Reinforcing mesh does a great job for most concrete work. But sometimes you need more than a flat sheet of steel. Precast slabs, bridge decks, and railway sleepers have to carry heavy loads over longer spans. A flat mesh won’t always cut it. That is when you need lattice girders.
A lattice girder is a triangular steel frame. One bar on top, two bars on the bottom, and diagonal wires zigzagging between them. The shape gives it strength without adding much weight.
A lattice girder welding machine is the equipment that makes these frames. You feed it wire coils, and it straightens, bends, welds, cuts, and stacks all in one continuous flow.
Overview of Lattice Girder Welding Machines
A lattice girder welding machine is a continuous production line for prefabricated steel trusses. It processes chord and diagonal wires from coils, controls the truss geometry, welds the intersections, and cuts each girder to length. The operator sets the recipe; the line repeats the forming and welding cycle.
The term needs one boundary. This machine normally makes welded reinforcement for precast floor slabs, double walls, and related concrete elements. It does not fabricate the large structural lattice girders used in bridges or long-span steel roofs.
Machines vary in automation. A basic line needs more manual adjustment. A fully automatic line coordinates feeding, forming, welding, cutting, and discharge. Some girder truss welding lines also store recipes for different heights and pitches.
The final girder drawing still comes from the precast designer or structural engineer. Machine flexibility does not approve a new reinforcement layout. It only determines which approved layouts the factory can produce.
Main Components of a Lattice Girder Welding Machine
The equipment is a group of linked stations. Each one controls part of the wire path or girder geometry.
- Wire payoff system. Uncoilers hold five wire coils. Brakes and tension detection prevent uncontrolled payoff.
- Straightening unit. Horizontal and vertical rollers remove coil set before forming. Poor setup can twist the girder.
- Wire guides and buffers. Guides hold each chord on center. Buffers balance continuous payoff with stepwise welding.
- Diagonal forming unit. This station bends two wires into zigzags. Its settings control height, pitch, and weld-node position.
- Upper and lower welding units. Electrodes clamp the wires. Current and pressure create resistance welds without filler metal.
- Clamping and feed system. The unit pulls the girder forward. Stable clamping protects pitch and cut length.
- Shear and discharge rack. The shear cuts at a programmed node. The rack supports and removes the girder.
- Control and utility systems. The PLC, drives, electrical cabinet, and cooling circuit synchronize the line. Guards and alarms protect the work area.
The YZ Welding XHJ-350 reference design includes uncoiling, straightening, the main machine, discharge, hydraulic and electrical control, and water cooling. That layout helps buyers check quotation scope.
How Does a Lattice Girder Welding Machine Work?
The production cycle follows the wire from coil to finished length. It repeats after the first-piece check.
- Load the five wire coils. The operator confirms the upper chord, lower chord, and diagonal wire specifications. Each coil is routed through its assigned payoff and guide.
- Straighten and tension the wire. Roller sets remove curvature. The payoff brakes and buffers maintain controlled tension without dragging the wire off-center.
- Form the diagonals. Two diagonal wires pass through the forming unit. Rollers or bending tools shape them into matching zigzags on both sides of the girder.
- Position the weld nodes. The machine brings the diagonal peaks and valleys into contact with the top and bottom chords. Guides and clamps hold the five wires in the required geometry.
- Resistance-weld the joints. The electrodes close, current flows through the contact area, and local resistance creates heat. Pressure holds the wires together during the short weld cycle. Current, weld time, electrode force, and contact condition must suit the wire combination.
- Advance and repeat. The feed system pulls the new section forward by one pitch. Forming and welding repeat as a continuous rhythm. A small feed error can accumulate, so operators check pitch over several waves rather than measuring one gap.
- Cut and discharge. When the programmed length is reached, the shear cuts at the chosen node. The rack supports the girder, then releases it for bundling or transfer to the precast area.
