Key takeaways
- A contact RFQ needs the electrical duty, the material, the joint and the acceptance test in one pack.
- State the load profile, including inrush and inductance, not just a nominal current.
- Say whether the contact is a rivet, tip, pad or welded assembly, because the joint process follows the form.
- Ask every supplier to quote against the same drawing revision and test plan, then compare.
Why contact quotes diverge
Two suppliers can quote the same drawing and land 30 per cent apart. The reason is rarely the hourly rate alone. A contact quote depends on the electrical duty, the material grade, the joint route, the test plan and the volume. If the RFQ leaves any of those open, each supplier fills the gap with its own assumption.
The fix is not a longer email. It is a structured pack that answers the questions a process engineer would ask before choosing a route. The checklist below follows the order of the decisions: duty, material, joint, test and commercial terms.
The electrical duty
State the current, the voltage and the type of load. For AC, give the frequency and the power factor. For DC, give the time constant. State the inrush current and its duration, because a motor or a capacitive load can draw several times the steady current at make.
Add the operations per life, the duty cycle and the ambient temperature. A contact that switches once a day is a different part from one that switches ten times a second. If the load is inductive, say so. If the contact carries current continuously as well as switching it, say that too, because the thermal duty changes.
The load profile should be a table, not a sentence. A supplier can price a clear profile. A vague one gets a conservative quote with a margin built in.
If the contact will be used at altitude, in a polluted atmosphere or in a sealed enclosure, add that to the duty. The ambient temperature inside an enclosure can be much higher than the room temperature on the test bench, and the contact material and the plating both respond to it.
Material and form
Name the form first: rivet, tip, pad, welded button or stamped contact. The form decides the joint process and the tooling. Then give the head material designation, including the oxide system and the manufacturing route if the drawing calls for it. Silver tungsten, silver nickel and silver tin oxide are not interchangeable at the same price.
Give the shank material, the temper and the plating, including any barrier layer. For a rivet, give the head diameter, head height, face form and edge radius, plus the shank diameter and length. For a tip, give the thickness and the face radius.
If the part is a composite, say which interface is critical. A drawing that only controls the outside shape leaves the bond to the supplier.
The joint and the carrier
A rivet cannot be quoted without the carrier. Give the carrier material, the blade thickness range and the hole diameter tolerance. State the clinch type, the staked height and the foot diameter. If the contact is welded, give the weld process and the bond-line requirement.
For a staked assembly, the protrusion above the blade and the hole clearance decide the joint strength. A supplier who is not told the blade thickness will assume one and price a joint that may not fit the application.
If the contact is supplied loose and staked by the customer, say so. The drawing then needs a joint specification for the customer process, and the supplier needs to know that the rivet will be measured after someone else forms it.
The RFQ items and what they change
The table below maps each item to the part of the price it moves. Use it as the structure of the RFQ, not as a list of optional extras.
| Item | What to state | Why it moves the price |
|---|---|---|
| Load profile | Current, voltage, AC or DC, inrush, time constant, operations | Sets the material grade, the face size and the life test |
| Head material | Full designation, oxide system and route | Changes the metal cost, the sintering route and the scrap value |
| Contact form | Rivet, tip, pad, button or stamped contact | Sets the tooling, the joint process and the cycle time |
| Shank and plating | Alloy, temper, layer, thickness and masked areas | Changes the current path, the forming route and the finish cost |
| Carrier and clinch | Blade thickness, hole tolerance, clinch type, staked height | Sets the staking tool and the pull-out requirement |
| Test plan | Method, current, limit, sample and type or lot | Adds inspection time and decides the accept or reject rule |
| Volume and release | Annual quantity, release size and ramp | Sets the tooling amortisation and the setup share |
| Packing and Incoterm | Protection, density and delivery point | Changes the freight and the risk transfer |
A quote is only comparable when every row is answered the same way for every supplier.
Test and acceptance
State the test, the limit and the sample. Contact resistance at a stated current, pull or shear strength, staked height and a cross-section are the usual checks. If a life test is required, say whether it is a type test or a lot test, and give the load profile.
Ask for the first article pack and any material certificates. If the part must meet a declaration, name it. Do not ask for a general compliance statement that the supplier cannot support with a record.
State the sampling rule as well as the limit. A test of one part proves that one part passed. A sample from each lot, with the sample size and the acceptance number, gives the supplier something to plan and the buyer something to audit.
Commercial terms and the comparison grid
Give the annual volume, the release size and the expected ramp. A supplier prices a 5,000 part order differently from a 500,000 part order. State the currency, the validity period and the Incoterm.
Then build a comparison grid with the same rows for every supplier: metal basis, conversion, tooling, joint, finish, test, packing, freight and lead time. A quote that is lowest on piece price but highest on tooling and freight may not be the lowest cost.
Finally, ask what is excluded. A quote that excludes tooling, testing or plating is not a complete price, and the omission will appear later.
Keep the comparison grid with the RFQ pack. When a supplier asks a question, the answer goes into the grid and is sent to every bidder. That way the quotes stay comparable even when the requirement changes during the process.
Frequently asked questions
What is the most important item in a contact RFQ?
The load profile. It decides the material, the face size, the joint and the test. A supplier can work around an unusual dimension, but it cannot choose a safe contact material without knowing the current, the voltage and the type of load.
Can I quote a contact from a drawing alone?
You can get a price, but not a comparable one. The drawing gives the geometry and often the material. It rarely gives the load profile, the carrier, the test limit or the volume, and those items move the price as much as the drawing does.
Should the RFQ include the carrier?
Yes for a rivet or any staked contact. The carrier thickness, the hole size and the clinch form decide the joint strength. Without them the supplier has to assume a joint, and the assumption may not match the assembly.
How do I compare quotes with different silver bases?
Recalculate each quote at the same silver price, currency and date. Then compare conversion, yield, recovery and test separately. A single piece price built on an unknown metal basis cannot be compared with another.
Sources and further reading
- IEC 61810-1, Electromechanical elementary relays, general and safety requirements
- IEC 60947-4-1, Low-voltage switchgear and controlgear, contactors and motor starters
- Qumek contact RFQ and drawing review notes
Qumek Engineering Desk
Engineering team
The engineering team behind Qumek drawings, DFM notes, tolerances and inspection standards. Every guide is reviewed against the drawings and processes used on live programmes.
Sending a contact out for quotation?
Send the drawing, the load profile and the carrier details. The engineering desk will reply with the missing items before the RFQ goes out.
Review the RFQ