Guide to Machining Steel

Table of Contents

• Machining Process for Steel
• Steel Machining Tips
• How is Machining Steel Different Than Other Materials?
• Common Steel Machining Applications

Stainless steel offers many benefits, from an attractive finish to high strength and durability. But those come at a cost for the machine and its operator. Steel can be a formidable opponent due to its strength and durability, but those features are what make it so useful in the first place. Between alloys, speeds and tool selection, many aspects will affect your final product and the process by which you create it.

Machining stainless steel parts takes a certain level of preparedness and understanding of the materials you’re working with. Below are some of our tips for machining steel.

Machining Process for Steel

When machining stainless steel, you’ll have to take into consideration all of its characteristics. Remember that it is strong, even at high temperatures.

1. Endmills

The tools you use will have a major impact on your project and the damage it can cause to your machine. The ideal type of endmill varies by application, but be sure to stick with a high-speed steel or carbide-constructed tool. High-speed steels include tungsten and molybdenum. Cemented carbides are a good choice when you need higher feeds or speeds. Make sure the cutting tool is sharp and in good condition to keep a high quality of cut.

• Roughing: An endmill with 4-5 flutes can offer sufficient roughing on steel. Remember that higher flutes make room for higher feed rates.
• Slotting: To slot steel, you’ll have to be aware of chip control and take enough care so your tools aren’t chewed up and your finish isn’t ruined. Try a four-flute endmill, which allows for chips to leave the cutting area more efficiently.
• Finishing: To finish steel parts, you’ll want a large number of flutes or high helix of over 40 degrees.

2. Feeds and Speeds

Now that you have the right tool selected, you need to ensure your speeds are appropriate. While it takes a little fine-tuning, a good starting point would be between 100 and 300 surface feet per minute (SFM) with chiploads ranging depending on the tool size.

Steel Machining Tips

Steel can be tricky to machine, but it’s not too bad if you are prepared and use the right settings and tools. Be sure to keep these concepts in mind as you machine steel.

• Keep heat low: Steel machining can generate very high temperatures, so take precautions to minimize their effects. Be sure to use a cutting fluid. Between work hardening and low thermal conductivity, keeping heat away from the cutting area is important to keep it in top shape. If excessive heat remains here, you may see distortion and a reduction in corrosion resistance. Cutting fluids help provide lubrication to wash away any chips, lower the wear on your tools and cool the endmill down. Common cutting fluids include mineral oils and emulsifiable oils. Make sure that you have plenty to use because any interruption of the coolant can lead to fluctuations in temperature, which can affect tool life.
• Avoid work hardening: Many steels have high work hardening tendencies. Make sure your tools are sharp and try to keep it moving to avoid any lulls in the cutting process that would lead to a buildup of heat.
• Control vibration: The strength of stainless steel and the speed it requires from the tool can cause extensive vibrations. Vibrations on your work surface can damage your finish while adding wear to your tool. You’ll need a robust, rigid tool capable of high-speed cuttings. Keep your workpiece firmly in place with clamps and minimize any tool overhang. You can also try using tools with a small nose radius.
• Know your material: Every steel alloy is a little different. Know the properties of the one you’re using so you can better adjust your machine to address its characteristics. The addition of sulfur, for instance, can allow for higher feeds by affecting the hardening of chips and helping the tool edge stay consistent. Lead allows for higher speeds since it provides a lubricating property that keeps the heat down.

How Is Machining Steel Grades Different Than Other Materials?

When machining steel, you’re not working with just one element. Steel is an alloy, comprised of carbon and iron, though other elements are often added to impart specific properties on the metals. This means that different types of steel are going to behave in different ways, and you have a lot of options. According to the World Steel Association, there are over 3,500 different grades of steel.

Alloys tend to have added strength from the inclusion of elements like nickel, chromium and copper. They may also improve its corrosion resistance, strength, ductility and ease of machining. Stainless steels use a larger amount of chromium to offer corrosion resistance. Some types of steel are even designed for easier machinability.

As for other metals, here is a breakdown of some of the more common options.

• Aluminum: In terms of machining steel vs. aluminum, the primary benefit of aluminum is that it is much lighter than steel. Aluminum also allows for faster machining, but it lacks the hardness and strength that steel has.
• Titanium: Titanium is one of the strongest metals out there, even in extreme or fluctuating temperatures. Plus, it has a low weight. The biggest trade-off is the cost of titanium, which is typically considerably higher than that of steel. Titanium is often chosen for sensitive applications like those in aerospace and defense.

Common Steel Machining Applications

Steel has a lot going for it in terms of strength and durability, but the biggest drawback is its weight. It typically is reserved for applications where weight isn’t much of a concern. This often includes structural components. Infrastructure like railways, buildings and roads commonly use steel. Other pieces like screws and bolts may also be made of steel. You can find it in industries like mining, shipbuilding and aerospace technology.

You may find stainless steel in even more places due to its attractive finish. It is versatile and common in furniture and appliances. The corrosion resistance of stainless steel also helps in these applications.

Boost Your Steel Machining Process

Whatever the application, the proper approach can make all the difference in your steel machining process. If you adopt high-quality tools and efficient practices, steel doesn’t need to be a tough opponent. Make things easier for your machine operators and minimize expenses associated with quickly worn tools and ruined workpieces.

Contact the experts at Astro Machine Works for more information on how you can improve your steel machining process today. With over 35 years of experience, we’ve got the knowledge and know-how to bring your machining capabilities to the next level.