The first-piece check matters more than a fast start. Measure height, width, pitch, straightness, and cut length. Then test welds by the approved method. If a weld fails, changing only the current may hide a feeding, pressure, surface, or electrode problem.
Common Applications of Lattice Girders
The main market is precast concrete. Lattice girders help a thin precast element during production, lifting, transport, and erection. Depending on the approved design, they can also connect the precast layer with concrete poured on site.
| Application | What the lattice girder does |
|---|---|
| Semi-precast floor slabs | Adds stiffness during handling and supports the connection with the in-situ topping |
| Precast double walls | Connects the two concrete leaves and helps maintain their spacing |
| Precast beams and deck elements | Provides project-specific reinforcement and positioning support |
| Special concrete components | Meets a confirmed drawing for height, wire combination, pitch, and length |
The Concrete Society overview of lattice girder slabs describes these slab units as precast soffits and permanent formwork for composite floors. The site usually adds top reinforcement and in-situ concrete according to the structural design.
Two floor-slab factories may need different heights, wire diameters, batch sizes, or cutoff rules. Start with approved drawings, not the application name.
Key Factors to Consider in a Lattice Girder Welding Machine
Begin with the products you must deliver. A few real girder drawings tell a supplier more than a request for the “fastest model.”
- Wire range and material. Confirm the diameter, grade, surface condition, and coil size for the chord and diagonal wires. These details affect the payoff, straightening, forming, and welding systems.
- Girder dimensions. Define the required height, width, diagonal pitch, and foot shape. Check the full adjustment range, not only one sample size.
- Finished length. Give the minimum and maximum girder lengths. The supplier also needs to know where the shear must cut in relation to the weld node.
- Product mix and changeover. List the standard products, special products, and typical batch sizes. Frequent small batches make quick, repeatable adjustment more valuable.
- Real production output. Compare accepted metres or finished pieces per shift. Include coil changes, setup, quality checks, cutting, and product removal in the calculation.
- Factory utilities and layout. Check the connected power, cooling water, compressed air, line length, and maintenance space before choosing a machine.
- Quality control. Agree on dimensional checks, weld tests, sampling frequency, and batch traceability. The machine settings should connect directly to the approved quality plan.
- Installation and support. Confirm commissioning, operator training, spare parts, remote support, and service response. These items affect production long after the acceptance test.
Published YZ Welding data for the XHJ-270 and XHJ-350 gives a useful reference range: 70–350 mm girder height, 190–210 mm wave pitch, 4–8 mm diagonal wire, and 6–14 mm chord wire. Treat those figures as model references, not universal limits. The XHJ-270 and XHJ-350 comparison explains how two lines with similar product ranges can still suit different production plans.
Quality requirements deserve their own discussion with the supplier. ISO 15630-2:2019 covers mechanical and chemical test methods and measurements of geometrical characteristics for welded fabric and lattice girders. The contract and local product rules must state the actual sampling and acceptance limits.
If you are planning to add a lattice girder welding line or upgrade your existing setup, start with your girder drawings and production targets. Send them to YZ Welding, and we will walk you through the configuration that fits your product range, output, and factory layout.
Related article: How to Choose a Truss Girder Welding Machine
FAQ
What does the lattice girder welding machine produce?
It produces welded steel lattice girders with upper and lower chord wires connected by formed diagonal wires. The finished girder is normally used as prefabricated reinforcement in precast or semi-precast concrete elements.
How is the zigzag wire formed?
The diagonal wire passes through powered forming rollers or bending tools before welding. The forming settings control the height and wave pitch, while guides bring each bend into the correct chord-wire contact point.
Does it use resistance welding?
Yes. Electrodes apply pressure while electrical current heats the contact area between the diagonal and chord wires. The process joins the wires without adding filler metal.
Can girder height be changed?
It depends on the machine. Some lines use manual mechanical adjustments, while more automated systems can change height through a stored recipe and powered positioning. The usable range must still match the wire combination and approved product drawing.
