what is the difference between “M”(Molded) and “G”(Grounded) inserts?

As the title suggests，a simple way to remember is “M” means molded and “G” means ground on the insert sides.

We can classify them from a manufacturing process perspective:

M Grade Inserts: PSTS Inserts

M grade inserts are also PSTS inserts, starnd for “Pressed and Sintered to Size.” meaning the finish size and edge prep is integrated into pressing and heating inserts to their final dimensions. This technologic often leaves some roughness on the sides of the insert, requiring finishing or grinding to attain the required dimensions and smoothness.

G Grade Inserts: PG Inserts

G grade inserts are also known as PG inserts, short for “Periphery Ground to Size.”  which usually a ground periphery to maintain the +/-.001″ tolerance or even less and by grinding it you can expect a sharper edge.
The primary distinction between them stems from their manufacturing processes, but there are additional nuances to consider. In most cases, M grade inserts are categorized as negative inserts, while G grade inserts are positive inserts. These categorizations are primarily based on the manufacturing process and intended applications.

However, it is not for absoulty.For example, M Grade inserts may also have Periphery Ground Inserts, and G Grade inserts may aslo have pressing processes inserts. The choice between M and G grade inserts depends on specific machining requirements and desired outcomes. Various factors come into play in real-world applications, and maintaining an optimal machining state is crucial.

Application

In practice, M grade inserts are often applicated for rough and semi-rough machining, while G grade inserts are the top choice for finishing and semi-finishing applications.Like working with materials such as aluminum, high-temperature alloys, superalloys, stainless steel, and more.