wire cores without hinges:

Where are the wire cores used ? 

They are usually used in acetate temples, plastic arms of eyeglass frame, to make these plastic temples stronger and enable it to be bent to certain shape.

What material are they usually ?

They are usually made of lead free nickel, normal nickel or stainless steel.

What size are they usually ?

usual length: 110mm to 150mm, 135mm and 140mm are most popular sizes; 

usual width: from 2.0mm to 8.0mm, 3.5mm to 6.0mm are most popular sizes ;

2.5mm width, the slimest model here is TW-1108, 140mm ; 

3.0mm width, TW-1202, 135mm length ;

3.5mm width, there are many models here, TW-55456, TW-3283, TTW-1968, TW-1817,TW-1112,TW-0769,TW-0358 etc, but their designs are different, neither the length of flat positions are.

4.0mm width, TW-1146A of 140mm length, TW-55701 of 135mm length; 

4.4mm width, TW-55400 of 135mm length.

6.0mm width, TW-1754 of 135mm length.

How could they be inserted into acetate temples or arms?

Usually in china, we use one wire core inserting machine to insert them into temples after they are heated to soft situation. But in southern American countries, manufacturers put them in the mold directly and when temples are injected out, wire cores is there already. 

Are there any related parts that wire cores will work together with ?

Usually, wire cores work with universal eyeglass hinges (rivets hinges) and single or double rivets, universal hinges and rivets makes the temples could connect with frame fronts.