Li-Ion Battery: Planning Around Yield and Scrap Honestly

Li-ion battery yield scrap planning, done honestly, means sizing each job so the started quantity covers expected scrap, and letting the finite-capacity engine load every step against that real number. A cell line that scraps a known percentage through formation and grading should be scheduled for the pieces that physically run, not the pieces that ship. EDGEBIC by User Solutions loads each routing step against the job's quantity as entered, so when a planner sizes a job to cover scrap, the plan reserves the machine time that scrap actually consumes.

This post is deliberate about what is shipped and what is not. For scrap reduction at the category level, see scrap rate reduction and first-pass yield. For the sector view, see li-ion battery production scheduling, and pair this with scheduling battery continuous lines. The full map is at how different industries use EDGEBIC.

Why yield matters to a battery schedule

Battery cell manufacturing loses material at multiple stages. Electrode defects, assembly rejects, formation failures and grading fallout each remove some fraction of the pieces that entered. Individually the losses look small; compounded through the line, they are not. A 96 percent step followed by a 94 percent step followed by a 92 percent step delivers well under 90 percent good output overall.

For scheduling, this matters in one concrete way: the number of pieces that physically pass through each machine is larger than the number that ship. If you schedule for the shipped quantity, you under-load the line, the plan promises a finish it cannot hit, and the shortfall surfaces at grading when it is too late to recover without expediting. The machine time to make the scrap was real, and the plan never reserved it.

The question is how to make the schedule account for that extra work. The honest answer is that it is a quantity decision, and it is a good one.

Size the job to the started quantity

The reliable, shipped lever is the order quantity. You size the job to the started quantity: the number of pieces you must release so that, after expected scrap, the good output meets demand. You compute that from your known yield, and you enter it on the order.

The finite-capacity engine then loads every routing step against that started quantity. Coating reserves capacity for the full started count, assembly reserves it, formation and grading reserve it. Every step's run time scales with the pieces it actually processes, so the plan reflects the real machine time scrap consumes rather than the optimistic time to make only the good units. The finite-capacity engine does not stack work beyond a machine's real hours, so a job sized for scrap shows its true footprint on the line.

This is not a workaround; it is the correct planning number. The started quantity is what the line runs. Treating it as the scheduling quantity keeps the plan and the floor in agreement.

A worked cell-line example

Suppose you need 1,000 good cells and your combined first-pass yield through the line is 90 percent. The started quantity is the good units divided by the yield: 1,000 divided by 0.90, which is about 1,112 cells. You release the job at 1,112.

Now the schedule loads coating, stacking, formation and grading against 1,112 pieces, not 1,000. Each step reserves the machine time to process the full started count, including the roughly 112 cells that will scrap. The plan's finish date reflects that extra work. When grading removes the expected fallout, you are left with about 1,000 good cells, which is what the order needed, and no end-of-run scramble to make up a shortfall the plan never saw.

The yield math is yours to apply when you set the quantity. The scheduler's job is to respect that quantity end to end, which it does.

Where the yield field lives

A product in the platform carries a yield fraction, and it is worth being precise about where it is used. That figure feeds the replenishment and inventory-projection planning, which inflates a suggested order quantity by computing the start as the required good units divided by yield: the same arithmetic you do by hand above, applied when the planning side proposes how much to make. That inventory and forecasting planning is described as a capability of the platform without a specific release commitment, and this post keeps that guardrail.

For the shop-floor schedule itself, the practical and dependable lever is the order quantity on the job. The scheduler loads steps against the quantity you enter. It does not, in a current build, inflate that quantity automatically step by step through a routing for yield; that automatic inflation is a described direction for the platform, not something to rely on today. Being clear about this is the whole point: the honest, shipped way to plan around scrap is to set the started quantity, and the plan will be correct.

Yield versus scheduling: keep them separate in your head

It helps to hold two ideas apart. One is planning how much to make, which is where a yield fraction belongs and where the inventory-projection planning applies it to suggest a start quantity. The other is scheduling the work, which loads whatever quantity the job carries against real capacity.

When you keep those separate, the workflow is clean: decide the started quantity using your yield, enter it on the job, and let the schedule load it. If you later drive yield up by improving the process, you lower the started quantity for the same demand, and the schedule reflects a smaller footprint on the line. Yield improvement shows up in the plan as less machine time, which is exactly the incentive you want. For the improvement work itself, see scrap rate reduction.

Keeping started quantities honest over time

A started quantity is only as good as the yield number behind it, and yield drifts. A new cathode lot, a reworked coater, a different formation profile: each can move the good-output fraction up or down, and a started quantity computed from last quarter's yield will over- or under-run.

The discipline that keeps this honest is logging what actually happened. When operators record the good units off each stage, you get the real yield the line delivered, not the one you assumed. Compare that against the started quantity you released, and the gap tells you whether your planning yield is still right. If a stage is scrapping more than it used to, the started quantities for the next batches should rise before the shortfall repeats, not after. This closes the loop: you plan the quantity from a yield, you run it, you measure the real yield, and you feed that back into the next plan. Over a few cycles the started quantities converge on numbers the line actually delivers, and the end-of-run shortfalls that trigger expedites stop being a surprise.

Because the schedule loads whatever quantity the job carries, this is a data-quality habit rather than a scheduling setting. The engine will faithfully load a wrong started quantity just as readily as a right one, so the value of measuring real yield is that it keeps the number you enter close to the truth.

Common mistakes with yield and scrap planning

Scheduling the shipped quantity. If you enter 1,000 when you must run 1,112, the plan under-loads the line and promises a finish that cannot be met after scrap. Enter the started quantity.

Expecting automatic step-by-step inflation. The scheduler loads steps against the job quantity as entered; it does not inflate it through the routing for yield today. Apply the yield math when you set the quantity, and be explicit about it rather than assuming the engine will.

Confusing the inventory yield field with the scheduling quantity. The product yield fraction drives replenishment suggestions on the inventory-planning side. For the schedule, the started quantity on the job is the number that matters. Do not rely on one to do the other's job.

Using an average yield when stages vary widely. If one stage scraps far more than the others, a single blended number can mislead. Base your started quantity on the real combined yield through the line, and revisit it as the process changes.

Rolling it out

1. Measure your real combined yield through the cell line, stage by stage, so you know the true good-output fraction.
2. Compute the started quantity for each job as the demand divided by that yield, rounded up.
3. Enter the started quantity on the order, treating it as the planning number the schedule will load.
4. Run the schedule and confirm each step reserves capacity for the started count, so the plan's finish reflects the scrap's machine time.
5. Keep the inventory yield field for planning suggestions, understanding it drives replenishment on the inventory-planning side, not automatic scheduling inflation.
6. Revisit started quantities as yield improves, so the plan's footprint shrinks when the process gets better.

Bring one cell-line routing, its stage yields and a demand quantity to a demo of li-ion battery production scheduling, and we will size the jobs and load the plan with you.