Capacity Requirements Planning: Resolve Work-Center Overloads

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Your material plan proposes the next manufacturing orders. Existing jobs are already competing for machine time. Before you release more work, you need to know which work centers can handle it and which will become a queue of late orders.

Capacity requirements planning (CRP) converts planned and open manufacturing orders into time-phased resource requirements, then compares that workload with available capacity. It tells you where the detailed production plan needs changing: a particular resource, a particular period and the orders behind the shortage.

The useful result is not just a red load percentage. It is a decision about what to move, what capacity to add or which commitment to revise. SkyPlanner APS helps you carry that decision into the production schedule. Arcturus calculates the timing of the operations around your resources and priorities; the Gantt view shows how the change affects the rest of the work.

What does capacity requirements planning check?

CRP checks whether the machine and labor capacity behind the material plan is sufficient for the manufacturing work it requires. The detail comes from orders and their operations: quantities, routings, setup and run times, remaining work, and the dates when each resource is needed.

A work center may be a machine, a group of comparable machines or a production team. Keep the comparison specific enough to reveal the constraint. Spare inspection hours do not compensate for an overloaded machining center.

CRP belongs alongside other planning activities, not in place of them:

Activity	What it checks or decides
Material requirements planning (MRP)	Which materials and components are needed, in what quantities and when, after considering stock and supply
Rough-cut capacity planning (RCCP)	Whether critical resources can support the master production schedule
Capacity requirements planning (CRP)	The detailed resource load generated by planned and open manufacturing orders
Finite-capacity scheduling	Where and when individual operations run within the available resource time

Traditional CRP can expose overloads without automatically removing the competing demands that caused them. A report showing 44 required hours against 36 available hours is valuable precisely because it leaves the shortage visible. Resolving it requires a production decision and a revised plan.

Build the load from the work that still needs doing

Start with a consistent order population. Include the manufacturing proposals you are evaluating and the remaining operations on open orders. When a proposal becomes a released order, it must not remain in the calculation as a second copy of the same work.

Use the material plan’s net manufacturing requirements rather than adding gross sales demand on top. Stock that already covers a requirement does not need manufacturing again; an open manufacturing order still consumes capacity for its unfinished work.

For each operation, you need:

• The remaining quantity and operation status, including any known rework.
• The routing, eligible work center and operation sequence.
• Remaining setup time and processing time, in a consistent unit.
• Planned operation dates or lead-time offsets for placing the requirement in time.
• The resource calendar, staffing and known unavailable periods.

The bill of materials tells you what goes into a product. The routing tells you where the manufacturing work happens and how much resource time it needs. CRP needs that second view as well as the quantities from material planning.

Calculate remaining operation hours

For a simple operation with a per-piece run time:

Remaining operation load = remaining setup time + remaining quantity × run time per piece.

Add the operation loads for each work center and period. A setup already completed is not another future requirement. If the remaining order must be split into separately set-up batches, include the additional setup instead of assuming the split is free.

Not every process follows a per-piece model. A furnace cycle may occupy capacity for a fixed batch duration. Apply the operation’s actual time basis rather than multiplying every duration by the piece count.

Keep machine-hours and labor-hours separate. A machine may run unattended for part of an operation, while an assembly task may require several people. Neither assumption should disappear inside a single factory-wide hours total.

Put the requirement in the period when the operation needs it

Do not place every operation in the finished order’s delivery week. Machining may be needed earlier so that finishing and assembly can follow. Use the operation dates or routing offsets to time-phase the load; where an operation spans periods, follow the allocation rules of your planning model.

Daily periods reveal conflicts that weekly totals can hide. Weekly periods can be useful for reviewing a longer load profile. Choose the detail needed for the decision, then check the actual operation sequence before treating a balanced period as a delivery promise.

Compare against usable capacity

Calculate availability from the dated working calendar, not from the fact that a machine exists. Start with scheduled resource hours and account for maintenance, holidays, staffing and other known restrictions.

For a straightforward hours comparison:

Capacity gap = available hours − required hours.

Capacity load ratio = required hours ÷ available hours × 100%.

A negative gap or a ratio above 100% shows an overload. If available capacity is zero, flag the requirement as unschedulable in that period rather than trying to divide by zero.

Keep the time basis consistent. If run times are standard hours and available capacity is adjusted for performance, document that adjustment. If the run times already include the same expected losses, do not deduct them a second time. Historical output is a useful reality check on optimistic capacity assumptions.

CRP example: find the eight-hour machining overload

Imagine a manufacturer reviewing next week’s work on one machining center. It has one eight-hour shift on each of five working days: 40 machine-hours. Four hours of planned maintenance leave 36 available machine-hours. No further efficiency deduction is used in this simplified example.

Three orders need machining in that week:

Order	Status and remaining work	Remaining setup	Run time per piece	Required machining hours
J101	Open order: 60 pieces remaining	0 h	0.25 h	15 h
J202	Planned order: 80 pieces	2 h	0.20 h	18 h
J203	Planned order: 40 pieces	1 h	0.25 h	11 h
Total				44 h

J101 originally contained 100 pieces. Forty are already machined, and its setup is complete. Only the remaining 60 pieces enter this machining load: 60 × 0.25 = 15 hours.

