Broken Yellow Plastic On Adapter Tip

Hello. This is probably a stupid question (I am a minor geek to say the least). I have a Lenovo laptop adapter. The plug that goes into the laptop is a rectangular shape, and is lined in yellow plastic on the tip. The bottom side of the rectangular plug has the yellow plastic broken off down to the metal. It works fine, the laptop runs as if the plug weren't broken.

Is it perfectly safe for me (and the laptop) to use this plug while it is broken in this way?
What is the yellow plastic tip for?

Thanks.

 

Does it look like the plug on the right?

 

"Perfectly" safe? No!

That plastic piece is being used as an insulator to prevent isolated electrical contacts from accidently coming into contact (causing an electrical "short") with another electrical contact. That plastic piece is also used to help properly align the connector when inserting and removing, and keeping the connector properly aligned while inserted so there are no accidental shorts.

It [most likely] is safe as long as the connector remains properly aligned at all times. That can be a challenge when used with devices designed to be mobile - like laptops. And that can be a challenge when such a connector is attached to things that can be accidently yanked or tripped over - like power cables.

 

Thanks, that is kind of what I was thinking.