Documentation
Sweep a weld schedule
Vary current, weld time or electrode force across resistance spot welding runs and compare the nugget outcomes, one confirmed run at a time.
You have a joint to qualify and you want to see where the weldable range sits — how low the current can go before the nugget shrinks below spec, what an extra cycle of weld time buys you, whether dropping electrode force helps or hurts.
Start with the honest answer: there is no sweep parameter in Phases. The spot welding tool takes a single current, a single weld time and a single force. A sweep is repeated runs — one confirmation card and one stored run version per point. That is more deliberate than a batch job, and it is also why every point in your sweep is separately auditable.
The confirmation card is mandatory#
Every spot welding request shows a Configure simulation card before anything runs. That applies even when you state every parameter yourself — your values are pre-filled into the card, and nothing executes until you press Run Simulation. There is no way to skip it from chat. Plan on one card press per sweep point.
Step 0: start from a calibrated template#
Do not invent a baseline. Ask what has already been calibrated:
Show me the calibrated RSW templates for DP600.
There are 22 templates: 17 symmetric single-grade cases and 5 dissimilar joint pairs. Three supported grades — 20MnB8, 25MnB5 and 29MnB7 — have no calibrated template.
Each template comes back as an id, a name such as RSW DP600 1.2mm, a joint type of symmetric or dissimilar, and the calibrated configuration itself: the two plate grades, the two thicknesses, the two coating flags, the boundary-condition mode, the current in kA and the solver potential, electrode pressure, weld time, total time, the solver time step dt, and whether microstructure and mechanical coupling were on.
What the listing does not return is the nugget-diameter band each case was calibrated against. That target lives in the case file's description text and is not surfaced by the tool. The bands are documented instead on RSW validation — the symmetric DP600 1.2 mm case, for instance, targets 5.5–6.0 mm at 6.0 kA and 32.7 MPa. Read the target there and the parameters from the template.
Show me only the dissimilar RSW templates.
Step 1: run the baseline#
Spot-weld two 1.2 mm DP600 sheets at 6 kA with 32.7 MPa electrode pressure, 0.42 s weld time and 3 s total time.
Press Run Simulation on the card. Note the peak temperature the summary reports.
Step 2: change one variable at a time#
Repeat that spot weld at 6.5 kA instead.
Now the same weld at 7 kA.
Each of these gets its own card, pre-filled with the values you named. Check the other fields on the card before you press Run — restate anything that matters rather than assuming it carried over. What you can vary, and the range the chat card accepts:
| Parameter | Accepted range on the card | Notes |
|---|---|---|
| Welding current | 1–12 kA (entered as 1000–12000 A) | Only editable in current mode |
| Electrode pressure | 1–200 MPa | 5–95 MPa is the usual spot-weld band; unusual but valid values require confirmation |
| Electrode force | 0.5–15 kN | Alternative to pressure; converted using a fixed electrode face area |
| Plate thickness | 0.3–5.0 mm per plate | Top and bottom set independently; 0.5–3.0 mm is the usual calibration band |
| Coating | On or off per plate | |
| Weld time | 0.01–1.0 s | Total time must be greater than or equal to weld time |
| Total time | 0.01–25.0 s | Includes hold and cooling; the solver-step budget can impose a tighter combination with weld time and dt |
| Microstructure | Off by default | Turn on for phase tracking and hardness |
In voltage mode the solver-potential field is editable from 1 to 100,000 mV, so you can perform either a current or voltage sweep. The historical voltage_V key stores mV (1062.2 mV is 1.0622 V). An invalid draft remains visible and blocks Run instead of being silently clamped.
What you cannot vary: electrode tip geometry, squeeze time, hold time and multi-pulse schedules are not exposed as parameters. The solver runs a fixed 2D axisymmetric electrode and mesh geometry; only plate grade, thickness and coating change the geometry.
Step 3: read the nugget outcome#
The result gallery includes a plot labeled Nugget & HAZ Analysis. It classifies every steel element by the peak temperature it reached during the cycle:
| Zone | Peak temperature threshold |
|---|---|
| Nugget | 1803 K and above |
| Upper HAZ | 1050 K and above |
| Lower HAZ | 750 K and above |
| Base Metal | Below 750 K |
It reports per-plate diameters for three of those four zones — Nugget, Upper HAZ and Lower HAZ, each annotated on the contour as D=…. Base Metal is drawn as a colour band and appears in the phase chart, but it gets no diameter.
