The Dodom catalog construction machinery does not compete with each other: each piece of equipment performs a different operation. Four of the five machines belong to the geomembrane installation world (hot air welding, extrusion welding, hot wedge welding, and audit manometer), and one handles industrial sack closing (portable sewing machine). The question is not "which is better" but "which fits the operation at hand." This comparison will tell you which one to order based on the specific task.
🎯 Choose in 10 seconds
- If you close polypropylene, kraft paper, mesh, or jute bags in a warehouse, scale house, or loading area: go to Portable sewing machine
- If you audit geomembrane seam integrity by air channel pressure test: go to Needle manometer
- If you weld details, corners, patches, or reinforcements in geomembranes where continuous wedge welding cannot reach: go to Hot air welding
- If you weld with filler rod to restore structural strength in critical HDPE points: go to Extrusion welding
- If you install large-format geomembranes with auditable double seams in dams, landfills, or reservoirs: go to Hot wedge welding
What to consider before choosing
Before requesting a quote, clearly identify the operation. Ordering an extruder when the job is linear hot wedge welding is very expensive and slow; ordering hot air for a large-scale dam ruins the schedule because the gun is for spots, not linear meters. These four criteria match the machine to the task:
- Type of operation: bag closing vs. geomembrane welding: the portable sewing machine (KORWINS 90 W) closes bags in a warehouse; the remaining four machines belong to the geomembrane installation ecosystem. If your operation is bulk dispatch, one question solves it: a sewing machine. If it's geomembrane, read on for the following criteria.
- Joint geometry in geomembrane: linear vs. punctual vs. audited: large-scale linear welding (dam, landfill, reservoir) requires motorized hot wedge welding. Details, corners, and patches require manual hot air welding. Critical repairs requiring full structural strength require extrusion with filler rod. Seam integrity auditing requires a needle manometer to pressurize the air channel of the double seam.
- Material thickness and strength requirements: light geomembrane (1-1.5 mm) in agricultural applications is welded with an 800 W wedge. Structural HDPE (2-2.5 mm) in dams and mining requires an 1800 W wedge. Repairs where the joint needs the mechanical strength of the original sheet can only be guaranteed with extrusion and a filler rod fused to the base material.
- Availability of contractual or environmental audit: projects with ISO 14001 environmental standards, public hydraulic contracts, or mining audits require a pressure test on the air channel of the double seam welded by hot wedge. Without a calibrated needle manometer, there is no certification, and without certification, the contract cannot be closed.
Portable sewing machine: fast bag closing in the warehouse
- 90 W motor for continuous full-day use
- One-hand operation: works in the loading area without moving the bag
- Compatible with woven polypropylene, kraft paper, jute, mesh, cotton
- Chain stitch that opens by pulling the thread at the destination
- Metal casing resistant to dust from mills and agrochemical companies
- Specific for bags: does not replace industrial fabric sewing machines
- Chain stitch is not for permanent joints (not for sewing clothes)
- Requires a specific thread spool for bag sewing machines
The KORWINS portable sewing machine —industrial bag closer— is the standard tool for any warehouse or scale house that dispatches bulk product. The difference from a domestic sewing machine is structural: the portable one has a feed system calibrated for slippery polypropylene bags and a motor sized for continuous operation in a warehouse throughout the day. The chain stitch is not a defect: it is the classic use condition of industrial packaging, where the recipient unstitches the bag by pulling the end of the thread. For rice mills, bean distributors, fertilizer factories, or cement dispatch in bags, this is the only practical answer.
Needle manometer: geomembrane seam integrity audit
- Calibrated metal body for continuous field use
- Stainless steel needle for precise insertion into the air channel
- Clear reading dial: detects pressure drop immediately
- Ergonomic wooden handle for applying force
- Connection hose with quick coupling to portable pumps
- Not a welding machine: only verifies already welded seams
- Only applies to double seams with an air channel (hot wedge)
- Calibration must be periodically revalidated for auditing
The KORWINS needle manometer doesn't weld anything: it's the quality control equipment that validates what the hot wedge welder has finished. The operation is simple: the needle is inserted into the air channel of the double seam, pressurized with a portable pump, and the dial is observed. If the pressure drops, there is a leak; if it withstands the declared cycle, the seam is sealed. Without a manometer, a geomembrane installed for a dam or landfill remains uncertified, and a contract with an environmental audit cannot be closed. It is mandatory equipment for serious contractors, not optional.
