What a sample is for
A custom grinding sample answers one question: is the geometry you specified the geometry that came off the line? It is a proof step against the drawing, not a product trial and not a favor to be rushed through. Everything downstream leans on it - bulk is produced after sample approval and inspected against the approved sample, so the sample is the one moment where a discrepancy costs days instead of a production run. Treat it with the seriousness of a contract signature, because functionally it is one.
Timing and what arrives
Standard catalog items ship as samples from stock in days. Custom grinding samples typically take about 15 to 25 days after the drawing is agreed - faster for small changes to standard geometry, longer for special profiles, and a few days more when samples are coated, since the batch waits for a coating line slot. How many pieces per specification the sample run covers is stated on the program sheet and confirmed per program; the desk states it before sampling starts, so you know what you will have in hand to measure. The reference table for all of these figures is collected on the MOQ and lead time page.
The approval checklist
Work the sample the way pre-shipment inspection will, because that is the standard bulk will be held to.
| Item | How it is checked | What approval means |
|---|---|---|
| Geometry | Optical measurement of diameter and flute profile against the drawing | The cutting shape matches the sheet, line by line |
| Runout | Indicator check at the cutting edge | Acceptance per the program's agreed basis |
| Coating | Family and appearance against the sheet | The ordered family, evenly applied |
| Marking | Content, position and legibility against artwork | Your mark reads cleanly on the approved shank |
| Box and label | Count, geometry code line, barcode fields | The packing line as specified |
Each row needs the right instrument: optical measurement for geometry, an indicator for runout, eyes and the artwork for marking. Runout deserves its emphasis - it is checked at the cutting edge because that is where it costs tool life and finish, and the acceptance basis is agreed per program and written down rather than assumed. The measurement vocabulary is in the inspection checklist post, and why edge runout matters so much is in the runout note.
Who samples, and with what
You do not need a metrology lab, but you need more than a caliper and good intentions. The realistic kit: an optical comparator or a measuring microscope for diameter and flute profile, a test bar and indicator for the runout check at the cutting edge, good light and a loupe for coating and edge condition, and the artwork file open beside you for the marking check. If none of that exists in-house - common for brand-side buyers - two alternatives work. A local machine shop or metrology lab measures to the drawing for a modest fee, or the desk arranges third-party measurement so both parties read the same report. What is not an alternative is skipping measurement; a sample whose geometry nobody measured is a photograph with metal in it.
The golden sample, and what it locks
When approval is given in writing, the approved sample becomes the reference the rest of the program is checked against - the golden sample. What it locks is specific: the geometry lines as measured, the coating family and appearance, the mark as it reads on the shank, and the box and label as specified. It does not lock a performance result. One tool cutting one workpiece on one machine proves the geometry, not a universal outcome - your speeds, your setup and your material decide that, and the honest framing stays "starting-point reference, adjust to your machine and setup". Keep the golden sample identified and stored; on reorders it is what the next production run is compared with, alongside the versioned sheet.
Common sampling mistakes
Five failures account for most of the value a sample round was meant to create. Approving from photographs - a photo cannot carry a diameter. Measuring with the wrong instrument, so the numbers are noise. Skipping the box and label, which surface as fulfillment errors instead. Reading one good cut as a universal performance verdict. And the quiet one: changing the drawing after approval, which reopens geometry, timing and price at once. The remedy for all five is the same habit the rest of sourcing runs on - measure, record, approve in writing, and freeze the version before bulk starts.
Samples on repeat programs
Reorders do not need a full sample round unless something changed - that is the point of the golden sample and the versioned sheet. A reorder against the archived sheet and the same golden sample reference can run straight to bulk, inspected at pre-shipment as always. A sample round returns when the sheet version changes, when a substrate or coating family changes, or when a trend in the inspection records asks a question. Deciding deliberately which is which keeps sampling meaningful: buyers who demand fresh samples on every reorder pay the sample weeks for reassurance, and buyers who never sample again stop knowing what they are shipping. The middle path - sample on change, inspect on every shipment - is the one the desk recommends.
After approval: bulk and re-check
Bulk typically takes about 30 to 45 days after sample approval, with a coated program adding a few days - all confirmed in writing per program. Pre-shipment inspection then repeats the sample checklist on the production batch: optical geometry measurement, runout at the cutting edge, coating appearance, marking, box and label, with a certificate of conformance and material certificates traveling with the shipment. The full list is on the quality control page. If your range is still being shaped, send the drawing and the open questions through the quote form and the first reply will name the sampling plan, the reference timing and what remains to be confirmed - the sequence from drawing onward is in the custom grinding guide.
Practical checklist
- Expect samples in about 15-25 days for custom grinding, confirmed in writing.
- Measure geometry optically against the drawing, line by line.
- Check runout at the cutting edge against the program's agreed basis.
- Verify coating family, marking content and box labels, not just the cutting shape.
- Approve in writing; the approved sample becomes the bulk reference.
- Store the golden sample identified, for use on reorders.
- Freeze the sheet version before bulk starts - no drawing changes after approval.