All kinds of problems can occur in cutting operations.
The most typical are chatter, poor surface finish, abnormal tool wear, and chip problems.
These are everyday occurrences on the shop floor, but if you understand their causes, you can respond quickly.
This page organizes the most common cutting problems and their causes.
In This Article
Chatter (Chattering)
Chatter is a phenomenon in which the tool or workpiece vibrates finely during machining, leaving striped patterns (chatter marks) on the machined surface.
It leads to degraded surface quality, reduced dimensional accuracy, and tool breakage.
The main causes are insufficient rigidity and resonance.
Chatter is more likely under conditions such as a long, slender workpiece that deflects easily, a long tool overhang, or an excessive depth of cut.
Countermeasures include shortening the overhang of the workpiece or tool, adjusting the depth of cut and feed, and changing the cutting speed to avoid resonance.
For long, slender workpieces, support from a guide bushing is also effective.
Poor Surface Finish
This is when the machined surface is rough or fails to reach the target surface quality.
Several causes are possible.
These include an excessive feed rate, a worn tool, an unsuitable cutting speed (in particular, a speed so low that built-up edge forms), and a mismatched nose radius.
Countermeasures include lowering the feed, replacing the tool, reviewing the cutting speed, and selecting a tool with an appropriate nose radius.
For finishing, it is also effective to separate roughing and finishing into different operations and use conditions dedicated to finishing.
Abnormal Tool Wear and Breakage
This is when tools wear out faster than expected or chip.
Causes include a cutting speed that is too high and raises the cutting-edge temperature, a tool grade or coating unsuited to the work material, and poor chip control.
Countermeasures include reviewing the cutting conditions (especially the cutting speed), selecting an appropriate tool grade and coating, and cooling the cutting edge (high-pressure coolant).
Chip Problems
These are problems in which long, stringy chips wrap around the tool or workpiece, or clog the inside of the machine.
They are especially common with gummy materials (stainless steel, aluminum, copper, etc.) and are a leading cause of stoppages during unattended operation.
Effective countermeasures include breaking chips up with oscillation cutting and evacuating them with high-pressure coolant.
Quick-Reference Troubleshooting Table
When a cutting problem occurs, being able to narrow down the cause from the symptom speeds up the response.
The table below organizes typical symptoms and the causes to suspect first.
| Symptom | Causes to Suspect First | Main Direction of Response |
|---|---|---|
| Striped patterns on the machined surface (chatter) | Insufficient rigidity, resonance | Shorten overhang; adjust depth of cut and speed |
| Rough surface | Excessive feed, tool wear, unsuitable speed | Reduce feed, replace tool, review speed |
| Tools wear or chip quickly | Excessive speed, unsuitable grade, insufficient cooling | Review conditions; optimize tooling and cooling |
| Chips wrap or clog | Insufficient chip breaking | Oscillation cutting, high-pressure coolant |
| Unstable dimensions | Tool wear, thermal displacement | In-machine measurement, tool-life management |
This table is only a starting point.
In practice, multiple causes can overlap, so it is important to isolate them by checking one factor at a time.
Frequently Asked Questions (FAQ)
Q. How can I stop chatter?
A. Keep the overhang of the workpiece and tool as short as possible, and increase rigidity with high-rigidity or anti-vibration holders.
Adjusting the depth of cut, feed, and cutting speed to avoid resonance ranges is also effective, as is reducing cutting forces with a smaller corner radius or lead angle.
On Swiss-type automatic lathes, tightening the guide bushing to suppress runout and deflection of the material helps control chatter.
Q. I cannot get a clean surface finish.
What causes this?
A. Possible causes include an excessive feed rate, tool wear or a chipped cutting edge, built-up edge or tearing caused by an unsuitable cutting speed, and a mismatched nose radius.
Start by using a larger nose radius and a lower feed, then check and adjust the conditions one at a time.
Depending on the work material, switching to cermet or diamond-based (DLC/PCD) tools can suppress welding and built-up edge and greatly improve surface roughness.
Q. My tools wear out too quickly.
A. The cutting speed may be too high, raising the temperature at the cutting edge.
Start by reviewing the cutting conditions and selecting a tool grade and coating suited to the work material.
In addition, using high-pressure coolant or through-coolant tools cools the cutting edge reliably and forcibly evacuates chips, which suppresses welding and boundary wear and extends tool life.
Summary
Chatter, poor surface finish, tool wear, and chip problems occur frequently in cutting operations.
In every case, the basic approach to a solution is to isolate the cause from the standpoints of rigidity, cutting conditions, tooling, and chip control, and to address each factor one at a time.
For related reading, see how to set cutting conditions and other trouble cases (Troubleshooting & Case Studies).