Key takeaways
- A laser-cut 3 mm CRCA part typically leaves 30–80 µm of dross burr, and hand deburring at about 25 s per metre costs 38 s on a 1.5 m perimeter part.
- Linishing overtakes manual deburring after roughly 35 parts of 1.5 m perimeter once 15 minutes of setup is counted.
- Powder on a sharp edge holds only 25–40% of the face film thickness, so a coated part needs R0.3 mm minimum rather than a burr-free knife edge.
- Thermal deburring is the only route into a cross-drilled hole, but it warps any free edge under 1 mm, so it is a design decision, not a finishing one.
- Specify the edge per ISO 13715 with a burr height and a radius; the words deburr all edges produce five different parts from five benches.
A 3 mm CRCA bracket leaving a 12 kW fibre laser carries 30–80 µm of dross on the underside of every cut and a recast skin a few micrometres thick on the cut face. Neither is visible from arm's length. Both decide whether the part passes the paint line, the glove check at assembly and the sliding fit on the customer's jig.
The four deburring methods compared here — manual, tumbling, linishing and thermal — are not interchangeable. Each clears a different burr shape, leaves a different edge radius, and puts a different amount of heat and handling into the part. Picking one because a bench is free is how a 1.2 mm lid ends up oil-canned and a 12 mm plate ships with dross still on it.
The rule that settles most cases: the drawing's edge requirement chooses the method, and part size plus thickness veto the choice.
What burr is actually on the part?
Four burr families reach the deburring bench, and they behave differently under the same tool.
Laser dross is molten metal that was not expelled from the kerf and solidified on the exit face. On mild steel up to about 6 mm on a 12 kW source it is thin and brittle. Past 12 mm it becomes a continuous, hard, oxidised bead that rolls a linishing belt instead of cutting.
Recast on the cut face is 5–50 µm of re-solidified metal. On stainless it is a chromium-depleted skin. It is not a burr, but it is the surface a conversion coat and powder key to, so a part deburred only on the exit face is half-finished.
Shear burr from a press comes out of the fracture zone: roll-over at punch entry, burnish, fracture, burr at exit. Its height tracks die clearance at roughly 10–20% of the clearance value, so 0.15 mm per side on 2 mm CRCA leaves 0.02–0.03 mm — harmless in most assemblies, but visible as a ridge under a 70 µm film.
Weld spatter and heat tint around a fabricated joint fail the same acceptance check: raised, hard, and impossible to coat evenly.
Deburring methods compared: what each one removes and leaves
| Method | Burr it clears | Edge left | Typical cycle | Distortion risk | Ganesh limit or note |
|---|---|---|---|---|---|
| Manual: file, scraper, hand deburring tool | Any, including dross on 12–20 mm plate | 0.1–0.3 mm chamfer, operator-dependent | 20–40 s per metre of edge | None | Edge break recorded at first article; used where access is one-sided |
| Abrasive linishing or belt grinding | Dross, spatter, rolled burr on long edges | R0.2–0.8 mm, consistent along the run | 5–10 s per metre | Medium below 1 mm: belt heat and pressure bow a panel | Long parts are cut on the 40 ft × 16 ft bed and linished before the 200 T brake |
| Tumble or vibratory finishing | Burr up to about 0.3 mm, all faces at once | R0.05–0.2 mm, uniform, edges brightened | 20–45 min per batch | Low, but parts impinge and media lodges in holes | Suits parts that fit the barrel and have no thin free flange |
| Thermal deburring (TEM) | Burrs at cross-drilled intersections and enclosed edges | Corner sharp, burr burned back to the base metal | 20–40 ms in chamber | High on sections under 1 mm; free edges warp | Not run at Ganesh; a part that needs it is redesigned for an accessible edge |
| Electrochemical deburring | Fine burrs on stainless and hardened parts | R0.05–0.15 mm, no mechanical marking | 30–90 s per part | No thermal effect; hydrogen risk on high-strength steel | Not run at Ganesh; a mechanical edge break is specified instead |
The fourth column is where specifications fail. A note reading "deburr all edges" will be executed five different ways across five benches, and none of them will match the sample the buyer approved.
How do you choose between them?
Choose by part size first, then by burr height, then by the edge the coating needs.
- Under 100 parts of any thickness: manual. Setup on a belt or a barrel costs more than the labour.
- Over 500 parts a month, largest dimension under 300 mm, burr under 0.3 mm: tumbling, because every face is treated in one operation and nothing has to be held.
