The Hardware Document Toolkit - Bill of Materials V1.2

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1		The purpose of this project is to make bill of materials (BOMs) more accessible to people trying to document their hardware, while also giving them context on the basic terminology for information being exchanged. Please see our original blog posts (LINKS) for more context.
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3	How to use	The Hardware Document Toolkit - Bill of materials consists of a glossary that defines common terms and 3 example BOMs.
4		Step 1: Read the glossary! Sounds elementary but that's the place to start.
5		Step 2: Decide what kind of BOM you want to build. We provide three examples that represent typical mechanical, electrical, or assembly BOMs. Use them as a starting point, or start from scratch
6		Step 3: Clone this workbook. We recommend Excel or Google Sheets, but CSV works too (for all you hackers out there)
7		Step 4: Build up a sheet with the properties and subtotals you feel are necessary (from the glossary you read)
8		Step 5: Share with your team, vendors, and other partners
9		Step 6: Contribute back to the project! This work is an MVP, and can be made better with your contributions. So please use this, share it, and add to it and make it your own. All we ask is that you attribute the original creators and let us know your thoughts too as we want to grow this project!
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11		This document is released openly under "Creative Commons Attribution-ShareAlike 4.0 International". All contributions will adopt the same license.
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13	Background Blog Posts	https://ryan-vinyard.medium.com/the-hardware-document-toolkit-bill-of-materials-537b55084fe4	VPD
14		https://www.getbommer.com/post/introducing-the-hardware-document-toolkit-bill-of-materials	Bommer
15		https://medium.com/root-ventures/the-hidden-costs-of-hardware-ec65bf179ebb	Root VC
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17	Get in touch	ryan@vpd.io - Founder, Vinyard Product Development - www.vpd.io
18		jesse@bommer.io - Co-founder, Bommer - www.getbommer.com
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21		Check it out at http://bom.hwdocs.com

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1	Basic properties (applies to all bills of materials)
2	These fields are the bare minimum you want in a bill of materials. They define organization, identity, and quantity for each of the parts in your ME, EE, or top level assembly.
3	BOM Field	What is it?	Why?
4	Item	Numerical list specific to each BOM.	Unique items numbers help keep the document organized by numbering and organizing each line item. They can also be used to represent hierarchy or assembly structure (e.g. 1.1.1 is a child of 1.1), and can be used externally to refer to items in the BOM.
5	Part Number	Distinct part number for each part the company will ever use.	Part numbers that are unique across your company let you identify specific physical items that can be included in a product. A part number, therefore, should be different for any part with functional, material, or aesthetic changes; you want to make sure you're including the right rev/material/finish of a part in your assembly! In our examples, we chose a very simple part numbering scheme: every part number starts with HDT (for Hardware Document Toolkit), then a dash, then a number (counted up sequentially from 1). This format makes them recognizable the values as part numbers and makes it easy to ensure they're unique; you can keep a list of "assigned part numbers" that gets added to as you create new parts.
6	Description	Official name or description of a part.	A human readable description of the part clears up ambiguity, and lets the designer/engineer/manufacturing specialist add intent to the bill of materials. When there isn't a better, dedicated place to capture a piece of information (e.g. part number, quantity), the description is a reasonable place to put it.
7	Quantity UOM	Unit of measure for quantity. e.g. Each, Inches, Packages, Kilograms, etc.	The unit of measure defines how to interpret Quantity, which really drives how to purchase or produce this part of the bill of materials. Most of the time, this will be "each" which means Quantity 1 means 1 part, but sometimes UOM can be linear unit (e.g. ft) which makes quantity equivalent to length of material required for this part. You will also sometimes see A/R for "as required" on items difficult to measure (e.g. oil on an o-ring).
8	Quantity	The number of components in this assembly.	Quantity specifies the number or amount that is needed for this part or line item, in units of Quantity UOM. Accurate quantities ensure that you can actually build the assembly; it also drives cost calculations, and any analyses that uses cost.
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10	Mechanical Engineering (ME) properties
11	These fields are most likely specific to mechanical engineering and include physical properties, manufacturing guidance, costing, and sourcing information
12	BOM Field	What is it?	Why?
13	Make/Buy/Modify	An indicator that a part is manufactured custom, purchased off-the-shelf, or purchased and then modified to spec.	This helps engineers in prototyping and operations in production to understand how to source this and how complicated it is to produce. This is called by many different things - could be Category, Class, Type, or any number of other names.
14	Material	The physical material that is used to produce this component.	It can help to visualize this on a BOM to see groups of material for sourcing. Sometimes includes detailed material properties like Ally or Temper. More details can also be captured here or in additional columns about how the component is made from the material including Finish and Process.
