate the final cost of a part to the different operations and goods used in that part. These descriptions are accurate at the time of the rules publications. The models may be expanded as necessary based on evolving requirements. 2 Raw materials 2.1 Raw materials refer to the material stocks used to produce parts from scratch, such as billet steel for machining or aluminum ingot for casting. Bar, sheet and tube stock are purchased using raw material costs. The raw material purchased must include machining allowance. Standard allowances are given in 4.1 and must be used 2.2 Gross weight will refer to the weight of the raw material, including all machining stock 2.3 Net weight will refer to the weight of the finish machined part 2.4 Material costs are based on part gross weight. For example a steel hub is machined from solid bar. The interior is removed by boring. The cost of the bar must include this interior material. Raw materials are normally cost by volume. A cost by weight is also given using an official density listed in the tables. Any parts that are weighed at competition to confirm cost will use the official density in calculating cost. 3 Assembly Labor The assembly labor model is based on the following parameters: 3.1 Mass – The mass of the part influences the time it takes the operator to assemble the part to the assembly or vehicle. Light parts can be installed with one hand. Heavier parts require two hands and the heaviest parts need a lift assist apparatus. These factors are accounted for by selecting the appropriate entry from the process labor tables. The actual part mass must be equal to or less than the value selected. For example a 300g part would have an assembly labor category of 1 kg. 3.2 Interfaces – The more interfaces a part has with the surrounding parts the longer it takes