what is a bill of materials bom 
a bill of materials bom is an extensive list of raw materials components and instructions required to construct manufacture or repair a product or service it lists the finished product at the top followed by individual components and materials engineering boms are used in the design process while manufacturing boms are used in the assembly process types of bill of materials boms using a bommanufacturers start the assembly process by creating a bom a bill of materials bom is a centralized source of information listing the items and instructions needed to create a product every line of the bill of materials includes the product code part name part number part revision description quantity unit of measure size length weight and specifications it includes all alternative and substitute part numbers and parts contained in the drawing notes creating an accurate bill of materials ensures that parts are available when needed and that the assembly process is efficient an inaccurate bom can cause production delays if time is required to locate missing parts this increases operating costs a manufacturing bom is essential in designing enterprise resource planning erp systems and in materials requirement planning mrp bom displaysa bom displays its information in one of two ways an explosion display or an implosion display an explosion display defines an assembly at the highest level broken down into individual components and parts a bom implosion display links the lower level parts to an assembly at the higher level for example a computer is exploded into hard drives chips random access memory panels and processors each processor is then exploded into an arithmetic unit a control unit and a register the requirements for the arithmetic unit control unit and register are imploded into the requirements for the processor which are imploded into the requirements for the computer 