Hot air welding: details and spot repairs in geomembranes
- 1600 W power with stable flow under continuous work
- Adjustable temperature: works on membranes from 1 mm to 2 mm HDPE
- Compatible with flat, round, and speed welding nozzles
- Balanced ergonomics to reduce operator fatigue
- Metal casing resistant to dust and occasional impacts
- Does not weld linear meters quickly (it's for spots, not for long seams)
- Operator controls speed and temperature: requires calibrated technique
- No filler rod: joins by fusion of the base material only
The KORWINS hot air gun —hot air welder, manual welder— is the natural complement to hot wedge welding. The wedge makes long, fast, clean seams, but it doesn't get into corners, doesn't go around pipe outlets, and doesn't apply repair patches. For all that, hot air. The technique is manual: the operator presents the material, directs the hot air stream with one hand, presses with a silicone roller with the other, and moves at a constant speed. It's detailed work that requires experience. For a large-scale dam project, hot wedge welding covers 80-90% of the seam, and the hot air gun covers the remaining 10-20%, the details.
Extrusion welding: filler rod for critical HDPE points
- 3400 W power for continuous extrusion without flow drop
- Double heating: air prepares surface + rod melts
- 360° rotating head with adjustable shoe for any angle
- Safe cold start system: protects motor and polymer
- Interchangeable Teflon shoes (angle, overlap, fillet)
- High investment equipment: not justified for small projects
- Requires HDPE filler rod compatible with the base membrane
- Slow operation: for critical points, not for linear meters
The MOLTEXO manual extruder —extrusion welder— is the answer when the joint requires the mechanical strength of the original sheet. The hot air gun joins by fusion of the base material without adding anything; the extruder adds a polymer bead of the same material that flows from the head and is fused to both sides of the joint. This restores the original geometry with full structural section, a condition required for patches on dam bottoms, sealing PVC pipe outlets at tank bottoms, or repairing damage to HDPE of 2 mm or more. It is professional equipment for heavy civil engineering works and custom chemical tank manufacturing.
Hot wedge welding: large-format geomembrane installation
- Double seam with air channel for subsequent auditing
- Motorized traction for constant advance: uniform seam
- Calibrated digital or analog thermal control
- Two power options: 800 W (light membrane) or 1800 W (heavy HDPE)
- Robust construction for field work in quarries or landfills
- Only welds linear seams: details are done with hot air or extrusion
- Heavier and bulkier equipment: requires site logistics
- Longer setup time (heating, pressure regulation)
The KORWINS hot wedge welder —hot wedge welder— is the primary machine for any large-scale geomembrane project. The molten wedge simultaneously drags two overlapping sheets and leaves a central air channel between the two beads; motorized rollers apply calibrated pressure. Typical speed 1-3 m/min depending on material and thickness. The 800 W option covers light membranes (1-1.5 mm) in agricultural applications and small reservoirs; the 1800 W option is the only valid one for structural HDPE (2-2.5 mm) in dams, sanitary landfills, or leach pads. Without this machine, a hydraulic project of several thousand m² is not feasible within the timeframe, and without the air channel of the double seam, the impermeability cannot be audited with the manometer.
