In-house or outsourced busbar fabrication: working the numbers

Most make-or-buy comparisons for busbar are written by someone with a machine to sell, and they all reach the same conclusion. This one is written to be run against your own numbers, and it includes the conditions under which the answer is no.

Before anything else, one arithmetic fact reframes the whole question. At mid-2026 copper prices, the metal in an outsourced busbar is roughly 95% of what you pay for it. A 1,200 mm length of 100 × 10 mm copper weighs 10.7 kg; at a delivered bar price of US$16,500 per tonne that is US$177 of metal. The conversion charge sitting on top of it, the part you would be bringing in-house, is a few dollars. So the decision is far less about machine efficiency than most vendor material suggests, and far more about whether you can buy copper as well as your subcontractor can.

The two cost stacks

What outsourcing actually costs

The quoted piece price is the visible part. The rest:

• Freight, both ways: copper is dense. A thousand 1.2 m bars in 100 × 10 is 10.7 tonnes, a full truck. Inbound freight is a cost per part, and outbound freight on a rejected batch is worse.
• Minimum order quantity or value: this is the one that hurts on prototypes, spares and single replacement bars. A US$400 minimum order on a part you need one of is a 400-dollar part.
• Lead time, and the inventory it forces: a ten working-day lead time means you carry safety stock equal to demand over ten days plus a buffer, in copper, on your balance sheet.
• Rework turnaround: a wrong hole means the part goes back and comes again: two lead times, plus the argument about whose drawing was wrong.
• Engineering change cost: revised drawing, requote, new batch, and write-off of the batch you already had. In switchgear the busbar is often the last thing frozen and the first thing changed.
• Metal price risk: most subcontractors quote with a copper surcharge, so you carry the metal risk either way. Read the escalation clause before assuming otherwise.
• Goods-in inspection and buyer time: small per part, not small per year.

What in-house actually costs

Worked with explicit assumptions, all of which you should replace:

The capital charge is an annuity, not straight-line depreciation: at 8% over 7 years the factor is 0.192, so US$150,000 of installed cost is US$28,810 a year. Use your own cost of capital; if you are financing at 12% the factor becomes 0.219 and the charge US$32,900.

Check the floor-space figure against a machine footprint rather than a guess. An EMAC-BP-60 occupies 9,585 × 3,454 mm, which is 33 m² of machine. Add bar infeed, part outfeed and aisle access and 70 m² of served floor is realistic. If your building is full, the true cost is not US$120/m² but the cost of the thing you displaced.

Two items people expect to matter and do not:

Energy. A 15.7 kW connected load at a 30% duty cycle over 1,800 hours is about 8,500 kWh, or US$1,300 a year at US$0.15/kWh. Under 2% of the fixed cost. Stop worrying about it.

Tooling. Punch and die consumption on copper is modest compared with steel; budget it per hole rather than per year, and see the tooling cost per hole working for how to build that figure. At around US$0.18 per part for a six-hole bar it is a rounding error against the metal.

Scrap is not in the fixed table because it belongs to the metal, and it applies to both options. It is not small: at 5% scrap on issued bar, a 10.7 kg part carries about US$2.10 of unrecoverable copper loss. Whether that counts for or against in-sourcing depends entirely on whose nesting is better, which is covered below and worked in detail in the nesting and scrap cost model.

Break-even, with every assumption exposed

Define the comparison on a representative part: 1,200 mm of 100 × 10 mm Cu-ETP, six punched holes, sheared to length, no bend. Finished mass 10.7 kg.

Assumptions:

1. Your delivered bare bar price: US$16,500/t (LME cash around US$14,500/t in mid-August 2026 plus an assumed US$2,000/t conversion premium). Both figures move; substitute yours.
2. Your subcontractor's conversion charge plus margin: US$10.73 per part. This is an assumption. Ask for a quote broken into metal and conversion, and if they will not break it out, quote them the same part in two sections and solve for it.
3. Inbound freight allocated: US$0.50 per part.
4. In-house tooling: US$0.18 per part.
5. In-house fixed cost: US$78,610 per year, from the table above.
6. Your subcontractor buys copper better than you do by Δ dollars per tonne. This is the variable that decides the answer.

Break-even volume N is fixed cost divided by the saving per part:

N = 78,610 / (conversion charge + freight + 0.0107 × Δ − tooling)

In tonnes of finished copper, the band runs from about 46 t/year at the favourable corner to about 410 t/year at the unfavourable one, with the base case landing near 125 t/year. If you want one number to carry around: on these assumptions the break-even sits somewhere between 50 and 400 tonnes of finished busbar a year, and where you fall inside that band is decided more by copper buying power than by part count.

That "never" cell is not a typo. If your subcontractor buys metal US$800/t better than you and charges only six dollars to convert it, no volume of simple punched bar justifies a machine. That situation is common for small panel builders buying from a fabricator who also serves the wire and cable trade, and anyone who tells you otherwise has not done the arithmetic.

Capacity, for context

At 90 seconds per part including bar handling, one shift of 1,800 hours is about 72,000 parts a year. So the break-evens above sit between 6% and 55% of single-shift capacity. Break-even is reached long before the machine is busy, which means the machine is rarely justified by throughput. It is justified by everything in the next section.

