Copper stamping

ETP copper C11000 is the usual grade for busbars and contacts; oxygen-free copper is specified where the part will be brazed in a reducing atmosphere or used in vacuum. Copper galls on tooling, so lubricant and die polish are critical. Because copper is soft, burr height and edge condition are harder to hold than on steel.

The commercial consequence is that copper is priced on its own material line, not blended into a steel rate. Material grade, thickness, tolerance and finish are quoted separately from conversion, so a change of specification is visible in the price.

Ganesh quotes to the drawing first and to ISO 2768 general tolerances where the drawing is silent. For copper stamping, the practical starting points are in the table below. They are starting points, not a guarantee: the part geometry, thickness and fixturing decide what can actually be held, and the quotation states the tolerance offered.

Blanking, piercing, forming and drawing are quoted as one press route; the number of stations, not the tonnage alone, usually decides whether a part is worth tooling. Busbars and current-carrying parts are specified by conductivity, not just by grade name; ETP C11000 is the common baseline and oxygen-free copper is reserved for vacuum or brazing duty. The route is quoted as one sequence so the customer does not have to coordinate a cutter, a former, a welder and a coater.

Stamping copper is the wrong route for small quantities of large busbars; cutting and forming from plate is cheaper and avoids a tool that will not be used again.

A manufacturability review before quotation is the cheapest place to find this out. Send the drawing, material, finish and annual quantity and the review comes back in writing.

• Busbars
• Contacts and terminals
• Shielding parts
• Heat spreaders

Use stamping when the geometry is frozen and the annual quantity repays the tool. As a working rule, a simple bracket in a single-stage tool becomes cheaper than laser-cut-and-formed at roughly 3,000–8,000 parts a year; a progressive tool needs more volume because the tool itself costs more. Below that range, laser and bend keeps the cash free and the revision cheap. Between the two, quote both and compare total cost over the programme life, not the first order. For copper the practical constraint is conductivity and heat: cutting parameters, bend radius and joint method are all set by the temper and the electrical requirement, not by the shape alone. Copper parts are often single-source by specification rather than by process, so the decision that matters is the temper and the edge condition, both of which should be on the drawing before a supplier is chosen.

State the material grade and blank thickness, the tolerance on every functional feature, the burr direction and height where it matters, the grain direction if the part is drawn, and whether the tool is customer-owned or supplier-built. Name the inspection level. If the part will be welded, say so, because the burr and the flatness that a welding fixture needs are not the same as for a plain bracket.

Inspection covers dimensional features, burr height, material thickness and hardness at sample frequency, plus a first article report before production. Ganesh holds tools in the in-house tool room, so die maintenance records and tool history are available with the part. PPAP documentation is available where the programme requires it.

Cost splits into material, tooling, press time, secondary operations and inspection. Tooling is a one-off and is quoted separately, so the piece price only makes sense against an annual quantity. Press time is driven by stroke rate and the number of stations, not by part weight. Secondary operations such as deburring, tapping, welding and coating often exceed the press cost on a small part. On copper, material is quoted as its own line at the prevailing rate for the grade and thickness, so a change of specification is visible rather than hidden in a blended rate.