Notes for owners · Industry playbooks
A sample lot of stamped and formed parts: what to send with it so the buyer signs off
Pressed parts fail sample approval on burr, springback and an undeclared soft tool more than on size, so the lot needs a short note on the tool, the coil and how each pressing feature measured.
The GullySales team · Updated 17 Oct 2026 · 5 min read
On this page
- What a pressed part is checked for that a machined part is not
- Start the note with the tool status
- The note, line by line
- Pieces from the run, not the best five
- Imagine: a press shop in Jigani and a battery tray bracket
- When to send less, or the buyer's own form
- Put the tool status on top of the next note
The box of brackets reaches incoming inspection with a delivery challan and nothing else. The quality engineer measures three pieces, finds the burr on the wrong side, and puts the lot on hold until someone explains. A sample lot of pressed parts gets signed off faster with a one-page note in the box. It says which tool made the parts, which coil they came from, how the pressing features measured, and where in the run each tagged piece was struck. Size may not be the problem. Burr, springback and an undeclared soft tool often are.
What a pressed part is checked for that a machined part is not
The general approval pack, a ballooned drawing with a dimensional report in balloon order, is set out in our post on first-article approval. A stamped or formed part adds checks of its own, and the engineer goes looking for them.
Burr comes first: its height, and which face it sits on. A burr facing a cable, a seal or an operator's hand fails even when its height is within limits. Bend angles come next, because springback moves with every coil. Holes pierced before a bend shift when the flange is formed, so their positions are measured after forming, from the datum on the drawing. Flat parts are checked for flatness after blanking. On a deep-drawn cup the engineer looks for wrinkles at the flange, splits at the punch radius and thinning in the wall that nobody can see from outside.
Start the note with the tool status
One line decides how the engineer reads everything below it. Were these parts made on the production die, on a soft tool, or on a mix such as laser-cut blanks formed in the production form tool?
Samples from a soft tool prove the design. They say little about your process. If the production die is not ready, send soft-tool samples by all means. Label them as such, and say when off-tool samples will follow. An approval given on parts the die never made is one you may lose at the first production lot.
The note, line by line
Fill it from the tagged pieces, and put it on top of the box and in the email.
| Line on the note | What to write | Why it matters on a pressed part |
|---|---|---|
| Tool status | Production die, soft tool or mixed; die number and number of stations | Soft-tool samples prove the design, not your process |
| Press and run | Press tonnage, strokes run, speed during the run | A die tried slowly can behave differently at production speed |
| Coil | Grade, measured thickness, supplier, coil or heat number, certificate attached | Thickness at the low end of its tolerance changes springback and burr |
| Grain direction | Bends across or along the rolling direction, where the drawing cares | Tight bends along the grain can crack |
| Burr | Height measured, and the side marked on the drawing | Wrong side fails even within height |
| Bends | Angle on each tagged piece, and how it was measured | Springback moves from coil to coil |
| Holes near bends | Position measured after forming, from the drawing datum | Pierced-then-bent holes drift |
| Deep draws | Wall thickness at the radius on a sectioned piece; wrinkles or splits seen | Thinning is invisible from outside |
| Finish | Plating or coating, with the plater's thickness report | Coating changes hole sizes and threads |
| Observations | Anything out of tolerance or uncertain, with a request for a written deviation | One hidden problem costs trust in the whole report |
Pieces from the run, not the best five
Run the die continuously before you pick samples. Tag pieces from the start, the middle and the end of that run, and write the stroke number on each tag. Five hand-picked pieces from the first minute show the die can make a good part. Pieces from across a run show it keeps making one, which is what the engineer is approving.
For a deep-drawn part, cut one cup in half and send it with the wall thickness marked at the radius and the side wall. Keep matching tagged pieces at your end, so a question about piece M-2 meets M-2's twin.
Imagine: a press shop in Jigani and a battery tray bracket
Imagine a press shop in Jigani, south of Bengaluru, sending 30 samples of a formed battery tray bracket to an electric scooter maker in Hosur. The details are illustrative.
The progressive die was a fortnight from ready, and the buyer wanted parts. So the shop laser-cut the blanks and bent them on a press brake. Every sample measured well, and they were approved. The first production lot from the die failed at the gate. The burr sat on the face towards the battery cable, and two holes beside a bend were 0.3 mm out, because the die pierced them before forming. The scooter line waited while the lot sat on hold, and the shop paid for the freight back and a second delivery.
The owner did not argue with the rejection. He told the quality engineer exactly how the samples had been made. The die was changed so the burr fell on the outer face, and the two holes moved to a station after the bend. A fresh lot went in from a 500-stroke run, tagged at strokes 1, 250 and 500. The first line of the note read "Tool status: production progressive die, six stations". It was approved on that submission. Since then, any part from a soft tool leaves the shop in a box labelled "Design sample: not from production tool".
When to send less, or the buyer's own form
A small buyer taking 200 washers may want only two pieces, the thickness, the bore and outside diameter, and the coil certificate. A full note may be more than they need, so ask.
Automotive and appliance buyers with a formal part approval process have their own forms. Fill theirs, in their order, and use this note as the covering page. Medical device, aerospace and electrical safety buyers work under approval rules that differ by sector and body, and the rules change. Get their document list in writing from their quality team.
Put the tool status on top of the next note
Write the tool status as line one. Tag pieces from across one continuous run, and mark the burr side on the drawing you send back. The rest of the press shop's selling job is on the forging and metal forming page. If you want the note turned into a sales collateral pack for your own press shop, tell us what you need.
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