Laser cutting or punching? Custom CUPAL parts from a drawing — which process pays off when
When your joint needs a part made to your own drawing rather than a stock washer or strip, the first question is not the material — that is CUPAL sheet — but which process cuts it. The answer is rarely technical and mostly economic: it depends on quantity, on how complex the shape is, and on how final the drawing still is. This article walks through the three processes that come into question, what is different with a bimetal compared with plain sheet, and what to put in your quote request.
In short
For strips and rectangles with straight edges, shearing is enough, with no tooling. For custom contours and samples, laser cutting is the right choice: no tooling cost, and the drawing can change at any time. For large runs of a frozen geometry, punching gives the lowest price per part but carries a one-off tooling cost. The usual path is laser-cut samples, then punched series once the drawing stops changing.
- 0.5–2.0mm
- Thickness range
- 24hours
- Quote from drawing
- 5–10working days
- Production lead time
- 500 × 500mm
- Minimum one sheet of stock
Three processes, three cost structures
The three processes differ not in quality but in cost structure — how much is paid once, and how much per part.
- Shearing — straight cuts across the sheet. The fastest and cheapest route to strips and rectangles, with no tooling cost; it cannot make arcs or holes.
- Laser cutting — the machine follows the contour of the DXF directly. There is no tool, so one part is cut the same way as a thousand, and the drawing can change freely between orders. The price per part is higher than punching, because every contour has to be cut in full.
- Punching (blanking, piercing) — a tool made for this one shape cuts the part, holes included, in a single stroke. Lowest price per part and fastest production, but the tool is a one-off cost and can make only that geometry.
Which process pays off when — six criteria are enough to decide.
| Criterion | Laser cutting | Punching | Shearing |
|---|---|---|---|
| One-off cost | None | Tooling, once per shape | None |
| Shape | Any contour, with holes | Any contour — but only the one the tool was made for | Straight edges only — strips, rectangles |
| Pays off for | Samples, small and medium runs, changing drawings | Large repeat runs, frozen drawing | Strips and rectangles in any quantity |
| Heat at the bond interface | Briefly, in a narrow band along the cut edge | None — cold process | None — cold process |
| Edge | May need deburring | Burr on the exit side — state on the drawing which side may carry it | Slight burr on the cut edge |
| Drawing changes | Any time, at no cost | Needs a new or modified tool | Any time |
What to watch with laser cutting a bimetal
Copper reflects laser light. Copper reflects most of the light from conventional CO₂ lasers, so copper and copper-clad material need a fibre laser, whose wavelength copper absorbs much better. Laser cutting is done by our partner.
The bond interface is heat-sensitive — but the laser only reaches the edge. The bond between CUPAL's two layers tolerates heat treatment at no more than 260 °C for no more than 4 hours; beyond that, the intermetallic layer at the copper-aluminium boundary starts to grow uncontrolled, which weakens the bond. That limit applies to heating the whole part for a sustained time. A laser heats only a narrow band along the cut edge, and only while it cuts. And in a bolted joint it is not the edge that carries the current but the two flat faces — copper face to copper, aluminium face to aluminium — which the cut does not touch.
One thing to flag in advance all the same: if you will form the part close to the cut edge — bend or flange it — say so in the quote request, because then the condition of the material along the edge matters too.
What to watch with punching
A cold process — no heat reaches the interface. CUPAL is made for cold forming — it can be punched, bent and deep-drawn much like copper — so blanking does not trouble the bond between the layers.
Fix the burr side on the drawing. In punching, the burr always forms on the exit side. With a bimetal that matters: if the burr is on the copper face, the copper contact face will not sit fully flat. Mark on the drawing which side may carry a burr — or ask for deburring — and we set the tool direction to suit.
A tool makes exactly one geometry. If the drawing can still change — because the sample still has to be fitted and tested — a punching tool is premature. Moving one hole means modifying the tool; with a laser it means a new DXF.
The usual path: laser-cut samples, punched series
Most custom parts reach series production in two steps:
- Samples by laser. A few parts or a few dozen, with no tooling cost. You fit them, test them and revise the drawing if needed — the next sample is just a new DXF.
- Series with a punching tool once the drawing is final and the quantity repeats. From then on the one-off tooling cost is spread over every part.
Where the break-even point lies cannot be said in general — it depends on the shape, the number of holes and the run size. So ask for a price on both processes: the samples and the series separately, with the expected repeat quantity for the series. The quote then shows the two cost structures side by side.
If you do not need a contoured part at all, only a strip of a custom width or a rectangle to exact size, you need neither: we shear it from CUPAL sheet or CUPAL strip stock.
What to send with your quote request
With the following we can give an accurate price first time, without coming back to you:
- Drawing — DXF is best, but PDF or JPG will do. No drawing? Give us the dimensions and we draw it.
- Thickness — 0.5 / 1.0 / 1.5 or 2.0 mm.
- Which face is copper. For an asymmetric part this is essential: the mirrored part is a different part, because the copper and aluminium faces swap. Mark on the drawing which view shows the copper face.
- Quantity — separately for samples and for the series, plus the expected repeat quantity if you know it.
- Tolerance — if you need tighter than the general tolerance of the drawing, tell us and we confirm whether it can be held.
- Burr — which side is allowed to carry it, or whether deburring is needed.
- Material certificate — EN 10204 2.2 as standard, 3.1 on request.
What does not depend on the process
Whichever process makes the part, the material is the same: 70 % aluminium and 30 % copper by layer thickness, with the same material certificate. Cutting does not affect the certification of the stock, and it does not change the installation rules either — those are in the CUPAL installation guide. The exact material data are on the CUPAL technical datasheet, and the terms in the CUPAL glossary.
If what you need turns out to be a round washer after all, check the 11 stock sizes on the CUPAL washer page first — and if the specification only says "transition washer", whether it means the bimetallic or the toothed kind. What is in stock is not worth having cut to order.
How ordering works, the minimum quantity and the sheet price of the stock are on the cut to size from your drawing page.
Have a drawing? Send it as DXF, PDF or a photo — we quote within 24 hours, samples and series separately.
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