What a tube's ‘zero tail’ means and when it is genuinely achievable ART-175

Start with an exact definition

Add a separate line to the RFQ: “Definition of tail remnant.” Ask the supplier to show in a diagram the two planes between which the remnant is measured, at what point in the cycle, in which mode, and what physically happens to the final fragment. The terms `zero tail`, `zero scrap`, `no remnant`, and `minimum scrap` cannot be treated as interchangeable without that explanation.

A sound definition should answer at least six questions:

• whether it concerns only the rear end of the loaded bar;
• whether the front process cut is included in the measure;
• whether the last part may have a contour at the very end;
• for which sections, weights, and wall thicknesses the mode is available;
• whether manual intervention, repositioning, or a special sequence is required;
• whether the agreed accuracy, edge quality, and safety are retained.

For the LT14 FIBER, BLM GROUP expressly describes its own “zero scrap” mode: three spindles support the profile, and the tail carriage disengages so that the head can process the end of the bar. This is an important primary example of a real technology. But it proves the function only for that platform under the manufacturer's stated conditions. It cannot be transferred to another model, another number of chucks, or every profile.

Five different types of loss

To avoid arguing about a single word, split the material balance into separate categories.

1. Front allowance. The part of the bar removed to form the datum end or bypass a damaged area. 2. Tail remnant. The length that cannot be turned into an accepted part because of clamping, support, collisions, or travel limits. 3. Process losses. Kerf width, cut-out holes, slots, slag, process tabs, and local cut-offs. 4. Changeover or setup material. Trial contours, process verification, the first part after a profile change, and material used for measurement. 5. Rejected result. Parts that did not meet geometry, edge quality, surface, or traceability requirements.

A reusable remnant is worth tracking as a sixth category. A short remnant is not always scrap: it can be identified, returned to stock, and used in another order if the machine can load it safely and ERP and CAM retain the material, heat, and actual length. ART-177 separately explains why the minimum loadable length matters to that strategy.

Why the last part is more difficult than the preceding ones

At the beginning of a bar, the chucks and supports have enough material to hold. At the end of the cycle, available length decreases, while the last part must remain controllable, avoid a collision with the head, and be received after separation. In different architectures, a machine may regrip the profile, move the chucks, pass the head between them, or change the processing side.

The ability to make a straight cut near the end does not yet prove the ability to make a complex final part. A hole, slot, bevel, angled end, or contour on several faces may need a different orientation and clearance. An open section, thin wall, or distorted bar adds a risk of displacement. A heavy part may be technically reachable by the head but unsupported after the final cut.

That is why zero tail is verified on the drawing, not on an abstract straight cut. The technical response should mark the working chucks, head zone, supports, last-part position, and its exit route.

When “zero” can actually be achievable

The mode has practical meaning when the specific configuration can process the full required bar length without unsafe improvisation, and the last part remains accepted against the agreed criteria. It normally requires a matched set of conditions: a supported section and weight, permitted part length, compatible contour, correct sequence, sufficient support, standard programming, and manufacturer-intended clamping movement.

Even then, the statement should be narrow: “For test part X in profile Y in configuration Z, no tail remnant remains after the cycle is completed.” That is much stronger and more honest than the general claim that “the machine works without waste.”

If the final part does not fit into the remaining length, zero-tail mechanics do not create material. CAM can change the nesting, use another order, or leave a reusable remnant. Where there is no matching demand, the mathematical remainder still becomes scrap even though the mechanical tail has been eliminated.

When a non-zero result remains

The limit may arise not from a weak machine, but from the part requirement. A margin is needed for stable clamping; the contour enters a prohibited zone; a support does not work with a particular open section; the tail part is too short for controlled unloading; the surface cannot tolerate contact; the last cut changes the centre of mass; or a bevel is inaccessible in the end position.

Nor should zero tail be planned through manually pulling the bar, bypassing guarding, or intervening in the automatic cycle. ISO 12100 provides a general framework for risk assessment and reduction, but the actions actually permitted are determined by OEM instructions and the local assessment of the particular process. If achieving the figure requires an operator to take an unanticipated action near moving assemblies, that is not a machine function but an unsafe nonconformity.

