Kinds of software that hold a BOM

Several kinds of software can hold a BOM. They differ in what they do with it. Some create the list. Some use it to plan buying. Some wrap it into a whole business system.

The labels blur, and one product can do several jobs. Use these as rough categories, then read each maker's own documentation.

PLM: where the product is defined

PLM stands for product lifecycle management. The core of it is creating and centrally managing all product data.¹ It describes a product's engineering side, from its descriptions and properties through development and useful life.¹

The BOM is one piece of that product data. Wikipedia says a BOM can describe the same product from four angles: design, sales order, build and upkeep.²

MRP: using the list to plan

MRP means material requirements planning. It's a system for production planning, scheduling and inventory control.³ Its aims include making sure raw materials are available for production and products are available for customers.³ It also plans manufacturing activities, delivery schedules and purchasing.³

You can't do any of that without a BOM. The list tells the system what a build needs, so it can work out what to buy.

ERP: the whole business in one suite

ERP means enterprise resource planning. It's usually described as a category of business management software, typically a suite of integrated applications.⁴ ERP systems can be local-based or cloud-based.⁴

Wikipedia's list of ERP manufacturing features includes bills of materials and work orders.⁴ One example is the ERPNext manual, where the BOM is described as a list of items and sub-assemblies with quantities, and may include operations.⁵

Inventory tools

Plain inventory software counts what's on the shelf. Some inventory tools also let you list the parts of a kit or assembly. Others don't.

That's the question to put to any tool: does it hold a multi-level list, or only a flat one? The difference is covered under levels in a parts list.

How they fit together in a small shop

Most small makers don't buy one of each. A shop might keep designs in drawing software, and the parts list and stock in one ERP or inventory system.

The risk is the same list living in two places. When a BOM is also tied to production orders, as the Wikipedia article describes, a wrong copy flows into reservations and purchase requests.²

So decide where the master list lives. Everything else should read from it or be fed from it.

Questions to ask a maker

Check the maker's documentation for:

• whether the BOM has levels
• whether it links to stock and purchasing
• how it tracks changes to a list
• whether it adds up costs from components
• how data gets in and out

Those five cover most differences between categories. Other pages here go through them: change tracking, cost roll-ups and stock links.

Tools change often. Features listed on a maker's page today may be different next year, so check the current documentation.