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Nitrogen Welding - Slot Tab Repair:
Standard Operating Procedure
Most automotive bumpers, side panels, and fuel tanks are made of polypropylene (PP) blends and are best repaired using the nitrogen welding process. A common point of damage on these parts is torn slot tabs.
This SOP will guide you through the repair process using Polyvance’s Nitro Fuzer plastic welder, 6146 Bumper Pliers, and polypropylene welding rod.
Step-by-Step Instructions
STEP 1: BEVEL THE EDGES OF THE TAB
Using a drum sander or die grinder with a tapered bit, bevel the edges of the broken slot tab.
STEP 2: SELECT THE PROPER PLIERS DIE
From the 6146 pliers kit, select the numbered die that best fits the desired slot size. Die should be snug, but not tight.
STEP 3: SECURE DIE IN SLOT
Secure the die in the slot with aluminum tape.
STEP 4: WELD AROUND THE DIE
Using Polyvance’s nitrogen plastic welder and R02 series plastic welding rod, weld around the die. You will most likely need to make two passes with the welding rod to match the original thickness. You may also have to weld a pass of rod beside your new welds in order to get the width to match that of the original tab.
STEP 5: REMELT THE FILLER ROD
Using the nitrogen welder, remelt the filler rod until it turns transparent.
STEP 6: FLATTEN THE WELD
Flatten the melted weld material using the numbered matching pliers until the plastic matches the original flange thickness.
STEP 7: REMOVE TAPE AND DIE
Once cool, remove the aluminum tape and the slot tab die. More rapid cooling can be accomplished by blowing the plastic with compressed air or by wetting the area with water.
STEP 8: SHAPE THE TAB
Now you can shape the tab with a variety of tools, such as the airless plastic welder, a drum sander, or a Roloc disc.
STEP 9: SAND SMOOTH
Once cool, use a DA sander or sand by hand to remove any extra material and refine the overall shape of the tab.
STEP 10: FINISH OUT THE TAB
Once you are satisfied with the tab's shape, finish sand, fill and prime with Polyvance products, and prepare the tab for paint.
