A complete analysis of machining burrs: a practical guide from understanding to solving them

When you get a metal part and find a tiny curl on the edge; when you disassemble a plastic toy and feel the burrs on the parting surface - these are machining burrs. Don't underestimate them, but they can cause parts to "strike" and production to "stuck". Want to know how burrs are generated? How to avoid and remove them? This article will use simple and easy-to-understand language to take you from understanding burrs to solving burrs, and become a "pitfall avoidance expert" in machining technology.

1. What are machining burrs? ​

(1) The nature of burrs

Machining burrs are excess burrs, protrusions or residues that appear on the edge or surface of a part during the cutting, stamping, casting and other processing processes. For example, the curling of the hole after drilling a metal part, the thin blade-like protrusion on the edge of a stamped part, and the transparent film at the gap of a plastic part mold are all common burr forms. They vary in size, with small ones difficult to see with the naked eye and large ones that can be clearly touched.

(2) Typical burrs generated by different processing methods (such as cutting, stamping, casting, cutting, etc.)

2. The impact of machining burrs on parts

(1) Impact on assembly and function

Assembly difficulties: Burrs on the edge of parts can cause jamming during assembly, such as the bearing cannot be smoothly installed on the shaft, affecting the matching accuracy of parts.

Function failure: Burrs on hydraulic pipe joints may puncture the seal ring, causing oil leakage; burrs on circuit boards may cause short circuits, affecting the normal operation of electronic components.

(2) Shorten the life of parts

Cause cracks: Burrs on the edge of parts will become the starting point of cracks during long-term use, especially when subjected to vibration or load, which can easily cause parts to break.

Accelerate wear and corrosion: Burrs at the meshing of gears will increase friction and accelerate tooth surface wear; burrs on metal parts are prone to water accumulation, causing rust to accelerate.

(3) Increase costs

High post-processing costs: Removing burrs requires additional processes, whether manual grinding or machine processing, which will increase processing time and cost.​

Risk of batch scrapping: If burrs are not detected, the entire batch of parts may be unqualified, causing significant losses.

3. Causes of machining burrs

(1) Material properties ​

Plastic materials: Soft metals such as aluminum and copper are prone to plastic deformation due to extrusion during processing, forming curling or flaky burrs. ​

Brittle materials: Such as cast iron and ceramics are prone to cracking during processing, forming granular or notched burrs. ​

(2) Tool or mold problems ​

Tool wear: When the tool edge becomes blunt, it cannot cut cleanly when cutting the material, and it is easy to squeeze and deform the material, leaving burrs. ​

Improper mold gap: The gap between the upper and lower molds of the stamping mold is too large, and the material will be stretched or torn during stamping, forming burrs. ​

(3) Unreasonable processing parameters ​

Excessive feed speed: When drilling or cutting, the feed speed is too fast, and the material cannot be completely cut off in time, which will form curling burrs on the edge.​

Lack of cooling and lubrication: When no coolant or lubricant is used during processing, the material is easy to stick to the tool, and sintered burrs are formed after cooling. ​

(4) Poor equipment stability ​

Machine tool vibration: The machine tool spindle or workpiece vibrates, causing the material position to shift during processing, forming irregular burrs. ​

Workpiece clamping is not firm: The workpiece is not clamped during processing, and it moves after being subjected to force, affecting the processing accuracy and generating burrs. ​

(5) Design defects ​

Right-angle edge: The part is designed with a sharp right angle, which concentrates stress during processing and easily generates burrs; if it is designed with a chamfer or arc edge, the burr generation can be reduced. ​

Irrational structure: There is no reserved space for tool withdrawal at the bottom of the blind hole, and it is easy for material to remain when the tool withdraws, forming burrs. ​

4. Methods for dealing with machining burrs

(1) Prevention in the design stage ​

Edge treatment: The sharp edge of the part is designed as a chamfer (outer edge) or arc (inner edge), usually with a chamfer size of 0.3-0.5 mm, to reduce stress concentration and reduce the probability of burrs.​

Hole feature optimization: countersunk holes are designed at both ends of the through hole, and a tool withdrawal groove is reserved at the bottom of the blind hole to provide tool withdrawal space to avoid material residue. ​

Material selection: Select appropriate materials according to processing requirements. Avoid using materials with too high plasticity or too brittleness for high-precision parts. Pre-treat the material (such as annealing and softening) when necessary. 

(2) Process control​

Tool management: Regularly check the tool wear and replace the blunted tool in time; ensure that the mold gap meets the processing requirements to avoid burrs caused by improper gap. ​

Parameter adjustment: Adjust the processing parameters according to the material characteristics, such as using a lower feed speed when cutting soft metal to ensure that the material is cut cleanly; use appropriate coolant or lubricant during processing to reduce material adhesion. ​

Equipment maintenance: Maintain the stability of the machine tool, regularly check the spindle accuracy and workpiece clamping conditions, and reduce the impact of vibration and displacement on processing. ​

(3) Burr removal method​

1) Manual deburring: 

Use tools such as files and sandpaper to manually remove burrs, which is suitable for small batch production or workpieces with complex shapes. 

2) Mechanical removal method

Belt grinding: Use a belt machine to grind the surface or edge of the part to remove obvious burrs, suitable for flat or outer burr processing.

Rotary file finishing: Use an electric grinding head to install a small file to finely trim the burrs of complex parts such as deep holes and curved surfaces.

Vibration grinding: Put the parts and abrasives into the grinder for vibration, and remove the batch burrs of small and medium-sized parts by friction.

3) Precision removal technology

Electrolytic deburring: Use electrochemical principles to dissolve burrs, suitable for burr removal in holes or complex structures of high-precision parts.

Laser deburring: Use lasers to accurately burn off tiny burrs, suitable for occasions such as microelectronic devices that require extremely high precision.

4) Emerging environmental protection technology

Water jet deburring: Use high-pressure water jets to flush away burrs, without heat-affected zones, suitable for materials such as aluminum alloys and plastics.

Dry ice deburring: Use the low temperature of dry ice particles to embrittle and break burrs, suitable for flash removal of injection molded parts, clean and environmentally friendly.​

(4) Inspection and improvement​

Visual inspection: Use high-definition cameras or automated inspection equipment to identify burrs on the surface of parts to ensure that no part is missed. ​

Functional testing: Check whether burrs affect the function of parts through simulated assembly or actual use testing, and find problems in time. ​

Continuous optimization: Record the location and cause of each burr problem, improve the design or processing technology in a targeted manner, and gradually reduce the generation of burrs.

5. Examples of responses in different industries​

(1) Automobile manufacturing​

Automotive parts such as gearbox gears and battery housings can effectively reduce casting and cutting burrs by optimizing mold gaps and using automated grinding equipment to ensure assembly accuracy and part life. ​

(2) Medical devices​

Precision medical devices such as artificial joints and syringes have extremely low tolerance for burrs. Electrolytic deburring and microscopic inspection are required to ensure that the surface of parts is smooth and avoid damage to human tissue. ​

(3) Electronic manufacturing​

Circuit boards, chips and other electronic components use laser deburring and high-precision visual inspection to prevent short circuits or poor contact caused by burrs and ensure stable product performance.

6. Summary

Although machining burrs are common, their impact can be effectively reduced through reasonable design, precise machining control and appropriate removal technology. Regardless of the industry, paying attention to burr problems and taking targeted measures can improve part quality, reduce costs, and lay the foundation for product reliability and precision.