CNC routing is compatible with soft metals like aluminum, wood, and plastic, but it has challenges machining steel due to the material’s hardness, toughness, and thermal properties. As a result, precision CNC routing becomes difficult, often requiring special equipment and techniques. For successful steel CNC routing, this article explores why CNC routing steel is difficult and provides tips on overcoming these obstacles.
CNC Router Steel
Steel is a valuable material used in many industries and parts manufacturing because of its strength, durability, and wear and corrosion resistance. However, these properties also make steel much harder to work with when using a CNC router that works more with softer materials.
CNC routers operate by spinning a cutting tool, or router bit, at high speeds to remove material in a controlled manner. While this works for softer materials like aluminum, steel’s mechanical properties necessitate some adjustments to the material, the tool, or CNC router damage.
The primary challenge lies in the router bit’s interaction with the material. Steel’s hardness dulls standard cutting tools, generates heat during routing, or causes vibrations that affect precision, leading to poor surface finishes, tool breakage, and excessive wear on machine components.
Why It Is Hard to CNC Router Steel
Precision steel CNC services often time recommend using other machining techniques when working with steel instead of CNC routing due to the following reasons:
Material Hardness
Steel’s hardness is a primary reason for its incompatibility with a CNC router. It requires more cutting force compared to softer metals like aluminum, plastics, and even wood, which can lead to increased wear and tear of cutting tools. Additionally, it necessitates using specialized router bits, often made from carbide or other super-hard materials, which can increase the cost of CNC machining.
Heat Generation
Due to the excessive cutting force, the routing process generates heat, which can weaken the cutting tool and lead to dulling or breakage. It can also lead to thermal expansion, warping, or hardening of steel, which complicates the cutting process.
Tool Wear and Tear
Steel hardness causes the wear and tear of CNC router bits, requiring the use of hard bits coated with carbide or diamond to maintain cutting efficiency over prolonged use. Nevertheless, the cutting bits also degrade faster compared to when cutting soft materials like aluminum.
Tool wear and tear reduce cutting efficiency, increase rougher finishes, and cause machine stress. It also causes chatter that reduces cutting accuracy and surface quality.
Precision and Tolerances
Steel density is high, which increases the chances of tool deflection and vibrations. Tool deflection occurs when the cutting bit bends during use, leading to inaccuracy and the inability to maintain tight tolerances.
Cutting Speed and Feed Rates
The speed at which the cutting tool rotates (spindle speed) and the rate at which the tool moves through the material (feed rate) must be carefully adjusted when routing steel. If the spindle speed is too high, it generates excessive heat and increases tool wear. If the feed rate is too low, the tool remains in contact with the material for too long, also causing heat buildup and reducing cutting efficiency. The balance between spindle speed and feed rate must be optimized to minimize heat, prolong tool life, and maintain a smooth, controlled cut.
Vibration and Rigidity
Steel’s density means that cutting it produces more resistance, leading to higher levels of vibration or chatter. These vibrations can affect the precision of the cut and the overall surface finish. CNC routers designed for softer materials may not have the necessary rigidity to handle the forces generated when cutting steel. Machines with more rigid frames, stiffer spindle mounts, and enhanced vibration dampening are required to minimize the impact of these forces.
Pro Tips for CNC Router Steel
Precision steel CNC routing services work around the factors discussed in the previous section by using the tips below:
Use High-Quality Cutting Tools
When CNC routing steel, always invest in high-quality cutting tools, such as carbide or diamond-coated bits. These tools can withstand steel’s hardness and abrasiveness for a smooth and efficient routing process. Avoid using standard bits such as the high-speed steel meant for wood or plastics, as they will dull quickly and result in poor-quality cuts.
Optimize Cutting Parameters
Adjust the spindle speed and feed rate to strike a balance between efficiency and heat generation. Typically, CNC routing steel should be done at slower spindle speeds and higher feed rates to minimize heat and reduce tool wear. Additionally, you should use a conservative depth of cut to prevent overloading the tool.
Cooling and Lubrication
Implement effective cooling and lubrication methods, such as misting systems or flood coolants, to manage the heat generated during the routing process. Coolants dissipate heat and reduce friction between the tool and the material during routing. As a result, they prolong tool life and improve surface finish.
Dry cutting is not recommended for steel, as it can lead to rapid tool wear and heat-induced damage to both the tool and material.
Choose a Rigid CNC Router
Use a robust and rigid CNC router designed to handle steel. Machines with heavy-duty frames, rigid spindles, and strong vibration-dampening systems are better suited for steel due to lesser chatter that reduces accuracy and surface finish.
Use Specialized Toolpath Strategies
Toolpath strategies like ramp entries and spiral plunges are preferable to straight plunges because they reduce the load on the cutting tool and machine. Additionally, adaptive clearing paths maintain a consistent chip load, improve cutting efficiency, and reduce tool wear. Taking multiple shallow passes rather than deep cuts also helps reduce the load on the tool, further preserving its lifespan.
Monitor Tool Wear Regularly
Given the wear and tear associated with CNC routing steel, regularly inspect the cutting tools for signs of wear. Dull tools reduce efficiency and cutting quality. Replace tools when you detect wear for consistent cutting performance and machine longevity.
Conclusion
Steel’s hardness, heat generation, and susceptibility to vibration make using CNC routing difficult. However, as highlighted in this article, with the right tools, proper cooling and lubrication, and optimized toolpath strategies, you can get quality results when using CNC routing steel. This article discusses why it is hard to use CNC router steel but further introduces tips to overcome this problem and deliver precise, professional results.
