Cold drawn steel bars have several advantages over hot rolled steel bars. 

Precision parts often require high dimensional accuracy and surface finish, which are both improved with cold drawn steel. The cold drawing process results in a smoother and more uniform surface finish, as well as tighter dimensional tolerances. This makes cold drawn steel a better choice for precision parts that require consistent and precise measurements.

In addition, cold drawn steel has improved mechanical properties such as higher tensile and yield strength, better surface hardness, and improved dimensional accuracy, which are all important factors for precision parts. This makes cold drawn steel a more reliable and durable material for precision components that need to perform under demanding conditions.

Overall, the improved surface finish, tighter dimensional tolerances, and superior mechanical properties make cold drawn steel a better choice for precision parts compared to hot rolled steel. These advantages make cold drawn steel bars a popular choice for a wide range of applications, including precision parts, machinery components, and others.