Feeder

1. Definition

A feeder is equipment that advances strip a controlled distance (pitch) into a press, shear, or other station. In coil-fed stamping and in roll forming lines with inline punching, the dominant modern form is an NC/servo feeder: servo motor, feed rolls, and programmable length with encoder feedback.

On continuous roll forming without discrete punch pitches, “feeding” may simply mean decoiler + guides into driven stands. This page focuses on pitch feeders and straightener-feeder packages that protect hole-to-hole and hole-to-end accuracy.

2. Roles on a Roll Forming Line

Hole patterns that must register to cutoff usually depend on feeder accuracy plus the cutoff length loop (see Machine Overview / cutoff notes).

3. Servo / NC Feeders

Servo feeder guides describe an automatic system using a servo motor, feed rollers, and programmable control to move strip at a set length into a press or cutter. Types include general NC servo feeders, high-speed variants, zigzag feeders for nested blanks, and feeders paired with shears.

Closed-loop encoder feedback is how vendors claim repeatable pitch. Trade literature for integrated systems often cites feeding accuracy on the order of ±0.1 to ±0.15 mm under stated conditions—illustrative class figures, not a universal guarantee for every thickness and surface.

4. Straightener-Feeder

Many packages combine leveling rolls with feed rolls: straighten to release coil-set stress, then feed programmed length. Straightening rolls are typically hardened and often chrome-plated; backup rolls appear for high-strength stock. Electric gap adjustment improves repeatability versus hand wheels alone.

Flip-up straightener/feed roll designs (hydraulic lift) help clean rolls—critical for coated strip cosmetics.

5. 3-in-1 Decoiler–Straightener–Feeder

Compact systems integrate uncoiler, straightener, and servo feeder on one chassis, eliminating long slack loops between separate machines and saving substantial floor space (vendor claims often cite on the order of 40–50% length reduction versus modular layouts). Loop control may use photo sensors; hold-down arms and keepers stabilize heavy coils.

These units are common in press rooms and also appear upstream of roll forming punch presses where space is tight.

6. Pilot Release and Press Sync

When feeding progressive or punch dies that use pilots, feeders provide pilot release (often air): feed rolls briefly open so die pilots can locate the strip without fighting the feeder. Incorrect release timing tears pilots, marks strip, or destroys pitch accuracy.

Sync signals between press/punch and feeder (feed complete, press safe, release) must be engineered, not improvised with spare relays.

7. Pitch Accuracy and Hole Registration

• Programmed pitch vs measured hole spacing on first article
• Thermal drift and roll diameter wear over long runs
• Slip on oily or polished strip—insufficient nip or worn rolls
• Back-tension from decoiler fighting the feeder
• Cutoff registration using timing holes created by the punch

Diagnose hole-to-end errors as a system: feeder + punch timing + cutoff encoder, not feeder alone.

8. Surface and Roll Care

Feed and straightener rolls contact show surfaces before forming. Keep them clean, polished appropriately, and free of zinc/paint pickup. Flip-up cleaning features exist for a reason. Lubrication films must be compatible with punch dies and later forming (Lubrication page).

9. Feeder vs Mill Drive

The forming mill also “feeds” strip continuously via driven stands. Do not confuse:

• Pitch feeder — discrete indexed lengths for punching/shearing
• Mill drive — continuous forming speed and interstand match

On combined lines, modes may alternate (feed–punch–release–form) or run continuous with flying punch concepts. Architecture must be explicit in the GA drawing.

10. Selection Checklist

1. Max width, thickness, yield (HSS needs backups/power)
2. Required pitch accuracy and max SPM / feed rate
3. Standalone feeder vs straightener-feeder vs 3-in-1
4. Pilot release requirement
5. Coated-strip surface class
6. Interface I/O with punch press and RF PLC
7. Loop control method and floor/pit constraints

11. Common Faults

12. Boundaries

This page covers strip feeders relevant to roll forming and inline punch cells. It does not quote brand-specific kW or guarantee advertised micron accuracies on every job. Related: Recoiler, Machine Overview, Die Overview (punch dies), In-line Inspection.

13. Buyer / Engineer FAQ

Do all roll formers need a servo feeder?

No. Continuous profile lines without pitched punching may only need decoiler and guides. Add a feeder when punch pitch matters.