Build a material balance

For every order, record the purchased length of all bars, the total net length of accepted parts, front trim, tail remnant, process loss, reusable remnants, and rejected output. Do not mix mass and length without allowing for the profile: for economics, it is more useful to convert each category into kilograms and money for the specific material lot.

The basic control equation is simple:

`Purchased material = accepted parts + reusable remnants + process losses + rejects + unidentified variance`.

The last category should tend to zero. It exposes accounting errors, uncounted front trim, lost remnants, or incorrect CAM data. This balance shows the economic effect, not a striking shot of the last cut.

Compare configurations on the same order portfolio. If machine A leaves a short tail but processes every profile quickly and reliably, while machine B has a model-specific zero-tail mode only for part of the range, one catalogue parameter does not determine the winner. Include accepted output, changeover time, remnant reuse, reject risk, and operator work.

Supplier data to request

Require an applicability table in the enquiry. Rows should be your representative profiles and parts; columns should be section type, size, wall, linear mass, bar length, last part, contour type, chucks, supports, software option, expected tail, and unloading method.

Also ask the supplier to state:

• whether the function is part of the base supply or requires an option;
• whether it works in automatic and manual loading;
• which profiles are excluded;
• whether productivity or sequence changes;
• how the actual remnant is recorded;
• what happens on a stop or cycle recovery near the end of a bar;
• whether CAM supports planning the last part without manual editing.

Do not accept a video of another model as evidence. It may explain a principle, but contractual evidence must concern the offered machine, its revision, and its options.

Full-bar acceptance test

A short demonstration offcut does not reproduce the complete material flow. Verification requires a full purchased format, or an agreed equivalent, from which the machine sequentially makes a batch and completes the last part. Before the test, record the actual length, end condition, straightness, material, profile, program, and quality criteria.

During the cycle, record front trim, every accepted product, process offcuts, the actual tail, and every operator action. After completion, weigh or measure the material-balance categories. Inspect the last part in the same way as a middle one: geometry, edge, contour positions, deformation, and surface cannot be given a relaxed criterion just to achieve zero.

Run at least scenarios with a typical profile, the most difficult strategic section, a short last part, and a contour near the tail. If the manufacturer claims operation with open profiles or bevels, test those separately; one round tube does not confirm the whole range.

Verify stability rather than a single success

One cycle can be manually prepared by the best technologist. For a production decision, what matters is whether the result repeats after a change of lot, diameter, thickness, and operator. Repeat the scenario, perform a normal changeover, and check whether the mode is selected and logged automatically.

If zero tail increases the time of the last part, compare the value of saved metal with the additional machine time. For an expensive profile, even a slow end cycle can pay off. For inexpensive high-volume material, a long complex sequence can sometimes lose to a stable minimum tail. Economics are determined by the portfolio, not by a principled pursuit of absolute zero.

Also assess availability. Extra movements, regripping, or options create their own maintenance points. That is not an argument against the technology, but service work, spare parts, and the recovery procedure must be included in TCO.

Specification wording

Instead of “zero tail is mandatory,” write a measurable criterion. For example: “On the agreed profile and program, the machine shall make all specified parts from a full blank; the maximum non-usable rear remnant shall be the value confirmed in FAT; the last part shall meet the same quality criteria; no non-standard manual intervention shall occur.”

If zero is confirmed only for some scenarios, create a matrix: `ZERO`, `MINIMUM CONFIRMED`, `REUSABLE REMNANT`, `NOT DEMONSTRATED`, `OUT OF RANGE`. For each status, retain the configuration, condition, and evidence. This gives the procurement team a real picture and technologists planning rules.

The central conclusion is that “zero tail” is a valuable model-specific function when it turns a formerly clamped length into an accepted part without losing quality or control. But zero tail is not equal to zero total waste. The decision should be made from the material balance of the complete order, confirmed on your own product mix.

