Running high-volume CNC production means every material decision affects your cycle time, tool life, and scrap rate. Free machining grades are built to cut faster and break chips cleanly. We’ve supplied precision-ground versions of these grades to manufacturers across the Chicago area, from Arlington Heights, since 1970.
Choosing the wrong grade costs you on inserts and machine time. This guide covers every free machining grade we carry, what each one does, and which application it fits best.
Free Machining Steel Grades: What They Are and Which One Fits Your Program
Free machining grades contain controlled additions of sulfur or lead that change how the material shears at the cutting edge. On a turning center running thousands of parts, that difference shows up directly in insert life and cycle time. Getting the grade right before you order is the simplest way to protect your program.
Each grade in this family trades something to gain machinability. Some give up weldability. Others limit heat treat options. Knowing those trade-offs upfront saves you from a costly mid-run grade change.
Carbon Steel Free Machining Grades
Carbon steel free machining grades are the most common starting point for high-volume CNC programs. They cut faster, produce cleaner chips, and reduce tool wear compared to standard carbon grades across screw machine, turning, and bushing applications.
12L14 and 1215
12L14 is the first grade most CNC shops evaluate. We carry it for screw machines, bushings, and hose fittings because it produces short, clean chips that don’t wrap tooling. If you’re holding tight diameter tolerances on small turned parts, 12L14 is a reliable starting point for your baseline.
1215 takes machinability further. We list it as the highest machinability carbon steel in our lineup. It reduces insert wear on long production runs and holds dimension cleanly during cuts. Neither grade suits welding or case hardening, so if your part needs either downstream, a different grade applies.
1117, 11L17, 1141, and 11L41
1117 is a resulfurized free machining steel that improves chip breakability without a lead addition. Its leaded variant, 11L17, gives you the same resulfurized base with a lead addition for faster cutting speeds where lead is acceptable in your supply chain. Both machines are better than standard 1018 and retain enough ductility for parts that see light forming after machining.
1141 steps up the strength level while keeping good CNC performance. Its leaded variant, 11L41, adds faster cutting speeds on top of that base. Both work well for heat-treated parts where resulfurized chemistry fits the design requirement.
1144 Stress Proof
1144 machines well and responds to heat treatment, making it useful for shafts, spindles, and components under cyclic loading. The stress-proof variant we carry is built around high fatigue resistance. It gives you CNC efficiency and structural performance together in a single grade.
If your program produces parts that go into loaded assemblies, 1144 stress-proof is worth specifying over a standard free machining grade. The fatigue resistance profile makes it the stronger choice for parts that see repeated stress cycles in service.
Free Machining Stainless Steel Grades
Stainless steel work hardens quickly and clings to cutting edges, which makes standard grades difficult to run at high volumes. Free machining stainless grades solve that by improving chip control so your tooling runs longer and your cycle times stay consistent.
303, 416, and 416 Condition T
303 is the austenitic grade we associate most with CNC stainless production. It’s in our lineup for its good machinability and is used for nuts, bolts, and gears across automotive and general manufacturing. Shops that don’t strictly need 304’s corrosion performance often spec 303 for more predictable cycles.
416 is the martensitic free machining option. It gives you corrosion resistance alongside chip control and hardness potential. We also carry 416 Condition T, a tempered variant for parts that need a specific hardened condition off the saw.
420F, 430F, and 440F
420F gives you the higher carbon content of 420 with improved CNC performance. It suits cutlery and surgical instrument production, where hardness matters alongside cycle efficiency. 430F is the free machining version of the ferritic 430 grade, useful for automotive trim applications that need faster cycles.
440F rounds out the group as the free machining member of the 440 series. We list it specifically for high-hardness, non-galling applications. If your part needs the hardness profile of the 440 family with better CNC performance, 440F is the grade to specify.
Free Machining Copper Alloys
Copper alloys present a different challenge on CNC equipment because standard copper grades are gummy and produce long, stringy chips that interrupt production. Free machining copper alloys are formulated to cut cleanly while preserving the conductivity and corrosion resistance that copper is specified for.
145 Tellurium Copper and 360 Brass
Copper is gummy on CNC equipment. The tellurium addition in 145 tellurium copper changes that by improving chip breakability while keeping the electrical and thermal conductivity that copper is specified for. We carry it as precision-ground round bar stock ready for your CNC cell.
360 brass is the most popular free-machining brass in our lineup. It’s a standard choice for screw machine work, fittings, and valve bodies. If you’re sourcing brass for CNC production without specifying 360, it’s worth checking whether your current grade is actually optimized for machinability.
Precision Ground Bar and In-House Services
Dimensional variation in incoming bar affects your program offsets and first-pass yield before your cycle starts. We centerless grind bar stock to tolerances up to .0001 inches with a surface finish of 8 micro inches or better. Your free machining bar arrives at a controlled diameter, so you’re not burning passes compensating for mill variation.
Our grinding capability runs up to 9 inches in diameter and 50 feet in length, with a specialized division handling up to 7 inches in diameter and 24 feet. Every order moves through quality control inspection at each phase, backed by our ISO 9001:2015 certification. Our saw cutting service uses cold saw blades on automated CNC equipment handling diameters up to 7 inches, producing clean ends with minimal waste. Chamfering and burnishing are available on-site as well.
Get a Precision Ground Free Machining Bar for Your Next CNC Program
Superior in Steel Production and Machining Operations, we’ve supplied free machining steel to CNC shops and manufacturers across the Chicago area since 1970. Whether you’re specifying 12L14 for a screw machine run or 303 stainless for a high volume turned part, we can supply it precision ground to the tolerance your program needs.
Reach out today with your grade, diameter, length, and tolerance requirements. You can call us at (847) 640-6050 or email sales@ohareprecision.com, and our team is available Monday through Friday from 9:00 am to 5:00 pm CST. You can also submit your full requirements through the Request a Quote form at ohareprecision.com/request-a-quote/ for a fast response.
FAQs
What is the difference between 12L14 and 1215 for CNC production?
1215 offers the highest machinability in our carbon lineup. 12L14 adds lead for fast cutting on small turned parts. Neither grade suits welding nor case hardening.
Can free machining stainless be precision ground to tight tolerances?
Yes. We grind 303, 416, 420F, 430F, and 440F to tolerances up to .0001 inches with a surface finish of 8 micro inches or better.
When should I choose 1144 stress-proof over 12L14?
Choose 1144 stress-proof when your part goes into a loaded assembly or sees cyclic stress. 12L14 prioritizes machinability alone.
How do I order a specific free machining grade?
Submit grade, diameter, length, and tolerance requirements through our Request a Quote form at ohareprecision.com/request-a-quote/ for a fast response.