Manufacturing
Glossary
Plain-English definitions for the terms that come up on a CNC shop floor — what each one means, how it's calculated, and where you'll run into it.
OEE (Overall Equipment Effectiveness)
OEE stands for Overall Equipment Effectiveness — availability × performance × quality, the share of planned time a machine spent making good parts at full speed.
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CNC macro variables
CNC macro variables are numbered memory slots — #100, #500 and so on — that a part program can read and write, turning a fixed program into one that counts, decides and remembers.
Read moreCNC operating modes (Auto, MDI, Jog)
CNC operating modes are the settings on the control panel that decide what the machine does with your input — run a stored program (Auto), run typed-in lines (MDI), or move axes by hand (Jog).
Read moreCycle time
Cycle time is how long a machine takes to make one part — from one finished part to the next, counting only the time the machine was actually running.
Read moreD
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Feed and spindle override
Feed and spindle override are dials on the control panel that scale the programmed feed rate and spindle speed by a percentage while a program runs — 100% means exactly as programmed.
Read moreFirst-piece inspection (FPI)
First-piece inspection is the check made on the first part after a setup, tool change or program change — the batch only runs once that part is approved.
Read moreFPY (First Pass Yield)
FPY stands for First Pass Yield — the share of parts that came out right on the first attempt, with no rework and no scrap.
Read moreFTP on CNC machines
FTP (File Transfer Protocol) is how many networked CNC controls exchange files — part programs, and on some controls, status, counter and log files.
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M-codes
M-codes are the miscellaneous commands in a CNC program that switch machine functions — spindle, coolant, tool change, program stop and program end — as opposed to G-codes, which drive motion.
Read moreMachine availability formula
Machine availability = run time ÷ planned production time — the share of the time you planned to run that the machine actually spent running.
Read moreMachine utilization formula
Machine utilization = actual production time ÷ total available time — how much of all the hours a machine could have run were spent running.
Read moreMTBF & MTTR
MTBF measures how long a machine runs before it breaks down. MTTR measures how fast it gets fixed once it does. Different questions, usually tracked together.
Read moreO
OEE (Overall Equipment Effectiveness)
OEE stands for Overall Equipment Effectiveness — availability × performance × quality, the share of planned time a machine spent making good parts at full speed.
Read moreOPC UA (Open Platform Communications Unified Architecture)
OPC UA stands for Open Platform Communications Unified Architecture — an open, vendor-neutral standard (IEC 62541) machines use to share data securely over a network.
Read moreP
Part count
Part count is the CNC controller’s running total of finished parts, usually increased by one each time the program reaches its end.
Read morePlanned production time
Planned production time is the time a machine is scheduled to make parts — the shift, minus planned stops like breaks and scheduled maintenance.
Read morePower-on, operating and cutting time
Three clocks most CNC controls keep: power-on time (control switched on), operating time (running a program in automatic) and cutting time (actually feeding into material).
Read moreS
Scrap rate
Scrap rate is the share of parts produced that had to be thrown away — scrapped or rejected quantity divided by total quantity produced, as a percentage.
Read moreSetup time (changeover time)
Setup time is the time a machine is stopped while it is prepared for the next job — from the last good part of one job to the first good part of the next.
Read moreShift handover
Shift handover is the passing of information and responsibility from the outgoing shift to the incoming one — what was made, what went wrong, and what is still open.
Read moreSMED (Single-Minute Exchange of Die)
SMED stands for Single-Minute Exchange of Die — a method for cutting changeover time down to single digits, by moving setup work out of the stopped-machine window.
Read moreSpindle load
Spindle load is how hard the spindle motor is working, shown as a percentage of its continuous rating — 100% is the power it can deliver all day without overheating.
Read moreSpindle utilization
Spindle utilization is the share of available time a CNC machine’s spindle is actually turning — the closest measure of how much of the day goes into cutting metal.
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Takt time
Takt time is the pace production must keep to meet customer demand — net available production time divided by the number of parts the customer needs.
Read moreTEEP (Total Effective Equipment Performance)
TEEP stands for Total Effective Equipment Performance — the share of all calendar time a machine spent making good parts at full speed. TEEP = OEE × utilization.
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