Kaeri Nashi and Burr-Free Notes: What Japanese Drawings Ask a Shop to Do

Drawings / 6 Oct 2026

Hand holding a small machined metal part with fine machining swarf beside it, burr removal at the bench

“No burrs” is the most common instruction on any machined part drawing and it is the one with the least agreed meaning. A Japanese drawing says it three ways. A small note in Japanese: カエリなし (kaeri nashi) or バリなし (bari nashi). A blanket note near the title block: バリ取りのこと, deburr. Or the JIS edge symbol, a small drawing of the edge with a number. All three ask for the same outcome, which is that the part can be handled and assembled without raised metal on any edge. How clean that has to be, and how the shop proves it, is where parts get rejected.

Diagram: Burr-Free Notes on Japanese Drawings: Kaeri Nashi Explained

This guide sets out what each wording asks for, how shops remove stainless burrs and what a buyer can verify on arrival.

Three words, one instruction, three levels of care

Kaeri (返り) means the lip of metal that folds back over an edge when a tool leaves the cut. Bari (バリ) is the general word for a burr or flash. Kaeri nashi and bari nashi both mean there are none.

This is a different instruction from an edge break. Itomen and C chamfers, covered in the itomen guide, tell the shop to cut the corner. Burr free tells the shop that no metal may stand above the edge. A sharp, square edge with no burr satisfies kaeri nashi. A broken edge with a burr on it does not. When a drawing carries both notes, the shop does both jobs. When it carries only one, the quote should say which is covered.

The JIS edge symbol

For critical edges, a drawing can replace the note with the edge symbol from JIS B 0051, which is based on ISO 13715. The symbol is a small outline of the edge drawn in the corner, with a number. The sign matters:

A plus value allows a burr up to that size above the edge.
A minus value allows an undercut or break up to that size below the edge line.
No value on the symbol means the limit is not stated, and the shop should ask before choosing one.

Two edges on the same part can have different symbols, so a bearing seat can be held to a small plus value while a handling edge nearby carries a minus value. If the drawing has the symbol and the shop works from the general note, the shop has ignored the stricter instruction. That is a reason to tell the buyer’s engineer where each edge sits when the quote is prepared. The exact values come from the drawing, and the symbol should be read against the standard it cites.

How much burr is too much

Neither the note nor the symbol gives a measure unless a value is written. Practice fills the gap with tests rather than numbers.

Test	What it detects	How strict
Fingernail drag across the edge	Raised burr about 0.05 mm or more	Common first article check
Visual at 10x magnification	Raised burr about 0.02 mm	Medical, sealing and food parts
Cloth or cotton pull	Loose fibres that catch on a thin burr	Clean assembly work
Optical comparator or microscope	Burr height as a measured number	When a value is written
Borescope in a bore	Burrs at cross holes	Hidden intersections

The numbers in the table are common practice and not part of the standard. A buyer who needs a measured limit should give one in microns and name the test, so the shop and the inspector use the same method.

How shops remove burrs from stainless

Stainless needs more deburring effort than carbon steel for the reasons set out in the itomen guide: the burr is tough and rolled and it work hardens. The methods are chosen by access and volume.

Method	Reaches	Suits	Watch for
Chamfer or deburr cut in the CNC program	Outer edges and bore mouths	Every production part	Needs the tool path and tool in the program
Back-chamfer or cross-hole deburring tool	Hole intersections	Manifolds, fittings	Wear on the cutter, tool length
Hand file, stone or scraper	Anything within reach	Prototypes, odd edges	Varies by operator
Abrasive nylon brush	Open edges	Light burrs	Do not use a plain steel brush on stainless
Vibratory or barrel finishing	Whole part, external	Small parts in volume	Part to part knocks, size change
Abrasive flow	Inside passages	Complex internal channels	Cost, tooling
Thermal energy method	Hidden burrs	High value manifold work	Equipment and setup cost
Electropolishing	Micro burrs	Clean and food parts	Removes a few microns, removes only small burrs

One rule is worth marking. A carbon steel brush on stainless deposits iron on the surface, and the iron rusts. This is the most common way a finished stainless part develops orange spots after it leaves the shop. Brushes and abrasives for stainless should be used for stainless only, and the passivation article covers how to remove embedded iron if it has happened.

