What utilization to expect by machine type

A manual CNC runs 40 to 60% of the shift, a coil-fed stamping press 65 to 80%, and a lights-out cell 80 to 90%, because how much of each cycle a person carries sets the ceiling on uptime. These are the planning ranges IoTFlows publishes for uptime measured inside your shifts. Use them to check that a machine’s number is plausible, then set its goal from its own history.

This guide is for plant managers and owners who have been handed one utilization target for every machine on the floor. It explains where each range comes from, works three CNC shifts and a press shift by hand, and ends with a goal-setting method you can run on your own data.

What uptime measures here#

Every range in this guide uses one definition, so state it before comparing anything.

IoTFlows reports the same percentage as Utilization on the Assets page and the Advanced Report, and as Uptime on a machine card. The uptime glossary entry gives the full definition. Other definitions divide by calendar time or by planned production time and give different numbers for the same machine. The guide to machine utilization and its four denominators works one week through all of them.

Uptime ranges by machine type#

The table collects the ranges IoTFlows publishes in its machine setup guides. Each range is for uptime measured inside your shifts, and each row is a loading method, not a machine brand.

The pattern is the same on all three machine types. Each step that takes a person out of the cycle lifts the bottom of the range by 10 to 25 points. A manual CNC and an automatic one differ by more than a CNC and a press with the same loading method.

Each row comes from one setup guide:

• CNC machining centers: the CNC setup guide.
• Injection molding machines: the injection molding guide.
• Stamping presses: the stamping press guide.

All three guides add the same instruction: start from your own baseline plus 5 to 10%, not from the table.

Why loading sets the ceiling#

A machine an operator loads is stopped while the operator works. Loading, unloading, deburring and measuring with the spindle off all count as stopped time, even on a shift with no breakdowns.

Handling time sets a ceiling on uptime before setups, tool changes or failures take their share.

For example, a part that cuts for 9 minutes and takes 3 minutes to unload, deburr and reload caps the machine at 9 ÷ 12 = 75%. Every setup and stop then comes out of that 75%, which is why an operator-loaded CNC lands at 50 to 70% rather than 75%.

CNC machines#

The three CNC ranges follow from three ways of running the same kind of machine. Work one 450-minute shift on each, with lunch already removed.

None of the three machines is performing badly. The manual mill sits inside its 40 to 60% range, the production mill inside 50 to 70% and the lathe inside 75 to 85%.

A fleet ranking that puts the manual mill last tells you about its loading method, not its losses. The guide to monitoring CNC machines reads a mixed fleet the same way.

Stamping presses#

On a press, how material reaches the die sets the ceiling. A hand-fed press stops whenever its operator does: to restack blanks, swap a full parts tote or check a part. A coil-fed press keeps stroking until the coil runs out, the strip jams or the die comes out.

That press sits inside its 65 to 80% range. The same press hand-fed, with the same die change and 120 minutes of blank restocking, tote changes, part checks and waiting on the shear, runs 285 minutes for 63.3%. The loading method alone moves it 12.2 points.

Injection molding machines#

A molding machine times its own cycle: inject, hold, cool, open, eject. An operator who removes parts or loads inserts adds handling time to every shot, which is why a tended machine runs 60 to 75%. Without a person in the cycle, the losses that remain are mold changes, color and material changes and process faults, and the range rises to 75 to 85%.

What lights-out uptime depends on#

Lights-out means a machine or cell runs through hours when nobody is on the floor. The ranges for it are 80 to 90% on a press and 85 to 90% on a molding machine. IoTFlows’ CNC guide suggests a goal of 85 to 90% for a CNC with lights-out automation.

Two things decide whether a lights-out figure reaches that range.

• The window. Measure the cell across the unattended hours it is scheduled to run. A window that covers only the staffed shift captures the loading, setup and restarts people do there, and none of the hours where the cell runs best.
• When it stops. With nobody to reset a fault, a stop lasts until someone arrives. For example, a cell scheduled from 22:00 to 06:00 (480 minutes) that alarms out at 04:40 runs 400 minutes, or 83.3%. The same alarm at midnight leaves it at 120 minutes, or 25.0%.

