Weldment Cut-list vs. BOM Conflict

Do you have the option of balloons for one list and triangles ( or another shape) for the 2nd list?

I'll check with the guy in drafting. That could help a lot.

I bet that I am still missing something fundamental to people that commonly document weldments. Having both "BOM Items" and "Cut List Items" referred to as "Item Numbers" seems like a problem others have worked around. Does one of them commonly get referred to by a different term? I can't be the first to look for a way to avoid this confusion.

Thanks,

Bruce

Most of the places I've worked at had their manufacturing support people do the sizing of the parts.

Engineering / Drafting was asked to provide a length for parts but we didn't figure out how many pieces could be cut from a stock length.

12AC2.5 1x2 aluminum channel, 2.5 inches long.

12AC2.9 1x2 aluminum channel, 2.9 inches long.

12SC3.8 1x2 steel channel 3.8 inches long.

24TC2.5 2x4 titanium channel 2.5 inches long.

Maybe this won't work, I don't know.

Is the BoM part of the drawing or in a separate programme? We transfer our drawing created BoM into a management programme & would list all of the cut parts as separate items. We work out what proportion of a standard extruded length the cut part needs & the programme adds the total to determine the number of lengths required. It also knows that the minimum order quantity is a complete extruded length.

He is currently using the BOM features of the program to create what I am calling a "Cut List".

What I call the BOM is in a separate database that is basically a management program. In the database I want the total requirements to purchase in feet, pounds, gallons, etc.

We are basically trying to use one BOM two different ways.

Things get a little more complicated when HeliCoils or captive nuts are added to the mix. That makes his cut list even more like the BOM that I am tinking of.

At times it is tempting to say that I need to change the way I create the BOM in the database. It is tempting to allow the same internal part number to appear multiple times on a single BOM. One entry might be 6 ea. at 12" length. Another entry might be 4 ea. at 20" length. This would then get complicated and confusing if the cut parts have different hole patterns drilled into them. Before we go too far with this we need to note that once we start cutting we should probably not use the raw material part number. Once we start drilling we must not use the raw material part number. Thus, what part number do we use? We don't want to assign part numbers to each little part used in the weldment. We, like most companies, want to only assign internal part numbers to the raw materials and the finished weldment.

The package was called VX and was an American product. About a year ago China bought the CAD company and the package is now called ZW3D. It is a medium good but slightly buggy 3D package where some developers expanded the GPL POVray rendering package up to a 3D drafting and design package.

Part of my problem comes from me wearing many hats at my job. When I have my database hat on I want a BOM to list a total quantity of material and an internal part number. For something like rectangular tube stock I would typically request about 125% of what we need to allow for saw kerf, stick remnants, etc. When I wear my machine shop hat I agree with the need for a table that lists all the cut lengths. Thus, two things that have different goals but both have "items" and both could be called "Bill of Materials".

Below is an example of what I am talking about.

From a provisioning and material costing point of view this weldment has 3 line items. It has rectangular tube, flat plate and captive nuts.

From a shop floor point of view this weldment has the 7 items shown below and the captive nuts not shown.

The database Bill of Materials has 3 items and the cut list Bill of Materials has 8 items.

The "bubble numbers" contain the item number from the Bill of Materials (which one?) inside a circle.

I suspect that part of the answer is one list is called "Bill of Materials" and the other list is called something else (possibly "Cut List"). But that still leaves me with a lot of room for expensive confusion when people try to use the list's line number as the number inside the circle.

Also, the shop floor needs the captive nuts listed somewhere but they are not exactly a "Cut List" item.

This seems to be down to the limits of the programme you use. I mentioned earlier that we transfer our drawing generated BoM into the management programme.

We don't bother aligning the drawing balloon numbers to the management BoM, we work by the individual part numbers. The management programme does allow me to assign whatever line item number I want to each item so, in our case, I could make the line item numbers the same as the drawing balloon numbers if I wanted to.

The companies I've worked for in the past would have a separate part number for each unique piece. Costing was done on a per inch basis (or sq in) basis. (could be feet or sq feet) That costing included a scrap rate.

It will be less confusing to go this route. Go with a cut list and drop the BOM with 3 line items.

Use some cost factors for holes, cut, welding.

ddk writes: "Go with a cut list and drop the BOM with 3 line items."

I would agree but would expand on that a little. Use the "Item" numbers from the BOM strictly as a way to illustrate how may different items are required to build your product. Then stop there.

Next, have your illustration with balloons reference only the "cut sheet". Your craftsman should be instructed to work strictly from your cut sheets and not the BOM. The reason for this is because each one (BOM and cut sheet) supply information for different reasons. Engineering, and invariably your procurement department, need the information from the BOM. The folks doing the work need the info from the cut sheet.

I think you are trying to have all parties work from the BOM and it gets confusing when you have to split a particular line item into several pieces. (as it naturally would)

Therefore, the simplest way to keep the information clear is to have each entity reference only the specific information that is applicable to their function. This is done in almost every mfg facility I've worked at. Give the folks on the floor only information they need to do their job. Otherwise you run into exactly this situation.

As for the captive nuts or any other item that does not have to be cut, there is no reason those too couldn't be added to the bottom of a cut sheet. For that matter, I wouldn't even call it a cut sheet. I'd call it "details" (or anything appropriate) where it lists cut pieces and any other items from the BOM that the craftsman needs to do the job.

The key is to give the folks doing the job only the information they need. Keep the BOM out of their area of concern.

Good luck!

Your response, a couple of other responses and my thoughts last night all seem to be converging upon the same solution.

1) The "Item Numbers" on sheet metal and machine shop drawings would only refer to "BOMs", "Cut Lists" or whatever we call the table on the fab drawings provided to the shop floor. Any line or item numbers in a procurement database would be isolated.

2) The "Item Numbers" on PCB assembly drawings would typically (probably always) refer to the item number assigned in the database. Many PCBs have dozens of item numbers often totaling between a hundred and several hundred ICs, capacitors, resistors, connectors, etc. These larger lists are typically handled much better by a database.

3) Other things would be handled on a case by case basis but typically if a table appears on the drawing then the table would control the item numbers. If item numbers are used but not listed in a table on the drawing (like a printed circuit board) then the database generated/maintained list and item numbers would be used.

Thanks to all for your help,

Bruce

My last supervisor was a member of ANSI, and was bound and determined to make our company follow the code. I had been in the business some twenty years using part bubbles. They have been replaced with "find bubbles". The ANSI BOM has changed quite a bit. I am on loan to another company now, and do not have my references. I believe it was ANSI 14.5. This caused quite a ruckus. Us older designers were used to using part bubles and so was our shops. But, our supervisor, being the expert he was, made our group use this new system of find numbers. What I remember was there were both find numbers and part numbers. One might consider the reviewing the ANSI standards.

I do like some of the previous suggested methods.

I remember in the mid to late 80s "experts" tried to force me to use the new logic symbols (and, nor, not, nand gates) that could be printed with a normal line printer. They were the new "standard" and Texas Instruments was using them in their data books. We were expected to convert over to avoid being left behind.

So far the standards and the TI data books are the only places in the world that I have ever seen those silly things. I still don't know what they mean or how to use them. I wasn't very worried then and 30 years later I still don't care to learn them. Your "find bubbles" story reminded me of this.

You can add the item numbers for parts and cutlist items in a single table and choose to have a continuous numbering scheme. This will avoid same numbers on the same drawing sheet.