15	Revision	Defines the formally changed version of the component used in an assembly.	Revision is important for knowing which version of a part should be made, or sourced, or otherwise included in the BOM. This is typically managed by your design or data management tools, e.g. PDM/PLM version number, and is represented in the BOM purely as information about the assembly you're building, costing, or sourcing.
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17	Electrical Engineering (EE) properties
18	These fields are most likely specific to electrical engineering and include board placement information, component values, and detailed manufacturer references
19	BOM Field	What is it?	Why?
20	Reference Designator	Alphanumeric callout for electrical component - C1, R23, J9, etc.	Keeps track of components by order within a component type. Should correlate to silkscreen on board to make correlating schematics, BOM, and PCBAs accessible.
21	Value	The rating or descriptive value of a component - e.g. Ω for resistors, F for capacitors, etc.	Often included in descriptions, the value can be helpful to track separately in order to see similarities for sourcing.
22	Manufacturer Part Number	The unique part number that a manufacturer uses to delineate the component in their system.	Manufacturers will have their own part number to track things in their systems, and sometimes will even create a custom part number for your component to track usage. In many cases, the manufacturer part number can represent a specific value, voltage rating, size, material, and other critical information.
23	Alternates	Alternate part numbers that will function in the system.	Sometimes the primary part number can be unavailable, too expensive, or has regional availability. Having alternates listed that will work in your system can saving your sourcing team or a vendor the time to find appropriate alternatives.
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25	Sourcing/purchasing properties (applies to all bills of materials)
26	These fields describe sourcing and purchasing of the components in your BOM. They include vendor and cost information; you can (and should) include this set of fields multiple times on a BOM to capture sourcing information from multiple vendors.
27	BOM Field	What is it?	Why?
28	Vendor	The vendor from whom you can source this component. This is also called Distributor on some (mostly EE) BOMs.	It is important to identify your vendor(s) early in the process so you know how a component will be manufactured and priced.
29	Vendor P/N	The part number or SKU for the part in the vendor's catalog.	Important to track for easy transfer into and out of vendor supply chain systems.
30	Minimum Package Quantity (MPQ)	The number of units of quantity in one shippable package, e.g. 100 fasteners in a bag, sold in increments of 20ft of tube.	Important to consider for part design and optimizing your logistics and material utilization.
31	Minimum Order Quantity (MOQ)	What is the minimum amount a vendor will sell in one order, PO, or shipment.	It's important to know the minimum amount a vendor will supply since they may be set up for certain scale that doesn't fit your supply chain. Sometimes this is just the MPQ.
32	Cost Each	The individual price per component (not price per package)	The core cost driver of any BOM is all of the individual costs. For more complicated BOMs this can also be split out by quantity purchased and/or vendor purchased from.
33	Extended Cost	Total cost of this component in this assembly. Equal to "quantity" multiplied by "cost each".	This column is what should be summed to the total cost.
34	Lead Time	How long does this component take to procure?	Can be helpful to capture your lead time (in days or weeks) in order to make sure you are tracking long-lead items and getting them ordered soon enough.
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36	Assembly/packaging/kitting properties
37	These fields represent values or information that describe true cost of your finished goods, and any assembly-specific information you need to capture. In some cases (especially for costs) they may represented as subtotals instead of separate columns. The Assembly BOM template assumes a simplified direct-to-customer shipment model with one warehouse. This can be more complicated when using multiple warehouses, distributors, or other sales channels for your product.
38	BOM Field	What is it?	Why?
39	Manufacturer Value Add (MVA)	The cost of labor and other manufacturing overhead involved with sourcing, storing, and assembling your product.	This can be all rolled up into one value in order to simplify your costing. See below for a more detailed breakdown of what gets included in MVA.
40	Cost of Goods Sold (sometimes called Ex-Factory)	What is your cost coming directly out of the factory. Typically calculated as Materials BOM + MVA.	This is the final cost you will pay to the factory. This can often be misleading since it does not include several of the indirect cost items listed below.
41	Freight In	The per-unit price of the bulk shipping of units from your factory to warehouse.	It's important to track this internal supply chain shipping cost as it can be large if you are manufacturing or distributing internationally. Shipping mode (air vs. sea) can have a major impact on this number.
42	Duty, Taxes, & Tariffs	The cost of importing your product between countries.	This can be a very complicated subject depending on what products and which countries you are dealing with.