The second point means a lights-out cell’s uptime swings from night to night more than a staffed machine’s. Read it over a month, and work on the faults that stop it early in the night first, because each one costs the rest of that night.

Why published figures disagree#

A utilization figure without its definition can’t be compared with anything. Most of the disagreement between published numbers comes from a different numerator, a different denominator or a different kind of machine.

In-cut time is narrower than uptime. Makino, a machine tool builder, reports a survey of more than 100 US plants in which the average vertical machining center spindle was in cut 34% of the time, against the 70% of in-cycle time Makino says it should reach.^[2] Makino attributes the gap to setup, loading and unloading, tool maintenance and chip clearing.^[2] In-cut time drops rapid moves and tool changes that uptime counts as running, so a 34% in-cut figure and a 60% uptime can describe the same machine.

Arc-on time is narrower still. Miller Electric puts the average arc-on time in a semi-automatic welding operation at 10 to 12%, and excludes fit-up, material preparation and post-weld cleaning from it.^[3] That figure describes a welder’s time at the station, not a machine’s running state. Never hold it against a CNC’s uptime.

Acceptable run time depends on the work. Mike Lynch, writing in Modern Machine Shop, notes that high-volume work can justify almost anything to pass 95% spindle run time, while some companies are satisfied below 20%.^[1] A machine in a cell, he notes, can sit idle for long periods and still be appropriately utilized.^[1]

Is your machine below, inside or above its range?#

Measure the machine for at least a few weeks, then place its baseline against the range for its type and loading method. Where it lands tells you what to do next.

Below the range. Put a reason on every stop, then rank the reasons by the hours they cost on the downtime Pareto chart. Setup is often the largest single loss on a CNC. A short list of downtime reason codes keeps operators classifying stops instead of skipping them.

Inside the range. The machine runs as well as its loading method allows. Further gains come from cutting handling time or setup time, or from changing how the machine is loaded, not from pushing the operator harder.

Above the range. Check the measurement before celebrating. A short-stop setting that counts every gap under a few minutes as running moves loading time into uptime. Check how short stops are handled on that machine, then check the category: a mill with a pallet changer that you filed as operator-loaded belongs in the automatic row.

Set a goal for each machine type#

The ranges tell you whether a baseline is plausible. The goal comes from the baseline itself.

1. Group machines by loading method

   Sort every machine into a row of the table: manual, operator-loaded, automatic or lights-out. Group by how the machine is loaded, not by brand or age.

2. Measure a full quarter

   Collect uptime for one complete quarter with the same shifts and the same rule for breaks throughout. A few weeks gives a first read, and a quarter covers the job mix.

3. Set the plant goal from the largest group

   Take the baseline of the group with the most machines and add 5 to 10%. For example, a shop where most mills run at 52% sets 57% to 62%, not 85%.

4. Override only the groups that differ

   Give a machine its own goal only when its loading method puts it in a different range, such as a lights-out cell in a shop of manual mills. When every machine carries its own goal, a green gauge no longer means the same thing on two machines.

5. Hold each goal for a quarter

   Leave goals alone for a quarter, then raise them when the machines get there. A goal a machine has never met teaches operators to ignore the number.

You don’t need a separate goal for every machine type in the plant. Two or three goals cover most shops: one plant goal, and an override for each group whose range sits well above or below it. The goal-setting guide shows where an override applies.

Track uptime against each machine’s goal#

IoTFlows puts a sensor on each machine that reads running or stopped from the machine’s own vibration, with no PLC or controller connection. A manual mill from the 1990s and a new lights-out cell report uptime the same way, so their figures sit side by side on one fleet view.

One organization goal colors every gauge green at or above it and red below it, and you override it per machine where the loading method sets a different ceiling. The Advanced Report gives each machine’s baseline over a quarter.

Storm Power Components doubled machine utilization with SenseAi on its CNC machines, lasers and presses, as told in the Storm Power story. For the full product, see machine utilization tracking.