It's far simpler to replace the full LCD/Glass/Frame assembly. Even majority of repair techs will change like this.
To change the top glass, is called refurbishing, and this requires more specialised equipment, so for someone who does the odd repair, this isn't cost effective at all. So it's best to keep these working displays, and sell to a refurbishing company (I'll gladly buy them if in the UK)
To replace the top layer of glass, you'll need all the tools which you already know of for a replacement, plus the following:
Frame seperating tool - Different types, but most effective is a high temp heat plate designed to push the frame into it and soften the glue on the frame.
Vacuum heat plate - Holds the LCD down and heats the LCD so you can cut the glass off.
Various other bits like blades/chemicals/wipes/sponges.
Then you (ideally) need a mould for LCD/glass alignment.
A laminator (basic is around £450 and a decent one up from £1000)
Then a debubbler to remove any bubbles created from the lamination process. (You can get some of these machines which do the two together)
And the last bit, you'll need quite a few displays to practice on, because I can guarantee, when you first do one, it'll break.
Plaves like replacebase/iparts 4 u sell just the glass, bit it's really not suitable if you don't have the equipment.
Replace the full assembly, and sell the working display (if you get it off nicely)
Here's a video I've done for an XR glass/touch replacement. Should become clear what's involved then. https://youtu.be/tlng-9ONOP4
Definitely worth investing in if you are repairing alot of devices, your margins are considerably increased….. once you've nailed it.
Hope that helps you understand it a bit better 😁
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