For J202, the calculation is 2 + (80 × 0.20) = 18 hours. J203 adds 1 + (40 × 0.25) = 11 hours.

The machining center therefore has 44 required hours against 36 available hours: an eight-hour overload and a 122.2% load ratio, rounded to one decimal place.

The same orders require 6, 8 and 4 labor-hours respectively at a separate deburring station. Its 18-hour load fits within 28 available labor-hours. Those ten spare labor-hours are useful, but they cannot do the missing machining work.

Compare a real response, not just a smaller red bar

Suppose J203 can run on an eligible alternative machine with 16 hours available in the required period. It is slower there: setup takes 1.5 hours and each piece takes 0.30 hours.

Moving the operation requires 1.5 + (40 × 0.30) = 13.5 hours on the alternative, not the original 11 hours.

Resource	Load after moving J203	Available capacity	Remaining capacity
Original machining center	33 h	36 h	3 h
Alternative machine	13.5 h	16 h	2.5 h
Deburring station	18 labor-hours	28 labor-hours	10 labor-hours

Both machining totals now fit. But the move increases total machining time from 44 to 46.5 hours. That may be worthwhile to protect the delivery date, yet it is not a productivity saving. Compare the additional machine time, tooling and any other transfer cost with the cost of overtime or a late order.

Then check the handoff. The alternative must finish J203 early enough for its four deburring hours before dispatch. Spare time after that handoff does not help. A balanced CRP result gives you a candidate solution; the detailed schedule tests its timing.

Decide how to resolve each overload

Before buying capacity, open the orders behind the peak. Check for duplicate proposals, completed operations still counted as open, outdated quantities and incorrect routing times. Correcting a data error avoids paying for overtime that the work never required.

If the shortage is real, compare responses against the affected orders:

• Move an operation to an eligible alternative. Use that resource’s actual setup and processing time, as in J203. Confirm tooling and staffing as well as free hours.
• Move work to another period. Earlier production needs materials and capacity earlier; later production may change the delivery commitment. Recheck the preceding and following operations.
• Add staffed working time. Target the resource and window that are short. An extra shift elsewhere in the factory does not resolve this overload.
• Subcontract suitable work. Include the supplier’s lead time, transport and any inspection before the next internal operation.
• Revise the commitment. If the work still cannot fit, agree a different date, quantity or split delivery rather than releasing an impossible promise.

Changing priority deserves particular care. It can protect an important order by making another one wait; it does not create capacity. Review which other commitments move before calling the urgent order solved.

Record the chosen action against the affected work, update the relevant order or capacity data and recalculate. Where dates or quantities alter material requirements, feed the decision back into material planning too. CRP is a feedback loop, not a report to file after the meeting.

Turn the capacity decision into a SkyPlanner schedule

Use SkyPlanner when your planners can identify the overload but spend too much of their day rebuilding the operation queues that follow. The gain is less manual coordination, better use of the capacity you have and a clearer basis for deciding whether extra hours are worth their cost.

Your ERP can remain the source of your business and production records. SkyPlanner integrates with any ERP or MES through its open REST API, connecting the orders and process-step information with detailed scheduling.

In SkyPlanner, workstations, shifts, operators, process steps and priorities provide the scheduling foundation. Known maintenance blocks resource availability. Arcturus calculates the schedule using the configured capacity, operation dependencies and priorities. With material-aware scheduling enabled, recorded material availability also affects the timing.

For the machining example, the useful workflow is to represent the approved resource choice and available shifts, recalculate, then inspect machining and deburring together in the Gantt timeline. You can see when the operations finish and which other orders are affected. If the alternative is unavailable until late in the week, the delivery consequence becomes a scheduling question you can assess rather than an assumption hidden in the totals.

You decide whether to accept that consequence, change priorities or provide more capacity. Arcturus handles the scheduling calculation. That is why SkyPlanner is a stronger operational next step than keeping a separate load report and manually adjusting every queue after each change.

What changed for Mamec

Mamec, a Finnish manufacturer of mixing technology and high-tech contract products, faced thousands of interdependent work orders. Its ERP’s rigid planning functions did not provide the overall picture the team needed. On the shop floor, supervisors prioritized work from delivery dates on paper orders, while management’s understanding of load depended on subjective estimates.

Mamec connected SkyPlanner with its Oscar ERP and adopted AI-powered finite scheduling. In its implementation, work queues are locked a week at a time, staff can look up an order’s progress and schedule, and management can see the production load from the same shared information.

Mamec reports a clearly lighter planning workload, less workstation downtime from a better work sequence and improved delivery reliability. Its experience illustrates the value of connecting the load picture to the work behind it: planners have less coordination to do by hand, and changes are easier to explain to the people who depend on the plan.

Make your next CRP review an actionable plan

Choose one overloaded work center from your current material plan. Identify the open and proposed orders behind it, verify their remaining operation hours and compare the practical responses. Then check the revised work as a connected schedule, including the operations that follow the overloaded resource.

SkyPlanner helps you do that scheduling work without repeatedly rebuilding it by hand. Start a trial with demo data to explore Arcturus and the Gantt timeline, or book a demo around your own overloaded work center. Bring its shifts, a typical routing and the delivery decision you need to make. That is the right starting point for seeing how SkyPlanner can turn your capacity decision into a production plan your team can use.