The Lincoln Electric 6-PACK RACK FLEXTEC 450 (K2957-2) is a high-density multi-operator welding power center that stacks six Lincoln FLEXTEC 450 CC/CV welding power sources into a single rack enclosure, capable of simultaneously supporting up to six independent welding stations from a common input power feed. Designed for heavy industrial applications where floor space is limited and productivity demands are high — shipbuilding, structural steel fabrication, offshore construction, and heavy equipment manufacturing — the 6-Pack RACK delivers 6 × 450 A of welding capacity with a shared infrastructure footprint of approximately 36 × 24 × 84 in.
Each FLEXTEC 450 power source within the rack is a fully independent welding machine capable of SMAW, GMAW, FCAW, GTAW, and Gouging processes. The rack configuration includes shared input power bus, common ground bus, and integrated safety disconnect rated for the combined input load. Individual machines within the rack remain serviceable without removing the entire rack — a critical maintenance advantage in production environments where downtime is measured in lost revenue per hour.
| Configuration | 6 × Lincoln FLEXTEC 450 power sources |
|---|---|
| Output per Machine | 5–450 A CC / 10–44 V CV |
| Rated Output per Machine | 450 A / 38 V @ 60% duty cycle |
| 100% Duty Cycle per Machine | 400 A / 36 V |
| Input Voltage | 380–575 V, 3-phase, 50/60 Hz |
| Input Disconnect Rating | Per combined 6-machine load (see nameplate) |
| Processes Supported | SMAW, GMAW, FCAW, GTAW, CAC-A (gouging) |
| Communication | ArcLink® per machine for compatible Lincoln wire feeders |
| Output Terminals | Twist-Mate™ per machine |
| Rack Dimensions (approx.) | 84 in H × 36 in W × 24 in D |
| Rack Weight | Approx. 1,400 lb (636 kg) assembled |
| Enclosure | NEMA 3R rated steel enclosure with lockable front panel |
| Lincoln Part Number | K2957-2 |
- Shipbuilding and offshore fabrication: Large vessel construction requires dozens of welding positions operating simultaneously in tight deck and hull sections. The 6-Pack RACK consolidates power distribution and reduces cable management complexity, allowing welders to access multiple output positions from a single rack location in a compartment.
- Structural steel fabrication shops: Bridge and building fabrication shops running multiple SMAW and FCAW stations benefit from shared infrastructure. The 6-Pack RACK eliminates the need for six individual disconnect panels and simplifies plant electrical layout by reducing branch circuit count from six to one (shared).
- Turnarounds and scheduled maintenance outages: Petrochemical plants and refineries often deploy 6-Pack RACKs during planned outages, where 20–50 welders must be onboarded quickly in a confined area. A single crane lift positions the entire power center; individual station cables deploy radially from the rack.
- Offshore pipeline fabrication: Pipe spool fabrication shops use 6-Pack RACKs at pipe rotator banks, where each station welds a different spool simultaneously. The FLEXTEC 450's CrossArc® technology provides excellent FCAW and SMAW performance for out-of-position pipe spool work.
- Rental fleet and contract welding: Equipment rental companies add 6-Pack RACK systems to their fleet because the common platform simplifies technician training and spare parts management. A single spare FLEXTEC 450 module covers all six positions in the rack.
The 6-Pack RACK requires installation by a licensed electrician. Key commissioning steps include:
- Input power connection: Connect the 3-phase input feed to the main disconnect panel on the rack's rear panel. Verify input voltage matches the K2957-2's tap configuration (380–575 V range). Confirm all three phases are balanced within ±5% before energizing.
- Ground bus connection: Connect the facility ground (equipment ground conductor) to the rack's common ground bus bar. This ground point serves all six machines — a poor ground connection at this point degrades arc quality at every station simultaneously.
- Individual machine commissioning: Each FLEXTEC 450 powers on independently. Verify the front-panel LED status indicators show green on each machine before connecting wire feeders or electrode holders.
- Wire feeder connection (for FCAW/GMAW): Connect ArcLink-compatible wire feeders (Lincoln Power Feed 25M, Power Feed 84, LN-25 Pro) to each machine's ArcLink output receptacle. ArcLink automatically negotiates process parameters between the feeder and the power source.
- SMAW operation: Select CC mode on the individual machine front panel. Connect electrode holder and work cable to the machine's Twist-Mate output terminals. Adjust output using the machine's front panel amperage control or a compatible remote amperage control (Lincoln K857 or K924).
