What is the difference between HSS-G and HSS-R drill bits?

Answer 1

HSS-R and HSS-G both belong to tool steel of high speed but difference is primarily in the production technology. HSS-R is rolled in warm state and sharpened at the end; HSS-G (ground) is cut in their shape with the help of diamond tools and cooled during the process.

HSS-R should be expected to be more elastic, and HSS-G more hard. Use HSS-G for more precise work because they are better centered generally. Use HSS-R for lower price and little rougher work.

If not accompanied with other designations on tool (like Co for cobalt, or Ti for titanium, or something else) both HSS-R and HSS-G are suitable for drilling the steel of similar strength, about 900MPa. Practically if no other designation is on the tool abandon using them for hardened steel, but instead for ordinary carbon steel, ordinary HSS sections, brass, copper.