Capacity planning
Capacity planning matches production capacity (machines, labor, and supplier throughput) against projected demand over multiple horizons. Long-range planning sizes plants and lines, rough-cut capacity planning checks the master schedule against bottleneck resources, and finite scheduling sequences the daily work. At every level it answers the same question: can we actually build the plan, and if not, what has to change?
Examples
Finding the constraint: Demand is 450 units per shift against 27,000 available seconds: a 60-second takt. The slowest station cycles at 72 seconds, capping output at 375 units. Options priced: a parallel fixture at that station ($85,000, ready in 6 weeks) or a partial second shift ($31,000 a month, available immediately).
Supplier ramp check: A molder's 4-cavity tool on a 45-second cycle yields about 320 parts an hour, or 4,800 across two shifts. Ramp demand is 6,200 a day. The buyer orders an 8-cavity tool 16 weeks ahead of ramp, inside the tool's lead time, instead of discovering the gap at start of production.
Definition
Capacity questions repeat at three horizons. Strategic: how many lines, shifts, and plants over the next 2 to 5 years, decided alongside S&OP volumes. Tactical: does this quarter's master production schedule overload any bottleneck resource. Execution: which jobs run on which machines tomorrow.
The arithmetic is takt-style. Divide available production time by required output: a line with 27,000 productive seconds per shift facing demand of 450 units has a takt of 60 seconds, and any station cycling slower than that caps the line. Capacity is rarely the nameplate number; subtract changeovers, downtime, yield loss, and absenteeism to get what is actually available.
Buyers do capacity planning too, just on the other side of the purchase order. A quote means little if the supplier cannot hit volume, so sourcing and NPI ramps should verify tooling cavities, shift patterns, and capacity already committed to other customers; chronic shortfalls become supplier development projects. Direct-materials teams use platforms like LightSource to capture supplier capacity commitments alongside quotes during sourcing, so the check happens before award rather than after the ramp slips.
Frequently asked questions
What is capacity planning in simple terms?
Capacity planning matches production capacity, meaning machines, labor, and supplier throughput, against projected demand over multiple horizons. At every level it answers the same question: can we actually build the plan, and if not, what has to change?
What are the three horizons of capacity planning?
Strategic capacity planning sizes plants, lines, and shifts over the next 2 to 5 years, decided alongside sales and operations planning volumes. Tactical rough-cut capacity planning checks whether the quarter's master production schedule overloads any bottleneck resource, and execution-level finite scheduling sequences which jobs run on which machines tomorrow.
How do you calculate production capacity?
The arithmetic is takt-style: divide available production time by required output. A line with 27,000 productive seconds per shift facing demand of 450 units has a takt of 60 seconds, and any station cycling slower than that caps the line. Capacity is rarely the nameplate number; subtract changeovers, downtime, yield loss, and absenteeism to get what is actually available.
Why should buyers do capacity planning on suppliers?
A quote means little if the supplier cannot hit volume, so sourcing and NPI ramps should verify tooling cavities, shift patterns, and capacity already committed to other customers. A molder running a 4-cavity tool on a 45-second cycle yields about 4,800 parts across two shifts, so ramp demand of 6,200 a day surfaces a tooling gap that is far cheaper to fix 16 weeks ahead than at start of production.
What happens when a capacity constraint is found?
Finding the constraint turns capacity planning into a priced decision. If the slowest station cycles at 72 seconds and caps output at 375 units against demand of 450, the options might be a parallel fixture at that station for $85,000 ready in six weeks, or a partial second shift at $31,000 a month available immediately. Chronic supplier shortfalls become supplier development projects.
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