How do I estimate the carbon footprint of a forged crankshaft?
Start with the steel bar mass bought, not the finished weight, since forging flash and machining remove a large share. Multiply by the steel supplier's CO2 per tonne, then add forging furnace fuel, heat treatment and machining electricity per piece.
Inputs
- Bar weight per piece, from the cut length.
- Steel supplier's CO2 per tonne, with its date.
- Furnace fuel and electricity per piece from monthly bills and output.
Scrap
Flash and turnings sold as scrap leave with your waste. Do not subtract them from the steel bought unless you follow a stated recycling method.
Worked example (illustrative figures)
- Bar bought: 20 kg per crankshaft.
- Supplier figure: 2.2 kg CO2 per kg of steel; 20 × 2.2 = 44 kg.
- Forging, heat treatment and machining: 6 kWh × 0.710 = 4.3 kg, plus 1.5 kg from furnace gas.
- Total: about 50 kg CO2 per piece.
What Senseible does here
Senseible reads your electricity bills, fuel invoices and purchase invoices into dated, fingerprinted records, so a per unit footprint can be traced back to the documents behind it. Estimates are labelled as estimates.
Sources: GHG Protocol Product Standard, ISO 14067:2018, Carbon footprint of products (iso.org), IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults)
Last reviewed 2026-10-22.