During CNC machining of metal casings, burrs are caused by material plastic deformation, tool-workpiece interaction, and improper process parameter settings. These burrs require comprehensive control through specialized process measures, including tool optimization, parameter adjustment, process routing planning, and post-process deburring. The following analysis focuses on core control strategies.
Optimizing tool geometry is fundamental to burr control in CNC machining. Increasing the tool rake angle reduces cutting deformation and burr formation; increasing the clearance angle reduces pressure on the workpiece by the cutting edge, preventing material tearing. Adjusting the lead and lead angles directly affects the residual area; increasing the lead angle and decreasing the lead angle can reduce burr size. For example, in the machining of aluminum alloy casings, a design with a large rake angle and a small clearance angle, combined with a composite tool structure, can simultaneously remove burrs generated by the previous tool during the cutting process, significantly improving machining quality.
Proper setting of cutting parameters is crucial for burr control. Excessively low cutting speeds can cause material stretching and deformation, resulting in burrs; excessive feed rates can cause material tearing. CNC machining requires dynamic parameter adjustment based on material properties. For example, when machining stainless steel casings, appropriately increasing cutting speed and reducing feed rate can reduce burr formation. Furthermore, tool wear and blunting can exacerbate burr formation, necessitating regular inspection and replacement of cutting edges to maintain cutting edge sharpness.
Process route planning must address burr generation at the source. By optimizing the machining sequence, burrs caused by workpiece deformation or incomplete fixturing can be reduced. For example, machining a flat surface before drilling a hole can avoid large burrs around the hole circumference. Preventing the tool from exiting the workpiece end face is key to burr reduction, as burrs are typically larger when the tool exits. Furthermore, workpiece clamping stability directly impacts cutting quality. Appropriate fixtures and clamping force are essential to prevent workpiece movement or vibration during machining.
The selection and application of cutting fluids also play a supporting role in burr control. Cutting fluids with poor lubrication and cooling properties increase friction between the tool and workpiece, leading to increased cutting heat and poor material cutting performance, which in turn causes burrs. CNC machining requires selecting the appropriate cutting fluid based on the material being machined. For example, when machining titanium alloy casings, using an oil-based cutting fluid can effectively lower cutting temperatures and reduce burr formation.
Post-process deburring is the last line of defense for ensuring the quality of metal casings. Chemical deburring uses a chemical reagent to react with the workpiece material, selectively corroding burrs and is suitable for complex, fine-grained parts. Electrolytic deburring removes burrs from hidden areas through electrolysis, offering high production efficiency. Thermal deburring uses instantaneous high temperatures to burn and oxidize burrs and is suitable for high-precision parts. Furthermore, flexible machining methods such as belt grinding, lapping, and spring-loaded grinding wheels can both remove burrs and improve surface finish.
Process innovation and specialized tool design are effective solutions for addressing burr issues in complex structures. For difficult-to-deburr areas such as cast seams within housing parts and annular grooves and flanges on inner bore surfaces, specialized tools and machine tools can be designed to improve product quality and production efficiency. For example, the use of specialized tools such as drilling-chamfering and tapping-chamfering tools can streamline the machining process and reduce burr formation.
Production management is equally important in burr control. Workpieces can be damaged by collisions and knocks during transportation, clamping, and assembly. Strengthening production management is crucial to reduce accidental damage. Furthermore, avoiding rough handling ensures consistent workpiece quality. Strict production management can further minimize the impact of burrs on product quality.
