How to Keep Your Chips Under Control

When it comes to best practices in machining, SECO is our first reference – an example being their piece about basic singular patterns in machining.  

We thought their article on How to Overcome Chips Challenges might be useful when you are doing machining and metal-cutting work. 

In the article, they cover: 

• How to influence chip formation 
• General description of basic chip types (segmented, continuous, built-up edge, shearing) 
• Different types of basic chip cross-sections 
• Chip breaking geometries 
• Influence of cutting speed on chip formation

They included helpful illustrations as well, such as these examples: 

• Different types of basic chip cross sections

• Examples of different chip forms in various workpiece materials

• Basic principle of a chip-breaking geometry: In general terms, when the rake angle decreases (negative tooling), chip curvature becomes tighter, which leads to shorter, broken chips. Chip breakers serve to reduce the radius of chip curvature and thus break chips into shorter lengths.
  • A. Chip
  • B. Without chip breaker
  • C. With chip breaker
  • D. Chip breaker
  • E. Tool
  • F. Workpiece

 As a conclusion, they basically suggest that you take these steps to achieve “trouble-free chip formation”:

1. Prioritize the process-optimization criterion: either productivity or cost efficiency. 
2. If chip formation is acceptable, go to step 5. 
   If chips are too long, go to step 3. 
   If chips are too short, go to step 4. 
3. If productivity is important, increase the feed. 
   If cost efficiency is important, change the chip breaker to a stronger geometry. 
   Keep the feed within the range of the chip-breaking geometry. 
   Go to step 5. 
4. If productivity is important, change the chip breaker to a sharper geometry. 
   If cost efficiency is important, reduce the feed. 
   Keep the feed within the range of the chip-breaking geometry. 
   Go to step 5. 
5. If cost efficiency is the priority, lower cutting speeds to improve it. 
   If productivity is a priority, increase cutting speeds to improve it.

AIMS' note on managing chips

• Tool geometry: Choose cutting tools with chipbreakers designed for the material you're machining. These chip-breakers introduce interruptions or curves into the cutting edge, forcing the chips to curl and break into smaller, more manageable pieces. Also, selecting the correct nose radius for your insert can help control chip formation.

• Cutting parameters: Adjust your feed rate and cutting speed. Increasing feed rates often helps break chips, while higher cutting speeds can produce thinner and more manageable chips. However, be careful not to push speeds and feeds beyond the tool's capabilities, as this can lead to tool breakage or poor surface finish. Refer to recommended parameters from your tooling manufacturer as a starting point. 

• Coolant: High-pressure coolant directed at the cutting zone can effectively break chips and flush them away, improving chip control. Ensure your coolant system is working optimally and use the correct coolant type for the job. 

• Machine rigidity: A rigid machine setup helps reduce vibrations that can lead to unpredictable chip formation. Make sure your workpiece and tooling are clamped securely to minimise unwanted movement.