Production Planning for High-Mix, Low-Volume Factories

Classical production planning — MRP, master schedules, finite capacity planning — was developed for factories that make the same products in large quantities over long horizons. If your shop makes 50 different SKUs in batches of 200, with the mix shifting weekly based on what orders came in, those frameworks fight you instead of helping.

Here's a framework that's worked for high-mix, low-volume SME factories.

Start With a Rolling Two-Week Horizon

Forget annual plans and monthly buckets. Plan in two-week rolling windows: week 1 is firm (work orders released), week 2 is provisional (work orders drafted, materials reserved). Anything beyond two weeks is a forecast, not a plan. This matches how high-mix orders actually arrive — and avoids the false precision of plans that get rewritten weekly anyway.

Sequence by Setup, Not by Date

In high-mix shops, machine setup time is often a bigger constraint than run time. Group work orders by similar setup (same material, same tooling, same colour) and run them in sequence. A naive date-sorted schedule will have you tearing down and rebuilding setups all day. A setup-aware schedule cuts changeover time by 30-50% with no capex.

Reserve Material at Order Entry, Not at Production Start

Material shortage is the most common cause of stalled work orders in high-mix shops. Reserve raw materials against an order the moment it's accepted — not when production starts. This surfaces shortages early, when you have time to react, instead of mid-week when the line stops.

Capacity by Bottleneck, Not by Average

Don't plan against the average machine. Plan against the bottleneck — the machine or operation that constrains throughput. Every other resource has slack; the bottleneck doesn't. If your bottleneck is fully loaded, the factory is fully loaded. If it's idle, you're leaving money on the table regardless of how busy the rest of the floor looks.

Plan Operators, Not Just Machines

In high-mix shops, skilled operators are scarcer than machines. A schedule that doesn't account for which operators are available and certified is going to break the moment somebody calls in sick. Plan operator coverage alongside machine schedules, with cross-trained backups for every bottleneck operation.

Re-Plan Daily, Not Weekly

A static weekly plan in a high-mix environment is a fiction by Tuesday. Build a five-minute daily replanning ritual: review yesterday's variances, slot today's actuals, push displaced work orders out. The plan stays current; the team stays aligned. This isn't more work — it's less than the firefighting that happens when the plan is wrong all week and nobody updates it.