Read those three numbers as cumulative extents, not ring widths. Each is measured over every element at or inside that zone, so the Upper HAZ figure is the outer extent of nugget plus upper HAZ together, and the Lower HAZ figure is the outer extent of all three. If you want a ring width, subtract.
The nugget diameter is the number your sweep is really about — compare it against the AWS D8.1M criterion of 5·√t mm minimum, where t is the thickness of the thinner sheet.
The gallery also gives you Nugget Evolution (animated), Temperature Contours, Temperature History, Nugget Zoom (end of welding) and Nugget Zoom (cooling), among others.
Hardness values only appear on the nugget/HAZ plot when the model has cooled below 473 K (200 °C) by the end of the simulated time and phase data are present — which means microstructure tracking must be on and your total time must be long enough. A run that ends hot reports no hardness.
Two cautions that change how you plan a sweep#
Nugget diameter is quantized by the mesh. It moves in discrete steps rather than continuously. A 0.2 kA increment may produce an identical reported diameter. Space your sweep points widely enough that the change is larger than one mesh step, and do not read fine trends into the diameter series.
The mechanical coupling is experimental and linear thermoelastic only. If you enable it, the card itself warns that plastic flow stress is not active in the current solve. Do not interpret displacement or von Mises output as validated electrode indentation, sheet thinning or expulsion. The flow_stress_model setting is a compatibility field and changing it does not change the result.
Step 4: compare the runs#
List my RSW runs.
Inspect run 4 and give me its peak temperature and configuration.
Inspecting a run returns its metadata — version, storage prefix, simulator type, status, summary and the configuration the run recorded — plus a presence map saying which of a fixed set of artifact names exist. It does not hand back RSW figures: neither the nugget animation nor anything in the plot gallery is on that fixed list, and inspection can only sign a link for a file the list reports, so asking the agent to show you an earlier weld's plots returns nothing.
The two places an RSW figure actually is: the gallery the run itself posted into the conversation when it finished, and the browsing surfaces — the Runs panel and the simulation panel's Results tab — which list every file the run wrote with a download button on each row.
In the Results tab each stored run shows Grades, BC, t_end and Peak T on one row, which makes a current sweep readable at a glance. See Reuse and share runs.
Grade coverage#
Spot welding is limited to 20 grades with validated bulk electrical, thermal and mechanical properties: DC01, DC03, DC04, DC05, DC06, HC260LA, HC300LA, HC340LA, HC380LA, HC420LA, DP450, DP500, DP600, DP780, 20MnB5, 22MnB5, 20MnB8, 25MnB5, 29MnB7 and EN13261. Anything else is rejected before the solver starts.
Those 20 grades map onto only two bulk property families — a DC04 family covering all DC and HC grades, and a 22MnB5 family covering all DP grades, all the boron press-hardening grades and EN13261. Two grades inside one family share the same electrical, thermal, density and latent-heat curves, so a thermal-only sweep that changes nothing but the grade within one family has nothing left to vary. A custom chemistry does not create a new spot welding grade; it rides along on one of the 20 base grades, and it only reaches the physics when microstructure tracking is enabled.
Variations#
Force instead of pressure. Switch the card's Mechanical field to Force [kN] and sweep 2, 3 and 4 kN. The card converts to pressure using a fixed electrode face area; the converted value must remain inside the full card's 1–200 MPa range.
Weld time. Repeat that weld with 0.30 s weld time and …with 0.55 s weld time, keeping total time at 3 s.
Dissimilar joint. Spot-weld 1.0 mm DC04 to 1.5 mm 22MnB5 and show me the nugget and HAZ analysis. Set the two plate grades independently on the card.
Budget the runs. The solver is stopped after 3600 seconds. Microstructure-enabled runs take substantially longer than thermal-only runs, so leave it off while you are locating the range and turn it on for the two or three points you want phase and hardness detail on.