Tech Talk丨Common Problems in Precision Drilling: Analysis and Practical Solutions
SNSTC 2026-07-20
In daily drilling operations, even experienced operators may encounter recurring machining problems. Abnormal drill breakage, premature tool wear, poor chip control, and out-of-tolerance hole diameters can all affect machining efficiency, while also having a direct impact on product quality and production costs. Systematic analysis shows that these problems are often related to common technical factors. This article reviews several common issues encountered in drilling operations, analyzes their possible causes, and provides practical measures to improve process stability and machining performance.
1. Abnormal Drill Breakage
Drill breakage is one of the common problems encountered in machining operations. The main contributing factors include:
1)Excessive feed rate, which can result in an excessive instantaneous load on the drill;
2)Asymmetrical drill grinding, causing uneven cutting forces on the two cutting edges;
3)Poor chip evacuation, which may cause chips to accumulate inside the hole and increase drilling torque, especially in deep-hole machining.
In addition to these common causes, improper drill selection, a mismatch between the tool material and workpiece material, insufficient machine rigidity, or unstable clamping conditions may also contribute to drill breakage.
Recommended Countermeasures:
Parameter Optimization: Set the feed rate appropriately according to the workpiece material and machining conditions to maintain stable and consistent cutting.
Tool Management: Regularly inspect the regrinding quality to ensure that both cutting edges are symmetrical and accurately ground.
Process Improvement: For deep-hole drilling, use step feed (peck drilling) to facilitate smooth chip evacuation and prevent chip accumulation inside the hole.
Equipment Selection: Where applicable, give priority to through-coolant drills to ensure that cutting fluid is delivered directly to the cutting zone.
2. Continuous Chip Entanglement
When machining ductile materials, long, continuous ribbon-like chips can easily form. These chips not only affect operational safety but may also damage the hole wall.
This problem is often related to a mismatch between the drill flute geometry and the workpiece material. In addition, an excessively low feed rate may result in chips that are too thin to break effectively.
Recommended Countermeasures：
Increase the feed rate appropriately to increase chip thickness and improve chip breaking.
Use drills with dedicated chip-breaking flute geometry to produce shorter, more manageable chips.
Optimize tool geometry and cutting parameters to achieve safer and more effective chip control.
3. Short Tool Life
Premature drill wear affects machining quality and efficiency. The main causes usually include improper cutting parameters, such as excessive spindle speed, which raises the cutting temperature and accelerates drill point wear. In addition, insufficient cooling can significantly shorten tool life. To extend tool life, the spindle speed should be selected according to the workpiece material, and sufficient cutting fluid should be supplied to the drilling zone to provide effective cooling and lubrication.
Recommended Countermeasures：
Optimize the combination of spindle speed and feed rate according to the workpiece material.
Ensure sufficient cutting fluid flow rate and pressure to effectively reach the cutting zone.
Select coated drills or tool materials with improved wear resistance.
Regularly inspect drill wear and establish a standardized tool replacement schedule.
4. Oversized Hole Diameter
An oversized hole diameter after machining can affect the fit and assembly quality of the component. Possible causes include asymmetrical cutting edges, which may cause the drilling path to deviate, as well as spindle play or insufficient clamping rigidity, which can generate vibration during drill entry and withdrawal. The key to maintaining hole diameter accuracy is to ensure accurate drill regrinding and regularly inspect the machine condition, including clamping stability and spindle accuracy.
Recommended Countermeasures：
Ensure the symmetry and accuracy of drill regrinding. Professional drill-grinding equipment is recommended.
Regularly check spindle radial runout and the stability of the clamping system, and perform machine maintenance when necessary.
For high-precision hole machining, consider using a pilot hole or guide-bushing process.
Reduce spindle speed and feed rate appropriately to minimize machining vibration.
5. Standardized Operation and Routine Maintenance
In addition to making adjustments for specific problems, good operating practices and routine maintenance are equally important. For example, preparing a pilot hole before drilling can help improve drill positioning. Regularly inspecting drill wear and regrinding the tool when necessary can help maintain its cutting performance. In addition, selecting the appropriate cutting fluid according to the workpiece material and controlling its flow rate can also contribute to improved machining quality and tool life.
6.Conclusion
Drilling is a fundamental machining process, and its quality can be affected by a variety of factors. Issues such as drill breakage, poor chip control, short tool life, and oversized holes highlight the importance of systematically managing cutting parameters, tool selection, and operating practices.
Through systematic analysis and standardized practices, drilling process stability and efficiency can be effectively improved.
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