Gearbox bill of materials: structure, BOM types, EBOM and MBOM (3D)
About this app
A gearbox as a 3D exploded view, linked to its product structure: quantity, structured and modular bill of materials side by side, engineering BOM against manufacturing BOM with the pre-assembled shaft as its own assembly. Build the structured BOM yourself and watch the parts appear in 3D.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
Product structure and types of BOM
The product structure shows a product as a tree: the product on level 0, below it the assemblies and single parts, each with its quantity per parent unit. According to DIN 199-2, three types of bill of materials read this tree in different ways. The quantity BOM lists every part once with its total quantity, without levels. The structured BOM drills every assembly down to the lowest level. The modular BOM contains one list per assembly with the next lower level only. Quantities multiply along the path from the product to the part.
What the app shows
The drive shaft of a manual gearbox from the lecture: lock rings, ball bearings, spacer rings, two gearwheels, a switching sleeve, a shaft and O-rings. The parts come off along the axis in reverse assembly order; item numbers as in an exploded-view drawing link picture and list. When you select a part, the part in 3D, its tree node and its BOM row light up together, and a field shows the total demand, for example for O-ring 19: 1 + 1 × 2 = 3 pieces per gearbox. The geometry is schematic.
What you try out
Switch between the engineering and the manufacturing BOM. In the EBOM, shaft 18 and all three O-rings hang directly under the drive shaft. In the MBOM, shaft 18 and two O-rings become the pre-assembled shaft 13 at a separate workstation, and the structure gains a level. The quantity BOM still shows three O-rings. Switch between quantity, structured and modular BOM, and in the exercise build the structured BOM yourself, item by item with feedback.
Frequently asked questions
- What types of bill of materials are there?
- DIN 199-2 has three basic forms: the quantity BOM lists every part once with its total quantity. The structured BOM shows the whole product structure, indented by level. The modular BOM consists of one list per assembly that names only its direct components.
- What is the difference between EBOM and MBOM?
- The EBOM (engineering BOM) is design oriented and structured by function. The MBOM (manufacturing BOM) is assembly oriented and structured by assembly steps: if an assembly is pre-assembled at a separate workstation, it gets a level of its own. Parts and total quantities stay the same, the structure changes.
- How do you calculate the total demand for a part?
- Multiply the quantities along each path from the product to the part and add up the paths. If an O-ring hangs once directly under an assembly and twice inside a sub-assembly that is used once, the result is 1 + 1 × 2 = 3 pieces.
- How does the “Gearbox bill of materials” app work?
- You take the gearbox apart with a slider, select parts in 3D, in the tree or in the list, and switch between EBOM and MBOM and the three types of BOM. In an exercise you put the structured BOM together yourself.
Subject: Industrial Engineering
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