- Compatible with all ArcLink-equipped Lincoln wire feeders: Power Feed 25M, Power Feed 84, Power Feed 84 Dual, LN-25 Pro
- Analog-compatible with Lincoln LN-7, LN-8, LN-9 feeders via 14-pin adapter cable
- Compatible with Lincoln K924 remote amperage controls and K857 remote voltage/amperage controls
- See also: Lincoln 4-Pack RACK FLEXTEC 650 K3144-1 for higher per-machine amperage requirements and Lincoln Power Wave S700 K3279-1 for advanced process applications
- Individual machine service: Each FLEXTEC 450 in the rack is individually removable by a trained technician. Hot-swap capability (with the rack main disconnect open) allows a spare machine to be installed without rack removal or production shutdown of the remaining five stations.
- Air filter maintenance: Each FLEXTEC 450 uses a fan-on-demand cooling system with foam air filters. Clean or replace filters every 500 operating hours or quarterly, whichever comes first. Blocked filters cause thermal overload and machine shutdown.
- Main disconnect inspection: Inspect the main input disconnect annually for arc scoring, loose lug connections, or overheated insulation. The main disconnect handles the full 6-machine input load — connection quality is critical to both safety and arc performance at every station.
- ArcLink cable inspection: Inspect ArcLink cable connectors at the machine junction annually. Bent or corroded pins in the ArcLink connector prevent the feeder from communicating with the power source, resulting in loss of CV mode and automatic parameter setting functions.
Q: Can all six stations in the 6-Pack RACK operate simultaneously at full output?
A: In theory, yes — each FLEXTEC 450 is independently rated for its own duty cycle. In practice, the shared input transformer and bus bars are engineered for a simultaneous duty factor (typically 50–60% of all stations at rated output simultaneously) consistent with production welding patterns. True simultaneous 100% duty cycle across all six stations would require an input transformer sized for 6 × full load — consult Lincoln Electric applications engineering for the specific K2957-2 simultaneous duty rating.
Q: What input breaker size does the K2957-2 require?
A: The input breaker size depends on the facility voltage and the simultaneous duty factor. At 460 V with all six machines drawing rated input current at 60% duty cycle, the input breaker is typically in the 400–600 A range. Refer to the K2957-2 nameplate and Lincoln's installation drawing for the specific breaker size — it varies with the as-configured tap voltage.
Q: Can individual FLEXTEC 450 machines be removed from the rack?
A: Yes. Each machine is bolted to the rack chassis and connected via bus bar quick-disconnect (on input) and output cable stabs (on output). Removal requires opening the main rack disconnect and following Lincoln's service procedure in document IM952. A trained technician can swap a machine in approximately 45–60 minutes without specialized tools beyond standard electrical hand tools.
Q: Does the 6-Pack RACK support CAC-A (carbon arc gouging)?
A: Yes. The FLEXTEC 450's CC mode supports CAC-A at up to 450 A DC, which covers all standard carbon arc gouging electrode sizes through 3/8 in (10 mm). Gouging generates significant heat and spatter — use appropriate heat shielding on the rack enclosure panels adjacent to the gouging station and ensure adequate ventilation in the area.
Q: Is the K2957-2 available with metric (380/400 V) input configuration?
A: Yes. The FLEXTEC 450's wide-range input accepts 380–575 V, 3-phase, 50/60 Hz, which includes European/metric standard voltages (380 V, 400 V, 415 V). The K2957-2 suffix covers this range. Confirm the tap position inside each machine matches your specific supply voltage during commissioning.
Q: What is the rack's weight and how is it typically moved?
A: Fully assembled, the K2957-2 weighs approximately 1,400 lb (636 kg). The rack base includes four-point lifting lugs for crane lifting and integral fork pockets for forklift transport. Never attempt to move a fully assembled rack by hand. A 2-ton overhead crane or 4,000 lb capacity forklift is appropriate for positioning the rack on a concrete pad.
Q: How does the 6-Pack RACK compare to running six individual FLEXTEC 450 machines?
A: The rack configuration reduces: (1) electrical installation cost by consolidating six individual disconnects into one; (2) floor footprint by approximately 65% versus six machines side-by-side; (3) cable clutter from input feeds; and (4) maintenance overhead by creating a common service point. The tradeoff is that a main bus fault can disable all six stations simultaneously — individual machines offer better fault isolation.