SAP BOM

Bill of Materials is used for production or subcontracting or sales activities. It gives you a list of components required to manufacture a product for a given base quantity. 

It is normally created by the product development team and changed over the product life-cycle by the same team.  

A simple day to day example would be, to make 1 cup of Milk Coffee, you would need a list of materials, like 6 gm of Sugar, 4 gm of Coffee Powder, 0.3 Litres of Milk and some units of Gas (to boil the milk). In this example the base quantity is 1 Cup of Milk Coffee. Based on this example if a vendor sells 500 Cups of Milk Coffee every day, he would need to procure 3000 Tea Spoons of Sugar, 500 Sp

Uses - A Bill of Material contains the list of components/sub-assemblies required in desired quantities to produce a certain base quantity of the header material 

• If this is the definition of a Bill of Material, it can be used by MRP or Production order to evaluate the components and their quantities requried for production 

•  MRP uses BOM to evaluate the components requried and computes the shortages of the same to trigger procurement

You can create the following BOMs in the SAP - SAP BOM Types

·        Material BOMs - We will Discuss Material BOMs only under SAP PP.

·        Equipment BOMs

·        Functional location BOMs

·        Document structures

·        Order BOM

·        Work breakdown structure (WBS) BOM 

With the use of the Bill of Material master data, you can create a list of materials required for producing an end product. The end product can be an assembly or a sub assembly.

Bill of materials in SAP is always created as single level bill of materials. Each level that is produced individually is represented by a Single Bill of Materials. All these relevant individual Single BOM subassembly levels if joined together form a Multi level BOM.

In general every product that is to be manufactured or subcontracted in SAP has a single level BOM. A combination of single level Bill of material exploded from top to bottom is called a multilevel Bill of Material.

For example

The Single level Bill of material of an Assembly “A” is as below

A (Base qty = 1 EA)

  > B = 2 EA (Raw Material)

  > C = 2 EA (Assembly)

The Single level Bill of material of a subassembly “C” is as below

C (Base qty = 1 EA)

  > E = 1 EA

  > F = 5 EA 

A Multi level Bill of material for “A” would then be as below. A Multi level Bill of material is created through joining many single level Bills of materials as shown below.

A multi level bill of material is used to evaluate the multi level component requirement for producing the header material. A multi level BOM is used by the MRP system to evaluate the Material Requirements. 

A (Base qty = 1 EA)

  > B = 2 EA (Raw Material)

  > C = 2 EA (Assembly)

            > E = 2 EA (for producing 2 of “C” you would require 2 of “E” and 10 of “F”)

            > F = 10 EA

When a BOM for a material remains the same regardless of the plant it is produced in, it is wise to create a central level BOM which has no reference to any plant, such a concept in SAP is called "GROUP BOM". You can then extend these Group BOMs' to all the plants where it is required. Thus you end up referencing the Group BOM to the plants rather than creating one at the plant which can be time consuming.

When you create a Group BOM, the system uses MARA level or client level materials. A specific material need not be extended to any plant for creating a Group BOM.

Creating a Group BOM - When you create a Group BOM you can use the same Transaction code CS01 to create it, but just ignore entering the plant code.

Extending a Group BOM - Using Transaction code CS07 you can extend the Group BOM to the plant, while doing this you have enter the plant at the bottom of the selection screen and not the plant option in the field number 2 of the selection screen.

Changing or Deleting and Extension - You can also delete an extension to a plant using transaction code CS08.

If you have a product that requires many Bill of materials because:

a)      of use of varied components periodically or seasonally

b)      of use of varied component quantities periodically or seasonally

c)      of use of varied components for producing a certain lot size of production

d)      of use of varied components quantities for producing a certain lot size of production

You should then go and create that many bill of material for the same product. This is possible through SAP BOM alternates.

Every time you create the first alternate SAP allocates the BOM Alternate number as “1”, the second alternate would get the BOM alternate number as “2” so on and so forth. You can create upto 99 Alternates for a material.   

