Before buying an automatic steel bar truss welding line, many factories ask for the rated speed first. That is useful, but it is not enough. To calculate steel bar truss welding line capacity realistically, you need to connect line speed with truss length, truss height, wire diameter, cutting cycle, discharge handling, changeover time, shift hours, and expected utilization.
The short answer: start with the rated operating speed, convert it into theoretical meters per hour, apply a realistic utilization factor, then divide by the truss length to estimate pieces per hour. After that, multiply by productive hours per shift and shifts per day. This gives a working capacity estimate before you request a formal quotation.
Steel Bar Truss Welding Line Capacity Formula
Use these formulas as a first-pass calculation:
- Theoretical meters per hour = rated line speed in m/min x 60
- Actual meters per hour = theoretical meters per hour x utilization factor
- Trusses per hour = actual meters per hour / truss length in meters
- Trusses per shift = trusses per hour x productive hours per shift
- Daily output = trusses per shift x number of shifts per day
The utilization factor is the correction that makes the calculation realistic. It accounts for coil loading, height adjustment, wire diameter changes, production start-up, operator checks, cutting, discharge, minor stops, inspection, and maintenance. For a new factory, a conservative factor may be 0.55-0.65. For a stable factory with trained operators and repeated products, 0.70-0.85 may be more realistic.
Steel Bar Truss Welding Line Output Example: 12 m/min Reference Speed
YZ Welding’s published truss welding line information lists a rated operating speed reference of 12 m/min, changing with truss height. Use this as a calculation example, not as a guaranteed output for every truss drawing.
| Calculation Step | Example Input | Result |
|---|---|---|
| Rated speed | 12 m/min | 720 m/hour theoretical |
| Utilization factor | 70% | 504 m/hour actual estimate |
| Truss length | 8 m | 63 trusses/hour |
| Productive shift time | 7 hours | 441 trusses/shift |
| Daily schedule | 2 shifts | 882 trusses/day |
In this example, the theoretical line speed looks simple, but the actual result depends heavily on truss length and utilization. If the truss length changes from 8 m to 12 m, pieces per hour drop even if meters per hour remain the same. If utilization drops from 70% to 55%, daily output changes again.
Why Rated Speed Is Not the Same as Factory Capacity
Rated speed describes machine movement under specific conditions. Factory capacity describes how many usable steel bar trusses your plant can produce during a real shift. The difference comes from product mix, operator workflow, raw material quality, changeover frequency, and downstream handling.
| Factor | How It Affects Capacity | What to Confirm Before Buying |
|---|---|---|
| Truss height | Taller or more complex trusses may require slower stable operation | Straight truss and bending-foot truss height range |
| Wire diameter | Larger bars affect feeding, forming, welding heat, and straightness | Upper chord, lower chord, and wave wire diameter |
| Truss length | Longer trusses reduce pieces per hour but may keep meter output high | Standard length and maximum project length |
| Wave spacing | More frequent bending and welding points affect production rhythm | 190-210 mm spacing or project-specific spacing |
| Cutting and discharge | Handling can become the bottleneck after welding | Discharge rack length, stacking, and operator access |
| Changeover | Frequent height or wire changes reduce productive time | Recipe setup, adjustment time, and operator training |
How to Match Product Specifications to Your Welding Line Capacity
For XHJ steel bar truss welding production lines, published specification points include straight truss height from 70-350 mm, bending-foot truss height from 70-300 mm, wave crest spacing from 190-210 mm, wave wire diameter from 4-8 mm, and upper and lower chord wire diameter from 6-14 mm. These values help define what the line can process, but they do not automatically define daily output.
A factory producing 70 mm trusses with short lengths and repeated specifications will not have the same shift output as a factory producing taller trusses with frequent length changes. Before comparing models, prepare your real truss drawing list and calculate capacity for your top three product sizes.
