Choosing the Right C18070 Temper and Controlling Total Cost

The earlier articles covered what C18070 is, how it performs and where it is used. This one is about specifying it correctly and spending sensibly — where the wrong choice quietly costs money.

Start from the bend, then check the strength

The most common error is ordering the hardest temper on the assumption that stronger is always better. With C18070 the bend requirement usually decides the temper, because bendability changes sharply across the range: R400 achieves a 0t bend both ways, while R580 needs up to 1.5t bad-way. Fix the tightest bend radius and its orientation first, choose the temper that survives it, then confirm the resulting strength still meets the load. For complex formed parts, R400 is the natural starting point; for simpler shapes that need more strength, a harder temper is available.

Identify the real requirement: relaxation or softening

As covered in the properties article, high-temperature performance is two separate properties. Before selecting, name the failure mode you are guarding against. If the risk is a contact that loosens under sustained load, specify against stress relaxation (the 200°C/1000h retention figure). If the risk is a part that softens after a heat exposure, specify against softening resistance. Choosing against the wrong one either leaves a part under-protected or pays for margin it never uses.

Specify thickness and tolerance realistically

For a current-carrying contact, thickness sets both the cross-section for current and the stiffness of the spring, so it is a design variable rather than a stock choice. Set the nominal gauge from the current and force requirements, then specify a tolerance class no tighter than the part needs — an unnecessarily tight tolerance narrows the supplier field and raises price without improving the part. C18070 strip is produced across a wide gauge range covering thin precision strip through to heavier connector stock.

Surface and plating

C18070 plates and solders well, and for a current-carrying contact the plating often governs the contact resistance and corrosion behaviour at the mating interface. Decide early whether you need bare, pre-plated or selectively plated strip, since it affects both routing and cost.

The C18080 comparison and total cost

Where a design currently calls for C18080, it is worth checking whether C18070 already meets the requirement. C18080 is a silver-bearing alloy in the same class; C18070 reaches high conductivity and strong relaxation resistance without that additional alloying, so it is generally the more economical choice when its properties are sufficient. The honest way to decide is to compare on the actual conductivity, relaxation and strength the part needs, rather than on headline grade. Many parts specified in the higher alloy run comfortably on C18070 with margin to spare; a few genuinely need the extra performance.

Reducing waste in production

• Order strip width and coil weight to match the stamping layout, so less material becomes edge scrap.
• Confirm edge condition (slit, deburred, rounded) to suit the tool and avoid a secondary operation.
• Agree the certificate and inspection level up front, so lots are not rejected or re-tested late.

Shanghai Xinye Metal Material can review a part's temper, gauge and surface against its actual current, bend and temperature requirements and supply to matched specifications, which is usually where the avoidable cost in a C18070 part is found.

Frequently asked questions

Which temper should I start from?

R400 for complex formed parts, because of its 0t bendability; a harder temper for simpler shapes that need more strength. Confirm the choice against the bend radius and load.

Is C18070 cheaper than C18080?

Generally yes, because it reaches comparable conductivity and relaxation performance without the silver addition of C18080 — provided its properties meet the requirement.

Next in this series: How to specify and order C18070 copper strip — the checklist that turns a drawing into a clean enquiry.