Item number: 

Since SAP gives you a facility to include Material components, texts, documents in the bill of materials, they need to be arrange sequentially one below the other, to do this you need to give an item number to each of the items added in the bill.  

The standard number range for this number in increments of 0010.  

Item Category

Therefore it is clear that a BOM is not only a list of components that is required to manufacture a product, but it also allows you to include texts, documents as items in the list. Therefore to avoid any confusion on what is the category of the item that is added, there is something called item category.  

An item that is added can be a Material component - available in Stock item (something that would always be available in stock) or a Non-stock item (something that would never be available in stock and needs to be procured when the production order is created), or a Variable size item, which is designed with a length, breath and height, or an Intra material which is produced intermediately in the production processes and is consumed in the process. It only lasts momentarily in the process (this qty is added with a negative sign)

An item that is added can be a text item (one line text of 40 characters) or a document item (excel file or CAD Documents, Word document or any other document type).

An Item that is added to the BOM can be a Class item, which is used in variant configuration to classify and select components belonging to the 200 class type. 

In the Picture above:  

Item 0010 and Item 0020 is a Raw Material which are assigned in an "alternate group"

Item 0030 is a semi-finished material which has an "Assembly indicator" - Meaning that it also has a single level BOM

Item 0040 is a Text item to which you can assign any meaningful text for the shop floor/production to understand.

Item 0050 is a material that is to be received as a by-product or co-product. In this case it is a by-product.

Quantity and Unit of Measure

Specify the Quantity of the component added to the bill of materials. The unit of measure of the quantity added is the base unit of measure or the unit of issue mentioned in the material master Work scheduling views or plant data storage views. You cannot use any other UOM other than them.

Note Again - The Quantity for a BOM Item is 

= Qty in base UOM  or                                                                                                         

= Qty in unit of issue in Matl Master Work Scheduling view or Plant Storage view  

Enter the following on the Item Detail – Basic Data screen –

Component Scrap 

This is the scrap percentage used to increase the required quantities of the components by the calculated scrap quantity. This increment is used in MRP and SAP PP order.

Operation Scrap

Operation Scrap is that scrap which is expected in one operation for the quantity of a component to be processed.

Co-product

You can declare a component as a Co-product by specifying it with an indicator here and adding it with negative sign.

A co-product is a product that is produced during the production of the main header material, but has an appreciable selling price in the market. It is entered as Stock item in the BOM. 

It is astonishing to find out that, when you produce something you can receive the main header material for which a production order is created as well as the co-product in the same way (through movement type MIGO or MB31 -101); to do you have to mention settlement proportion rule in the material or in the order thereby allocating percentage proportion of the production of each o the items (say 93% of the main header material and 7% of the co-product). You can only receive the quantities mentioned in the rule.

Fixed Quantity

You can mark a component and the quantities in the BOM as fixed quantities. By doing this the requirement qty of the component will always remain the same and will not be a multiple of the production order/planned order demanded quantity.

Recursive component

When you include the header material for which you are creating the BOM, back in to the list of components as a component used for production, the recursive indicator for that component should be put on.

For example, to produce H2S04, you require some amount of H2S04 as a Catalyst in the production process, so H2S04 component in the production of H2S04 is a recursive material component.

Other example can be use of recursivity when you are creating a BOM for "Reworking", which means you would be issuing the same material to produce/rework the same material. 

Alternate Group

An alternate group is a grouping of components added to the BOM which belong to the same family. You can include alternates of a family that would co-exist in the BOM and its withdrawal/reservation for production will depend upon the usage probability, priority, strategy mentioned.

For example when you are producing a “PEN”, you require the Plastic A or Plastic B depending upon the availability in the market.

As soon as you enter an alternative item group in the item detail screen (say =”01”), you see an additional dialog box with the following data: ranking order, strategy, usage probability.

