Article

Why 100% machine utilization destroys HMLV profit

If your custom machine shop runs at 95 percent utilization, you are probably increasing your lead time rather than your profit.

Standard manufacturing KPIs tell managers to keep every engineer busy and every CNC spindle turning. That works for mass production, where the process is stable and the parts are identical every day.

Custom automation does not behave like mass production. In an HMLV environment, variability is the normal condition. Run a high variability system at maximum capacity and you have removed every shock absorber you had.

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The mathematics of queue time

The problem is not the machining time. It is the waiting time. In a queue based system, waiting time does not grow in a straight line. It grows exponentially.

Push utilization from 70 to 80 percent and you might see a small delay. Push it from 90 to 95 percent and waiting time can easily double. The machines are busy, and the parts spend most of their life sitting on a pallet.

The cascade of failure

When engineering and the floor are both fully booked, one unexpected event becomes a general disruption, because there is no spare capacity to absorb it:

1. The design change. One mid project change from a customer forces engineers to pause other work, delaying three separate releases.
2. The rush job. Sales pushes a high priority PO into the system, so a machine setup stops and planned work is displaced.
3. The financial penalty. Catching up means authorizing expensive overtime and triggering heavy machiningOutsource premiums. The margin disappears.

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Idle time is capacity insurance

High utilization in a custom shop usually just means high waiting time. You do not need every machine busy at all times. You need controlled spare capacity to absorb the natural variability of custom work.

Idle time is not waste if it protects the critical path and ships projects on time without outsource fees.

Stop measuring how busy the machines are. Start measuring how fast a project flows from quote to factory acceptance test.