Feeder Centerline and Material Pass Line: Two-Axis Setup and Re-alignment Guide
Separate vertical pass line, horizontal centerline and feeder angleโthen verify the complete coil path after die or adapter changes.
Correct feeder alignment requires two independent conditions: the strip must enter the die at the approved vertical material pass line, and the feeder must point along the die-defined horizontal centerline without yaw. Raising or lowering the feeder can correct height, but it cannot correct sideways offset or angular misalignment. The final setup must be verified with the actual press, die, strip, guides, feeder, upstream coil equipment and safeguarding.
This guide explains how to separate height, centerline and angle errors; establish a stable die-entry reference; re-align the line after die, subplate or adapter changes; and document evidence for production acceptance or a feeder RFQ.
Material pass line and feeder centerline are different controls
The two terms are often mixed together, but they describe different axes.
| Alignment control | Direction | Reference | Typical adjustment |
|---|---|---|---|
| Material pass line | Vertical | Approved die-entry height or released press passline | Feeder elevation, mounting bracket, support table or approved spacer arrangement |
| Feeder centerline | Horizontal | Die-defined strip centerline, edge datum or asymmetric entry datum | Feeder lateral position, mounting slots, bracket position or die/guide reference |
| Feeder squareness | Angular in plan view | Strip travel direction through the die | Feeder yaw or mounting-face correction |
A line can be at the correct height and still push the strip toward one guide. It can also be horizontally centered but too high, causing the strip to bend down into the die entry. Treat each axis as a separate measurement and change one identified variable at a time.
Start with the die-entry datum, not the feeder frame
The required pass line is defined by the job and die, not by a convenient edge on the feeder housing. Before adjustment, identify the released reference used by the plant, such as:
- a die drawing dimension from the bolster or die shoe;
- an approved gauge point at the die entry;
- a die-set edge or strip support datum;
- a documented press passline combined with the installed subplate or adapter stack;
- a job-specific asymmetric strip edge datum when the material path is intentionally off-center.
Do not assume that the visual center of the die shoe is the strip centerline. Progressive dies may use unequal carrier widths, side scrap, cam space or an intentionally offset entry. Record the actual datum before moving the feeder.
Freeze the exact setup before measuring
Alignment changes when the installed stack or material condition changes. Record the condition that will be approved for production:
- press and die identification;
- bolster, subplate, adapter plate and parallels installed;
- shut height and slide position used by the released setup;
- feeder model, mounting plate and current height/lateral settings;
- strip thickness, width, coil condition and burr direction;
- die-entry guides, stock supports and feeder guides installed;
- straightener exit height, loop condition and any support table;
- current symptoms and the settings that produced them.
The strip should not be used as the only measuring reference. Coil set, sag, loop pull, residual curvature and guide pressure can make a strip appear high, low or sideways even when the rigid equipment references have not moved.
Set the vertical material pass line
Use the measurement method released for the equipment. The sequence should answer four questions.
- Where is the die-entry reference? Establish the approved vertical point or plane at the die entry.
- Where is the feeder exit reference? Use the feeder's documented strip-exit or roll-tangent reference rather than the top of a cover.
- Is the transition supported? Check whether the strip is being lifted or pulled down by a bridge, stock guide, tray or unsupported span.
- Can the approved adjustment range reach the target? Move the feeder only through its designed elevation mechanism or engineered mounting arrangement.
After an elevation change, re-check lateral centerline, feeder level, mounting bolt engagement, cable and hose routing, guarding interfaces and the strip's clearance through the full permitted motion. A height change can disturb other relationships.
Set the horizontal feeder centerline
Horizontal alignment is not simply โequal clearance on both sides.โ The target is the line defined by the die entry and strip progression.
- Mark or measure the approved die centerline or edge datum at two separated points.
- Establish matching feeder exit references appropriate to the model.
- Compare lateral position close to the feeder and again near the die entry.
- Move the feeder or its mounting plate without using guide pressure to force the strip into position.
- Re-tighten the mounting system in the approved sequence and verify that tightening did not pull the feeder sideways.
If the die uses an intentionally offset strip path, record the offset. Do not โcenterโ an asymmetric process to the press opening or feeder housing.
Check yaw, roll and pitchโnot only X and Y position
Two points can share the same nominal centerline while the feeder is still rotated. Feeder yaw makes the strip approach the die at an angle; roll can make one material edge higher; pitch can make the strip climb or descend between feeder and die.
Use separated reference points so that angle becomes visible. A short measurement close to the feeder may not reveal a small angular error that creates a large side displacement at the die. Verify the mounting face, bracket, feeder body and strip-exit geometry according to the machine documentation.
Re-align after die, subplate or adapter changes
Any change to the installed stack can alter one or more interfaces.
| Change | What can move | What to re-check |
|---|---|---|
| Different die | Entry height, strip centerline, guide location and support span | Vertical pass line, lateral datum, yaw, support and pilot entry |
| Added or removed subplate/adapter | Die-entry height and feeder-to-die distance | Feeder elevation, mounting capacity, stock support and guarding |
| Die shifted on bolster | Horizontal centerline and feeder angle | Die datum, feeder lateral position, yaw and clamp clearance |
| Straightener or support adjustment | Upstream exit height, tension and strip angle | Loop, strip support, feeder entry and die-entry behavior |
| Maintenance or feeder removal | Mounting repeatability and cable/hose position | All recorded datums and acceptance checks |
Do not use loose shims, stacked temporary blocks or unapproved fabrication as a substitute for a correctly engineered mounting range. If the required position is outside the feeder or bracket's designed adjustment, the mounting solution needs an engineering review.
