Finding the Correct Welding Temperature for your Plastic Welding Project

Every plastic has a set of parameters (temperature, pressure, time/speed) at which it should be welded. However, the perfect temperature for the application can vary depending on environmental conditions. If you are welding in a less than ideal environment, the only way to find the perfect welding temperature for your project is trial and error. If welding is taking place outdoors be sure to perform test welds periodically throughout the day to ensure your temperature is set correctly, as the environment can change over time.

​With this in mind, here are some guidelines to help you narrow down the starting temperature depending on the material being welded:

Material	Hot air temp. (°C)	Air flow (l/min
PE-HD	300 - 320	​40 - 50
PP	305 - 315	​40 - 50
PVC-U	330 - 350	​40 - 50
PVC-C	340 - 360	​40 - 50
PVC-P	300 - 370	​40 - 50
PMMA	320 - 370	40 - 60
PVDF	365 - 385	45 - 55

Welding a different plastic? See our more in-depth temperature charts for Hand Welding and Extrusion Welding. 

There are also indicators that can help guide you to the correct temperature. The ultimate sign of correct welding temperature is a strong weld

Indicators: Welding temperature is too HIGH

• The material is discoloured, scorched, or burned
• PP & PE – The material on either side of the weld has a shiny finish
• PVC – The material on either side of the weld has a dull finish or there is brown discolouration
• Hand Welding – The welding rod is completely flattened or smeared
• Extrusion Welding – When probing the material in the preheated zone ahead of the welder, there is significantly more than 0.5mm of penetration
• Presence of smoke - Smoke is a sign that the welding temperature is too high

Indicators: Welding temperature is too LOW

• The weld breaks easily
• Hand Welding – The welding rod retains most of its original shape (hardly flattens) and doesn’t penetrate deeply into the base material
• Extrusion Welding – When probing the material in the preheated zone ahead of the welder, there is less than 0.5mm of penetration

Indicators: Welding temperature is GOOD

• PP & PE – The material on either side of the weld has a dull finish
• PVC – The material on either side of the weld has a shiny finish
• Hand Welding – The welding rod is partially flattened and may have a small bead running down either side of the weld
  • Note: This is also dependant on proper welding pressure
• Extrusion Welding – When probing the material in the preheated zone ahead of the welder, there is approximately 0.5mm of penetration
  

Read our article on evaluating your welding seam for tips on what to look for in a weld.
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Originally Published: 10/22/2014