How do you calculate energy cost per cycle in rotomolding?

Multiply connected load by runtime to get kWh, then multiply by the energy rate. A 12 kW load over 8 hours at $0.12/kWh uses 96 kWh and costs $11.52 for the cycle.

How do I get energy cost per part?

Divide the cycle energy cost by parts produced. At $11.52 for the cycle and 1,000 parts, energy is about $0.0115 per piece. For low-volume single-cavity tanks that per-part number climbs sharply.

Why is rotomolding so energy-intensive?

Every cycle heats the full mold mass and oven to melt temperature and cools it again, with no steady-state to amortize against like injection molding. That's why an 8-hour cycle here draws 96 kWh.

Should I use nameplate load or metered power?

Nameplate connected load gives a quick estimate but overstates draw during the cooling phase. For accurate costing, meter actual kWh over a cycle and back-calculate effective load; the formula still holds with metered energy.

What is a good energy cost per part for rotomolding?

It depends entirely on part size and cavity count. High-cavity small parts, like the $0.0115 figure here, are cheap; a large single-cavity tank can run dollars per part. Track it against your own baseline rather than a universal target.

How can I lower energy per cycle?

Shorten heat and cool time with better airflow, insulate the oven and ducting, use pressurized or forced cooling, and batch more cavities per cycle so the fixed oven energy spreads across more parts.

Rotational Molding calculator

Energy Per Cycle Calculator

Energy per cycle turns a rotomolding oven's connected load and cycle time into a hard dollar cost, then splits it across the parts that came off the arm. Rotomolding is energy-intensive because the entire mold and a heavy gas or electric oven have to be brought up to melt temperature and back down every cycle, so energy is often the second-largest variable cost after resin. Process engineers use it to compare oven settings, justify insulation or burner upgrades, and load energy into a per-part quote. As electricity and gas rates climb, this number increasingly decides whether a part is profitable.

What this calculator does

Energy per cycle turns a rotomolding oven's connected load and cycle time into a hard dollar cost, then splits it across the parts that came off the arm.
Use it when energy per cycle in rotational molding is up for an upgrade and you want a defensible savings story.
It computes the energy cost of one oven cycle from connected load, runtime, and rate, then divides by parts produced to get energy cost per piece.

Formula used

Energy cost = connected load × runtime × energy rate
Energy Per Cycle energy per unit = energy cost ÷ processed units

Inputs explained

Oven and machine connected load:
Cycle runtime (heat plus cool):
Electricity or gas rate:
Parts produced in the cycle:

How to use the result

Use it when quoting energy into a part price, comparing cycle recipes, or building the case for oven insulation or a more efficient burner.
It treats connected load as constant across the cycle; real ovens modulate between heat-up and hold, so measured kWh from a meter may differ from the nameplate-load estimate.

Current U.S. benchmarks

As of Apr 2026, industrial electricity averages 8.7 cents per kWh across the U.S. (EIA), up 5.5% from a year earlier. State averages range widely, so plants should confirm against their own tariff.
The producer price index for plastic resins and materials stands at 319.371 (BLS, May 2026), up 19.5% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate energy cost per cycle in rotomolding? Multiply connected load by runtime to get kWh, then multiply by the energy rate. A 12 kW load over 8 hours at $0.12/kWh uses 96 kWh and costs $11.52 for the cycle.
How do I get energy cost per part? Divide the cycle energy cost by parts produced. At $11.52 for the cycle and 1,000 parts, energy is about $0.0115 per piece. For low-volume single-cavity tanks that per-part number climbs sharply.
Why is rotomolding so energy-intensive? Every cycle heats the full mold mass and oven to melt temperature and cools it again, with no steady-state to amortize against like injection molding. That's why an 8-hour cycle here draws 96 kWh.
Should I use nameplate load or metered power? Nameplate connected load gives a quick estimate but overstates draw during the cooling phase. For accurate costing, meter actual kWh over a cycle and back-calculate effective load; the formula still holds with metered energy.
What is a good energy cost per part for rotomolding? It depends entirely on part size and cavity count. High-cavity small parts, like the $0.0115 figure here, are cheap; a large single-cavity tank can run dollars per part. Track it against your own baseline rather than a universal target.

Last reviewed 2026-05-12.