A threaded tungsten copper electrode is a small part with several jobs. It carries welding current, transfers electrode force, seats repeatedly in a gun or holder, and still needs to come out cleanly at the next tip change. A drawing that identifies only the thread diameter leaves too many decisions to the machine shop.
This guide turns the part into an RFQ that a supplier can quote and inspect without guessing. It applies to threaded electrodes for resistance-welding guns, projection fixtures, and automated cells in W/Cu 75/25 or W/Cu 70/30.
1. Start with the mating interface
Specify the complete thread, not just its nominal diameter. The drawing should state:
- Metric or UNC/UNF thread form.
- Nominal diameter and pitch or threads per inch.
- Internal or external thread.
- Right-hand or left-hand direction when it is not standard.
- Fit class required by the mating holder.
- Usable thread length, relief, and shoulder location.
The fit class matters because the joint is both mechanical and electrical. A loose fit can change seating and encourage vibration; an excessively tight fit makes tip changes difficult and increases the risk of cross-threading. If the original drawing is unavailable, identify the gun or holder and provide a measured sample rather than asking a supplier to infer the thread from a photograph.
For repeat orders, keep the same drawing revision and thread callout. ArcTung machines metric, UNC/UNF, and special forms to drawing and verifies batches with go/no-go gauges.
2. Define the seating surfaces
The thread locates the electrode, but the shoulder or taper usually controls how it seats. Mark the datum surface and dimension the relationship between that datum and the working face. Include:
- Shoulder diameter and squareness.
- Taper angle and contact length, if used.
- Overall length and stick-out from the holder.
- Any wrench flats, drive features, or removal slots.
- Concentricity requirements between the thread, shank, and face.
These dimensions are especially important in automated stations. An electrode that sits at a different height or angle after replacement can change gun closure geometry and may force an avoidable robot-cell adjustment. Repeat parts should therefore run from the same machining program and drawing revision.
3. Specify the working face separately
Do not let the thread callout overshadow the end that makes the weld. State the face geometry—flat, radius, dome, or a profile to drawing—and identify the dimensions that may be dressed during service.
Face wear and thread failure should also be diagnosed separately. Threaded W/Cu electrodes typically reach end of life at the working face through mushrooming, coating pickup, or normal dressing loss. If parts are instead being rejected for damaged threads, investigate cross-threading, holder condition, seating practice, or vibration before changing alloy.
For coated or high-strength steel, face stability may be the reason to use tungsten copper in the first place. The site’s resistance-welding application guide explains the selection logic in more detail.
4. Choose W/Cu 75/25 or 70/30 by duty
Both grades can use the same thread and shank geometry, but their material balance differs:
- W/Cu 75/25 is the harder, higher-density option and is generally preferred when deformation and wear life limit the process.
- W/Cu 70/30 provides higher electrical conductivity and is useful when current and heat removal are the stronger constraint.
Do not change grade silently between trial and production. The alloy should appear on the drawing, purchase order, and inspection record so that a validated weld schedule receives the same material on every reorder. See the W75Cu25 vs W70Cu30 guide for a fuller comparison.
5. Show cooling passages and internal features
If the holder or electrode uses internal cooling, provide a section view. Dimension the bore, depth, wall thickness, counterbore, and any transition that affects water flow or sealing. Avoid notes such as “cooling hole as standard”; there is no useful standard if the passage must align with a specific gun.
Cooling geometry should be reviewed together with the working face. Tungsten copper can conduct heat away from the weld zone, but that advantage depends on the surrounding holder and water circuit actually removing the heat.
6. Put inspection requirements on the RFQ
A practical inspection package for a threaded electrode can include:
- Go/no-go gauge result for the specified thread.
- Overall length and critical shoulder dimensions.
- Face diameter or radius.
- Concentricity or runout where the application requires it.
- Alloy identification and batch traceability.
- Dimensional inspection record against the drawing revision.
Ask for the records your receiving team will use, not a generic certificate bundle. Requirements added after production can delay shipment even when the parts are correct.
7. Send one complete RFQ package
The fastest quotation includes the drawing in PDF plus DWG or STEP when available, alloy grade, quantity, destination, and required inspection paperwork. If no drawing exists, send an unworn sample or the best available used part with clear measurements and photographs.
ArcTung supplies standard threaded shapes with no minimum order and lists typical lead times of 10–14 days for standard work and 20–25 days for custom geometry. Before ordering, confirm the current quoted schedule rather than treating a typical lead time as a shipment promise.
Threaded-electrode RFQ checklist
Before sending the RFQ, confirm that it answers these questions:
- What exact thread form, size, pitch, direction, and fit class mates with the holder?
- Which shoulder or taper is the seating datum?
- What are the overall length, stick-out, and critical concentricity requirements?
- What working-face geometry makes the weld?
- Which alloy—W/Cu 75/25 or 70/30—was validated?
- Are there cooling bores or internal features that require a section view?
- Which dimensions and material records must accompany the batch?
- Which drawing revision controls repeat orders?
A complete answer turns a “custom electrode” into a controlled repeat part. Send the package to sales@arctung.com for a drawing review and quotation, or compare it with the current threaded-electrode product specification.