What a burr does after delivery

A burr is not cosmetic. It has three ways of causing a failure, and the failure usually shows up at the customer, not in the shop.

It changes the fit. A burr on a shaft shoulder lifts the mating part off its seat by the height of the burr. At a few hundredths of a millimetre that is enough to put a bearing out of square, and the fit guide shows how little clearance a precision fit has to spare.

It breaks loose. Tool marks and rolled burrs flake off under vibration, thermal cycling or the first wash cycle. A flake the size of a grain of sand is enough to score a sealing face or jam a small valve.

It carries the corrosion problem. The root of a rolled burr on stainless is a crevice. Moisture and chlorides sit in it. On a part for a wet or salty environment, a burr left on an edge is a place where corrosion starts, even on a grade that would normally resist it.

The same logic is why a drawing for a pump, valve or food contact part reads the burr-free note strictly, while a decorative cover plate does not.

Burr free and surface finish are separate calls

Buyers sometimes expect that asking for a fine surface finish also asks for burr-free edges. It does not. A face finished to Ra 0.8 can still carry a burr at its boundary, because finish describes the flat of the surface and the burr sits on the edge. The two instructions are written in separate places on the drawing and checked in separate ways. For finish symbols, see the surface finish guide.

The same applies to sequence. If the part is to be ground or lapped after machining, the burr must come off before, because a burr in a grinding fixture marks the face. If the part is to be passivated or electropolished, deburring comes before that step. Mentioning the finishing route in the quote request lets the engineer plan the order of operations so the edge work happens at the right time.

Where kaeri nashi is read most strictly

The note goes onto almost every Japanese drawing, but a few part types treat it as a hard requirement:

Sealing parts. A burr on a sealing edge cuts an O-ring or keeps a gasket from seating.
Fluid and food parts. A loose burr ends up in the product. For food equipment, see the food machinery guide.
Press and slip fits. A burr on a bore mouth shaves metal off the pin as it goes in.
Moving assemblies. A burr that breaks off in a bearing or a slide can seize it.
Medical and clean parts. Particles are a quality failure by themselves.

On a bracket or a cover plate, the same words mean something looser, and a shop that treats them the same on both is either over-deburring or under-deburring. Saying what the part does in the quote request avoids that.

Checking burr-free on delivery

An engineer follows every order and inspects edges before the parts are packed. A buyer receiving the parts can run three quick checks without any special equipment:

Run a fingernail along every edge of three or four sample pieces. A burr catches.
Look at hole mouths and cross hole intersections with a loupe or a phone camera in macro mode, with a torch held at a low angle.
Wipe the part with a lint-free cloth and look for fibres left on the edges.

Photographs of the edges on the first article, sent with the inspection report, are usually enough to approve the standard before the batch is made.

How to write it so it is clear

State the default: “all edges burr free, edge break 0.2 mm max” covers most parts.
Call out the exceptions with the JIS B 0051 symbol: sealing edges, press fit lead-ins, knife edges.
Name the test: fingernail, 10x or a measured limit.
Say whether internal intersections are included.
Say when the deburring happens relative to passivation or polishing.

If your drawing has only the Japanese note, send it for a quote. The engineer reads the note, asks about the edges that need a stricter standard, and puts the confirmed instruction on the order. The quality page describes what the inspection before packing covers, and the drawing checklist lists other items to confirm.

Questions

What is the difference between kaeri and bari?

Both mean burr. Kaeri, written with the character for return, usually points at the rolled-over lip of metal left on an edge. Bari is the general word for any burr or flash. On a drawing the two are treated as the same instruction: no burrs.

Does burr free mean the edge must be chamfered?

No. Burr free means no raised or loose metal on the edge. The corner itself can stay sharp unless the drawing also gives an edge break note such as itomen or a C chamfer.

What is the JIS B 0051 edge symbol?

It is the JIS edge-condition symbol, based on ISO 13715. It draws the edge shape and gives a value, where a plus sign allows a burr up to that size and a minus sign allows an undercut or break of that size. Read the values from the drawing itself.

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