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How to deal with chips in CNC machining?

by elias•

In the realm of CNC machining, chips are an inevitable by – product. As a seasoned CNC machining supplier, I’ve encountered various challenges related to chips and have developed effective strategies to handle them. In this blog, I’ll share my insights on how to deal with chips in CNC machining, covering aspects such as chip formation, problems caused by chips, and practical solutions. CNC Machining

Understanding Chip Formation

Before delving into chip management, it’s crucial to understand how chips are formed during CNC machining. When a cutting tool engages with the workpiece, it shears off material, creating chips. The shape, size, and type of chips depend on several factors, including the material being machined, the cutting tool geometry, and the cutting parameters.

There are three main types of chips: continuous chips, segmented chips, and discontinuous chips. Continuous chips are long and ribbon – like, often formed when machining ductile materials such as aluminum and mild steel. Segmented chips have a series of breaks along their length and are typically produced when machining materials with medium ductility. Discontinuous chips are short and irregular, commonly seen when machining brittle materials like cast iron.

Problems Caused by Chips

Chips can cause a range of problems in CNC machining, which can affect the quality of the machined parts, the efficiency of the machining process, and the lifespan of the cutting tools.

  1. Surface finish: Chips can scratch or damage the surface of the workpiece, leading to a poor surface finish. When chips get caught between the cutting tool and the workpiece, they can create grooves or burrs, which are unacceptable in many applications.
  2. Tool wear: The presence of chips can increase the friction between the cutting tool and the workpiece. This additional friction generates heat, which can accelerate tool wear. In some cases, chips can also cause chipping or breakage of the cutting tool, resulting in costly tool replacements.
  3. Machine jams: Excessive chips can accumulate in the machining area, causing the machine to jam. This can disrupt the machining process, leading to downtime and reduced productivity.
  4. Safety hazards: Flying chips can pose a safety risk to operators. They can cause eye injuries, cuts, or burns if proper safety measures are not in place.

Strategies for Dealing with Chips

1. Optimize Cutting Parameters

  • Cutting speed: By adjusting the cutting speed, you can control the chip formation. Higher cutting speeds generally result in smaller and more manageable chips. However, it’s important to find the right balance, as excessive cutting speeds can lead to increased tool wear and poor surface finish.
  • Feed rate: The feed rate determines how fast the cutting tool moves through the workpiece. A higher feed rate can produce larger chips, while a lower feed rate can result in smaller chips. Experimenting with different feed rates can help you find the optimal setting for your specific machining application.
  • Depth of cut: The depth of cut affects the chip thickness. A larger depth of cut will produce thicker chips, which may be more difficult to manage. Reducing the depth of cut can result in thinner chips that are easier to remove.

2. Use Appropriate Cutting Tools

  • Chip breakers: Many cutting tools are equipped with chip breakers, which are designed to break the chips into smaller, more manageable pieces. Chip breakers work by interrupting the flow of the chip, causing it to break into segments. This helps prevent long, continuous chips from forming, which can be difficult to handle.
  • Tool geometry: The geometry of the cutting tool can also influence chip formation. For example, a tool with a positive rake angle can reduce the cutting force and produce smaller chips. Additionally, tools with special coatings can improve chip flow and reduce friction.

3. Implement Effective Chip Removal Systems

  • Coolant systems: Coolant plays a crucial role in chip removal. It helps to lubricate the cutting tool, reduce heat, and flush away chips. There are different types of coolant systems, including flood coolant, mist coolant, and minimum quantity lubrication (MQL). Flood coolant systems are the most common, as they provide a continuous flow of coolant to the machining area. Mist coolant systems use a fine mist of coolant, which can be more environmentally friendly. MQL systems use a very small amount of coolant, which is sprayed directly onto the cutting tool.
  • Chip conveyors: Chip conveyors are used to remove chips from the machining area. There are several types of chip conveyors, including belt conveyors, chain conveyors, and screw conveyors. Belt conveyors are suitable for handling large volumes of chips, while chain conveyors are more durable and can handle heavier chips. Screw conveyors are ideal for removing chips from deep holes or narrow spaces.

4. Regular Maintenance and Inspection

  • Cleaning: Regularly cleaning the machining area and the chip removal systems is essential to prevent chip accumulation. This includes cleaning the coolant tanks, chip conveyors, and the machine tool itself.
  • Inspection: Inspecting the cutting tools, coolant systems, and chip removal systems on a regular basis can help identify potential problems before they become serious. This includes checking for tool wear, coolant leaks, and blockages in the chip removal systems.

Case Studies

To illustrate the effectiveness of these strategies, let’s look at a couple of case studies.

Case Study 1: Machining Aluminum
A customer came to us with a project to machine aluminum parts. They were experiencing problems with long, continuous chips that were getting tangled in the cutting tool and causing surface finish issues. We recommended optimizing the cutting parameters by increasing the cutting speed and reducing the feed rate. We also used a cutting tool with a chip breaker. As a result, the chips were broken into smaller pieces, which were easier to remove. The surface finish of the machined parts improved significantly, and the productivity of the machining process increased.

Case Study 2: Machining Cast Iron
Another customer was machining cast iron parts and was having trouble with discontinuous chips clogging the chip conveyor. We suggested using a flood coolant system to flush away the chips more effectively. We also adjusted the depth of cut to reduce the size of the chips. After implementing these changes, the chip removal process became more efficient, and the machine downtime was reduced.

Conclusion

Dealing with chips in CNC machining is a critical aspect of the manufacturing process. By understanding chip formation, identifying the problems caused by chips, and implementing effective strategies for chip management, we can improve the quality of the machined parts, increase the efficiency of the machining process, and extend the lifespan of the cutting tools.

Low Volume Manufacturing As a CNC machining supplier, we are committed to providing our customers with high – quality machining services. If you have any questions about chip management or need assistance with your CNC machining projects, please feel free to contact us for a consultation. We look forward to working with you to meet your machining needs.

References

  • Trent, E. M., & Wright, P. K. (2000). Metal cutting. Butterworth – Heinemann.
  • Kalpakjian, S., & Schmid, S. R. (2014). Manufacturing engineering and technology. Pearson.

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