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Originally Posted by lewster ...you need a welding rod of the same material. THIS IS KEY TO SUCCESS!! You heat the seam and rod to the melting point and as you apply the rod to the seam, you will see the plastic flow from the rod and the base material will 'juice' or just slightly melt. This process is very necessary for a solid weld.
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Again, selection of the proper welding rod is very important to the process. If you are not sure if the materials are alike, do a burn test. The rod and base material should react identically as to smell, smoke and burn characteristics if the are indeed the same.
The flow setting on the welder is equally important and should be vaied during the test and practice sessions to obtain the optimal air flow (and the associated heat setting) ... |
Lew, the obvious sometimes escapes me! A simultaneous burn test! Wow, now I don't have to figure out if it smells like a "candle" or is "acrid." Thanks.
Yes, the proper rod is important, that's why I can't figure out why the "suspect" rod won't weld. The sheet and rod are both supposed to be LDPE. Even a piece of the sheet won't weld to itself. A plastics house here told me that
it's extremely difficult to get LDPE to weld. Maybe this is an example of that.
Here's a shot of the HF welder. You can see the router speed control in the background. I don't have a
too hot problem, so the controller is handy because it has a convenient on-off switch. The heat (per the expert mentioned above) is properly applied
between the rod and the groove.
I've got photos of successful welding [yesterday] of the HDPE, polypropylene, and the cutting board that
Bedfords left me. I used rod and sheet for the HDPE and polypropylene test, and a strip cut from the cutting board for that test. The welds are pretty ugly, but at least they demonstrate good adhesion. I don't think the welder is hot enough--the welding is slow--but I've reduced the air pressure to 3-1/2 psi to get it as hot as I dare, which is getting pretty close to burning out the welder. Here's just one example of the polypropylene weld--the others are similar.
Zep