Steel bar truss welding line selection should start with finished truss height, pitch, bar diameter, and saleable pieces per shift, because those numbers define the frame, welding heads, feeder, shear, and stacking system. If your plant runs 70-350 mm truss height with 190/200/210 mm pitch, don’t buy a line rated only by maximum speed; check repeatability at your hardest size.
Steel Bar Truss Selection Criteria
Use this steel bar truss welding line selection process:
- Confirm finished truss height range.
- Match top, bottom, and web bar diameters.
- Lock pitch options and pitch tolerance.
- Calculate saleable trusses per shift.
- Verify straightening, welding power, cutting, stacking, commissioning, and spare-part support.
A steel bar truss is a small structure, but the line that makes it has to control several movements at once: top chord feeding, two bottom chord positions, diagonal web bar forming, resistance welding, cutting, and finished truss discharge. One weak station slows the whole line. Usually it’s the web bar forming and weld timing, not the final shear.
If you are comparing Chinese suppliers, ask for a real configuration sheet before price negotiation. A serious girder truss welding line supplier should map your drawing to machine parameters: height range, pitch range, wire diameter, transformer capacity, line speed, air pressure, installed power, floor space, and operator count. A quotation that only says “automatic truss welding machine” is too thin for a plant investment.
This advice doesn’t apply to one-off prototype work or a manual welding fixture. It applies when you’re planning steady production for steel bar truss decks, precast concrete slabs, AAC panel reinforcement, or truss floor support plates.
Height Range Sets The Frame
Height decides the mechanical envelope. A 90 mm truss and a 300 mm truss don’t behave the same in feeding, forming, welding, or cutting. Taller trusses need more stable side guidance, more clearance around the welding area, and stronger control of diagonal bar tension. Short trusses punish poor alignment because a small error eats a larger share of the finished height.
A practical buying range is to specify both your normal height and your outside cases. For example: “Daily production: 100-250 mm. Occasional orders: 70 mm and 350 mm.” That one sentence changes the machine conversation. If the supplier designs only around 100-250 mm, your 350 mm truss may run slowly or need manual help at discharge.
For YZ Welding, the XHJ-350 type range is usually discussed when buyers need a line that can cover common floor deck and precast truss heights without changing the whole welding frame. When you review a steel bar truss welding production line, check whether the height adjustment is servo-controlled, handwheel-adjusted, or fixture-based. Servo adjustment costs more, but it pays back when you change product sizes every day.
Plant-floor check: ask the supplier to weld the lowest and highest truss in your order book during acceptance testing. Don’t accept a sample made only at the easiest middle height. The machine must keep the top chord centered, bottom bars parallel, and diagonal bars landing at the same weld point after 20-30 minutes of continuous running.
Pitch Decides Welding Rhythm
Pitch is the distance between repeated diagonal connection points. In truss production, pitch controls weld timing, diagonal bar forming rhythm, and cut length accuracy. A line that handles 200 mm pitch cleanly may still struggle when you ask for 190 mm or 210 mm pitch with frequent changeovers.
Here is the blunt version: fixed-pitch machines are fine for one product family; adjustable-pitch machines are better for export factories serving contractors with different slab systems. The drawback is price and setup discipline. If your operators don’t record recipes and verify the first five pieces after each change, adjustability just gives them more ways to make scrap.
| Buyer Situation | Better Pitch Setup | Why It Works | Check Before Purchase |
|---|---|---|---|
| One floor deck product | Fixed pitch, mechanical stop | Lower cost and simple operation | Confirm future drawings won’t change |
| 2-4 common products | Manual or semi-auto pitch adjustment | Good balance for mid-volume plants | Ask for changeover time in minutes |
| Export orders with mixed drawings | Servo pitch control with recipe storage | Faster changeover and fewer setup errors | Test all pitch values during FAT |
| High-speed standard truss | Fixed or servo, depending on tolerance | Speed depends on weld stability | Measure pitch after 100 pieces, not 5 |
Tolerance matters because truss welding errors travel downstream. If the pitch drifts, the truss may not match panel jigs, deck welding fixtures, or slab reinforcement drawings. ASTM International’s A1064/A1064M-22 covers carbon-steel wire and welded wire reinforcement for concrete; when export buyers reference ASTM-style documentation, your material certificates and finished reinforcement records need to match the order file.
Output Requires Real Cycle Math
Catalog speed is a starting point. Saleable output is the number that pays the loan.
Start with shift time. A 10-hour shift is 600 minutes, but you won’t weld for 600 minutes. Coil loading, straightener adjustment, pitch change, electrode dressing, first-piece inspection, lunch breaks, and minor alarms take time. For a new plant, using 70-80% effective production time is more honest than quoting perfect-condition speed.
