Key takeaways
Short answer: Batch scheduling runs a big quantity of one product, then changes over to the next — fewer setups, but lots of inventory and slow response to a changing mix. Heijunka levels production into a repeating small-mix sequence, so you make a bit of everything often. It smooths demand on upstream and suppliers and shortens response time, but it requires fast changeovers to be viable. See also changeover vs setup time.
Batch scheduling runs large quantities of one product before switching. It minimises changeovers per unit, which feels efficient, but it builds inventory and responds slowly when the order mix changes — you are committed to the big run already in progress.
Heijunka (production leveling) spreads the mix into a small, repeating pattern — make a bit of everything, often, in a steady sequence. Instead of a month of product A then a month of B, you cycle through a balanced sequence every day, so output matches demand more closely and smoothly.
A plant batches: a week of product A, then a week of B, then C. Suppliers and upstream cells see huge demand spikes — a wall of A-components, then nothing, then a wall of B — and carry inventory and firefight to cope (the bullwhip effect). Switch to heijunka — ABCABC every day — and suppliers see a steady, predictable trickle of each component, so inventory falls and the panic disappears. The catch: the plant now changes over far more often, so it only works because it cut changeover time first with SMED.
Big batches create demand spikes that ripple upstream as the bullwhip effect — amplified swings in orders and inventory at every tier. Heijunka turns lumpy demand into a steady drumbeat, so upstream processes and suppliers run smoothly with less inventory and less firefighting.
Heijunka only works with short changeovers. Without SMED, the extra setups from a levelled mix overwhelm capacity — you spend all day changing over and never produce. Reduce changeover time first, then level. This is the single most common reason leveling attempts fail.
1. Leveling before reducing changeover time. The extra setups swamp capacity.
2. Batching by habit. Big runs chosen for comfort, not economics.
3. Ignoring the bullwhip cost. Upstream inventory and firefighting are real and hidden.
4. Leveling a genuinely unstable demand. Heijunka suits repetitive demand, not wild swings.
Leveling steadies the load on each machine, reducing the starve-and-block and rushed changeovers that hurt OEE Performance — provided changeover time is already low. Done right, smoother flow shows up as a steadier, higher Performance number.
Fabrico exposes the changeover and flow losses that decide whether leveling is viable, so you can see if SMED has made heijunka possible. Book a demo to see your changeover and flow data.
Yes — which is why it needs fast setups (SMED) first.
Demand spikes and the bullwhip effect on upstream processes and suppliers.
When changeovers are long and demand is stable.
Changeover reduction — leveling is not viable with long setups.
Best for repetitive demand; very erratic demand is harder to level.
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