---
title: "Validating Mini-Tuber Grade Boundaries and Lot Changes"
url: https://www.spudmate.com/zh_cn/mini-tuber-grading-lot-change-validation/
description: "A size grade is only useful when its boundary is measurable and its lot identity survives handling. This guide explains how to select five or six outputs,…"
published: 2026-10-15
updated: 2026-10-08
author: "xtlaigc"
site: "Tianjin Goldilocks Co., Ltd."
---

# Validating Mini-Tuber Grade Boundaries and Lot Changes

## Key takeaways

- Define physical size boundaries and exact-boundary assignment before selecting outputs.
- Use both boundary reference groups and representative natural-lot samples.
- Treat lot clearance as a separate acceptance check from grade separation.
- Link each output container to its lot, grade definition and run segment.

## Treat grade accuracy and lot identity as separate acceptance problems

A mini-tuber batch can appear neatly separated while still failing the buyer’s requirements. One problem is physical classification: material close to a boundary may enter an adjacent output. The other is lot identity: a small quantity left from the previous batch may join the next batch. These failures need different evidence. Measuring output samples evaluates grade separation; checking residual material and container records evaluates batch control. Neither result substitutes for the other.

Before selecting equipment, write two acceptance statements. The first should define the size categories and how output samples will be judged. The second should define how the previous lot is closed, how residual material is handled and when the next lot may start. Keep biological seed certification separate from both. A screen-based size grade does not establish disease absence, germination performance or certification status, and a complete lot record does not establish those properties either.

## Understand what screen separation measures—and what it does not

The [Mini-tuber sorting machine](https://www.spudmate.com/products/mini-tuber-sorting-machine/) uses chain drive and vibrating screens. Different screen openings guide each size to a corresponding discharge belt and semi-automatic bagging machine. The engineering principle is physical passage through an opening: a tuber must encounter that opening in an orientation that permits passage. Consequently, the opening dimension and the buyer’s measurement definition must be evaluated together rather than treated as automatically equivalent.

An elongated tuber may behave differently from a round tuber with the same measured width. Presentation, contact with other tubers and opportunities to meet the screen can also affect separation during a trial. These are reasons to test representative material, not claims about quantified machine precision. Vibrating-screen grading is designed to reduce skin damage, but that design intent is not a guarantee of damage-free handling. Assess visible condition separately from size classification and document the inspection method.

[![Mini-tuber grading machine with its long screen assembly, discharge sections and red support frame.](https://www.spudmate.com/wp-content/uploads/2026/10/spudmate-mini-tuber-sorting-machine-1024x512.jpg)](https://www.spudmate.com/products/mini-tuber-sorting-machine/)

Mini-tuber sorting machine, Five-grade / six-grade: physical size grading and bagging.

## Turn buyer size categories into a reproducible boundary rule

Start with the buyer’s actual grading definition. Specify whether size means a measured width, a defined gauge-passage result or another agreed physical measurement. State how tubers are oriented during measurement and how a reading exactly on the boundary is assigned. A written interval rule prevents two inspectors from putting the same tuber into different reference grades. Do not substitute weight for a dimensional category unless the buyer explicitly requires weight-based classification.

For example, in a **hypothetical** agreement, a boundary could belong to the larger interval, with all readings below it assigned to the smaller interval. The numerical boundaries would still come from the buyer, not from this example. Make a reference set containing clearly classified tubers and tubers immediately around each boundary. Measure them consistently and retain their identifiers for the trial. The reference set tests difficult decisions; it should supplement, not replace, sampling of the natural lot.

## Choose five or six grades from required destinations

Choose the output count by mapping each required size category to a destination. Include material outside the buyer’s preferred range in that mapping rather than silently merging it into a saleable category. Five grades may suit a specification with fewer separate destinations; six may be appropriate when another size interval must remain distinct. An extra grade does not, by itself, establish sharper separation at a boundary. The required openings and demonstrated output distribution remain the deciding evidence.

The configuration comparison below gives the published dimensions and electrical figures without predicting production rate. Use the dimensions to start a site review, then allow separately for access, containers and bag handling; machine dimensions are not a complete working-area requirement. The [crop-handling solutions overview](https://www.spudmate.com/#solutions) can help frame the wider process discussion. Treat every additional output as another stream that must be sampled, identified and closed correctly during a lot change.

| Parameter | Five-grade | Six-grade | Meaning for selection |
| --- | --- | --- | --- |
| Grade configuration | Five-grade | Six-grade | Select according to the number of required separate size categories. |
| Dimensions | 7900 × 1620 × 1500 mm | 9300 × 1620 × 1500 mm | The six-grade configuration is longer; the listed width and height are the same. |
| Power | 2.85 kW five-grade | 3.5 kW six-grade | The published power differs between configurations. |
| Voltage | 220 V | 220 V | The published voltage is the same for both configurations. |

## Test boundary behavior with both challenge and natural-lot samples

Run two complementary sampling exercises. First, pass the measured reference material through the selected configuration and record where each boundary group emerges. Keep introduced groups identifiable by controlled, separated trial runs rather than assuming an automatic tracking function. Second, run representative lot material under the proposed operating conditions. Take samples from every discharge at the beginning, middle and end of the trial so that a single favorable collection does not become the entire acceptance record.

