For example, AISI 316L has a very low carbon content, only 0.03%, and is a typical mild steel that is very commonly used. In the course of communicating and trading with various companies over the years, we found that medical instrument companies like to use this material. To prototype or customize small batch steel parts, CNC machining is usually the first choice. CNC machined 316L steel parts usually do not require surface treatment or any heat treatment process. CNC mild steel parts can be used as final products, not just prototypes. Other common products such as fishing tools are also heavily used in AISI 316L.

However, mild steels are also difficult to process because they are too soft. Chips that appear during CNC machining tend to stick and build up, which can lead to longer cleanup times and potentially damage to the tool. The ideal carbon content for easy processing is about 0.20%.

For example, some mild carbon steels are too soft and can cause chip accumulation problems. One method we sometimes use is to first surface harden the mild steel. The low carbon steel is hardened on the outside, the inside of the steel remains soft, thus solving the chip accumulation problem, and because the core of the steel is still soft, when the external stress generated during the processing process is applied to the material, the softness or ductility of the low carbon steel will still absorb the stress, so that the part cannot break.

For the short-term production of mild steel parts, CNC machining is the only way. The low carbon steel material used in CNC machining is what we call "block material", which is of good quality and reasonable price.