Machining performance isn’t determined by tools or technique—it’s determined by material selection. Metal machinability plays a major role in your outcomes, from production efficiency to tooling costs, part quality, and profitability. Choosing the right metal can mean the difference between smooth outcomes with tight tolerances, and wasted product with missed deadlines.
Read on to learn what machinability means, why it matters, and how to select the right material.
What is Metal Machinability?
Metal machinability goes beyond how easy a metal is to cut. Highly machinable metals can be cut efficiently while:
- Minimizing wear on toolsÂ
- Producing a good surface finishÂ
- Maintaining tight dimensional accuracyÂ
- Allowing for high cutting speeds.Â
Machinability is influenced by various factors:
- Hardness and strengthÂ
- Chemical composition
- MicrostructureÂ
- Thermal conductivityÂ
- Tendency to work harden
Because there are so many factors involved in the machining process, metal machinability can be hard to pin down. A number of methods are used to determine the machinability of metals, from the length of time a tool lasts to the amount of power machining consumes. Machinability rating is another common measurement method. This compares the machinability of a given metal to the machinability of a standard steel, expressed as a percentage.
Why Metal Machinability Matters
The machinability of a metal directly impacts efficiency, tool wear, part quality, and total cost.
Production Efficiency
Parts made from highly machinable metals can be made very quickly. They allow for higher cutting speeds and faster production times. There are also fewer interruptions in the production process. Tools don’t need to be changed as often and production processes are less complex.
When machinability is poor, production takes much longer. Shops need to work more carefully to avoid damaging their equipment.
Tooling Wear
The less machinable a metal, the more wear and tear it puts on tools and equipment. Poor machinability shortens tools’ lifespan. They may break, chip, or simply wear down.
Part Quality
A metal’s machinability has a significant impact on the final outcome of the part. Machinability affects the part’s surface finish, burr formation, and dimensional accuracy. Better machinability leads to smoother finishes and more accurate results, while poor machinability can lead to uneven finishes, burrs, and other defects.
Total Cost
As machining complexities increase, so do costs. Longer production times, more tool replacements, and less predictable part outcomes all cost money. In some cases, it’s worth investing in a highly machinable material with a higher pricepoint. Spending a bit more upfront can save you machining costs down the line.
Metals for Superior Metal Machinability
Machinability varies significantly between metal types, grades, alloys, and more. Let’s review the best metals and grades for superior machinability.
Stainless Steel Machinability
Stainless steels are known for their corrosion resistance, but the factors that increase their corrosion resistance often make them less machinabile. Fortunately, there are a few grades of stainless steel designed for improved machinability. They include:
- Grade 416: This is the most machinable grade of stainless steel at 85% machinability. The addition of sulphur increases machinability, but lowers formability and corrosion resistance.Â
- Grade 303: Sulphur is used to make this stainless steel more machinable, too. It’s the best austenitic stainless steel for machining, but isn’t recommended for welding.Â
Carbon Steel Machinability
Carbon steel machinability ranges from good to great. As their carbon levels get higher, carbon steels become less machinabile. As they lower, their machinability increases.
- Grade 1018: The most machinable carbon steel, 1018 has between 70% and 78% machinability. That said, its low carbon content tends to make this steel “gummy.” It can build up on the cutting edge and isn’t ideal for drilling or threading.Â
Super Alloy Machinability
Super alloys tend to have pretty poor machinability. Their high temperature strength and heat resistance makes them more difficult to machine. Iron-based super alloys are more machinable than nickel or cobalt.
- Grade A-286: This iron-based super alloy has 40% machinability. While that’s a fraction of the machinability of stainless steels, it’s considered quite high for super alloys.Â
How Material Selection and Supplier Support Impact Outcomes
For the best possible outcome, collaborate with a knowledgeable metal supplier from the start. The right metal supplier has an in-depth knowledge of machining processes and metal services. They can help you make smarter material decisions that improve efficiency. With their help, you can find metals that meet your needs in terms of both strength and machinability.
Source Machinable Metals From Fry Steel
For an experienced metal supplier, choose Fry Steel. Our experts know how material properties translate to machining performance. We’re also proud to offer machining capabilities in-house, from saw cutting and centerless grinding to heat treating, as well as local support. Find a Fry Steel location near you.
