Wiring/Harness Drawings - Page 1
Forum section: electronics / general

author: abquke
author_rank: Regular Contributor
timestamp: June 04, 2022, 01:30:44 pm
content: So at work on top of regular electronics design and things I'll do design and documentation of wiring as well. As an improvisation, I've abused KiCAD into doing wiring diagrams so I have a drawing and can spit out a BOM... but I'm wondering what is done in the real grownup world as far as having a drawing that could be sent off to a contract manufacturer if I were having zillions made suddenly. Thx

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 06, 2022, 12:10:08 pm
content: Well, this can be very simple or it can get complex. I was in charge of designing cabling for the CST-100 (Starliner), from Boeing and it got very complex. However, if your wiring is simply from board to board it can be very easy.Perhaps you can describe some of your wiring requirements and I can give you someplace to start.

author: abquke
author_rank: Regular Contributor
timestamp: June 06, 2022, 09:14:39 pm
content: These fall under the category of "simple" I'm sure. Things like 14 pin molex connector goes from the board with the SMPS to a bunch of 2 pin molex connectors that power other boards, this interlock switch is has wires yea long going to this connector...

author: mon2
author_rank: Frequent Contributor
timestamp: June 06, 2022, 10:00:21 pm
content: You should certainly have a definition for your specs but for us, we share the wiring and expected connectors and have the cable shop create the diagram. Has worked very well for us with 30+ years of offshore sourcing. A good shop will not care about the volume to win your longterm business.If there is an interest, can share the contact details of vendors we have worked with and continue to do so.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 06, 2022, 10:20:37 pm
content: Quote from: abquke on June 06, 2022, 09:14:39 pmSo you could simply define each cable with a wire list and a BOM in such a fashion below by just a spreadsheet.Connector reference designator | Con pin number | signal description | wire ref des or number | wire length | wire color | ending con pin num | end con ref des | short descriptionAdd a column for any other item, such as a sheath or shrink tube etc.BOM references each part's reference designators.Hope this helps...

author: abquke
author_rank: Regular Contributor
timestamp: June 06, 2022, 10:21:00 pm
content: Part of this is also that creating a diagram makes it easy to get a BOM at a push of a button which allows for inventory/ordering to go smoothly down the line.ISO-13485 and friends are in the cards for when real quantity is going to be needed, in case you already know of manufacturers with those particular certs.

author: abquke
author_rank: Regular Contributor
timestamp: June 06, 2022, 10:22:03 pm
content: Quote from: tpowell1830 on June 06, 2022, 10:20:37 pmI like that level of unambiguous definition. Thanks

author: TimFox
author_rank: Super Contributor
timestamp: June 06, 2022, 10:36:26 pm
content: Of course, board-to-board requires only length and pin-to-pin connections (along with the other variables listed above).Many wiring harnesses, such as automotive (or even aircraft) also need to specify break-out locations along the bundle for different boards, etc.I believe that my former employer, for small-quantity harnesses, used a normal drafting program (Autocad) to show the configuration and dimensions, with separate sheets for the BOM and the pin wiring.

author: abquke
author_rank: Regular Contributor
timestamp: June 07, 2022, 12:35:26 pm
content: Quote from: TimFox on June 06, 2022, 10:36:26 pmThat'd take some coordination on where a MechE would actually (put) things, right?

author: TimFox
author_rank: Super Contributor
timestamp: June 07, 2022, 01:42:01 pm
content: Quote from: abquke on June 07, 2022, 12:35:26 pmFor wiring over a macroscopic machine, where wires go in different directions between switches, boards, motors, etc., of course the mechanical engineer determines the dimensions and locations, while the electrrical engineer determines the connectors, pinouts, etc. If the pinouts require a relatively small table, it was only shown in the right side of the Autocad drawing.

author: nvmR
author_rank: Regular Contributor
timestamp: June 07, 2022, 01:57:36 pm
content: From what I've seen, Solidworks Electrical has features for harness design. The BOM is clearly listed in a table, making it easy to understand along with the drawing.https://www.gsc-3d.com/blog/solidworks-2019-top-10-new-features-in-ecad/

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 07, 2022, 03:13:40 pm
content: Quote from: abquke on June 06, 2022, 10:21:00 pmIf you are a medical device company, ISO-13485 is a pricey, but necessary route. However, much of the requirements in ISO-13485 suggests that your documentation have a strong base and adherence to specific methods.In other words, your documentation process needs to be bulletproof and seamless, both on your end and the company that does your harnesses. I also worked many years at a company that mfg pacemakers and I was directly involved in both process and design engineering. The QC department had high requirements for documents related to mfg machines created in house to produce pacemakers as well as any ancillary equipment used to produce pacemaker product such as leads. This also applied to vendors who made such equipment.With that said, you, as the primary mfg are responsible to ensure that your vendors meet these requirements in tandem with ISO-13485 officials assigned to monitor your vendors. This is partly done with requirements documents at the outset of a contract for such purposes. This can get deep...Quick search on Thomasnet reveals this vendor, there are probably more:https://news.thomasnet.com/fullstory/medical-cable-and-wire-harness-assembly-services-meet-iso-13485-standards-40002162Are you in charge of how documentation is created at your company, or do you have a QC or documentation department that disseminates how documents are made?The method we used for harnesses was straightforward, but in-depth. The harness document consisted of a cover page that had the harness number and a technical/legal description and "shall" and "should" statements as needed. This page could include a technical textual description of harness as well. The next page consisted of a more descriptive page which had a sketch where breakouts and any other specifics that could not be included in wire list or BOM, such as placement of tape or sheath etc. unless a formboard dwg was included, which covers much of this info (you specified that these were simple enough harnesses that formboard dwg not needed). The next sheet contained the wire list and the last sheet was the BOM. All of these sheets were 1 document.As I said before, some of this may or not be necessary, but should be considered.

author: abquke
author_rank: Regular Contributor
timestamp: June 07, 2022, 08:32:42 pm
content: Quote from: tpowell1830 on June 07, 2022, 03:13:40 pmWe're at the stage of setting up a QMS system and getting contract manufacturers figured out. It'll be a bit before we get in a position of internal manufacturing, let alone having any of that kind of certification.At the moment, I'm responsible for everything on the EE end from design to documentation. As I understand it once we're through upcoming trials with our prototype run, then the real adult supervision shows up.In theory all the engineers will be put through some kind of Manufacturing Extension Program, but I'm asking questions now to get a sense of the documentation bus I'm about to be under.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: June 08, 2022, 12:38:25 am
content: Wow, the prototype phase is easy compared to getting systems in place for mfg.Hope everything turns out okay.Edit: Wish I was there to help!