Scheduling Precast Concrete Around Form Beds and Cure Time

A precast plant does not run out of concrete, it runs out of form beds. EDGEBIC by User Solutions models each casting bed as finite capacity, carries cure as real elapsed time on the routing, and pools interchangeable beds so a pour lands where a bed is genuinely free rather than where a wall chart said it would be.

The mixing, the rebar, and the crew are rarely the limit. The limit is how many beds you own and how long each piece sits in one.

The Bed Is the Work Center

In most precast plants the schedule lives on a whiteboard, and the whiteboard has no concept of capacity. Somebody writes a pour into a bed, somebody else writes a different pour into the same bed, and the clash surfaces on the morning of the pour.

Model each bed as a work center. Give it a capacity, a calendar, and a name that matches what the yard calls it. Now the scheduler can only place one pour into a bed window at a time, because finite capacity means the engine will not double-book a resource that is already committed. The difference between that and infinite capacity planning is covered in finite vs infinite capacity scheduling.

If a bed is longer and can hold two shorter panels, that is not a scheduling exception, it is a capacity number. Set the bed's capacity to reflect what it actually holds and the engine fills it accordingly.

Cure Is Elapsed Time, Not Worked Time

The most common precast scheduling error is treating cure as if it only counts during working hours. A sixteen-hour cure on an eight-hour shift calendar becomes a two-day cure in the plan, or worse, the schedule strips the piece at the end of the shift because nobody modeled the wait at all.

Put cure on the routing as its own step with its real elapsed window so the calendar carries it straight through the overnight and the weekend. A 3 PM Friday pour with a sixteen-hour cure is ready Saturday morning. If the plant does not run Saturday, the strip crew picks it up Monday at 7 AM, and the schedule shows that honestly instead of pretending the piece shipped Saturday.

Steam cure and accelerated cure are just different numbers on the same step. If a heated bed cures in eight hours and an ambient bed takes twenty, those are two different steps or two members of a bed group with their own effective times.

Pooling the Beds

Not every bed is special. A plant with twelve beds usually has three or four families of genuinely interchangeable beds, and the routing names one specific bed only because someone wrote it that way when the mold was new.

Bind the pour step to a work center group instead. At schedule time the engine expands the group into its members, compares each member's projected availability against live load, and places the pour on the bed that frees up soonest. Members carry their own effective time, so a heated bed that turns a piece faster is modeled honestly rather than averaged away. How the pooling works in detail is in how a work center group shops a pool of machines.

Beds already cast stay where they are. Only pours that have not started re-shop the pool on a reschedule, which is what keeps the plan stable for the crew that already set forms this morning.

The Steps Around the Pour

A precast routing is short but every step matters, and the ones nobody schedules are the ones that break the week.

Model the crane as its own work center if one crane serves all beds. On many plants the crane, not the bed, is the true constraint on strip day, and nobody has ever measured it because it never appeared on a schedule. Flagging it is covered in production bottleneck identification.

A Worked Week

A twenty-piece double-tee order through a routing on a plant with a bed group of four long beds.

The form set and pour landed on Bed 3 rather than the Bed 1 written on the ticket, because Bed 1 was still occupied by a Tuesday pour that ran long. The cure ran continuously through Wednesday night, so the strip crew had a real Thursday morning start instead of an optimistic Wednesday evening one. The crane was placed against its own capacity, so the second strip that morning went to 10 AM rather than colliding.

When a Pour Runs Long

Operators log start, stop, and quantity from the floor, so a pour that took two extra hours pushes only the work that has not started. Completed operations are never moved by a reschedule, so the record of what actually ran stays intact through every replan. That matters in precast, where a piece cast and cured is physically finished and no plan should ever suggest otherwise. See how to log actual hours and pieces.

Promising a Delivery Date

Precast is sold on a date, and the date is usually a guess about bed availability three weeks out. Quote simulation runs the proposed order against current finite capacity and returns a realistic promise window with the bed occupancy that produces it. If the answer is too late, you can test a second shift on the bed line or an alternate bed family in the same simulation before committing. The mechanics are in how a quote simulation produces a realistic date.

Heritage in Heavy, Slow-Cycle Manufacturing

User Solutions has built finite capacity scheduling since 1991, more than 35 years, for operations where a physical resource is the constraint and the cycle is long: US Navy, GE, BAE Systems, and Cummins across 33 locations. The lineage behind EDGEBIC, including the RMDB heritage, drove GE Railcar on-time delivery from 30 percent to 90 percent in an environment of long cycles and shared heavy resources. A precast plant fighting bed conflicts and unscheduled cure is the same shape of problem.

Where to Start

Enter your beds as work centers with real capacity. Put your actual cure hours on the routings as an elapsed step. Group the beds that are genuinely interchangeable and bind pours to the group. Then schedule a normal week and compare planned bed occupancy against what the wall chart claimed.

For fundamentals, what is production scheduling covers the basics and batch vs discrete scheduling covers the pour-and-cure pattern. A neighboring sector with the same oven-and-wait shape is composites cure oven scheduling. The industry fit guide maps the rest, and EDGEBIC is the product hub. Want to see your real bed occupancy for next week? Contact US for a demo.