Is ±0.15 mm always real?

It is a common catalog class under stated test conditions. Validate on your thickest HSS and glossiest PPGI.

Feeder or flying punch without feeder?

Architecture choice. Flying systems change the mechanical problem; they do not eliminate registration engineering.

Can one feeder serve many dies?

Yes via recipes; verify release and pitch per die, and roll surface for cosmetics.

14. Operating Discipline

• Store pitch recipes by part number and coil family
• Verify first-piece hole spacing with calibrated scale/CMM sample
• Clean rolls on a schedule, not only after claims
• Lock recipe edit permissions
• After coil change, re-check pilot release and nip

15. Integration with Cutoff

When a punch creates a timing feature for cutoff, feeder pitch error becomes length registration error at the exit. Closed-loop cutoff (rotary transducer / encoder wheel) and feeder accuracy must be budgeted together. Improving only one side leaves residual scrap patterns that look random.

16. High-Strength Notes

HSS increases straightener force and springback of coil set. Vendors emphasize 3-in-1 and backed straighteners for high-strength feeding. Undersized straighteners pass curve into the punch and then into the mill as tracking problems.

17. Related Encyclopedia Topics

• Recoiler
• Roll Forming Machine Overview
• Die Overview (punch dies)
• Machine Accuracy
• Lubrication / PPGI

18. Commissioning Checks

1. Verify width/thickness capacity vs purchase order
2. Teach/verify encoder length with known ground bar or marked strip
3. Prove pilot release with the actual die
4. Run cosmetic coil through straightener/feed rolls before production PPGI
5. Document I/O map with punch and RF PLC
6. Train operators on recipe recall and roll cleaning

19. Feed Modes Worth Naming in Specs

• Continuous feed — rare for punch; more CTL shear contexts
• Intermittent pitch feed — classic press/punch indexing
• Multi-pitch recipes — different hole groups in one part
• Jog / inch — setup only; never leave production in jog logic

Write the allowed modes into the functional spec so vendors cannot substitute an underspecified feeder that only “moves strip somehow.”

20. OEE Impact

Feeders affect OEE through coil-change thread time, pitch scrap at start-up, and unplanned stops from loop faults. A slower but more stable feeder that never loses registration often beats a faster unit that scrapes every tenth coil. Measure scrap tied to hole position separately from forming scrap so the right module gets the CAPEX.

21. Safety

Feed rolls are in-running nips. Guarding, hold-to-run jog, and lockout for roll cleaning are mandatory. Pilot release dumps air energy—bleed down before reaching into the die area. Loop pits need covers and fall protection where used.

22. RFQ Questions That Separate Real Bids

1. What encoder resolution and closed-loop method are used?
2. What is the proven accuracy on our thickness/yield, not only brochure steel?
3. Is pilot release included, and how is timing taught?
4. What is the roll material/finish for PPGI?
5. Who owns the I/O handshake document with the punch and RF PLC?
6. What spare feed/straightener rolls are recommended for year one?

Bids that cannot answer these are catalogs, not engineered feed packages.

23. Shift Handoff

Handoff must include: active recipe ID, last measured hole pitch, any slip alarms, roll cleaning done/not done, and coil ID. Otherwise the night shift inherits a drifting feeder and blames the mill flower until scrap piles high enough to notice.

Print a one-page “feeder health” card: nip pressure band, straightener dial positions, last calibration date of the length check method, and the escalation phone for controls support. Keep it at the HMI, not in a shared drive nobody opens mid-shift.

24. Myths to Drop

• “More nip always means better accuracy” — over-nip marks coatings and can induce camber
• “The mill will pull pitch true” — mill drive is not a punch indexer
• “Any 3-in-1 fits any press” — height, pass line, and I/O differ
• “Brochure microns equal PPAP capability” — only tryout data counts

Dropping these myths shortens arguments between press techs and roll-form setup crews when hole positions drift.

25. Summary for Specifiers

Specify feeders when pitched punching or shearing demands indexed length. Choose servo/NC accuracy class, straightener needs, and 3-in-1 vs modular layout based on space and HSS. Engineer pilot release and cutoff registration as one system. Clean rolls protect cosmetics as much as chrome forming rolls do.