A good definition of Bill of materials comes from wikipedia
Bill of materials (BOM) is a list of the raw materials, sub-assemblies, intermediate assemblies, sub-components, components, parts and the quantities of each needed to manufacture an end item or final product.
All products have bill of material from engineering bill of materials, manufacturing bill of materials and service bill of materials. When you are required to estimate the time to manufacture a finished product you must take into account the bill of material of the finished product.
Bills of materials for quoting and cost estimating can be broken down into 3 categories. The first category is raw material. Raw material are those bill of material items that are the building blocks to create a finished or final product. This would include items such as wood, sheets of metal, coils, wire, plastic, rubber, etc. These type off bills of materials are usually some sort of commodity, especially when you get into sheet metal, wood, etc. The second category is hardware. Hardware are those bill of material items which can be purchased and added to a finished product or it could be consumable which is used in the production of the finished product. Examples would be nuts, bolts, screws, etc. Examples of consumables would be paint and gas. The third category of bills of material would be outside services. Outside services would be purchased 3rd party processes like machining, painting, silk screening which are added to a finished product.
All three of these types of bill of material, raw material, hardware and outside processing make up your bill of material list. Estimating software makes it much easier to manage bills of material then spreadsheets and paper.
MIE Solutions provides software products to make your business process more efficient so please take a look at our product line below. MIE Trak and QuoteIt are two products which provide an efficient way to do job shop cost estimating.