Example: your target is 1,200 pieces per 10-hour shift, each 6 meters long. If the line makes 3.5 meters per minute in stable running, the math looks fine on paper. Then you add three product changes, two wire coil changes, and a 25-minute electrode cleanup. Now the line must recover with stable welds, not just fast motion.
Use this buyer calculation:
- Required finished length per shift: pieces x truss length
- Effective welding minutes: shift minutes x realistic running rate
- Required stable line speed: finished length divided by effective minutes
- Scrap allowance: add 2-5% for commissioning period, then reduce after operators settle
For high-output plants, pay close attention to wire feeding. Straightened bar from coil saves handling, but poor straightening creates a twisting truss. Pre-cut straight bar can improve stability for some diameters, but handling and loading cost go up. YZ Welding usually reviews bar diameter, coil condition, and finished truss length before recommending the feeding method, because a fast welding head can’t rescue bad incoming wire.
Configuration Table For Buyers
Your line configuration should match the hardest routine product, not the easiest sales sample. Ask for every value in writing.
| Selection Item | Low-Mix Factory | Mixed Export Factory | What To Ask YZ Welding |
|---|---|---|---|
| Truss height | One main range | 70-350 mm style coverage | Minimum, maximum, and adjustment method |
| Pitch | One fixed value | Several pitch recipes | Changeover time and recipe storage |
| Bar diameter | Narrow material list | Multiple top, bottom, web diameters | Transformer power and electrode plan |
| Output | Stable daily SKU | Frequent drawing changes | Good pieces per shift, not no-load speed |
| Cutting | One finished length | Multiple lengths per order | Cut accuracy and burr control |
| Stacking | Manual collection | Auto counting and stacking | Bundle size, discharge height, operator access |
| Control system | Basic PLC | PLC plus servo recipes | Available brands: Siemens, Mitsubishi, Delta, or requested equivalent |
| Service | Local maintenance team | Overseas startup support | Installation days, training plan, remote support |
Electrical and safety items belong in the purchase decision, too. Resistance welding equipment needs guarded controls, interlocked panels, shields for sparks, emergency stop buttons, and periodic inspection records; the United States Occupational Safety and Health Administration 29 CFR 1910.255 states these requirements for resistance welding equipment. Even if your plant is outside the United States, those points make a good checklist for factory acceptance.
One more question: can your power supply handle the line under load? A truss welding line draws current in pulses. The nameplate installed power doesn’t tell the full story. Ask for transformer capacity, recommended cable size, air compressor demand, cooling-water demand if used, and whether the supplier has run the same configuration on 380V/50Hz, 415V/50Hz, or your local voltage.
Commissioning And Quality Checks
Commissioning should prove four things: the machine can make your drawing, operators can repeat the setup, the welds hold under agreed inspection, and the finished truss fits your downstream process. If the line passes only because the supplier’s engineer is standing beside it all day, you’re not ready for handover.
Run acceptance testing with your real materials. Use the same top chord, bottom chord, and diagonal web bar diameters you plan to buy in bulk. If your factory will weld 5 mm web bar to 8 mm chord bar, don’t test only 4 mm to 6 mm because it looks cleaner. Keep 20 finished pieces from the test run and measure height, pitch, straightness, weld consistency, cut length, and end shape.
A practical FAT/SAT checklist:
- Weld 30 minutes at minimum height and maximum height.
- Change pitch, then inspect the first 5 pieces and piece 50.
- Cut short and long finished lengths.
- Stop and restart the line, then check the first weld after restart.
- Train two operators, not only one supervisor.
- Record electrode wear, air pressure, voltage, and alarm history.
This is where experienced suppliers earn their price. YZ Welding’s team can review your drawings, bar diameters, plant voltage, output target, and packing method before recommending the truss line configuration. Good steel bar truss welding line selection is less about buying the biggest model and more about buying the line that holds your daily size range without drama.
FAQ
What height range should I choose?
Choose a line that covers your normal truss height plus your known edge sizes. If daily production is 100-250 mm but orders sometimes require 350 mm, specify 70-350 mm class coverage during quotation.
Is servo pitch control necessary?
Servo pitch control is best when you change drawings often or export to several slab-system buyers. If your plant runs one fixed 200 mm pitch for months, a simpler fixed-pitch setup can be the better buy.
How is output calculated?
Calculate output from saleable finished meters per shift, then subtract time for coil loading, product change, inspection, and electrode maintenance. Catalog line speed alone doesn’t tell you how many accepted trusses you’ll pack.
What should commissioning include?
Commissioning should include drawing-based test runs, operator training, weld inspection, pitch measurement, height verification, cutting accuracy checks, and alarm handling. Ask for remote support and spare-part lists before shipment.
Send YZ Welding your truss drawing, required height range, pitch values, bar diameters, target pieces per shift, voltage, and plant layout. We’ll match those numbers to the right welding line configuration and quote the equipment, installation, commissioning, and after-sales support package for your factory.