Treat the upstream coil line as part of the alignment
The feeder can be correctly located relative to the die while upstream equipment still pulls the strip out of line. Check the complete path from decoiler through straightener, loop and feeder.
- A loop that is too tight can pull backward or sideways on the feeder.
- A straightener exit that is too high or low can tilt the strip at the feeder entrance.
- A coil that is not centered can create persistent edge tracking pressure.
- Excess residual curvature can make the strip touch a guide or support intermittently.
- A support table can introduce drag or a new height reference if it is not aligned.
The feeder should index material; guides should not be used to bend a misaligned strip path into the die.
Route symptoms to the correct variable
| Symptom | Plausible alignment cause | Check before moving the feeder |
|---|---|---|
| Strip buckles before the die | Pass line too high/low, unsupported span, loop pull or residual coil set | Die-entry reference, support, straightener exit and loop condition |
| One edge rubs a guide | Lateral offset, feeder yaw, guide over-constraint or burr/coil shape | Die datum, two-point centerline, guide clearance and strip condition |
| Feed is repeatable but parts shift sideways | Centerline or die-guiding relationship is wrong | Feeder/die datum, pilot condition, die clamps and lateral movement |
| Setup works without coil tension but fails in production | Upstream line is pulling or lifting the strip | Decoiler centering, loop, straightener exit and support drag |
| Strip rises or dives at die entry | Vertical mismatch, feeder pitch angle or support transition | Feeder exit reference, die-entry height and bridge/support geometry |
| Alignment changes after bolts are tightened | Mounting face is uneven or tightening moves the bracket | Mounting surface, bolt sequence, bracket stiffness and measured position |
Do not keep changing feeder height until a symptom disappears. That can hide a horizontal, angular, die, guide or upstream-tension problem. The site's thin strip buckling guide provides a separate routing path for material that rises or collapses before the die.
Verify in controlled stages
After static alignment is recorded, verification should proceed under the site's approved setup process.
- Confirm all mounting, clamps, guides, supports and guarding are in the released condition.
- Hand-thread or load material only under the approved safe method.
- Observe the strip path with the line stopped and with tension sources identified.
- Complete controlled inch or single-stroke cycles using a safeguarded observation method.
- Confirm the feeder does not force the strip sideways and the die entry does not lift or depress it abnormally.
- Check pilot entry and feeder release behavior where the die uses pilots. Use the separate pilot release timing guide for the handoff window.
- Measure feed pitch and stamped features over consecutive parts. The feed pitch accuracy guide explains cumulative and repeating error patterns.
- Increase speed only at approved hold points and repeat the evidence checks.
Acceptance should record the die and material, installed plate stack, vertical datum, horizontal datum or offset, mounting settings, speed stages, measured part results and any abnormal strip behavior.
North American RFQ checklist for alignment and rework
For a new NC servo feeder, mounting bracket, die change or retrofit review, provide enough data to define both axes.
| RFQ field | Information to provide |
|---|---|
| Press | Manufacturer/model, bolster dimensions, feed direction, available mounting face and guarding limits |
| Die | Die ID, entry height, horizontal strip datum/offset, die width, shut height and installed plate stack |
| Material | Grade, thickness, width, coil ID/OD, coil weight, burr and surface restrictions |
| Feeder | Model, roll center/exit reference, adjustment ranges, mounting pattern and current position |
| Upstream line | Decoiler/straightener models, exit height, loop arrangement, support tables and line speed |
| Production duty | Feed pitch, target SPM, pilot use, tolerance, part/die progression and recipe count |
| Evidence | Side, front and plan-view photos; drawings; current measurements; symptoms; sample part results |
| Acceptance | Required datums, measurement method, speed stages, sample quantity and documentation |
Clear photographs help establish equipment relationships, but they cannot prove an exact pass-line dimension by themselves. Include a scale, drawing or measured datum where dimensional review is required.
Frequently asked questions
Is material pass line the same as feeder centerline?
No. Pass line normally describes the vertical strip height. Feeder centerline describes the horizontal path toward the die. Both must match the die-defined reference.
Can I align the feeder by looking at the strip edges?
Visual checks are useful for screening, but coil set, loop pull, burr, guide pressure and an asymmetric strip layout can mislead the observation. Use released equipment and die datums.
Does a thicker adapter plate require feeder adjustment?
Usually the die-entry height changes when the installed plate stack changes. Recalculate or measure the new pass line, then re-check horizontal centerline, support, mounting capacity and guarding.
Why does the strip still run to one side after the height is correct?
The feeder may be laterally offset or yawed, the guides may be forcing the material, the die may have moved, or upstream coil equipment may be pulling sideways. Height correction alone cannot solve these conditions.
Should feeder guides pull the strip into the die centerline?
No. Guides should control the approved path without forcing a misaligned strip into position. Correct the equipment relationship first, then set guide clearance according to the job.
What should HENLI receive for an alignment review?
Send press, die and feeder models; die-entry and strip datums; material and speed requirements; installed plate stack; upstream equipment; side/front/plan photos; current measurements; symptoms and acceptance criteria.
Need Help Defining the Feeder-to-Die Alignment?
Provide the press, die and feeder information above together with measured pass-line and centerline references. HENLI can review the feeder mounting range, strip path, upstream interfaces and the evidence needed for a new installation or retrofit. Final settings must still be verified on the actual safeguarded production line.
