CASTING VS INJECTION MOLDING—WHICH METHOD WORKS BETTER?
Funny timing—I just had to replace a batch of injection-molded fence caps that warped after two summers. Meanwhile, the old cast aluminum ones on another site are still going strong, even with all the weather swings we get here. I get why injection molding is tempting for cost and speed, but for anything exposed to the elements or regular use, cast metal usually wins out in my book. That said, I’ve seen some high-grade plastics hold up surprisingly well... but you’re definitely not getting those in budget hardware store packs.
CASTING VS INJECTION MOLDING—WHICH METHOD WORKS BETTER?
I get where you’re coming from, but I’ve actually had the opposite luck. The cast iron mailbox flag on my old house snapped clean off after a couple winters—meanwhile, the injection-molded plastic one I replaced it with is still kicking after five years. Maybe it’s just the quality of the batch or the specific use case, but I wouldn’t write off injection molding for outdoor stuff entirely. Some of those plastics are tougher than they look.
CASTING VS INJECTION MOLDING—WHICH METHOD WORKS BETTER?
That’s interesting—my experience has been almost the reverse. I’ve always thought cast metal would outlast plastic, especially outdoors, but maybe I’ve been underestimating the newer plastics. Out of curiosity, do you know what kind of plastic your replacement flag was made from? I’ve seen some injection-molded parts labeled as UV-resistant polycarbonate or ABS, and those seem to hold up way better than the generic stuff.
I wonder if the failure point for cast iron is more about brittleness in cold weather. I had a cast aluminum gate latch snap on me last winter, and it looked like it just couldn’t handle the freeze-thaw cycles. On the other hand, I’ve got some injection-molded PVC trim that’s been outside for years and still looks fine, though it’s a bit faded.
I guess it comes down to the specific material and the way it’s used. For something like a mailbox flag, maybe the flexibility of plastic actually helps it survive impacts and temperature swings. But for structural stuff—like brackets or hinges—I still lean toward metal, just for peace of mind.
Has anyone tried using fiber-reinforced plastics for outdoor hardware? I keep seeing those pop up in catalogs, but I haven’t tested them myself. Wondering if they’re a good middle ground between the two methods, or if they just end up being more expensive without much benefit.
CASTING VS INJECTION MOLDING—WHICH METHOD WORKS BETTER?
- Totally agree that the material choice is huge. I’ve seen “UV-resistant” plastics last way longer than expected, especially on outdoor furniture.
-
— That’s been my experience too. Some of the newer plastics flex just enough to avoid cracking, which is great for things like mailbox flags or even planters.“maybe the flexibility of plastic actually helps it survive impacts and temperature swings”
- Fiber-reinforced plastics are popping up in hardware catalogs I use for projects. They’re pricier, but I’ve noticed they don’t get brittle as fast as plain plastic. Still, for anything load-bearing, I’d rather stick with metal—just feels safer.
- Fading is a thing, though. Even the best plastics seem to lose color after a few years in direct sun... but at least they don’t rust.
