In the video a battery, ref des BT1, is entered on the schematic diagram and is not connected to the rest of the circuitry, because later a battery holder (socket) is added, which is placed on the back side of the board. It is not clear how both parts should be handled. Here is how. Both parts should be on the schematic diagram as both of these items are part of the assembly. From IEEE 315, clause 22.4 the class letter “X” is for a fuseholder, lampholder, and a socket. By extension the battery holder/socket would be ref des XBT1. There would be no land pattern for the battery, of course, and both items would appear in a parts list (PL) derived from the schematic.
I think an intro for new users is not the place to get into the nuances of MRP systems…
But it’s a moot question anyway, some sites will have different procedures. At ours, we only put things on the schematic that are relevant up to reflow/wave solder. Processes and components fitted after that are handled by MRP.
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So you have two schematics? One for components/parts that are on a PCB and then another schematic that is for the assembly? How do you keep track of that? The finished product or end customer, what would be in a maintenance manual, would use the schematic diagram for the complete assembly. It doesn’t matter what the process steps are or at what stage the items are put on the assembly. This is the difference between engineering documentation and manufacturing documentation. I am speaking here of electrical/electronic components. Items such as hardware, heatsinks, heatshrink tubing, knobs, etc. would of course be on the parts list (PL) for the assembly. I wasn’t speaking of manufacturing resource planning systems. What I was trying to get across was the proper use of reference designators and having those parts show up on the PL.
Yes, you were. Perhaps you don’t know it.
What do reference designators have to do with it if they do not appear on the schematic? You assign reference designators to scews, knobs, heatsinks and heatshrink tubing? I certainly don’t!
You keep referring to “the” parts list, generally there is more than one. A PCB would have it’s own parts list and there would be another parts list for a sub-assembly that would contain the PCB, but not all of it’s components, as well as an enclosure, heatsink, screws … and this might be part of a larger assembly which has it’s own parts list etc.
Neither of which likely end up in a maintenance manual.
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This is pretty basic engineering stuff. Maybe enrol on an engineering training course? http://www.my-product-engineer.com/assembly-drawing.html
Actually there is some debate within our company whether the MRP system (SAP) should be the master source of the BOM, or whether the engineering drawings should be. Answer depends on whether you are engineering or manufacturing department …
We don’t ship customer serviceable products, apart from trivial stuff like oil changes. For that there is a set of customer manuals produced by technical documents dept. We do have service hubs, but all parts of the company that need it have access to the MRP system and the engineering database. We’ve been in business nearly 100 years. I’m not saying we could not improve, but it’s pretty well worked out.
Generally for non-electrical/electronic parts an item number or find number is used and this is what would appear on an assembly drawing for an assembly. However, IEEE 315 clause 22.4 does have class letters for hardware, class letter “H”; mechanical parts, class letters “MP”; and yes even hydraulic parts, class letters “HP”. So, yes, I do assign reference designators to these items in a PL. Schematic diagrams using modern day schematic capture electronic design software use reference designators, consisting of a class letter(s) and a number, and not item numbers.
Yes, you are correct, there would be a parts list at each “level” of assembly. See ANSI/ASME Y14.44 Reference Designations…, Figure 7 Typical System Subdivision.
There are a number of scenarios where the schematic diagram, for a printed circuit board assembly, would show electronic parts for the assembly, and thus the parts would appear in the PL, but the parts that would have land patterns for a PCB would be a cut set of the assembly schematic. Two situations are: 1) A fuse that is put into a fuse holder or a pair of fuse clips and 2) ferrite beads put on the leads of a THT (leaded) transistor or on a THT (leaded) connector. In these two cases you have parts on a schematic diagram that do not touch the PCB and, therefore, do not have land patterns, but are, of course, on the PL (for the assembly).
The MRP system should follow the engineering drawings/documentation exactly (don’t you think?). Remember we are always just one ECO away from being perfect.
That assembly drawing that you have the link to seems to be a completely mechanical assembly. Thus the use of item numbers is appropriate and, of course, there would be no schematic diagram. However, if there would be an electric motor there would be a schematic diagram that would show the electrical connectivity. My background was working on airborne radar and in commercial avionics, both of which had maintenance manuals or what is called Illustrated Parts List (IPL), so it depends on what industry your in.
Define “working on”, it would seem not to involve any engineering/design.
Your inconsistent use of the terms “assembly”, “assembly drawing”, “Schematic diagrams”, “assembly schematic” leaves me wondering if you are really that confused. It took me three or four reads just to understand what you are trying to say. You refer to IEEE and ANSI standards as if they are somehow relevant to the discussion. You also seem to think that a schematic and parts list are the only engineering documents that are produced for a PCB. Not all components that end up on a PCB must be on the schematic.
KiCad is for schematic capture and PCB layout therefore that is what we tend to discuss here on this forum. If you want to create a parts list for an assembly that includes screws, heatsinks, knobs and heatshrink tubing and assign them reference designators according to IEEE 315, that’s great! But your original post in this thread suggested that in order to have a battery holder in our parts list we must put it in our schematic and refer to it as XBT1. This may be how you chose to handle it but others are sure to disagree. The rest of the discussion is moot at best.