43	Fulfillment	The cost of storing your product at the warehouse.	This covers them receiving your product, holding inventory, and shipping to end customers
44	Freight Out	The average cost to ship an individual product from the warehouse or fulfillment center to the end customer.	This is one of the few costs your customer may pay for directly, in which case you would not include it in your COGS.
45	Warranty Reserve	The cost added to protect against manufacturer's warranty claims.	This rate (normally a percentage) and your overall warranty can be negotiated as part of the MSA (Master Service Agreement) with your factory.
46	Credit Card Processing Fee	The cost you pay to a credit card processor to process the transaction.	This is typically 2.5-2.75% of your product’s selling price.
47	Operational Cost of Goods Sold (OCOGS)	The final cost to you to produce and deliver a unit to the customer. Typically calculated as COGS + all indirect operational costs (rows 41-46).	This is the most important ultimate number from your BOM that you will want to include in financial models and share with investors.
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49	MVA Detailed Breakdown
50	These are all components that typically get rolled up into the MVA charged by a manufacturer. It is best practice to always ask for this breakdown. Many factories will instead just give you a total MVA dollar value or percentage. Detailed breakdowns help make sure that certain portions aren’t inflated or assumptions incorrect -- plus it helps with quote comparisons and negotiations.
51	BOM Field	What is it?	Why?
52	Yield Loss	This is the number of units you expect to scrap (throw away) out of every 100 produced.	Note that scrap only happens after all attempts at rework and repair have failed. This should be pre-negotiated with your factory, and written into their master services agreement. Negotiate to have this percentage applied to the minimum reasonable material BOM cost (for example, make sure that packaging and accessories are NOT included in the calculation).
53	Labor & Overhead	How much human “touch time” is required to assemble your product. Hourly labor rate x total amount of time required to assemble one product.	Hourly labor rate varies dramatically from region to region. Make sure your factory tells you the actual labor rate that you're being charged.
54	SG&A	Selling, General, and Administrative Expenses.	This covers everything required to keep the lights on in the factory. It rolls up all costs that are NOT directly related to the production of your product. This can include facilities, utilities, office staff, sales, travel, management, etc. It’s typical to see this calculated as a percentage of your material BOM cost.
55	Profit	This is the profit that the factory pockets for each unit they manufacture.	It’s typical to see this calculated as a percentage of your material BOM cost
56	VAT	This is the value-added tax imposed by certain countries on any products assembled or produced.	It’s typical to see this calculated as a percentage of your material BOM cost. It varies from country to country (products made in the US do not have this, but China does).Make sure this doesn't get double-counted (included in both material BOM & MVA).
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	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q
1	Item	Part Number	Description	Quantity UOM	Quantity	Material	Make/Buy	Primary Vendor	Primary Vendor Part Number	Primary Vendor MPQ	Cost Each	Extended Cost	Secondary Vendor	Secondary Vendor Part Number	Secondary Vendor MPQ	Secondary Vendor Cost Each	Secondary Vendor Extended Cost
2	1	HDT-0002	Assy, Enclosure
3	1.1	HDT-0003	Enclosure, Top, Blue	Each	1	PE	Make	AcmeCo	AC-OSBT-01	1	$2.52	$2.52	FakeCo	FA-OSBT-01	1	$2.57	$2.57
