What Is a Time Fence in Planning? Demand and Planning Fences
User Solutions TeamA time fence is a window measured forward from today inside which the planning system behaves differently, in order to protect the near-term plan from being driven by estimates or reshuffled by automatic changes. Two fences do most of the work. A demand time fence, inside which only firm orders count and forecast is ignored. A planning time fence, inside which the system suppresses new suggestions and does not overwrite quantities a planner has already committed.
This entry defines time fences and shows how they behave inside EDGEBIC by User Solutions. For the wider index of planning terms, see the manufacturing glossary, and for the demand rule the fence interacts with, see forecast consumption. A generic definition also lives in the time fence glossary entry; this entry takes the planner-facing view of the two fences and what each one locks.
How it works
Think of a kitchen planning next week's menu. There is a cutoff after which the near-term menu is locked: the ingredients are ordered, the prep is scheduled, and no more changes are accepted for the days that are already in motion. Further out, the menu is still a draft that anyone can revise. A time fence is that cutoff, drawn on the planning horizon so that the imminent plan is firm and the distant plan is flexible.
The two fences answer different questions:
- Demand time fence. Inside this window, forecast is suppressed and only firm orders drive gross requirements. The logic is that close to today, real orders should already have replaced the estimate, so continuing to count the forecast would over-build against demand that has already materialized. Outside the fence, forecast counts again because firm orders have not yet arrived that far out.
- Planning time fence. Inside this window, the system does not generate new order suggestions and does not overwrite build quantities a planner has committed. The near-term plan is protected from automatic revision. Outside the fence, in the open horizon, the system suggests freely and does not shield committed quantities from re-planning.
The two fences nest. The demand fence is typically the shorter window, and a bucket can be inside the planning fence yet outside the demand fence, a zone where forecast contributes to requirements again but committed quantities are still protected.
A concrete example
A precision shaft has a demand time fence of 14 days and a planning time fence of 30 days. Today is the 13th.
| Bucket start | In demand fence? | In planning fence? | Behavior |
|---|---|---|---|
| Day 1 (13th) | Yes | Yes | Only firm orders drive requirements; no auto-suggest or overwrite |
| Day 10 (23rd) | Yes | Yes | Same |
| Day 20 (3rd next month) | No | Yes | Forecast counts again, but committed quantities are still protected |
| Day 35 (18th next month) | No | No | Forecast and firm both count; suggestions appear and committed quantities are not protected |
A planner who commits 50 units to the day-20 bucket can be confident it will not be zeroed by a planning run, because it sits inside the planning fence. A planner who commits 50 units to the day-35 bucket should double-check after a rerun, because that bucket is in the open horizon where automatic revision is allowed. The fences turn "how stable is my near-term plan?" into an explicit, per-product setting rather than a matter of hope.
How EDGEBIC uses it
In EDGEBIC, both fences live on each product as a demand time fence and a planning time fence, measured in days. They are surfaced as boolean flags on every row of the master production schedule grid: an in-demand-fence flag and an in-planning-fence flag. When a row is inside the demand fence, the planner sees only firm orders driving requirements and can ignore the forecast column for that bucket. When a row is inside the planning fence, the system withholds suggestions and preserves the planner's committed build quantity.
Because the fence days sit on the product, each item gets the horizon that fits it. A high-turnover consumable might use a 7-day demand fence, while a long-lead casting might use 60 days. The fences are computed on every calendar load, so changing a product's fence days takes effect on the next refresh with no rebuild.
To set the fences step by step and see the demand-versus-planning distinction with worked buckets, read firm demand, forecast and time fences in EDGEBIC and the how-to for setting a time fence in EDGEBIC. To understand the committed demand the demand fence lets through, continue with firm demand in planning.
Expert Q&A: Deep Dive
Q: I committed 50 units to a bucket, then a planning run zeroed it. How do I stop that?
A: Extend the planning time fence far enough to cover that bucket. Inside the planning fence, the system does not auto-overwrite a committed build quantity, so your 50 is protected from an automatic rerun. A bucket outside the planning fence sits in the open horizon, where the system may revise or suggest against it freely, which is why your quantity was cleared. Set the product's planning time fence days to a horizon that matches how far ahead you make firm build decisions, and commitments inside it will survive planning runs.
Q: A near-term bucket still shows a big forecast number even though real orders are lower. Is the forecast wrong?
A: The forecast may be fine; the issue is likely that the bucket falls outside your demand time fence, so forecast is still competing with firm demand near term. Inside the demand fence, forecast is suppressed and only firm orders count, which is what you want close to today where real orders should have overtaken the estimate. If the demand time fence is set to zero, forecast keeps counting right up to today and can inflate near-term requirements. Set a demand fence that matches your order lead visibility, and the near-term buckets will reflect committed orders instead of a stale forecast.
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