For each output, record the total examined and the counts assigned by the agreed reference measurement to each grade. Separate borderline disagreements from material clearly outside the intended interval. Record sample sizes, feeding conditions and any changes between runs; otherwise, results from different settings cannot be compared fairly. Agree allowable misclassification and the treatment of borderline readings before testing. Use the diagnostic matrix below to select the next investigation, not to infer a universal accuracy limit or a production-rate claim.

| Observation | Evidence to collect | Next check | Release decision |
| --- | --- | --- | --- |
| Reference measurements disagree between inspectors | Repeated readings of the same identified tubers using the written method | Measurement orientation, gauge method and exact-boundary assignment | Resolve the reference rule before judging machine separation. |
| Disagreements cluster near one boundary | Measured size distribution from both adjacent outputs | Opening identification and behavior of the boundary reference group | Compare results with the pre-agreed boundary acceptance rule. |
| Clearly out-of-grade material appears in an output | Output identity, reference measurements and trial conditions | Screen condition, opening identification and discharge routing | Hold the affected trial output pending investigation and retest. |
| Output distribution changes during the run | Beginning, middle and end samples with feeding observations | Incoming size distribution and changes in material presentation | Do not accept from one favorable sample alone. |
| Previous-lot material is found after changeover | Recovery location, quantity and clearance record | Retention points, container exchange and release authorization | Hold potentially affected new-lot output and determine disposition. |

## Clear the material path before releasing the next lot

At a lot change, the last bag is not necessarily the last material from that batch. Residual tubers may remain along the grading and discharge path or in collection containers. Stop introducing the old lot, segregate material still leaving the process and inspect accessible retention points using the approved site procedure. Where access requires isolation, follow the applicable machine instructions and site isolation procedure. Do not reach into moving equipment to speed up clearance.

Define the destination of recovered material before starting the changeover. It may remain associated with the old lot or be held separately for an agreed disposition; it should not silently become part of the new lot. If clearance cannot be demonstrated, hold the affected output and investigate rather than relabeling it as unmixed. The [seed-potato handling sequence guide](https://www.spudmate.com/seed-potato-handling-equipment-sequence/) provides context for identifying upstream and downstream hand-offs that also need a lot boundary.

- Close the old lot's input record and stop further additions.
- Identify every active bag, collection container and residual-material container.
- Allow remaining material to discharge under the approved procedure, keeping it separate from the new lot.
- Inspect accessible screen, transfer, discharge and bagging areas after any required isolation.
- Record recovered material and its destination; investigate unexplained leftovers.
- Remove old lot labels and reconcile full, partial and empty containers.
- Record the clearance check and authorize introduction of the new lot.
- Hold the first new-lot outputs for boundary and identity checks before release.

## Build a record that connects each container to the grading decision

A useful lot record links the incoming identity, the grade definition and the physical output containers. Include the lot identifier, configuration used, screen-opening identification, specification revision, run times and operator. Assign each output a clear grade label and record container identifiers, quantities and any held or reworked material. State the quantity basis consistently: count and mass are not interchangeable totals without an established conversion. This is an operating record to implement, not a claim of built-in software traceability.

Attach the boundary-sampling results and changeover clearance record to the same lot entry. If settings, openings or grade definitions change within a batch, create a distinct run segment so that earlier output is not attributed to the later arrangement. Reconcile incoming and outgoing quantities on the chosen basis, recording samples and recovered material separately. Investigate unexplained differences; reconciliation supports the audit trail but does not independently prove the absence of carryover.

1. Batch
2. Boundary check
3. Graded outputs
4. Lot record

Conceptual validation workflow for mini-tuber grading and lot identity; not a machine layout or scale drawing.

## Accept a defined operating case, not an unlimited promise

Complete acceptance only after demonstrating both grade separation and the agreed changeover procedure. The signed record should state the tested crop characteristics, physical boundary rules, configuration, feeding conditions, sampling plan and release criteria. Include the observed output distribution and visible-condition observations without converting them into an unsupported general guarantee. Retain exceptions and corrective actions alongside accepted results so the operating team knows which conditions were actually demonstrated.

Repeat the relevant checks when crop shape, size distribution, grading definitions or operating conditions materially change. A successful trial on one lot does not automatically validate every later lot. For planning short runs, the [small-batch potato grading guide](https://www.spudmate.com/small-batch-potato-grading-3-10-tph/) offers related operating context, but its topic must not be used as a throughput rating for this sorter. We recommend choosing the configuration around verified category needs and commissioning it against explicit, project-specific acceptance criteria.

## Plan a mini-tuber grading and lot-change trial

Send representative crop samples, including tubers near each proposed boundary, to support a project-specific review. Use our [mini-tuber grading project contact form](https://www.spudmate.com/#contact) to share the buyer’s size intervals and measurement method, required output categories, incoming size and shape distribution, lot sizes, target operating rate, available floor space, electrical supply, container method, carryover requirements and proposed acceptance limits.