Ramp-Up, Learning Curve and Design Freeze

Why it matters

In the first production period of a new product, workers get to know the part, tool placement is corrected and the work sequence is applied more consistently. Times may fall for this reason. But not every fall is learning. Material may have arrived better prepared, inspection may have been moved outside, an experienced helper may have been added or the measurement boundary may have changed. The learning curve is a planning model that explains how unit time may change as cumulative production grows within a comparable scope. It does not by itself prove the cause of the observed fall. Moreover, speeding up by breaking the safe method cannot be counted as learning success. The standard time is not updated without knowing the nature of the change that lowered the time; first it is verified that the work done is the same work.

In this lesson the 80% learning rate belongs to the unit-time model. When cumulative production doubles, the model time of the product at that position becomes 80% of the previous one. This does not mean 80% time savings; the reduction between two doublings is 20%. Nor does it mean the average time of the whole batch. The model point belonging to a specific product differs from the total load of the products in between. The weekly quantity is not the cumulative product count either. If these distinctions are not kept, correct multiplications turn into a wrong capacity result. The name of the model, its starting point and its validity condition must be written together with the calculation; sharing only a percentage is not enough.

Ramp-up is broader than growing the quantity by the calendar. At each ramp-up stage, resource sufficiency, worker competence, first-time conformance and safety conditions are reassessed. Adding a new worker does not mean the whole team is at the same learning level. If the product or fixture changes, the earlier time series may not be continued directly. When the scope changes while the cumulative count grows, the model may appear to fit well. For this reason the method version and the product condition of the measurements are preserved. Training capacity and production capacity are tracked separately. The time of the person who gives support during training must also be visible in the resource plan.

Freezing the design does not mean saying that no change can be made any more. It means taking the verified product and process conditions as the basis and running later changes in a controlled way. The work sequence, fixture, inspection method, resource arrangement and training requirement of the frozen scope become clear. If there is an open problem, its limit and the decision are stated; a safety gap cannot be closed by the calendar. Declaring capacity only according to the short time the curve promises goes against this discipline. The measurement chain in M3 is preserved: first the defined method, then comparable observation, performance rating and the allowance on the right base. A new standard becomes defensible only with this chain.

Formula