NC servo feeding ยท Program logic
Multi-Step NC Servo Feeding
Feed lengths, repeats and cycle logicโunderstand the complete pattern before it reaches the press.
Explore a feed sequence โ
A multi-step NC servo feeder program describes a sequence: how far to feed, how many times to repeat that distance, and which segment comes next. It is useful when an approved production process needs more than one feed length within a repeating pattern.
The important distinction is between the programmed sequence and the machine sequence. A program can specify six feed actions, but that does not mean one trigger should execute all six. Each movement still needs the correct request, permission and coordination with the press, shear or line controller.
Start by separating length, repeat count, active segments and production quantity. They answer different questionsโand confusing them can make a correctly entered program behave differently from the intended process.
01 / Program structure
What makes up a multi-step feed program?
A segment normally pairs a feed length with a repeat count. The installed controller determines the exact field names and how its counters operate.
| Program term | What it describes | What it does not establish |
|---|---|---|
| Feed length | The commanded travel for a feed action in that segment | The number of finished parts |
| Repeat count | How many feed actions use that segmentโs length before the sequence advances | The number of different segments |
| Active segment count | How many segments participate in the current program | How many times the whole program runs |
| Program loop | A complete pass through the intended active sequence | The controllerโs production-count definition |
| Production target | A stopping or counting requirement interpreted by the applicable control logic | A universal conversion from feeds to parts |
In this guide, a repeat count of 3 means three feed actions in total, not the first action plus three additional repeats. It does not mean one move at three times that length. Likewise, changing the active segment count does not automatically change the repeat count within each segment.
Some interfaces show more rows than the current job uses. Check which rows are active and what the controller does with unused rows. Do not assume that entering zero always disables a segment; that behavior belongs to the specific program version.
02 / From rows to movements
A three-segment example: six feeds, 680 mm
Consider this teaching example, assuming the tooling and process permit the sequence:
| Active segment | Feed length | Repeat count | Travel within the segment |
|---|---|---|---|
| 1 | 100 mm | 3 | 300 mm |
| 2 | 150 mm | 2 | 300 mm |
| 3 | 80 mm | 1 | 80 mm |
The expanded sequence is:
100 โ 100 โ 100 โ 150 โ 150 โ 80 mm
Worked example: complete action record
| Feed action | Segment | Repeat within segment | Commanded length | Cumulative commanded travel |
|---|---|---|---|---|
| 1 | 1 | 1 of 3 | 100 mm | 100 mm |
| 2 | 1 | 2 of 3 | 100 mm | 200 mm |
| 3 | 1 | 3 of 3 | 100 mm | 300 mm |
| 4 | 2 | 1 of 2 | 150 mm | 450 mm |
| 5 | 2 | 2 of 2 | 150 mm | 600 mm |
| 6 | 3 | 1 of 1 | 80 mm | 680 mm |
One complete pass contains 3 + 2 + 1 = 6 feed actions and 100 ร 3 + 150 ร 2 + 80 ร 1 = 680 mm of commanded forward travel.
These totals describe the example program. They are not six finished parts, a material-utilization figure or a machine-capacity claim. Actual material consumption may also include threading, lead-in, tail-out, trimming or rejected material.
If the applicable controller is configured to repeat the program, the intended sequence returns to segment 1 after the final repeat of segment 3. Verify that transition and the conditions that allow production to continue. The example does not establish the controllerโs automatic-stop, reset or restart behavior.
Explore the feed sequence
Change the length and total feed moves in each stage, then follow one complete program loop. This teaching model shows order and commanded travel, not machine timing or finished-part output.
Demo input limits: 1โ3 stages, 0.001โ10,000 mm, and 1โ20 moves per stage. These are tool limits, not machine ratings. Zero-count behavior depends on the controller and is not simulated.
- Feed actions per program loop
- 6 moves
- Commanded travel per program loop
- 680 mm
Feed-action order โ equal-size tiles, not a distance or time scale
Illustrated loop 1 ยท Feed 1 of 6
Stage 1 ยท move 1 of 3 ยท command 100 mm
Cumulative commanded travel within this loop: 100 mm
Next in the pattern: stage 1 ยท move 2 of 3.
Each physical feed must still follow the installed press, shear or line-control sequence. Selecting a tile here does not represent a machine command.
03 / Sequence ownership
Each feed still belongs to a control cycle
The program determines the next required distance. The press or line sequence determines when that move may happen and what must be confirmed afterward.
In a press-controlled arrangement, a feed request must be coordinated with the permitted material-movement interval, feed completion and any required pilot-release sequence. In a feeder-controlled cutting arrangement, movement and position confirmation may precede a cut request, followed by the applicable return-ready or completion condition.
The number of feed actions per press stroke or cutting cycle must therefore be confirmed separately. Do not infer it from the number of rows in the program. A program expander illustrates order; it does not reproduce the machineโs electrical handshake.
For the interface review, use the NC feeder synchronization and acceptance guide. The controller and machine documentation should identify what advances the repeat counter and what advances the active segment.
04 / Know what is counted
Program loops and production quantity are different counts
For the example above, one completed loop means six commanded feeds. It does not automatically mean six press strokes, six cutting cycles or six accepted parts.
