Attaching to a BOM or sub-assembly

Both the BOMBill of MaterialsA bill of materials tells Assemblified how to build one unit of a finished good. When a customer orders the finished-good variant, Assemblified deducts the right component quantities from inventory automatically. Read more → detail page and the sub-assemblySub-AssemblyA reusable assembly block that composes into bigger BOMs. Define it once, include it in any BOM. At execution time, Assemblified expands the sub-assembly into its own components recursively. Read more → detail page carry an Additional costs section, sitting alongside Raw Materials and Sub-Assemblies. It’s where you say how much of a cost factor one finished unit consumes.

On this page

• Attaching a factor
• The quantity is per one finished unit
• Reading it back in the Costs tab
• How sub-assembly costs roll up

Attaching a factor

1. Open a BOM (or sub-assembly) detail page and stay on the components view.

2. Scroll to Additional costs.

3. Pick a factor from the Add a cost factor… dropdown. The dropdown shows each factor’s rate and unit, and hides the ones already attached.

4. Type the quantity consumed per one finished unit.

5. Click Add.

There’s no separate save step. Attaching, detaching, and editing a quantity take effect immediately, and every cost on the page re-computes.

To change a quantity later, type over it in the Qty / unit column and click away. To detach a factor, click the delete icon on its row — that removes it from this BOM only; the factor stays in the catalogue.

The quantity is per one finished unit

This is the one thing worth getting right:

line cost = quantity × rate

The quantity is what one finished unit consumes, not what a batch consumes. If a candle takes one minute of a $40 / hour labour factor, the quantity is 0.0166667 — hours, because that’s the factor’s unit.

Quantities are fractional and stored exactly as typed. Don’t round 0.0166667 to 0.0167 to make it look tidy; on a run of 10,000 units that’s a real number of dollars.

Caution

No waste %. Unlike a raw material, a cost factor has no waste multiplier. Waste describes matter you consume but don’t ship. Process time isn’t wasted that way — if a rework costs you more labour, raise the quantity.

The section footer shows Additional costs per unit — the sum of every attached factor’s line cost, for one finished unit.

Reading it back in the Costs tab

The Costs tab of a BOM or sub-assembly shows an Additional costs card next to Raw Materials and Sub-Assemblies, each with its own subtotal. Expand it and every attached factor is listed as quantity unit × rate with its line cost.

The card only appears when the BOM actually has additional costs. If you don’t use the feature, the Costs tab looks exactly as it always did.

The grand Total Cost at the bottom is:

total = raw materials + sub-assemblies + additional costs

Because the total now includes additional costs, the Margin on the Overview tab reflects them too. A BOM whose margin dropped after you attached labour was always making that little — you just couldn’t see it.

How sub-assembly costs roll up

A factor attached to a sub-assembly folds into that sub-assembly’s cost, and therefore into the cost of every BOM that uses it — automatically, and counted exactly once.

That means the Additional costs card on a BOM lists only the factors attached directly to that BOM. A sub-assembly’s own factors are already inside the Sub-Assemblies subtotal, as part of that sub-assembly’s cost. Adding the two cards together would double-count them.

Note

Nesting works to any depth. A factor on a sub-assembly that sits inside another sub-assembly that sits inside a BOM still reaches the BOM’s total, once.

See also

• Cost factors on work orders — where the same factors behave differently.
• Check BOM margin and cost breakdown — the whole Costs tab, walked through.
• Composition — how the material lines work.