Example verification on a family of parts

Imagine not a single part, but a typical frame set: two long side members, four cross-members, and several short brackets from one rectangular profile. If CAM nests the set so that, after the last cross-member, a length shorter than a bracket remains, zero-tail mode may remove the mechanical tail but will not increase the number of accepted parts. A different sequence or combining two orders may use the length better.

Perform three calculations: without order optimisation, with grouping of like profiles, and with permitted mixing of sets within traceability limits. For each, show the number of full bars, accepted parts, reusable remnants, tail, process loss, and time. Then it will be clear what share of the effect comes from machine mechanics and what share comes from planning.

Do not allow the optimiser to silently violate set completeness or due date. If better yield moves parts of an urgent assembly to a future bar, material savings can create a delay. The measure must account for accepted kits on time, not only the percentage of length used.

Separate FAT from production observation

FAT or a demonstration confirms technical capability on the agreed configuration. It does not guarantee that annual material yield will be the same. After commissioning, establish a thirty- or sixty-day baseline: actual tail by profile, the share of reused remnants, write-off reasons, rejected output, and the last-cycle time.

If actual losses are higher than in the test, first separate the causes: another mix, inaccurate stock lengths, lack of orders to combine, an unused software function, profile limitations, raw-material instability, or operating discipline. Do not revise the hardware conclusion without that decomposition.

A useful KPI is not the number of cycles labelled `zero scrap`, but the cost of unusable material per tonne of accepted output. Alongside it, show the share of remnants labelled reusable that never returned to production. Otherwise, the warehouse visibly accumulates “valuable metal” that has already become waste economically.

Questions that expose a weak promise

Ask the supplier to answer in writing: whether zero is achieved for a straight end or all contours; whether the result is the same for round, square, rectangular, and open profiles; what changes with a bevel; how the last part is handled after an emergency stop; whether the mode is available with every loader; which software options are required; and how the limitation is shown in programming.

A strong answer contains a configuration code, drawing, or video test of the specific model, a list of conditions, and a measurable acceptance criterion. A weak answer repeats the feature name, shows another machine, or gives the smallest catalogue tail without a part and profile. Mark such an answer `NOT VERIFIED`; do not supplement it with buyer assumptions.

In the contract, separate a guaranteed result from an optimisation objective. If zero tail is confirmed on reference parts, those parts and conditions become the acceptance set. For the rest of the range, record a verification method and status without promising the unknown.

Make the final decision from a repeatable material balance, last-part quality, cycle time, and exception rules. If even one element is unverified, the correct status is conditional capability, not a confirmed zero remnant for the entire production range.

Allow for measurement error

When the claimed tail is tens of millimetres, the measurement method can change the conclusion. An uneven or angled end, burr, distortion, and temperature affect the reference point. Before FAT, agree the measuring instrument, datum, units, rounding, part condition, and rule for an uneven edge. An operator must not select the shortest point simply because it looks better in the report.

For the material balance, length is insufficient when profiles of different mass are compared. Also record the mass of the unusable remnant or calculate it from agreed data. Assess cost at the actual purchase price and remnant status. A short piece of expensive alloy may matter more than a longer offcut of a commodity profile.

Repeatability is better shown by a distribution than by one minimum. Record the median, the worst acceptable result, and reasons for exceptions across a series of bars. If one attempt achieved zero but others required a substantial allowance, the function has not demonstrated a stable outcome.

Agree the behaviour with a partial bar

Production often uses a remnant, not only new full blanks. Ask separately how the system identifies the actual length, establishes the available clamping zone, checks the loader minimum, and plans the final part. Do not assume that the zero-tail mode for a full bar automatically works for a short remnant.

If a remnant is fed through another channel, its cycle should be counted separately: finding, identification, feeding, measuring, programming, recutting, and returning the unused part. The function must create an acceptable economic result, not merely make a cut technically possible.

After an emergency stop near the end of a bar, recovery is performed only under the standard OEM procedure. In a procurement test, it is sufficient to verify the defined safe state, preservation of identity, and the result after permitted recovery; an unsafe demonstration or bypass of safeguards should not be requested.

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