Free Machining Alloys

Free machining materials often yield the fastest speeds and lowest cost to the end user. These alloys often allow for machining quality that is predictable and management, resulting in high quality parts with a quick turnaround. Below is a list of the free machining alloys we most often work with.

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Brass CDA
360/385

The U.S. standard for high machinability.   Especially suitable for crimping and knurling applications due to higher lead content.

Phosphor Bronze
CDA 544

This popular alloy is often selected for electronic spring contacts due to its high tensile strength. Machines almost as fast as brass.

Nickel Silver
CDA 798 NM2

This high tensile strength alloy is the best machining option of the nickel silver family.

Nickel Silver
CDA 793 N12

Tough on tools but it creates a highly corrosion resistant part that is equally as tough.

Beryllium Copper
CDA 173

Often chosen for its hardening characteristics after Heat Treat.  This alloy can be inconsistent to machine and tough on tools. Machines more like steel rather than a copper based alloy.

Tellurium Copper
CDA 145

This highly conductive material is extremely soft, lowering it’s machineability rating.  Popular in electronics and glass to metal applications.

Aluminum
2011

This excellent “free machining” aluminum runs as fast as brass and creates small easy to work with chips.

Aluminum
7075

This very high tensile strength aluminum alloy is more difficult to work with than 2011 due to its tough and long chips.

Aluminum
6061

This aluminum alloy is known for its high strength, solderability and corrosion resistance. Difficult to machine at high speed

Delrin
 

This is the best machining alloy of the plastic family.

Steel
12L14

12L14 is the best machining alloy of the steel group.

Steel Sandvik
20AP

This steel can be hardened to Rc 65 and commonly used for shafts and similar applications.  It is approximately equal to ASTM A1095.

Steel
52100

This tough alloy is commonly used for bearings and other parts requiring high impact resistance.

Stainless Steel
416

This is the fastest machining stainless steel , but has a hardening limit of RC 38-42 through heat treatment.

Stainless Steel
430F

430F is the free machining version of 430. Cannot be hardened by heat treatment.

Stainless Steel
420F/4C27A

420F is an excellent choice for a high machining stainless steel.  It can be hardened to Rc 52.

Stainless Steel
303

This alloy machines well, but slowly. Machine type and part geometry can change this rating dramatically.

Stainless Steel
316L+S+Cu

This variation of 316L provides a significantly better machining rate and more resistance to corrosion than typical 316 alloys. However, the sulfur content does reduce the weldability compared to standard 316.