Extruded or cast rubber which is best?


What would you say and why?



I would say extruded is likely to be more consistent in quality (whether that quality is good or poor),
but I don’t know if it’s better.
Does anyone even do cast? I figured it was all extruded.


Henry Unger explained that they used cast. The rubbers came two together and were cut down the middle with a razor. Each was cast at size in the mold.



Care to elaborate on the definitions of the two terms?


Cast rubber uses a mold whereas extruded rubber is pressed through a die. There are other differences. There are also other ways of processing rubber. Different formulations also. This is a very intense science.



tomato tomatoe potato potatoe


Not really.


Well, technically it is tomato potato.

It would seem like the cast would be more consistent, especially for harder rubbers. Pour the rubber in, press, done.

Not sure how consistent extrusion would be with rubber. It would seem like you’d have weak spots depending on whether the push was consistent, temperature variations, etc.


I have really no opinion which is a better method as I’m not sure what type is used for the rubbers I use…

I will say this, when it comes to lawn mower decks the pressed steel ones (which are the majority major brands) are lower quality than the welded and assembled ones. So in that case pressed is a lower quality…


I remember trying a couple different extruded rubbers… wasn’t impressed. And I haven’t heard good things about the Sorbo extruded rubber. But if you want blades longer than 41" or so, I guess extruded is the only option.


Do you know what ettore is?


95% sure it’s cast. (Along with most rubbers). If you look along the round (bottom) edge of the rubber, you’ll see rough spots or little hangy pieces that indicate it was cast in a mold.

The extruded rubbers I tried were all some type of silicone/hybrid rubber. I’m not sure if natural rubber can even be formed through extrusion.


Yeah, that’s pretty neat. If you order Black Diamond rubber, they ship them out still attached. They cut through both sides so that there’s just a tiny “thread” of rubber still connecting the two blades. I think it looks really cool, and helps protect the edges until you’re ready to use it.


Is wagtail rubber extruded to make those 9m rolls?
I like the big roll cause it reduces cut-off waste (if only by a small amount). Their rubber seems to be pretty good quality as well.


That’s a very good question.