Common Problems And Solutions in CNC Lathe Cylindrical Turning

In CNC machining, cylindrical turning is one of the most basic and commonly used processes, typically performed on horizontal CNC lathes. This article focuses on common issues encountered during cylindrical turning and their causes, including poor surface finish, built-up edge formation, difficulty controlling roundness, chatter marks, and taper generation.

1. Causes and Countermeasures for Dimensional Inaccuracy

Common Causes:

· Loose workpiece clamping

· Worn or dull turning tool with chipped edges

· Improper or worn tailstock tension when turning long shafts; improper adjustment of follower rest or steady rest

· Misreading drawings or dial scales; no trial turn performed

· Measurement tool errors or inaccurate measurement

· Thermal expansion causing dimensional changes

· Failure to stop automatic feed timely, causing CNC lathe feed overrun

· Incorrect tool width or depth calculation during grooving

Preventive Measures:

· Correctly use drawings and dial scales; perform trial turn

· Calibrate measuring tools; avoid measuring at high temperatures

· Stop automatic feed promptly; select appropriate tool width

· Accurately calculate groove width and depth

2. Causes and Solutions for Taper Formation

Causes:

· Tailstock axis misaligned with spindle axis during one-point or two-point support

· Incorrect position of the cross-slide

· Bed guideways not parallel to the spindle axis

· Excessive workpiece overhang causing deflection under turning forces

· Gradual tool wear and elastic deformation of long, slender shafts

Solutions:

· Align the tailstock axis with the spindle axis

· Correct cross-slide position

· Adjust bed guideways to be parallel with the spindle

· Reduce workpiece overhang; increase support rigidity

· Replace worn turning tools promptly

3. Causes and Prevention of Roundness Out of Tolerance

Common Causes:

· Excessive spindle clearance

· Uneven stock allowance causing variable turning thickness

· Poor contact or looseness of center holes or tailstock during two-point support

Prevention:

· Regularly check spindle clearance; replace bearings if needed

· Properly allocate rough and finish machining allowances

· Adjust tailstock tightness to minimize radial runout

4. Causes and Solutions for Poor Surface Roughness and Built-Up Edge

Causes:

· Improper turning parameters (speed, feed, depth of cut)

· Dull or damaged tools causing excessive turning forces, heat, and hardness changes

· Poor chip evacuation leading to the built-up edge and surface damage

· Surface waviness caused by vibration (due to motor vibration, loose or out-of-round spindle bearings, hollow or overhanging workpieces, loose tool post)

Solutions:

· Optimize turning parameters; maintain sharp tools

· Ensure smooth chip flow; regularly clear chips

· Check CNC lathe machine rigidity and tighten components

· Control workpiece overhang; increase support

5. Causes and Elimination of Surface Waviness

Mechanical Causes:

· Poor meshing between feed rack and pinion

· Friction or poor assembly precision of lead screw and carriage box

· Excessive spindle bearing clearance causing unstable transmission

Elimination Methods:

· Adjust rack and pinion meshing

· Replace low-precision gears and lead screws

· Repair transmission parts to restore coaxially and parallelism

· Maintain proper lubrication and tightening

6. Causes and Remedies for Workpiece Size Fluctuations

Common Causes:

· Loose workpiece clamping

· Worn or dull turning tools

· Improper tailstock tension or worn components

· Improper adjustment of follower rest or steady rest

Remedies:

· Check and secure clamping

· Replace or sharpen tools

· Adjust tailstock tension; replace worn parts

· Maintain lubrication to reduce wear

Summary

The quality of cylindrical turning is influenced by equipment, tooling, and operational factors. Maintaining CNC machine precision, optimizing turning parameters, securing stable workpiece clamping, using sharp tools, and applying proper cooling and lubrication can effectively improve machining results. OTURN not only focuses on continuous equipment and process optimization but also offers one-stop services from project consultation, solution design, and custom manufacturing to after-sales maintenance. Through professional technical support, strict quality control, rapid after-sales response, and regular follow-ups, we help customers efficiently solve machining challenges and ensure every product is precise and reliable. Choose OTURN for comprehensive, professional machining service assurance.