- Any edge longer than 1 m, or dross on 8 mm and above: linishing. A belt follows an edge; a barrel cannot hold a 2,400 mm panel.
- A burr at a cross-hole or an internal 90° intersection: thermal or electrochemical, because no mechanical tool reaches it. If neither is available, the design has to change.
- A visible coated edge: R0.3 mm minimum, because a knife edge cannot hold film.
The manual-to-linishing crossover is worth doing on paper. Lining up a belt, setting the rest and dressing a new belt takes about 15 minutes. At 25 s per metre by hand against 6 s per metre on the belt, the saving is 19 s per metre, so the setup is recovered after 900 seconds divided by 19 seconds per metre — 47 m of edge. On a bracket with a 1.5 m perimeter that is about 32 parts. Below that, the belt is the more expensive route however good the edge looks.
What does a burr cost per part?
Take a 400 × 300 mm enclosure side with four 10 mm holes. The cut perimeter is 2 × (400 + 300) = 1,400 mm, plus 4 × π × 10 = 126 mm, so about 1.53 m. On a 1,000-part release:
- Manual at 25 s per metre is 38 s per part, or 10.6 hours across the batch.
- Linishing at 6 s per metre is 9 s per part, or 2.5 hours, plus 15 minutes of setup.
- Tumbling 150 parts per 30-minute cycle works out at 12 s per part, but the batch waits for a full barrel.
The labour difference between the first two lines is roughly eight hours on a thousand parts, which is a full shift of one operator. That is the number a process engineer needs when a customer asks why the quotation carries an edge-break line at all.
The cost that does not appear on the route card is the downstream one. A burr left on a locating face puts the part 0.1 mm out in a fixture, the fixture is blamed, and the fixture is measured and re-shimmed to compensate for a burr that will fall off in the paint line.
Why does the edge radius matter more than the burr height?
Because the coating fails at the corner, not on the flat.
Powder is applied by electrostatic attraction and then flows in the oven. At a sharp 90° corner the field is concentrated, the film is thin, and the surface tension of the melting powder pulls material away from the edge. Measured on a production part, edge film typically lands at 25–40% of the face value, so a 70 µm face specification can carry 18–28 µm at the corner. At that thickness the edge rusts first, the rust creeps under the film, and the panel fails from the outside in.
An R0.3 mm edge roughly doubles the film at the corner compared with a knife edge and gives the powder something to wrap. That is the engineering reason to spend money on an edge break, and it is a different argument from operator safety, which is served by 0.5 mm.
The same geometry decides gasket performance. A 0.05 mm burr around a bolt hole in a stamped cover defeats a 1 mm compressed gasket, because the burr holds the cover off the face around the hole and the leak path is invisible under torque.
Which method distorts a thin panel?
Linishing distorts thin sheet by heat, not by force. A 1,000 mm long 0.8 mm CRCA panel that picks up 40 °C on one face expands by 0.48 mm relative to the other face at a coefficient of 12 × 10⁻⁶ per kelvin. Restrained by the rest of the panel, that shows as a visible bow. Run the belt in short passes, alternate faces, or back the panel with a support plate.
Thermal deburring distorts by geometry. The chamber reaches 2,500–3,000 °C for 20–40 ms, and the part bulk stays cool, but a free edge 0.5 mm thick has almost no mass to conduct heat away. It heats through, oxidises and warps. Thick parts and enclosed intersections are the good candidates; thin visible flanges are not.
Tumbling does not distort, but it dents. Parts under 1 mm dropping over each other for 30 minutes collect small impact marks, and soft aluminium collects more than steel. Separate loads, reduce the barrel speed, or use a plastic medium for cosmetic faces.
The sequence matters as much as the method. An edge break removes material, so a first-off dimensional report taken before linishing describes a part that no longer exists. Fix the order — cut, deburr, form, inspect — and write it on the route card, or the inspector will pass a part the customer measures out of tolerance.
What does ISO 13715 give the drawing?
ISO 13715 covers edges of undefined shape: it sets how to indicate a burr, an undercut or a passing edge on a technical drawing, and how to dimension the size. It exists because "sharp" and "deburred" are not measurable instructions, and because a part can legitimately need a small burr on one edge and none on another.
The practical use is a drawing note plus a symbol per edge class. State the maximum burr height in millimetres, the radius or chamfer where the edge is visible or coated, and which edges are exempt. ISO 9013 does the same job upstream: it classifies thermal cut quality, including perpendicularity and drag, for laser cuts from 0.5 mm to 32 mm. Referencing a cut quality class on the drawing caps the dross before the deburring discussion starts, which is cheaper than removing it afterwards.
