COMET 700 Hot Wedge Welding Machine – the New Leister High-Flyer

Product Stories26 Nov 2021

Despite the astronomical name, Leister’s COMET 700 hot wedge welding machine cannot fly yet. Thanks to its LQS, digital display of joining pressure and voltage, alarm function and other features, it delights users in the underground engineering sector. In this blog post, we will take a closer look at the new high-flyer among the hot wedge welding machines.

Author: Silke Landtwing, Manager of Corporate Communications, Leister AG

If you lay geomembranes in underground engineering and then weld them, for example to seal landfills and mines, you will know how important the quality of the welding seam is. After all, your customers expect the welded geomembranes to be leak-tight, because they want to be certain that no pollutants enter the soil and groundwater.

Even when sealing ponds, reservoirs and aquacultures, the leak-tightness of the welded geomembranes is of primary importance. After all, the precious water should not seep into the ground. But how do you find out whether the quality is right and the welding seam is tight?

Documented welding parameters thanks to Leister Quality System (LQS)

Do you prefer to check and document the quality of your welding seam right away at the construction site?

No problem: Simply weld your next welding seam with the Leister COMET 700. Featuring the Leister Quality System (LQS), WIFI and GPS, the COMET 700 documents welding parameters, speed, temperature and joining force, including coordinates via data report in the myLeister app. You will then receive the report on your welding directly on your smartphone or tablet at the construction site.

Time is money

The saying “time is money” by Benjamin Franklin is age-old. It now exists in all possible languages. The meaning is clear: The faster you complete something, the more you earn. For example, think of the deadline pressure on the construction site. Or the next order that is already waiting. Either way, the COMET 700 saves you even in terms of speed, because it reaches a high speed of 8 m/min / 26 ft/min.

Joining pressure under control

Trust is good, but control is better! Clearly, everything revolves around the quality of your welding seam. And this is related to the joining pressure, among other things. When welding with the COMET 700, you can view it via the display. And in the event that you need to concentrate on something else, the COMET 700 will signal you with an acoustic signal when the joining pressure leaves the range you have defined.

Optimized hot wedge shape for efficient heat transfer

The optimized shape of the hot wedge ensures particularly efficient heat transfer during overlap welding with the COMET 700. The hot wedge has two lengths: 60 mm/2.36 in and 90 mm/3.54 in. Why? With the 90 mm wedge or 3.54 in wedge, you can weld 1.5–3.0 mm or 59–118 mm thick geomembranes. For the thinner geomembranes, take the 60 mm wedge or 2.36 in wedge.

Do you want to weld geomembranes made of HDPE and LDPE? For this purpose, Leister offers hot wedges made of copper. For welding PVC, Leister offers hot wedges made of steel.

Always the right accessories

In addition to various hot wedges, Leister also offers various drive rollers and kits. For example, users can choose between drive rollers of different widths made of steel or silicone and with or without a test channel. You may already be familiar with the drive rollers from your Leister Geo welding machines TWINNY T7 and TWINNY T5 or from the previous COMET model. They are already successfully used worldwide, which is why we are not reinventing the wheel, but designing our drive rollers in such a way that they fit all Leister Geo welding machines in the TWINNY and COMET family.

High heating power reserves to balance undervoltage

Do you know anyone who has never had any problems with undervoltage when working on an underground construction site? Neither do we. The high heating power reserves on the COMET 700 ensure high-quality welds, even if undervoltage occurs.

Constant welding speed in tough environments

You would prefer to have smooth floors and even terrain on the construction sites. Unfortunately, we cannot fulfill this request. But your COMET 700 has a powerful drive motor and its field kit (mounted as standard) provides more distance to the ground, which helps with challenging terrain. Whether steep or bumpy or both: With your COMET 700, you can always weld confidently and at a constant welding speed.

Cleverly placed

Our product designers have also thought of you when positioning the handles of the COMET 700. Because we want to make the work and handling of our automatic welders as easy as possible for you. That’s why the COMET 700 is equipped with three cleverly positioned handles and can be easily guided and lifted by you.


The COMET 700 is extremely well equipped for reliable welding of thick and thin geomembranes. Thanks to its innovative electronic equipment and particularly high heating output, the new Leister high-flyer sets the benchmark among hot wedge welding machines in underground engineering.

COMET 700 – the best at a glance

  • WIFI, GPS and Leister Quality System (LQS) for documentation of welding parameters
  • Speed up to 8 m/min / 26.2 ft/min and without gearbox conversion
  • Optimized wedge shape for efficient heat transfer
  • Hot wedge in 60 mm/2.36 in and 90 mm/3.54 in length available
  • Digital display of joining pressure with acoustic alarm
  • Digital voltage display
  • High heating capacity reserves help with undervoltage
  • Robust drive motor and field kit for constant welding speed in tough environments
  • Intuitive operation with digital display of the relevant parameters
  • Good handling thanks to cleverly positioned handles
  • Slim design for overlap category 125 mm/4.92 in


The little brother COMET 500

The COMET 500 hot wedge welding machine is so to speak the little brother of the COMET 700. It is also very well suited for overlap welding of thick and thin geomembranes. Thanks to its intuitive operation, but without LQS and advanced electronic functions, it is the perfect alternative for purists and beginners with a smaller budget.