Injection Molding Idle Shutdown Break-Even Calculator

Find the idle duration at which avoided ready-state power repays measured restart and stabilization energy.

Formula and method

Break-even hours = restart energy / (ready-state idle kW − reduced-state kW). Net avoided energy = power difference × idle duration − restart energy.

Inputs and units

Measure ready-to-operate idle power, the intended reduced or shutdown state, restart/stabilization energy, expected idle duration, and local electricity rate. Keep thermal stabilization and first-good-part requirements in the restart record.

Worked example

At 18 kW idle, 3 kW reduced-state power, and 12 kWh restart energy, break-even is 0.8 h (48 minutes). A 3 h idle window avoids 33 kWh net.

When to use it

Use this for a known production gap after defining what can safely be reduced or stopped.

How to interpret the result

An expected idle window longer than break-even is an energy signal, not permission to shut down. Apply OEM material, heater, hydraulic, mold, dryer, and restart procedures.

Assumptions and limitations

The tool excludes restart labor, startup scrap, thermal degradation, delivery risk, and demand-charge effects unless those are included in the measured energy or reviewed separately.

Validation guidance

Measure multiple representative idle and restart events. Verify first-good-part time, energy, quality, and equipment procedure before adopting a threshold.

FAQ

Can this result replace a measured production trial?

No. Preserve the meter, time window, product quality, machine, mold, material, process, and boundary with the result.

Sources

EUROMAP 60.1 machine energy and idle method · Plastics Engineering energy-management guidance