A tool may produce multiple parts per stroke. A progressive process may also require initial progression through its stations before finished parts emerge. Scrap, rejected parts and interrupted cycles further separate a movement counter from an accepted-product count.
Before setting a production target, establish:
- What event increments the displayed quantity.
- Whether that count represents feeds, machine cycles, completed patterns or another event.
- Which control owns the target and stop request.
- What happens if the target is reached partway through a program loop.
- How rejected material and incomplete patterns are handled in the production record.
The programโs mathematical totals remain useful: feed actions per loop equal the sum of the repeat counts, and travel per loop equals the sum of each length multiplied by its repeats. Converting either total into good parts requires the actual tooling and counting logic.
Here, โprogram loopโ means repeating a sequence. It is unrelated to the physical strip loop between coil-preparation equipment and the feeder.
Actions per loop
Add the total moves from every active stage.
N = nโ + nโ + โฆ + nโ
Travel per loop
Multiply each length by its move count, then add.
D = Lโnโ + Lโnโ + โฆ + Lโnโ
05 / Tooling comes first
Confirm the die or cutting process permits different lengths
Programmable feed lengths do not make every die suitable for variable progression. A conventional progressive die usually has a designed station pitch. An arbitrary change in feed length can put the stripโs holes, formed features or pilots in the wrong position relative to the next station.
Check the strip layout and approved process before building the program. The tool designer or responsible process engineer should identify where different lengths are allowed and how the resulting positions are used. For a fixed-pitch die, repeating the correct progression may be the requirement; a multi-length sequence is not automatically an improvement.
For punching or cutting applications that intentionally use changing intervals, relate every programmed distance to the drawing. Also identify whether the entered value represents the required advancement between operations or must account for a separately defined trim, part reference or process allowance. Avoid adding an allowance twice.
The feed-pitch accuracy guide explains the distinction between a commanded feed and the result measured at the strip or part.
06 / Length and time
Check timing at every segmentโnot only the average
The example averages about 113.3 mm per feed, but no individual command is 113.3 mm. Selecting equipment around that average would hide the 150 mm movement.
Review each distinct length against its available time, material load and actual motion profile. The longest move often deserves attention, but shorter moves can have different acceleration, positioning or sequence demands. Do not assume all segments share the same permitted interval unless the application confirms it.
Use the servo feeder feed-time calculation guide to examine the time window. A displayed speed percentage or motor-speed value is not automatically material speed in m/min; use the controllerโs documented units and scaling.
07 / Check the complete pattern
Verify the whole pattern, including its boundaries
Prepare an expected action list before tryout. The list should show segment, repeat number, required feed length and cumulative travel. It becomes the reference for checking transitions rather than relying on memory or the first acceptable movement.
Follow the machineโs approved safeguarded commissioning procedure and record:
- Program identity: the job, drawing revision, active segments, lengths and repeats.
- Delivered movement: measurements suitable for each length and the required accuracy.
- Transitions: the last repeat of one segment, the first repeat of the next, and the return from the final active segment to the intended next state.
- Control events: the request, completion feedback and corresponding press or cutting operation.
- Production result: representative strip or parts checked against the agreed criteria.
Stopping and restarting deserves its own check. Establish from the applicable documentation whether a pause, reset, alarm recovery or power interruption retains or changes the current segment and repeat position. A โresumeโ action must not silently repeat or skip an operation the product still requires.
After any interruption, reconcile the physical strip position with the approved recovery procedure before returning to automatic operation. The NC servo feeder commissioning guide provides a broader framework for controlled trial and verification.
08 / From requirement to equipment
What to send when selecting a multi-step NC feeder
Provide the intended length-and-repeat table, the process drawing and the required output definition. Add material grade, thickness, width, surface requirements, target production rate and the press or cutting-machine details.
Ask the supplier to confirm the supported active-segment count, repeat-count behavior, control interfaces and the documented stop/restart behavior for the proposed configuration. If job storage or recall matters, request that feature explicitly; multiple active lengths do not by themselves prove that multiple saved recipes are supported.
Include the coil-preparation arrangement, strip support and feed-entry position. These details help connect the program requirement with the actual load and installation.
Have a sequence your line needs to run?
Send the lengths, repeats, process drawing and material details. HENLI can review the NC feeder configuration and line interfaces for your application.
09 / Common questions
Frequently asked questions
Does a multi-step program execute every segment after one feed trigger?
Not necessarily. The program defines the sequence of lengths and repeats. Each move still follows the installed controllerโs trigger and permission logic. Confirm how it coordinates with the press or cutting cycle.
Is the repeat count the same as production quantity?
No. A repeat count applies to feed actions within a segment. Production quantity depends on what the control counts and how the tool produces parts. Define both before setting a target.
How many segments does an NC servo feeder support?
The limit depends on the controller and configuration. Confirm the active-segment capacity for the quoted machine; a screen from another model or software version is not sufficient evidence.
Can multi-step feeding be used with a progressive die?
Only when the approved tool and strip layout allow the intended sequence. A fixed-pitch progressive die normally requires its designed progression, not arbitrary changes between programmed lengths.
Will the program resume at the same segment after a stop?
That is configuration-specific. Pause, reset, alarm recovery and power interruption may have different effects. Use the documented recovery rules and verify the stripโs physical state before continuing.