Build a Simple Capacity Table Before Requesting a Quote
A practical buyer should build a table before asking for a quotation. This helps the supplier recommend the right line configuration and prevents misunderstandings about output.
| Product | Truss Height | Length | Estimated Speed | Utilization | Pieces/Shift |
|---|---|---|---|---|---|
| Floor deck truss A | 120 mm | 8 m | 12 m/min | 70% | 441 |
| Precast truss B | 200 mm | 10 m | Confirm with supplier | 65% | Calculate after speed confirmation |
| Heavy truss C | 300 mm | 12 m | Confirm with supplier | 60% | Calculate after trial or supplier estimate |
The numbers in the first row show the method, not a universal guarantee. For taller or heavier trusses, ask the supplier to confirm a safe operating speed and expected output based on your drawings.
Do Not Forget Shift Losses
A common mistake is multiplying rated speed by the full shift length. An 8-hour shift is rarely 8 hours of continuous welding. Productive time may be reduced by start-up checks, coil loading, raw material inspection, first-piece inspection, height adjustment, wire change, electrode checks, short stops, and end-of-shift cleaning.
- New factory: use 5.0-6.0 productive hours per 8-hour shift until operators are trained.
- Stable production: use 6.5-7.2 productive hours if product mix is repeatable.
- Frequent changeover: reduce productive time according to the number of height, length, or wire changes.
- High inspection requirement: include time for straightness, weld quality, and length checks.
Check Utility Capacity Before You Trust the Output Number
Capacity is not only mechanical speed. The factory must support the line with stable power, compressed air, hydraulic pressure, and cooling. Published data for YZ truss welding lines includes 380V 50Hz power, three phase-four wire, 0.6-0.8 MPa air pressure, cooling liquid flow above 150 L/min, cooling liquid temperature at 30 C or lower, and 7-11 MPa oil pressure. If these utilities are unstable, the line may not maintain planned output.
Factory layout also matters. Published equipment dimension is 39.4 m x 4.4 m x 3.3 m, but your production space must also include coil storage, operator aisles, hydraulic station, cooling area, finished truss discharge, forklift movement, and maintenance access. For layout planning, see our floor deck truss production line layout guide.
What to Send to the Supplier
To get a meaningful capacity estimate, send the supplier more than a target output number. A good request should include real drawings and production assumptions.
- Truss drawings with height, width, wave spacing, foot type, and length.
- Upper chord, lower chord, and diagonal wire diameters.
- Expected daily or monthly demand by product type.
- Number of shifts and planned working hours per shift.
- Expected changeover frequency by height, length, and wire diameter.
- Available power, compressed air, cooling water, and floor space.
- Downstream handling method: manual discharge, rack, stacking, or transfer.
- Required quality checks for straightness, weld strength, and cut length.
You can also compare models in our XHJ-270 vs XHJ-350 steel bar truss welding line guide and review how to choose a line by height, pitch, and output. For operating quality, read about truss straightness control and common steel bar truss welding defects.
Steel Bar Truss Capacity Planning: Rule of Thumb
If your product mix is simple and repeated, calculate capacity with a higher utilization factor after supplier confirmation. If your factory changes product size often, use a conservative factor and calculate each product type separately. The goal is not to get the biggest theoretical number. The goal is to know whether the welding line can support real orders without creating bottlenecks at feeding, cutting, discharge, or inspection.
For a specific capacity estimate, visit the Girder Truss Welding Lines category or contact YZ Welding with your truss drawings, output target, and shift plan.
FAQ
How do I calculate truss welding line output per hour?
Multiply line speed in m/min by 60 to get theoretical meters per hour. Then multiply by a utilization factor and divide by the truss length in meters to estimate pieces per hour.
Is rated speed the same as daily capacity?
No. Rated speed is a machine reference. Daily capacity depends on truss length, height, wire diameter, changeover, shift time, discharge handling, inspection, and operator skill.
What utilization factor should I use?
For a new factory, use a conservative factor such as 0.55-0.65. For stable production with repeated products and trained operators, 0.70-0.85 may be more realistic after supplier confirmation.
Why does truss length change the number of pieces per hour?
The machine produces length over time. Longer trusses use more meters per piece, so pieces per hour decrease even if meters per hour remain stable.
What data should I send before asking for a capacity estimate?
Send truss drawings, height, length, wire diameters, wave spacing, daily demand, shift plan, changeover frequency, factory utilities, and handling method.
