Considerations for Precision Machining Hard Metals

2023-10-18 12:01

Hard metals are the only choice for certain aerospace, automotive, energy, and other applications. But if you need parts made from a material like 400 stainless steel, Inconel, or titanium, it is important to find a precision machine shop that is truly capable of machining these materials to your desired specifications.

Why? Because hard metals are notoriously difficult to machine, and not every manufacturer has the equipment, mindset, and expertise to handle them.

Know Your Hard Metals

First, let’s take a look at some of the most common hard metals in precision machining:

Precision Machining

  • 304L stainless steel: Found in countless home and commercial applications, this versatile alloy is widely used in kitchen appliances, food processing equipment, and architectural trims.

  • 316L stainless steel: This weldable, malleable material is highly resistant to corrosion and chemicals and is frequently used in marine applications.

  • 400 series stainless steel: You’ll find this high-strength, highly wear-resistant alloy used in agricultural equipment, gas turbine exhaust silencers, hardware, motor shafts, and more. 

  • 17-4PH stainless steel: Providing moderate corrosion resistance, this material’s strength and toughness can be enhanced or diminished via heat treatment.  

  • 15-5PH stainless steel: Its corrosion resistance and transverse properties make this stainless a premium pick for aerospace structural components and nuclear reactor components. 

  • 1018 alloy steel: Offering high surface hardness and a soft core, this alloy is used to improve machining processes and in parts like chain pins, ratchets, and oil tool slips. 

  • 4140 alloy steel: This grade’s toughness, abrasion and impact resistance, and high fatigue strength make it perfect for applications such as shafts, gears, collars, and machinery. 

  • 4340 alloy steel: Primarily used for aircraft landing gear and other structural applications, look for this alloy in sprockets, chucks, and molds.

  • Inconel 600 and 700: With excellent oxidation corrosion resistance, these alloys perform well in harsh environments and are frequently found in aeronautical applications. 

  • Titanium & titanium alloys: As strong as steel at half the weight, titanium materials are used in wide-ranging applications from jewelry to prosthetics and cell phones to surgical tools.

Challenges of Machining Hard Metals  

Precision machine shops must be equipped to overcome these challenges that commonly arise when working with hard metals: 


A term for excessive vibration that can occur during the precision machining process, chatter leads to quality issues such as poor surface finishes and unmet tolerance specifications. Chatter also causes uneven wear on the machine tool and can cause the tool to break. 

To control chatter, shops may need to use shorter and wider cutting tools, slow the spindle speed, perform shallower radial cuts, and support thin-walled parts with filling material.


Caused by a cutting tool with diameter inconsistencies, runout occurs when the tool does not accurately engage the workpiece on radial cuts. During end mill rotation, every tooth must cut into the same place on the workpiece or the part’s corner radii will be inaccurate. 

Shops can minimize runout with a combination of leveraging high-speed machining, employing high-quality tool holders, and engaging full look-ahead on machining centers to reduce feed rates as needed.  

Work hardening

Work hardening is the result of excessive heat transfer from the cutting tool to the workpiece. Along with increasing the material’s hardness and making machining even more difficult, work hardening often causes tool breakage and renders parts unusable. 

Shops can prevent work hardening by maintaining sharp cutting cools, reducing the cutting tool’s radial engagement, and incorporating a through-spindle coolant.

Why Trust Precision Parts Fast with Your Hard Metal Parts 

Hard metals may be difficult to machine, but they offer unmatched benefits for applications as diverse as aeronautics and home appliances. 

Because these ultra-tough materials play such critical roles in modern society, Minggong Machinery  is proudly equipped with the knowledge and skills necessary to machine your hard metal parts.

These Four house standards keep us at the top of our game:

1. We’re a team of problem solvers

Our machinists are  excellent problem solvers. When we encounter any issue, we don’t let it stand in our way. We explore all the variables at play and make adjustments until we come up with a solution.

2. We invest in premium equipment 

We pair our excellent-quality, rigid CNC machining centers with hydraulic chuck tool holders to counter runout on hard materials and ensure maximum surface contact with the cutting tool shaft. And while most CNC mill spindles utilize only coolant to suppress heat, our machines also incorporate high-pressure air to further increase thermal stability.

3. We prioritize excellent workholding

Our top-tier workholding controls chatter with consistently clamped workpieces. Leveraging specialized workholding and custom fixturing allows us to apply ideal clamping pressure to each part according to the hardness of its material.

4. We’re always improving

As we’ve shared, machining hard metals comes with unique challenges. Our passion for our customers, our team members, our precision machine shop, and the manufacturing industry as a whole drives us to endlessly seek opportunities for improvement. Just like with all the materials we machine, it is this mindset that enables us to constantly deliver premium parts to our customers. 

Unexpected challenges come up with many projects, but it is the willingness to solve problems and never give up that distinguishes good shops from great shops. It is our commitment to you to always evolve, improve, and deliver your precision parts to specification every time.

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