The manufacturing solution concept

The key to improving manufacturing productivity lies in recognising that end-to-end productivity is determined by the production rate at the slowest step (production constraint) in the production line.

This simple reality offers massive productivity gains at very low cost.

Improving production rates at other steps in the process independently, doesn't improve end-to-end productivity, it actually degrades it.

Here are the simple steps (adapted from TOC's manufacturing solution) for improving manufacturing plant productivity dramatically in a simple production line containing 5 machines:

Work out the rate which each machine in the production line can produce what's needed for a single finished item. This is the productivity rate. (If a step can process 4 units worth per cycle and a cycle takes 12 minutes, then the productivity rate at that step is 20 units per hour.)
Identify the production constraint - the machine with the lowest productivity rate. (The productivity constraint determines whole-plant productivity. Any productivity rate improvements at the production constraint translate directly into whole-plant productivity)
Maximise the productivity rate at the production constraint:
1. Reduce cycle-time, idle-time, setup-time and down-time.
2. Introduce quality control immediately before it in the process. (This reduces wasted capacity at the productivity constraint.)
Reduce productivity rates at other machines in the process, to the productivity rate at the production constraint. (This reduces total inventory investment, storage costs and lead-times. It's often hard for people to do, because of the apparent loss in efficiency at each machine. The trick is to focus them on the excess inventory that having every machine running at full capacity creates.)
Protect productivity at the productivity constraint with an inventory buffer. (The size of the buffer should enable the production constraint to continue operating when upstream machines fail - until they are operational again.)
Augment the productivity constraint's production rate with pre-, post-, or parallel processing. (Even highly inefficient processing is worth considering, because anything gained at the productivity constraint is gained for the entire system.)

Note that, although efficiencies at non-constraints have dropped substantially, total throughput has increased 100% as a result of this process. Total inventory has dropped significantly, as has lead-time, resulting in a dramatic gain in whole-system productivity.

Although few production lines are as simple as the one in the illustration, the principle is just as valid for more complex production systems. It's just a little less obvious where the production constraint is.