We have had issues for many years with blade ejectors breaking/seizing. I know much of this is the nature of the design but I'm wondering if anyone has come up with any solutions to this? Many thanks

In the case of seizing, have you tried diamond coating? United Protective Technologies has extensive experience coating molds and ejector pieces of various materials, including aluminum at very affordable prices. Please send me an inmail to discuss further.

A few questions first, Stephen.

Are the ejector blades store-bought or home-made? Material and hardness?
What is the insert material and hardness?

You might try decreasing some of the bearing surface, that it glides on? If you can't do that make sure that they have plenty of free float in the ejector pin retainer plate so they can self center in case there is any binding on full ejection stroke because of possible missed locations. Blades do not like gassing that vents down, so make sure you have plenty of venting on the datum line of the cavity. Make sure you use a good grease, that will stay on the blade and not wipe clean. I prefer thru hardened blades , but depends on the application? Hard to say without seeing, what's going on. It can be approached in several ways.

I've used many blades in molds for many years and have found that the blade installation is the most important issue. Always have the ribs that you are having to use blades split inserts. then say you have a .072 thick rib you use a .062 thick blade pin, you machine the .062 thickness pocket all on one side leaving a .005 step away from the side wall, the other side insert a .005 step. this keeps the blade in the center of the rib and all the blade pin on one side eliminates binding and breakage of the blades. as far as bearing surface .312 to .375 is a good rule of thumb

I prefer Misumi blades. They are great quality, but more importantly, I can specify the exact shoulder length I want. Yes, you want to minimize the bearing land to about 3/8", but just as importantly you want to minimize the free length of blade back in the clearance hole. When the ejectors stroke forward, the shoulder should almost bottom out in the clearance. This prevents the free blade in the clearance from flexing during that first instant of push. That's what bends and breaks blades. Also watch out for side slip if you push on a sloped face that's not good or it will bellmouth the hole on the downhill side.

Great conversation... anyone else? (Still waiting to hear from Stephan)