That SAP Business ByDesign Business scenario Materials in Projects is relevant for project-based service providers who also offer materials in addition to services (e.g. service providers for IT infrastructure or for energy infrastructure such as gas pipelines or wind turbines).

You have to plan and schedule materials for projects, procure them from within the project and bill them together with the project services in a project invoice.

With the business process Plan a project you can create, plan and structure your project as well as set up the project team and staff the project with employees. When planning materials at the project task level, you must clearly state whether a material is being tracked and consumed from inventory.

You can use the Create Project Inventory Order business process to send the material requirement to the supply chain so that the materials are reserved for the project.

With the planning material business process, which is part of the supply chain process, the supply chain planner can make the appropriate planning for the requirements from the project.

The Reserve Inventory business process is part of the supply chain process. In this process, inventory is assigned to the project by reserving the inventory at the location for direct consumption or collection, or by pre-shipping the inventory to the desired location.

In the Use Inventory business process, the reserved inventory in the project is used to carry out the project task. The entire reserved amount does not necessarily have to be used at once. The amount can also be used in several phases.

The Billing business process offers two options for billing the quantities used for an existing project order. These are the manual creation of the project invoice request and the automatic creation of the project invoice request based on the project and its corresponding billing.

Source: help.sap.com, as of March 2017