Resilient Floor Welding with Leister

A welding rod, as recommended by the manufacturer, must be used when installing linoleum, rubber, PVC, or TPU surfaces. Welding rods are generally available with 3 to 5 mm diameters. Speak with your material manufacturer or supplier to find out more.

Before welding, the seam edges must be milled or grooved to approx. 2/3 of the thickness of the material. The welding rod is then welded into the groove to create a strong bond. It is important that the welding rod fully penetrates the milled groove otherwise the seam may fail prematurely.
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The welding rod is then trimmed in two stages: The first pass is done with a trimming guide immediately after welding. This removes the bulk of the excess rod. The second pass is done once the material has cooled completely. This helps prevents concave seams, producing an even, flush seam with a long service life. 

Welding in 4 Steps

Grooving

The floor covering must first be affixed to the surface with adhesive. Follow manufacturer directions to properly prepare the substrate to achieve a solid bond.

Caution: Before milling a groove, the adhesive between the substrate (screed) and the floor covering must be dry.

A groove must be milled at any seams in the floor covering. An automatic grooving machine is preferred over a hand groover for speed and consistency.

Different blades are available and the correct one should be chosen based on the properties of the floor covering and the welding rod being used.

Consult the material manufacturer for information on groove depth. However, basic guidelines for milling depth (Fig. 1):

• A maximum of half of the wire thickness
• 2/3 of the material thickness
• Linoleum to the substance (jute/scrim)

​The milled groove should be centered on the seam, otherwise the weld will not be adequate and may fail prematurely (Fig. 2).

Welding – preparation

​Test welds should be performed on scrap material to determine the correct speed and temperature for each job. Besides material type, environmental factors can effect welding temperature and speed. Welding rod should penetrate the entire groove with no gaps (Fig. 3).

Material	Manual Welding Temperature	Automatic Welding Temperature
Linoleum	Approx. 300–400°C	Approx. 400–450°C
PUR/TPU	Approx. 350–400°C	Approx. 450–500°C
PVC	Approx. 350–450°C	Approx. 450–550°C

​A welding nozzle with a narrow air outlet is recommended to avoid damaging the surface of material near the seam. This damage only becomes visible after several cleaning cycles.
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An automatic welder such as the UNIFLOOR or MINIFLOOR should be used for longer seams. Automatic welders produce more consistent welds at a faster speed. Short seams can be welded with a hand tool such as the TRIAC ST/AT or the HOT JET S.

Welding – implementation

Welding with an automatic welder (UNIFLOOR / MINIFLOOR)

Recommended due to time savings and higher weld quality that is easily reproduced.

• Constant (high) speed
• Constant pressure
• Constant temperatures (UNIFLOOR E / MINIFLOOR with TRIAC AT)

Caution: When using UNIFLOOR, the 2/3 flap must be closed for linoleum.

Manual welding (TRIAC / HOT JET S / GHIBLI)

Recommended for short grooves, repairs, or transitions.
For a consistent weld quality, the following must be taken into consideration:

• As constant a speed as possible
• As constant a pressure as possible
• Constant temperature (TRIAC AT)

The TRIAC AT uses closed-loop temperature control to compensate for fluctuations in voltage and environmental conditions which might affect temperature. 

Trimming

The welding rod is trimmed in two stages to prevent the seam from becoming concave after cooling. The first trimming stage takes place before the weld has cooled using a sharpened quarter-moon knife and a trimming guide (Fig. 4).

The second trimming stage takes place after the weld has cooled. The cut is made flush to the surface of the material using a quarter moon knife without the trimming guide (Fig. 5).

• Rest period for linoleum approx. 15 minutes
• Rest period for PVC approx. 5 minutes

​Be sure to consult the manufacturer for the rest period before the floor can be used or cleaned. However, typically:

• Rest period for linoleum approx. 12 hours
• Rest period for PVC approx. 1 hour