Parts list , also known as a bill of materials (BOM) is a tabular list of the items used to make an assembly. Parts list is usually combined with the assembly drawing, but it is a separate and individual document and can be and provides a complete list of all parts needed to build the complete project.
The information associated with the parts list generally includes:
- Item number
- Item numbers are based on the assembly structure, that is, the order in which parts are displayed in assembly.
- Part number
- Part number or drawing number which is a reference back to the detail drawing.
- Description is usually a part name or a complete description of purchase part or stock specification, including size and dimensions.
- The number of that particular part used on this assembly.
The four elements listed are the most common items and placed in the assembly drawing.
Parts list location
When placed on the assembly drawing, the parts list can be located in the upper-left or upper-right corner of the sheet, above or to the left of the title block, or in a convenient location.The location also depends on company standard.
When the parts list is so extensive , the best location is the upper-right corner of the assembly sheet, in this case a new group of column is added to the right-side of the first one. If additional parts are added to the assembly, then space on the bottom of parts list is always available.
When the parts list is so extensive, the best location is the upper-right corner of the assembly sheet, in this case a new group of column is added to the right-side of the first one. If additional parts are added to the assembly, then space on the bottom of parts list is always available.
If the parts list is located in the bottom of page, then each row of data is provided from the bottom of the sheet upward, that is less natural.
Most companies prepares parts list in database software, so information can be retrieved and edited easily. When the set of working drawings is prepared on a CADD system, the parts list can be parametrically associated with with the details and assembly, so changes to any are automatically updated on all.
Parts list in separate sheet
The parts list is not always placed on the assembly drawing. Some companies prefer to prepare parts list on separate sheets. This method allows the parts list to be computer generated separately from the drawings. Separate parts list are usually prepared on a computer so information can be edited conveniently.
GD&T Training Center Inc.
|Assembly name:||Assembly number:|
|Number of parts:||Date:|
|Item||Part number||Description||Qty||Notes or Remarks|
An engineering chang request (ECR) can require to removal of a component from the parts list. When this happens, the balloon and the parts list numbers are not usually renumbered, becuse other documents may reference the balloons the parts list numbers. Instead, the word REMOVED is placed in the parts list next to the balloon number that has been deleted. Not all companies use this practice. Instead, they renumber the balloons and parts list and correlate all other related documents.
Purchase parts, also reffer to as standard parts, are parts that are manufactured and available for purchase from a supplier. Purchase parts are items such as fastener. pin, key, washer and other common products. It is generally more economical for a company to buy these items than to make them. Purchase parts do not require a detail drawing, because a written description completely describes the part. For this reason, the purchase parts found in an assembly must be describe clearly and completely in the parts list. when the part description is too long and there is not enough space for putting that into the the parts list, then using a Note Drawing can be a better way.