What Ganesh runs for cut and formed parts
Parts are cut on a 12 kW fibre laser with a 40 ft × 16 ft bed, supported by two 6 kW and two 3 kW machines, in mild steel, CRCA, stainless, aluminium, brass and copper up to 20 mm on the laser and 30–40 mm on the iron worker for plate work. Forming runs on a 200 T 5-axis CNC brake with a 4,450 mm bed to 10 mm, and volume parts run on 20–300 T presses with 250 T punching. Edge break is applied on the fabrication route before the part goes to seven-tank pretreatment and the powder booth, and the requirement is confirmed at drawing review rather than assumed.
The plants hold ISO 9001:2015 and ISO 14001:2015, work to ±0.5 mm typical sheet metal tolerance with tighter features by agreement, and offer first article inspection and PPAP. The laser cutting hub carries the thickness and edge data behind these numbers, and the laser cutting capability page lists the bed sizes and materials.
What to put on the drawing and the DXF
- Edge condition per ISO 13715, with the maximum burr height in millimetres and the direction of any permitted burr.
- Radius or chamfer for each edge class, and a list of edges that are exempt — weld prep, faying surfaces and joggle lines usually are.
- Cut quality class per ISO 9013 where dross is not acceptable on the exit face.
- Faces that must keep clean recast-free metal because the coating keys to them.
- Threads, dowel holes and sliding fits that must be hand-finished rather than tumbled.
- Which parts may share a barrel, because tumbling steel and aluminium together leaves a galvanic smear that shows up as corrosion under the film.
The edge quality article covers what a 12 kW source leaves at each thickness, and the hole and slot guide explains when a small feature needs a different cut strategy before the burr question arises.
When a mechanical edge break is the wrong answer
A burr inside a closed box section welded shut cannot be reached afterwards. Deburr the blank before the box is closed, or design a service opening, because no method in this table will save the part once the last seam is welded.
An edge that must be visually crisp — a furniture reveal or an appliance fascia — loses its definition under a 0.5 mm radius. Specify a sheared or laser edge with a controlled roll-over instead and accept a tighter burr limit.
A hand linish after final inspection takes the part outside its tolerance, and a tumble cycle on a part with a 0.2 mm locating slot rounds the slot. In both cases the deburring operation and the tolerance have to be resolved together before the first part is cut. If the edge is decorative, cut quality matters more than burr height, and the mild steel thickness and edge guide is the place to start.
Send the drawing with the edge callout in place through the quotation route; the manufacturing route is fixed before the price, not after.
Frequently asked questions
Is tumbling cheaper than hand deburring for a 200 mm bracket?
Usually, above a few hundred parts a month. A barrel load of 150 brackets runs in about 30 minutes, which is 12 s per part against 20–40 s per metre by hand. Below about 100 parts the loading, unloading and media separation cost more than the labour saved.
Can thermal deburring replace linishing on a coated panel?
No. Thermal deburring burns the burr back but leaves the corner sharp, so a powder coat still thins at the edge. It also warps free edges under about 1 mm. Use it for internal intersections and finish visible edges mechanically.
What burr height should I allow on a laser-cut part?
0.1 mm maximum for a handling edge and 0.05 mm where a gasket or sliding fit sits. Above 0.2 mm the burr shows through a 60–90 µm powder film and lifts the coating at the edge.
Does deburring change the part dimensions?
It does if the edge break is large. A 0.3 mm chamfer on four edges of a 300 mm plate removes a measurable amount from the outline, so measure and inspect after the edge break, or specify which dimensions the burr operation must not touch.
Why does my supplier deburr after bending instead of before?
Because the blank is usually deburred first and the formed part finished afterwards. Deburring a formed part by hand is slow and can mark the bend, but a burr left on the compression face is pressed into the tool and a burr on the tension face can crack.
Sources and further reading
- ISO 13715:2017 — Edges of undefined shape: indication and dimensioning on drawings · reviewed 3 Nov 2026
- ISO 9013:2017 — Thermal cutting: classification of thermal cuts, quality tolerances · reviewed 3 Nov 2026
- BIS — IS 513 cold reduced carbon steel sheet and strip, and general standards catalogue · reviewed 3 Nov 2026
Have a part with an edge callout?
Send the drawing with the burr limit, the edge radius and the coating you need. The fabrication team confirms which edge break the route will hold before quoting.
Request a quote