Cycle Time: What 20–30 Seconds Delivers
Cycle time is quoted as a band — 20 to 30 seconds per cut at the entry class — and the band is the honest version of a number that moves with the material. This article is what the cycle actually delivers: what happens inside those seconds, why the band exists, and how the cycle time and the daily tonnage interact. The reference machine is the Q91-400, and the logic applies at every class.
What Happens Inside the Cycle
The 20 to 30 seconds is not the blade stroke — it is the complete indexed-and-ready sequence:
- Feed advance. The pushing cylinder advances material to the preset cutting position.
- Clamp. The hold-down cylinder locks the material so it cannot shift during the cut.
- Cut. The blade descends, completes the cut and retracts.
- Release and index. The hold-down releases, the pushing cylinder indexes the next piece forward, and the cycle is ready to repeat.
All four steps are on the PLC’s presets, and the preset values change with the material — a tight bundle of rebar indexes differently from a single heavy section. The band exists because the material moves the cycle, and any factory quoting a single cycle number without naming the material is guessing at your feed.
Why the Band Exists
Three things move the cycle inside the band, and all three are operational rather than mechanical:
Material geometry. A dense, uniform bundle cuts at one pace; an irregular piece at another. The hold-down has to lock what it is given, and the locking time varies with what arrives.
Cut length preset. A longer cut means more feed advance and a longer index. The preset follows your buyer’s charge specification, and the specification moves the cycle.
Loading rhythm. The cycle assumes the tank is charged. A machine fed in surges runs at the cycle’s ceiling and then starves; a machine fed in rhythm runs at the cycle’s middle, which is where the tonnage figure lives.
The Q91-400’s published band — 35 to 55 tons per day — is the tonnage that the cycle delivers when those three are under control, and the class guide covers the material the band assumes.
How Cycle Time and Tonnage Interact
The interaction is arithmetic with an operational shadow:
The ceiling. The cycle sets the maximum cuts per hour, and the cuts per hour multiplied by the tons per cut gives the theoretical ceiling. The published tonnage band sits below that ceiling, honestly, because no yard runs at the ceiling — loading, discharge and shift change all take their share.
The drift. The cycle stretches as the machine wears — blades past their rotation interval, the gap drifting wide, hydraulic temperature climbing. The stretch is gradual and invisible in any single shift, and it shows up first in the tonnage figure. The weekly feeler-gauge check and the blade log are what catch it early, and the plate and section guide covers the cadence.
The rhythm. A machine fed and discharged in rhythm holds the cycle’s middle for the whole shift; a machine fed in surges alternates between the ceiling and a stop. The difference between the two, over a shift, is most of the distance between the bottom and the top of the published band.
Reading the Cycle as an Operating Instrument
The cycle time is not just a specification — it is the machine’s most honest health indicator. Three signatures are worth a trained eye:
- Cycle time stretching on routine material is the classic early signature of edge or gap drift — check both before anything else.
- Hydraulic temperature climbing means the system is working harder for the same cut, usually the same root cause.
- The cycle stalling with no alarm and no hydraulic symptom is almost always the discharge zone filling — look at the pile before you look at the machine.
All three are visible from the control station, all three are cheaper to catch at hour two than at hour six, and all three are the cycle doing its second job — telling you how the machine actually is.
The Preset Detail
The PLC presets are where the cycle becomes operational rather than mechanical. Each material gets a preset — feed distance, clamp pressure, cut length, cycle timing — and switching between rebar, profile and mixed feed is a preset change rather than an operator recalibration. The presets are set at commissioning against your material, and they are re-checked when the mix changes seasonally.
Three practices keep presets honest: set the cut length from the buyer’s specification rather than from habit; verify the preset against the material, because the same preset behaves differently on a tight bundle than on a single piece; and review the preset list when the mix turns. The plate and section guide covers the cadence at the commercial class.
The Cycle as Instrument
The cycle time is the machine’s most honest health indicator, and the three signatures are worth teaching every operator. Cycle time stretching on routine material is the classic early signature of edge or gap drift — check both before anything else. Hydraulic temperature climbing means the system is working harder for the same cut, usually the same root cause. And a cycle that stalls with no alarm and no hydraulic symptom is almost always the discharge zone filling — look at the pile before you look at the machine.
All three are visible from the control station, all three are cheaper to catch at hour two than at hour six, and all three are the cycle doing its second job — telling you how the machine actually is rather than how the specification sheet says it should be.
The Cycle, Priced
The cycle time prices in tons, and the pricing is the arithmetic from the strokes guide: cycle rate times tons per cut, times the loading and discharge factors, minus the maintenance window. The cycle is the capability; the factors are the operation; and the tonnage is what the two produce together. A buyer who prices from the cycle alone plans at the ceiling and discovers the gap in month one.
The cycle also prices the machine’s health. A stretching cycle on routine material is the early signature of edge or gap drift, and the drift prices as lost tonnage per shift until the weekly check catches it. The feeler-gauge measurement and the blade log are what keep the cycle honest, and the cadence guide covers the routine that holds the published band.
The Cycle as the Machine’s Voice
The cycle time is the machine’s most honest report on its own condition, and the three signatures — stretching cycle on routine material, climbing hydraulic temperature, a stall with no alarm — are the vocabulary. Teach them to every operator, because all three are visible from the control station and all three are cheaper to catch at hour two than at hour six.
The weekly feeler-gauge check and the blade log are what keep the cycle honest, and the cadence guide covers the routine that holds the published band. The cycle is the specification telling you how the machine actually is.
Buyer FAQ
What does the cycle time include?
The complete indexed-and-ready sequence: feed advance, clamp, cut, release and index. The blade stroke is one of the four steps, not the whole cycle.
Why is the cycle time a range?
Because material geometry, cut length preset and loading rhythm all move it. A single number would be a guess at your feed — the band is the honest version.
How does the cycle time relate to daily tonnage?
The cycle sets the ceiling in cuts per hour; the published tonnage band sits below it honestly, because loading, discharge and shift change take their share of every shift.
What does a stretching cycle time mean?
Almost always accumulated wear discipline — blades past rotation or a gap drifting wide. The weekly feeler-gauge check catches both before they reach the tonnage figure.
What is the most common cause of a stalled cycle?
The discharge zone filling — cut pieces banking up until the box cannot clear. Look at the pile before you look at the machine; the most expensive version of this stop is an hour spent diagnosing a machine that was never the problem. Teach the three signatures to every operator, because all three are visible from the control station and all three are cheaper to catch at hour two than at hour six — the cycle is the machine telling you how it actually is. Teach the three signatures to every operator and the cycle becomes the machine’s own report on its condition — all three are visible from the control station, and all three are cheaper to catch at hour two than at hour six. The weekly feeler-gauge check and the blade log are what keep the cycle honest, and the routine that holds the published band is the same routine that catches the drift before it reaches the tonnage figure.