Why Do Some Plastic Crankbaits Swell From Heat?

[Chuck Young]

I have read about this sonic welding. Believe it or not, it is stronger than glue. Just try tearing apart that clam-shell packaging. In the same way metal that is welded is stronger than metal that is soldered. 

[SW Lures]

Actually a "fusion" or weld, if done properly is much stronger the the plastic or steel. In my profession the joining of plastics is referred to as fusing. Fusing by a heated plate then pressure is put on the two pieces. However in joining large plastic tanks the joint is referred to as welding. It's welded like a TIG process.

Interesting that in that industry it's referred as welding, when friction and pressure causes the joint. I will have to watch the video.

Thanks for the FYI,

Dale

p.s., It was interesting. Would enjoy setting down with Marilyn and chat about painting lures. She must be a treasure trove of knowledge. Unbelievable!!!

Edited June 5, 2016 by DaleSW

[Chuck Young]

Some companies use high frequency vibration to fuse the two sides together,you can watch on YouTube how ratltraps are done this way.since no glue is used in this process wonder if anyone has had them swell?

The laws of physics still apply. The plastic will soften and even melt if it gets hot enough. The Air inside will want to expand and go through the softened plastic at it weakest point. That point won't be the weld. But the bait will still be ruined. I am afraid there is no plastic bait that is impervious to heat. It is just a matter of degree - pun intended. The solution is to take care not to expose baits to high temperatures while fishing or storing. 

[RayburnGuy]

If you want to get an understanding of why a lure swells in the heat go outside and build a small fire. Now throw a can of pork and beans into the fire. It won't be long and comprehension will smack you right in the face.

 

Ben

[Chuck Young]

Actually a "fusion" or weld, if done properly is much stronger the the plastic or steel. In my profession the joining of plastics is referred to as fusing. Fusing by a heated plate then pressure is put on the two pieces. However in joining large plastic tanks the joint is referred to as welding. It's welded like a TIG process.

Interesting that in that industry it's referred as welding, when friction and pressure causes the joint. I will have to watch the video.

Thanks for the FYI,

Dale

p.s., It was interesting. Would enjoy setting down with Marilyn and chat about painting lures. She must be a treasure trove of knowledge. Unbelievable!!!

As a long time welding supply salesman I can tell you Dale is right about the end results of welding. It really doesn't matter the method used to melt the substrate (base material) - heat, friction, electric arc, high frequency sound, explosives, etc. As long as the substrate(s) are fused without chemical alteration (glues) they are welded and become one contiguous piece. Some industries use different words for for the process (fusion) . Dale is absolutely right. The weld itself is as strong and usually stronger than the material itself. Unfortunately, in the case of plastic lures, the substrate itself has serious, although manageable, limitations. 

[SW Lures]

LOL Ben, I seen something like that.

I have to tell this story.....The guys, way back in the day took can foods and put them on a compressor motor to warm them up. One gent took a can of pork and beans and did this. About five minutes later a boom was heard. The can of pork and beans blew up all inside of the motor compartment. The good thing was the side doors was close.

I looked around and I asked "did you open the can in some way". The answer was, "nope". Pork and beans was everywhere and took time to burn off.

I would think a lure is most likely the same way.

I'm sorry I had to tell that story since it related to the topic in some ways.

Dale

Edited June 6, 2016 by DaleSW

[mark poulson]

We used to warm our can goods in the winter on the hot tar kettle, but we made sure to open them first.

[Chuck Young]

The sad part is that hungry cowboys trailed that car for months, being lured in by the smell.

[tendelta]

Have been thinking of this problem, has to be increase of air pressure inside of baits.  Checked some old swelled baits. Some were hollow, several foam filled, only happened during hot days 90+, inside Plano boxes that all lures are stored in, inside closed compartments no light, and boat not inside for boat parking, even with boat cover on boat outside swelled lures happened. Never had one swell while boat inside shop out of direct sunlight even outside temps 90+ in Alabama, shop is not air condition to control temps. The chemical compounds used to manufacture mostly produced from petroleum products. The lures have to producing a highly expandable gas and excessive inside air pressure to swell or split lures along their weakest spot, the joint where to halves are joined. I had a nearly empty closed gas can siting in direct sunlight swell up like a ballon, when opened liquid gas particles spewed out in a funnel spray pattern, got hit two feet behind nozzle, then not only did the gas hit me, but the solution to the swelling of lures. It is the chemicals used in manufacturing or glue used to join the 2 halves. Without an analysis of chemical compounds used in manufacturing, I can not be 100% positive, only by using the best observation I can to find the cause of this problem. Although I could be so very wrong.   Reno  

Edited June 16, 2016 by tendelta