Comparison table
| Feature | Sewing Machine | Manometer | Hot Air | Extrusion | Hot Wedge |
|---|---|---|---|---|---|
| Primary Operation | Bag Closing | Seam Auditing | Spot Welding | Filler Rod Welding | Linear Welding |
| Target material | Polypropylene, paper, jute | Air channel in geomembrane | Geomembranes, PVC, TPO | Structural HDPE | HDPE / LLDPE Geomembrane |
| Power | 90 W | — | 1600 W | 3400 W | 800 W or 1800 W |
| Brand | KORWINS | KORWINS | KORWINS | MOLTEXO | KORWINS |
| Type of joint | Chain stitch | — | Fusion without filler rod | Filler rod | Double bead with channel |
| Contractual auditability | — | Yes (it is the audit) | — | — | Yes (air channel) |
| Travel speed | Fast manual | — | Slow manual (details) | Slow manual (points) | Motorized 1-3 m/min |
| Application | Warehouse / dispatch | On-site quality control | Details and patches | Critical points | Dam / spillway |
| Relative investment | Low | Medium-low | Medium | High | High |
Use case matrix → recommended product
When quoting a large-scale geomembrane project, it is correct to budget for the four ecosystem machines (hot wedge, hot air, optional extruder depending on specification, pressure gauge) plus consumables (filler rod, sealing tape, fixing wire). The common mistake is to buy only the wedge thinking that the hot air gun is optional; in real work, the details, patches, and reinforcements required by the gun can represent 20% of the operation. Without a gun, the work gets stuck at every corner or pipe outlet.
The pressure gauge and hot wedge work together. If you buy a hot wedge to install geomembrane in a project that will later be audited, the needle pressure gauge is not an accessory: it is mandatory to certify the double bead. Ordering only the wedge without the pressure gauge guarantees a technically well-welded job that cannot be formally delivered to the contractor until the pressure gauge is acquired and the pressure test is performed meter by meter.
Don't know what machines your geomembrane project needs?
A 5,000 m² dam does not require the same kit as an 800 m² agricultural reservoir. Indicate the area to be installed, the thickness of the geomembrane in your specification, and if the project has a contractual audit; the assistant will guide you on which machines to combine.
All compared products
Frequently Asked Questions
Can a single machine weld all the geomembrane on my project?
No, on a real project at least two machines are combined: hot wedge for linear seams and hot air gun for details. The extruder is optional depending on the specification and material thickness. A single machine only covers one type of joint.
Is the portable sewing machine suitable for sewing tarpaulins or industrial clothing?
No, that is not its purpose. The portable sewing machine is calibrated for woven polypropylene bags and industrial packaging. Sewing transport tarpaulins, clothing, or industrial uniforms requires a fixed industrial sewing machine with a different stitch and a motor sized for dense fabrics.
What filler rod does the extruder need?
The rod must be made of the same polymer as the base geomembrane (HDPE with HDPE, PP with PP). Typical diameters: 4 mm or 5 mm in a continuous reel presentation. Ordering a compatible rod is the installer's responsibility; if you need specific guidance, consult the assistant.
Does the 800 W wedge weld 2 mm HDPE?
It is not recommended. The 800 W is sized for light membrane 1-1.5 mm (agricultural LLDPE, small reservoirs). For structural HDPE of 2 mm or more, 1800 W ensures stable temperature and homogeneous fusion. Welding 2 mm HDPE with the 800 W wedge produces weak seams that fail the audit.
How long does the pressure test with the manometer take?
It depends on the seam section to be audited. The typical operation is: insert needle, pressurize the channel to the declared pressure, maintain the cycle for the time established by the standard (5-10 minutes typically), record initial and final readings. If there is no drop, the seam is watertight. A complete audit of a dam can take several days.
Does the hot air gun replace the extruder?
Not for critical points. The gun joins by melting the base material without adding filler rod; the extruder adds material and returns a complete structural section. For reinforcement patches on an audited dam or sealing pipe outlets in a tank, the extruder is mandatory.
Do I need a compressor to operate the manometer?
No, the manometer connects to a portable manual or low-capacity air pump. The typical test pressure is relatively low (enough to detect leaks in the air channel), it does not require an industrial compressor.
Can the hot wedge be used on 2.5 mm HDPE in a dam?
Yes, the 1800 W wedge is suitable for structural HDPE up to 2.5 mm in dams, sanitary landfills, and leaching cells. Verify that the travel speed adjusts to the thickness: for greater thickness, slower speed to ensure complete material fusion.
Do these machines require regular maintenance?
Yes. The hot wedge and extruder require cleaning the shoes after each day to prevent burned polymer accumulation; the hot air gun requires checking nozzles and filters; the manometer requires periodic recalibration to maintain auditable accuracy. Ask the manufacturer for the specific schedule for your model.