4	1.2	HDT-0004	Enclosure, Bottom, blue	Each	1	PE	Make	AcmeCo	AC-OSBT-02	1	$2.41	$2.41	FakeCo	FA-OSBT-02	1	$3.33	$3.33
5	1.2.1	HDT-0005	Threaded Insert	Each	4	Brass	Buy	McMaster	92395A113	50	$0.24	$0.96	Fastenal	185923	1	$0.45	$1.79
6	1.3	HDT-0006	Screw, Machine Head, 6-32, 1 in LG	Each	4	Steel	Buy	McMaster	92196A165	100	$0.09	$0.35	Fastenal	11587839	1	$0.17	$0.68
7	1.4	HDT-0007	Seal, O-Ring, 7.443in OD	Each	1	EPDM	Buy	McMaster	9557K207	5	$1.80	$1.80	Fastenal	413705	1	$0.83	$0.83

	A	B	C	D	E	F	G	H	I	J
1	Item	Part Number	Description	Value	Reference Designator	Quantity	Manufacturer	Manufacturer Part Number (MPN)	Cost Each	Extended Cost
2	1	HDT-0001	Assy, Arduino UNO				BoardCo
3	1.1	HDT-0015	PCB, Arduino UNO			1	BoardCo		$5.00	$5.00
4	1.2	HDT-0016	Component Cost Roll-up, Arduino UNO			1			$10.00	$10.00
5	1.2.1		PIN HEADER, 1X06		AD, POWER	2
6	1.2.2		CAPACITOR, European symbol	100nF	C1,C2,C4,C5,C6,C7	6
7	1.2.3		CAPACITOR, European symbol	1uF	C3,C8	2
8	1.2.4		CAPACITOR, European symbol	22pF	C9,C10,C11,C12	4
9	1.2.5		DIODE, M7		D1	1
10	1.2.6		INDUCTOR, European symbol	500mA	F1	1
11	1.2.7		Adjustable Output Low Dropout Voltage Regulator	800mA	IC1	1		MC33269ST-5.0T3
12	1.2.8		Adjustable Output Low Dropout Voltage Regulator	800mA	IC2	1		MC33269D-5.0
13	1.2.9		PIN HEADER, 2X03		ICSP,ICSP1	2
14	1.2.10		PIN HEADER, 1x08		IOH,IOL	2
15	1.2.11		LED	YELLOW	L	1
16	1.2.12		Ferrite Beads, EMI suppression, SMD		L1	1		BLM21
17	1.2.13		LED	GREEN	ON	1
18	1.2.14		POLARIZED CAPACITOR, European symbol	47uF	PC1,PC2	2
19	1.2.15		CRYSTAL	16MHz	Q1,Q2	2
20	1.2.16		RESISTOR, European symbol	1MΩ	R1,R2	2
21	1.2.17		RESISTOR, European symbol	27RΩ	R3	1
22	1.2.18		Switch, Temporary		RESET	1		TS42
23	1.2.19		Array Chip Resistor	10KΩ	RN1	1
24	1.2.20		Array Chip Resistor	1KΩ	RN2	1
25	1.2.21		Array Chip Resistor	22RΩ	RN3	1
26	1.2.22		Array Chip Resistor	1KΩ	RN4	1
27	1.2.23		LED	YELLOW	RX	1
28	1.2.24		MOS FET		T1	1		FDN304V
29	1.2.25		LED	YELLOW	TX	1
30	1.2.26		OP AMP		U1	1		LM358D
31	1.2.27		LINEAR REGULATOR, Low-dropout ultra-low power	150 mA	U2	1		LP2985-33DBVR
32	1.2.28		IC MCU 8BIT 8KB FLASH		U3	1		ATMEGA8U2-MU
33	1.2.29		POWER SUPPLY		X1	1		DC21MMX
34	1.2.30		BERG USB connector		X2	1
35	1.2.31		RESONATOR	16MHz	Y1,Y2	2
36	1.2.32		VARISTOR		Z1,Z2	2		PGB1010604
37	1.2.33		MICROCONTROLLER		ZIC1	1		ATMEGA8
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40	Notes: further reading https://www.autodesk.com/products/eagle/blog/creating-bom-pcb-manufacturing-basics-2/
41	Pulled from http://solderpad.com/solderpad/arduino-uno/, https://forum.arduino.cc/index.php?topic=83194.0

	A	B	C	D	E	F	G
1	Item	Part Number	Description	Quantity	Cost Each	Extended Cost
2	1	HDT-0001	Assy, Arduino UNO	1	$15.00	$15.00
3	2	HDT-0002	Assy, Enclosure	1	$8.04	$8.04
4	3	HDT-0008	Assy, Temperature Sensor	2	$10.00	$20.00
5	4	HDT-0009	Assy, User Interface	1	$10.00	$10.00
6	5	HDT-0010	Power cable	1	$5.00	$5.00
7	6	HDT-0011	USB cable	1	$5.00	$5.00
8	7	HDT-0012	Instruction manual, R1-01	1	$5.00	$5.00
9	8	HDT-0013	Packaging, Outer Box	1	$10.00	$10.00
10	9	HDT-0014	Packaging, Insert	1	$10.00	$10.00
11						$88.04	Subtotal
12						$15.00	MVA
13						$103.04	COGS (Ex-Factory)
14						$4.00	Freight In
15						$4.00	Duty, Taxes, & Tariffs
16						$3.00	Fulfillment
17						$11.00	Freight Out
18						$7.00	Warranty Reserve
19						$6.00	Credit Card Processing Fee
20						$138.04	OCOGS

	A	B	C
1	Date	Version	Notes
2	2020-05-13	1.0	Initial release
3	2020-07-13	1.1	Major contributions by Chrissy Meyer (chrissy@root.vc) of Root Ventures on ASSY BOM items leading to addition of new section of Glossary, "MVA Detailed Breakdown". Minor typo corrections and clarifications.
4	2021-03-31	1.2	Added links to original blog posts in "How to use" since they are helpful usage guides