The BOM of “PEN” is as below:

PEN (1 Pen)

  > Plastic A = 120 gm

(Alternate Group 01 / Priority 1 / Usage probability 100% / Strategy 2)

  > Plastic B = 125 gm

(Alternate Group 01 / Priority 2 / Usage probability 0% / Strategy 2)

  > Refill 

SAP also provides strategies to help you decide between the alternates in the group.

Strategy 1 = by using strategy 1 in the alternate group, you can make the system withdraw components for production by using the usage probability (for example “A” = 70% and B = 30% always). Priority in this case is only used for sorting the materials in the usage order.

Strategy 2 = by using the strategy 2 in the alternate group, you can the system withdraw components for production only if 100% of any one of them is available. If 100% of none is available for withdrawal or reservation, the availability check for all items will confirm the available and in that case the reservation only occurs for the available quantity. 

Special procurement & Phantom Assembly

If a certain product is marked with the special procurement = “50” in this view, the phantom indicator would be put on for the assembly.

A Phantom indicator indicates that the material master level mentioned here or the assembly level mentioned here is virtual or imaginary and MRP or production should not account for planning/reservation of this phantom assembly level by itself, though MRP or production should account for the planning/reservation of all the exploded child components in the phantom assembly BOM.

Normally the Bill of Material components are allocated to the operations in discrete manufacturing or the Phases in the Process manufacturing through the Routings or Recipes.

Use of Allocation of Components in Routing/Recipes - 

Point number 1 - The allocation of operations or phases to the BOM components in the Routing or Recipes respectively is created to make a certain component available on the start date of that operation/phase. When you create a production order or process order with a Routing/Recipe which is already allocated with components, the MRP and the order creation programs in SAP use this information to make the component available on the start date of the operation/phase. 

Point number 2 - The allocation of operations or phases to the BOM components in the Routing or Recipes respectively is created so that the necessary backflush components are automatically issued when you confirm the respective operation or phase. 

If You Dont Allocate an operation or phase to the components - 

SAP assumes that all the components are allocated to the first operation/phase and they would be available at the start of the Production order/Process order and they will be issued when the first operation/phase is confirmed.    

A Phantom BOM is a prepetual BOM or an Virtual BOM structure included in the Higher Level BOM for information purpose. 

A Phantom BOM has an header material and components. The Header Material for which you want to create a Phantom BOM is  declared as Phantom Material in the material master MRP View 2 (the special procurement key should be 52). 

A Phantom Level itself is an Virtual level and is not considered as a stockable item in SAP and SAP Skips this Phantom Level in MRP while planning the overall higher level BOM structure and does not plan any material or scheduling requirements for the same. 

Note: You can nevertheless stock a phantom level by creating the views like accounting, costing and plant storage location views. The requirement to stock a Phantom Level can only arise in very minimal number of business cases. 

For example: 

Normal BOM without Phantom Assembly: 

A Car has Left Front Tyre, Left Back Tyre, Right Front Tyre and Right Back Tyre, Which can be represented as below:

CAR

        > Left Front Tyre

        > Right Front Tyre

        > Left Back Tyre

        > Right Back Tyre

Adding a Phantom Level to a Normal BOM :

The Level - "Tyres" is an Virtual level (an useless level) which is added in the overall BOM structure for information purpose and SAP will not plan the requirement for the material - "Tyre" but it will plan the requirements for Materials Left Front Tyre, Right Front Tyre, Left Back Tyre and Right Back Tyre.  

CAR

        > Tyres (Phantom Level)

        > Left Front Tyre

                    > Right Front Tyre

                    > Left Back Tyre

                    > Right Back Tyre

It is a know fact that every BOM Level is to be produced through seperate production order or process orders. Though if you want to have 2 (assembly level and sub-assembly level) levels in the same order, you can declare the sub-assembly level as a phantom level, which would result in creating only one order for the assembly level while the sub-assembly level would be exploded in this production order as components and you would aviod creating the sub-assembly level order.

Read more on how to do this on this website - http://www.sapsword.com/home/learn-sap-pp/sap-shop-floor-control/why-do-you-create-sap-production-order-or-process-order

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