Burr in metal processing is a problem that everyone will encounter, such as drilling, turning, milling, plate cutting, etc. One of the hazards of burr is easy to cut. In order to remove burr, it is usually necessary to carry out a secondary operation called deburring. The three deburring and edge finishing of precision parts may account for 30% of the cost of finished parts. In addition, the secondary finishing operation is difficult to automate, so burr has become a very difficult problem.
Here are all the machining problems that bothered us
How to solve burr
1. chemical deburring
Chemical deburring is the use of chemical energy for processing, chemical ions will adhere to the surface of the parts, forming a film with high resistance and low conductivity to protect the workpiece from corrosion, and the burr can be removed by chemical action because it is higher than the surface. This deburring method is widely used in pneumatic, hydraulic, engineering machinery and other fields.
2. high temperature deburring
First, put the parts to be deburred into the tight sealing chamber, and then put them into the hydrogen oxygen mixture with a certain pressure, ignite the mixture to explode, release heat, and burn off the burr of the parts without damaging the parts.
The parts and abrasives are put into the closed drum together. During the rotation of the drum, the dynamic torque sensor, parts and abrasives are grinded together to remove the burr. Abrasives can be quartz sand, sawdust, alumina, ceramics and metal rings, etc.
This method is more traditional and the most time-consuming and laborious. Mainly through manual use of steel file, sandpaper, grinding head and other tools for grinding. Now the most commonly used in production is trimming knife.
5. process deburring
Edge rounding can refer to all actions to remove the edge of metal parts. However, it is usually associated with the radius at which the part edge is created.
Edge rounding is not simply to remove sharpness or burr, but to break the edge of metal parts to improve their surface coating and protect them from corrosion.
Rotary setback: suitable for laser cutting, stamping or machining the edge of parts.
Manual grinding machine: suitable for metal processing projects requiring grinding and edge rounding or deburring.
Burr in special difficult milling parts
In milling parts, deburring is more complex and costly, because multiple burrs are formed in different positions of different sizes. At this time, it is very important to choose the right process parameters to minimize the burr size.
main factors affecting burr formation in end milling
① Milling parameters, milling temperature and cutting environment have certain influence on the formation of burr. The influence of some main factors such as feed speed and milling depth is reflected by the plane cutting angle theory and the tool tip exit sequence EOS theory.
② The better the plasticity of the workpiece material, the easier it is to form I-type burr. In the process of end milling brittle materials, if the feed rate or plane cutting angle is large, it is conducive to the formation of type III burr (defect).
③ When the angle between the end face of the workpiece and the machined plane is greater than the right angle, the formation of burr can be restrained due to the increased support stiffness of the end face.
④ The use of milling fluid can prolong the tool life, reduce the tool wear, lubricate the milling process, and reduce the burr size.
⑤ Tool wear has a great influence on the formation of burr. When the tool is worn to a certain extent, the arc of the tool tip increases, not only the size of the burr in the exit direction of the tool increases, but also the burr in the cut in direction
⑥ Other factors such as tool material also have some influence on the formation of burr. Under the same cutting conditions, diamond tool is more conducive to restrain burr formation than other tools.
Using appropriate cutting conditions to restrain burr
It is an effective method to eliminate the space of burr in order to restrain the burr. For example, chamfering can be used to reduce the space before cutting.
In order to reduce the cutting residue as much as possible, the most suitable tool and cutting condition must be selected. The cutting tool with large rake angle and sharp cutting edge is selected to improve the cutting speed and cutting characteristics. Especially in finishing cutting, the minimum cutting depth and feed must be used.
The space between the tool and the workpiece determines the size of the burr. Let’s take a look at the following diagram.
In fact, burr can not be avoided in the process of processing, so it is better to solve the burr problem from the process and avoid excessive manual intervention. The use of chamfered end milling cutter can reduce the burr space, effectively remove burr, and is also a very suitable method to remove burr.