Over the next couple of weeks I will be covering Bill of Materials for Standards Tuesday, or Parts Lists as they are referred to in Section 5 of ASME Y14.34M-1996. Today I will concentrate on some of the elements that make up a BOM including which columns are mandatory and which are optional. Most material covered here will not be new to some of you but you may be surprised. When I was researching for this post I learned a few things that surprised me and I immediately recognized mistakes I have made in the past. I know I have learned things that will improve my drawings in the future and I hope you will feel the same.

BOM Heading

Section 5.1.3 dictates that the BOM heading shall be PARTS LIST but in my experience I have seen many companies use BILL OF MATERIALS as the header or exclude a header all together. As I mentioned in previous post, the ASME standards are not the be all end all and if your company strays from the standards in should be properly documented. In previous companies that I have been involved in the creation of standards, I have created a document that completely describes all non-conformance to ASME standards.

BOM Mandatory Columns

The following columns are required per Section 5.3.1 and apply to both BOMs integrated into the drawing and separate BOMs.

Quantity Required or QTY - The number of QTY columns must match the number of assemblies listed in the BOM with the column header indicating which configuration the column coincides with. SolidWorks has this ability built in already in the Bill of Materials and will be addressed in a future post. The item quantity, volume, length or other unit of measure is to be entered into this column. You may also enter the unit of measure in fields other then the item quantity, as in 10″, but my preferences is to have a separate Unit of Measure column. When you do not know the exact amount of an item listed, such as glue, you may enter AR with no value for AS REQUIRED or EST with a value for ESTIMATED.

If a component listed is a substitute for another component in the BOM, both items must have the same Find Number or Item Number and the alternate component will list SUB or ALT in the QTY column.

Part or Identifying Number – The part or identifying number including the dash number, if applicable, is to entered in this field.

Next Assembly - This column is required only if application data is used in the BOM. Section 3 defines application data as:

the next assembly(ies), and the model number, nomenclature, or equivalent designator of the assembled unit(s), of which a part  or assembly is a component.

In this column enter the part number of the drawing that details the assembly of which the item is a component.

Used On – This column is required only if application data is used in the BOM. In this column enter the part number, description or or designator of the assembled unit of which the item is a component.

Nomenclature or Description – Enter the noun or noun phrase that is used as the part description. I hope you read Standards Tuesday – Titling your drawing before naming your parts.

BOM Optional Columns

Find Number or Item Number – I know your instinct suggest that this should be a mandatory column but there are indeed cases that the Item Number is not mandatory.  Per the standard, you can leave out the Item Number column when the required entries are not frequently used and the required information is referenced in another column such as the Notes or Remarks column.

CAGE Code – This is an optional column but when your company requires it, enter the Commercial and Government Entity Code per the Cataloging Handbook H4/H8. You can ask me what this means but I would just look at you like my grandmother would when you ask her to describe the Theory of Relativity.

Weights of Units and Assemblies – This is a completely optional column but I have been at companies that would use the information in this column to estimate packaging weights for shipping and it could prove to be useful.

Notes or Remarks – You can place what ever notes your company deems important to be listed in the BOM such as reference to Specifications, flagnotes, vendor information, etc.

Unit of Measure – This column is optional but when it is used only standard units of measurements should be used such as IN, FT, mm, G, EST, etc.

Drawing or Document Number – This does not refer to the part number but instead to other referencing drawings and documents such as material spec documents, referenced documents, a separate drawing number applicable to the item listed, etc.

Size – The drawing or document size may be listed in this optional column.

Next week we will be looking more into Parts List as described by the ASME stadards. I will also be able to address any questions you may have , so please feel free to email with any questions you may have.

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