Advice · Welding rod
Welding rod consumption for sheet welding
How many metres of rod - or how many spools - does the job need? The calculator below gives the indicative welding rod consumption for PE-HD and PP sheets in wall thicknesses from 3 to 20 mm, divided by joint type: single-V butt joint 60°, double-V (X) joint and edge welding (a-dimension). The basis is the joint geometry in DVS 2207-3 and DVS 2207-4 combined with the materials' density and an empirical factor for bead and losses.
Calculate your consumption
Consumption per metre
26 g/m
0.026 kg/m
Total consumption
0.26 kg of rod for 10.0 m of seam
Spools of 3 kg
1
Our welding rod is typically supplied in spools of approx. 3 kg. Always buy whole spools, and rather one spool too many: the same colour and batch should be used throughout the job.
* needs special conditions or equipment · (x) cannot be welded
Indicative consumption tables (3-20 mm)
The figures are grams and kilograms of welding rod per metre of seam, calculated with the factors above. Choose the joint type and read for both materials.
Welding method: Hot gas / hot plate (DVS 2207-3, -1/-11)
Single-V 60° butt joint
| mm | PE-HD g/m | PP g/m | PVC-U g/m | PVDF g/m |
|---|---|---|---|---|
| 3 | 6 | 6 | 9 | 12 |
| 4 | 11 | 11 | 17 | 21 |
| 5 | 18 | 17 | 26 | 33 |
| 6 | 26 | 25 | 38 | 48 |
| 8 | 46 | 44 | 67 | 85 |
| 10 | 71 | 68 | 105 | 134 |
| 12 | 103 | 98 | 151 | 192 |
| 15 | 160 | 154 | 236 | 300 |
| 18 | 231 | 221 | 340 | 433 |
| 20 | 285 | 273 | 420 | 534 |
Double-V (X) joint
| mm | PE-HD g/m | PP g/m | PVC-U g/m | PVDF g/m |
|---|---|---|---|---|
| 3 | 3 | 3 | 5 | 6 |
| 4 | 6 | 5 | 8 | 11 |
| 5 | 9 | 9 | 13 | 17 |
| 6 | 13 | 12 | 19 | 24 |
| 8 | 23 | 22 | 34 | 43 |
| 10 | 36 | 34 | 53 | 67 |
| 12 | 51 | 49 | 76 | 96 |
| 15 | 80 | 77 | 118 | 150 |
| 18 | 116 | 111 | 170 | 217 |
| 20 | 143 | 137 | 210 | 267 |
Edge weld (a-dimension)
| mm | PE-HD g/m | PP g/m | PVC-U g/m | PVDF g/m |
|---|---|---|---|---|
| 3 | 5 | 5 | 8 | 10 |
| 4 | 9 | 9 | 13 | 17 |
| 5 | 14 | 14 | 21 | 27 |
| 6 | 21 | 20 | 30 | 38 |
| 8 | 36 | 35 | 54 | 68 |
| 10 | 57 | 55 | 84 | 107 |
| 12 | 82 | 79 | 121 | 154 |
| 15 | 128 | 123 | 189 | 240 |
| 18 | 185 | 177 | 272 | 346 |
| 20 | 228 | 218 | 336 | 427 |
Purging rod: keep the screw clean between jobs
A purging rod (also called a purge rod) is a rod of a suitable polymer that is run through the hand extruder when the job stops or when you change material or colour. The rod pushes the molten plastic out of the screw, barrel and nozzle so no residue is left behind to burn on. It is not welding rod: it must never end up in the joint, only carry the plastic out.
Why it matters for the weld
Plastic left in a hot screw degrades. It oxidises, turns dark and forms carbonised lumps that follow the melt into the next joint. The result is dark specks, pores or a weak spot in the seam - and in the worst case a joint that has to be redone.
PVC is the clearest example. PVC degrades quickly at welding temperature, and residue in the screw becomes sticky and burns onto the metal. At the same time hydrogen chloride (HCl) is released, which is corrosive to both screw and barrel. PVC must therefore never be allowed to cool inside the machine, and cleaning must happen while the plastic is still hot enough to follow the rod out.
When to purge
| Situation | Why | How |
|---|---|---|
| End of the working day and shutdown | Plastic that cools in the screw solidifies around it and has to be removed mechanically next time. | Run purging rod through while the machine is still at working temperature, and only shut down once clean rod comes out. |
| Change of plastic material | Residue of the old material mixes into the new weld and gives poor bonding - especially between PE and PP. | Purge until the rod comes out free of colour and material residue before filling the new material. |
| Change of colour | Dark residue shows through a light weld as streaks in the seam. | Same procedure as a material change: purge until the rod is a single colour. |
| Before a visible or documented joint | A clean screw gives an even seam without specks and pores. | Purge at the start of the job if the machine has been idle or has been switched over. |
How to do it in practice
- Follow the manufacturer shutdown procedure. Purging rod comes after - not instead of - the prescribed cleaning.
- Purge at working temperature and low screw speed so the plastic follows the rod out instead of being burnt.
- Purge until clean rod comes out, and empty the machine completely before shutting it down.
- Use only tools the manufacturer allows, and never push a steel rod into a hot, pressurised barrel. Remove the nozzle only after the machine is depressurised.
- Do not use solvents unless the manufacturer approves them.
If the plastic has already burnt on, the screw has to come out and be cleaned mechanically. The procedure is described in service and maintenance of welding machines.
Purging rod comes in several materials and diameters. Choose a rod that matches the material you weld and the temperature and rod range of the machine - ask us if in doubt.
How the figure is calculated
- Single-V 60°: area = s² · tan(30°) ≈ 0.577 · s² mm² (joint geometry per the DVS 2207 series, root gap covered by the factor).
- Double-V (X): area = 2 · (s/2)² · tan(30°) ≈ 0.289 · s² mm² - less rod than the V joint because the wall thickness is split over two sides.
- Edge weld: triangular area = a²/2 mm², with the a-dimension set equal to the wall thickness.
- Mass per metre = area · density · empirical factor (1.3 for V/X joints, 1.2 for edge welds). The factor covers bead reinforcement on top of the seam plus start/stop losses.
- Method factor: hot gas/hand welding 1.3 (V/X joints) and 1.2 (edge welds); extrusion welding 1.5 and 1.4, because the seam gets a reinforcing bead and more start/stop waste.
- Densities: PE-HD 0.95, PP 0.91, PVC-U 1.40, PVDF 1.78, ECTFE 1.68 and ABS 1.05 g/cm³ (PTFE 2.2, but PTFE cannot be fusion welded).
- Standard references: hot plate welding of PE and PP is described in DVS 2207-1 and DVS 2207-11, hot gas welding in DVS 2207-3, extrusion welding in DVS 2207-4 and hot plate welding of PVC-U in DVS 2207-12. The joint geometry (60° V, X, edge weld) follows the DVS 2207 series.
The values are indicative calculated figures based on the DVS 2207-3/-4 joint geometry - not official table values. Rod diameter, the actual root gap and your welding technique affect consumption. For large jobs we recommend calibrating the consumption on a test seam first.
Do you have a job that requires extrusion welding of large areas? Ask us about the extruder and the rod for the job.