FXT40 Pro 8-Zone × 8-Stage Programming: How Layer and Position Control Work Together
FXT40 Pro 8-Zone × 8-Stage Programming: How Layer and Position Control Work Together
The FXT40 Pro orbital welding power source uses a two-dimensional parameter programming structure: 8 zones and 8 stages. These two numbers describe two distinct axes of control — and understanding what each axis represents explains why the system produces consistent results on all-position thick-wall pipe welding where simpler systems do not.
The Two Axes of Control
Zones correspond to the welding pass sequence — the layers of a multi-pass weld.
Thick-wall pipe (above approximately 5 mm wall) requires multiple passes to fill the joint cross-section. A typical TIG weld on 10 mm wall carbon steel pipe involves: root pass, hot pass, two to three fill passes, and cap pass. Each pass has different requirements:
- Root pass (Zone 1): lowest current, AVC is most critical, no or minimal weave — goal is full penetration without burn-through - Hot pass (Zone 2): slightly higher current, follows the root immediately to eliminate any porosity - Fill passes (Zones 3–7): increasing current and oscillation width as the groove fills - Cap pass (Zone 8): widest oscillation, controlled height — goal is appearance and dimensional conformance
Each zone has independently stored current, oscillation amplitude, travel speed, and pulse settings. The root pass program looks nothing like the cap pass program — and they should not. The physical requirements of forming the root are different from the requirements of completing the cap.
Stages correspond to the angular positions around the 360° rotation — the positions that gravity affects differently.
Within each zone, the 360° rotation is divided into up to 8 stages, each covering approximately 45°:
- Stage 1: 0–45° (overhead start, arc initiation) - Stage 2: 45–90° (descending toward horizontal) - Stage 3: 90–135° (horizontal toward flat) - Stage 4: 135–180° (flat position — most stable) - Stage 5: 180–225° (flat toward horizontal, other side) - Stage 6: 225–270° (horizontal) - Stage 7: 270–315° (ascending toward overhead) - Stage 8: 315–360° (overhead return, arc termination)
Within each stage, current, travel speed, and pulse settings can be adjusted relative to the zone baseline. Stage 4 (flat) typically runs the highest current and fastest travel speed. Stages 1 and 8 (overhead) run the lowest current and the most carefully managed travel speed to prevent pool sag.
Why Both Axes Are Required
A system with zone control but no position stages would apply the same overhead and flat parameters within each weld layer — meaning the flat-optimized current would overheat the overhead stage, or the overhead-optimized current would under-penetrate at flat. Zone-only control addresses the layer sequence but not the positional variation within each layer.
A system with position stages but no zone differentiation would apply the same overhead-to-flat variation to every layer — meaning the thin-penetrating root pass would try to use the same current profile as the wide-weaving cap pass. Stage-only control addresses the angular positions but not the pass-by-pass parameter evolution.
The 8-zone × 8-stage structure addresses both simultaneously. For each combination of zone (which layer) and stage (which angular position), an independent parameter set can be stored. The system knows not just "lower current at overhead" but "lower current at overhead specifically for the root pass" — different from the overhead parameters for fill passes, where accumulated heat in the groove changes what the appropriate heat input is.
In Practice: Not All 64 Combinations Are Always Used
The training documentation notes: "理论上，8区×8段=64组独立参数。实际使用中，不是每个区都需要8段——打底层通常需要细分8段（仰焊位压力大），盖面层可能只需4段（摆动已覆盖差异）。"
In practice, the root pass (Zone 1) typically uses the full 8-stage position breakdown because the root pass has the least tolerance for positional variation — incomplete root penetration at overhead is the most common RT rejection on all-position pipe welding. Fill and cap passes may use fewer stages (4 is common) because the oscillation weave already compensates for some positional variation.
The FXT40 Pro's automatic programming function generates an initial parameter set from the input pipe diameter and wall thickness — a starting point for procedure development, not a final qualified procedure. The procedure engineer then adjusts zone and stage parameters based on first-pass test welds, RT results, and the specific material and groove geometry. The qualified program is then stored and used for production.
The AVC-Stage Interaction
AVC (Automatic Voltage Control) and stage programming operate simultaneously. AVC maintains constant arc length by adjusting torch height in response to surface variation — pipe ovality, weld bead topography, fixturing eccentricity. Stage programming changes the target current and travel speed at each angular position.
These two systems work on different sources of variation: - Stage programming addresses gravity's effect on the weld pool (systematic, predictable by position) - AVC addresses surface geometry variation (stochastic, varying by pipe and pass)
Without AVC, surface geometry variation produces arc length excursions that the stage programming cannot compensate for — stage programming adjusts by position, not by surface geometry. Without stage programming, the flat-position current overheat the overhead position regardless of how well AVC maintains arc length.
Both are required for consistent all-position quality on industrial pipe.
Program Storage and Traceability
The FXT40 Pro stores up to 50 qualified welding programs in onboard memory. Each weld generates a printed parameter record — current, voltage, travel speed, wire feed speed, and travel angle — for quality documentation. The USB port is used for firmware updates only; program management is through the onboard system and the parameter printout.
On multi-machine projects, programs are transferred by reprinting the qualified program parameters and re-entering them on each unit, or via the automatic programming function using the same input parameters. The printed weld record from each machine serves as the per-weld documentation for quality audit.
What This Means for Procedure Development
The 8-zone × 8-stage structure means that a welding procedure is not a single set of parameters — it is a matrix of parameters, each combination corresponding to a specific layer at a specific angular position.
Developing this procedure correctly requires: 1. Starting from the automatic programming output for the pipe OD, wall, and material 2. Running test welds with RT verification to identify where position-dependent defects occur 3. Adjusting the stage parameters for the zones (layers) where RT rejections cluster — most commonly the overhead stages of the root and first fill passes 4. Qualifying the adjusted program per the applicable welding code (ASME B31.3, API 1104, etc.)
A program qualified at one pipe size does not transfer without re-qualification to a significantly different diameter or wall — the zone and stage parameters that produce correct results at 114 mm OD, 8 mm wall will not be optimal at 219 mm OD, 12 mm wall. The matrix must be developed for each qualified condition.