What the sensitivity actually tells you

Complexity in-sources before volume does. Look down the right-hand column. A simple part needs 38,500 pieces a year to justify the machine; a punched-and-bent part needs 5,600. Subcontract pricing rises steeply with operation count because their setup and handling dominate, while your marginal cost barely moves once the machine is running. The counter-intuitive result holds: complex, high-mix, low-volume work in-sources first, and long runs of plain punched bar in-source last. Most people assume the opposite.

Yield is a two-way argument. A subcontractor nesting across many customers has a broader length pool than you do and may run one to two points better on scrap. At 10.7 kg per part and a net loss of about US$3,740 per scrapped tonne, two points of yield is US$0.80 per part, which is a meaningful fraction of the conversion charge. On the other hand, they are nesting to their own yield, not yours, and you pay by finished piece. Ask which.

Mix fragmentation breaks the cycle-time assumption. If your parts run across eight sections in small quantities, in-house setup time per batch climbs and the 90-second average fails. Rebuild the fixed table with the operator hours you will actually get, not the ones the brochure implies.

Bending changes the machine, not just the number. If a meaningful share of your parts need bends, the single-machine assumption breaks. Either add a dedicated bender such as the EMAC-BB-H12, which raises fixed cost and capacity together, or use an all-in-one such as the SMART-603CNC-S, which punches, shears and bends in one footprint at lower capital and lower throughput. Check the sections you actually run against the machine's capability with the bending force calculator before you assume one machine covers your range.

The variables that usually decide it

Nobody has ever bought a busbar machine because of a spreadsheet, and the spreadsheet is not usually wrong. The decision gets made on three things the spreadsheet handles badly.

Engineering change lead time

Ask a simple question: from the moment a drawing is revised, how many days pass before the correct bar is on the assembly bench? In-house, hours to a day. Outsourced, typically five to twenty working days including requote, plus the write-off of the superseded batch.

Then count your engineering changes. If a typical project carries three busbar changes and each costs a fortnight of float, the machine is being justified on schedule risk, not on piece price. Put a number on a week of programme slip on your largest contract and compare it to US$78,610 a year. For most switchgear builders that comparison is not close.

Rework turnaround

The same argument applied to your own mistakes and theirs. In-house, a mis-punched bar is recut before lunch. Outsourced, it is two transit legs and a commercial conversation. The frequency matters more than the cost: count how many rework returns you raised last year and multiply by the days lost.

Intellectual property exposure

Your busbar layout encodes your thermal design, your short-circuit bracing and your enclosure strategy. Handing the full 3D copper set to a subcontractor exposes all of it, and the test is concrete rather than paranoid: does your subcontractor, or anyone in their group, build panels? If yes, you are sending your design to a competitor's supply chain. That may still be acceptable, but it should be a decision rather than an oversight.

Verification responsibility does not transfer

Worth stating plainly because it is regularly misunderstood. Under IEC 61439, verification of the assembly is the original manufacturer's and assembly manufacturer's responsibility, by testing, by calculation, or by comparison with a verified reference design. Temperature-rise verification in particular depends on bar section, spacing and joint quality: the standard's limits allow 105 K for bare copper busbars and 70 K at terminals for connection of external conductors, and those numbers are only meaningful against the geometry you verified.

If a subcontractor substitutes a section, changes a hole pattern or alters a joint to suit their tooling, your verification basis has moved and you own the consequence at type test and in the field. Outsourcing punching and cutting does not outsource that. Whatever you decide, the drawing and the material specification have to be controlled by you, and incoming inspection has to be able to detect a substitution.

The honest case for staying outsourced

This section is not a formality.

• No capital, no floor, no maintenance, no recruitment. The fixed table above is US$78,610 a year that a subcontracting shop simply does not spend.
• Their metal buying power is usually better, and at current copper prices that single factor can outweigh everything else, as the break-even table shows.
• They absorb your peaks. If your demand is three large projects a year, a machine sits idle for eight months and you still pay the capital charge, the floor and most of the labour.
• Their tooling library already exists. Every unusual hole size or slot you need is a tool you would otherwise buy.
• Process knowledge is already paid for. Your first six months in-house will be worse than their tenth year.

If your annual conversion-equivalent volume is under roughly 15,000 simple parts, nobody in the building will own the process, your subcontractor is close and turns work in three days, and your floor is already full, then the answer is not yet. Coming back to this in two years with twelve months of clean data is a better outcome than buying a machine that runs at 8% utilisation.

What to measure before deciding

Four datasets, all of which you already have:

1. Twelve months of subcontract invoices, split into metal content and conversion charge. This is the single most valuable number and almost nobody extracts it.
2. Engineering changes and their cost. Count them, count the days, count the written-off batches.
3. Rework returns. Count, cause, days lost.
4. Your actual part mix, by section, by operation count, by quantity per order. The operation count drives the break-even harder than the quantity does.

With those four you can rebuild the table above in an afternoon with your own numbers rather than mine, and the answer will be defensible in front of a board.

The hybrid answer is often the right one and rarely gets proposed: bring prototypes, spares, engineering changes and short runs in-house where responsiveness is worth money, and keep the long uniform runs outside where someone else's metal buying and yield beat yours. That splits the volume in a way that makes the machine's fixed cost easier to carry and puts it on exactly the work where its lead-time advantage is worth the most.