“Precautions for CNC Machining Centers in Mold Processing”
As a key equipment for mold processing, the precision and performance of a CNC machining center directly affect the quality of molds. In order to process ideal products better, when using a CNC machining center for mold processing, the following aspects need to be noted.
I. Tool selection and use
When using a ball-end milling cutter to mill curved surfaces:
The cutting speed at the tip of a ball-end milling cutter is very low. When using a ball-end cutter to mill a relatively flat curved surface perpendicular to the machined surface, the surface quality cut by the tip of the ball-end cutter is poor. Therefore, the spindle speed should be appropriately increased to improve cutting efficiency and surface quality.
Avoid cutting with the tool tip, which can reduce tool wear and improve machining accuracy.
Flat cylindrical milling cutter:
For a flat cylindrical milling cutter with a center hole at the end face, the end edge does not pass through the center. When milling curved surfaces, it must not be fed vertically downward like a drill bit. Unless a process hole is drilled in advance, the milling cutter will be broken.
For a flat cylindrical milling cutter without a center hole at the end face and with the end edges connected and passing through the center, it can be fed vertically downward. However, due to the very small blade angle and large axial force, it should also be avoided as much as possible. The best way is to feed obliquely downward. After reaching a certain depth, use the side edge for transverse cutting.
When milling groove surfaces, process holes can be drilled in advance for tool feeding.
Although the effect of vertical tool feeding with a ball-end milling cutter is better than that with a flat-end milling cutter, due to the excessive axial force and the influence on the cutting effect, this tool feeding method is best not used.
When using a ball-end milling cutter to mill curved surfaces:
The cutting speed at the tip of a ball-end milling cutter is very low. When using a ball-end cutter to mill a relatively flat curved surface perpendicular to the machined surface, the surface quality cut by the tip of the ball-end cutter is poor. Therefore, the spindle speed should be appropriately increased to improve cutting efficiency and surface quality.
Avoid cutting with the tool tip, which can reduce tool wear and improve machining accuracy.
Flat cylindrical milling cutter:
For a flat cylindrical milling cutter with a center hole at the end face, the end edge does not pass through the center. When milling curved surfaces, it must not be fed vertically downward like a drill bit. Unless a process hole is drilled in advance, the milling cutter will be broken.
For a flat cylindrical milling cutter without a center hole at the end face and with the end edges connected and passing through the center, it can be fed vertically downward. However, due to the very small blade angle and large axial force, it should also be avoided as much as possible. The best way is to feed obliquely downward. After reaching a certain depth, use the side edge for transverse cutting.
When milling groove surfaces, process holes can be drilled in advance for tool feeding.
Although the effect of vertical tool feeding with a ball-end milling cutter is better than that with a flat-end milling cutter, due to the excessive axial force and the influence on the cutting effect, this tool feeding method is best not used.
II. Precautions during the processing process
Material inspection:
When milling curved surface parts, if phenomena such as poor heat treatment, cracks, and uneven structure of the part material are found, processing should be stopped in time. These defects may lead to tool damage, reduced machining accuracy, and even scrapped products during the processing process. Stopping processing in time can avoid wasting working hours and materials.
Pre-start inspection:
Before each start of milling, appropriate inspections should be carried out on the machine tool, fixture, and tool. Check whether various parameters of the machine tool are normal, such as spindle speed, feed rate, tool length compensation, etc.; check whether the clamping force of the fixture is sufficient and whether it will affect machining accuracy; check the wear condition of the tool and whether the tool needs to be replaced. These inspections can ensure the smooth progress of the processing process and improve machining accuracy and efficiency.
Mastering the filing allowance:
When milling the mold cavity, the filing allowance should be appropriately mastered according to the roughness of the machined surface. For parts that are more difficult to mill, if the surface roughness of the machined surface is poor, more filing allowance should be left appropriately so that the required surface quality can be achieved in the subsequent filing process. For easily machined parts such as flat surfaces and right-angle grooves, the surface roughness value of the machined surface should be reduced as much as possible, and the filing workload should be reduced to avoid affecting the accuracy of the cavity surface due to large-area filing.
Material inspection:
When milling curved surface parts, if phenomena such as poor heat treatment, cracks, and uneven structure of the part material are found, processing should be stopped in time. These defects may lead to tool damage, reduced machining accuracy, and even scrapped products during the processing process. Stopping processing in time can avoid wasting working hours and materials.
Pre-start inspection:
Before each start of milling, appropriate inspections should be carried out on the machine tool, fixture, and tool. Check whether various parameters of the machine tool are normal, such as spindle speed, feed rate, tool length compensation, etc.; check whether the clamping force of the fixture is sufficient and whether it will affect machining accuracy; check the wear condition of the tool and whether the tool needs to be replaced. These inspections can ensure the smooth progress of the processing process and improve machining accuracy and efficiency.
Mastering the filing allowance:
When milling the mold cavity, the filing allowance should be appropriately mastered according to the roughness of the machined surface. For parts that are more difficult to mill, if the surface roughness of the machined surface is poor, more filing allowance should be left appropriately so that the required surface quality can be achieved in the subsequent filing process. For easily machined parts such as flat surfaces and right-angle grooves, the surface roughness value of the machined surface should be reduced as much as possible, and the filing workload should be reduced to avoid affecting the accuracy of the cavity surface due to large-area filing.
III. Measures to improve machining accuracy
Optimize programming:
Reasonable programming can improve machining accuracy and efficiency. When programming, according to the shape and size of the mold, select appropriate tool paths and cutting parameters. For example, for complex curved surfaces, methods such as contour line machining and spiral machining can be used to reduce tool idle travel and improve machining efficiency. At the same time, cutting parameters such as spindle speed, feed rate, and cutting depth should be set reasonably to ensure machining quality and tool life.
Tool compensation:
Tool compensation is an important means to improve machining accuracy. During the processing process, due to tool wear and replacement, the machining size will change. Through the tool compensation function, the radius and length of the tool can be adjusted in time to ensure the accuracy of the machining size. At the same time, tool compensation can also be used to compensate for the errors of the machine tool and improve machining accuracy.
Accuracy detection:
During the processing process, the mold should be inspected for accuracy regularly. Detection can be carried out using equipment such as three-coordinate measuring instruments and projectors to detect the size, shape, and position accuracy of the mold. Through detection, problems in the processing process can be found in time, and corresponding measures can be taken for adjustment to ensure machining accuracy.
Optimize programming:
Reasonable programming can improve machining accuracy and efficiency. When programming, according to the shape and size of the mold, select appropriate tool paths and cutting parameters. For example, for complex curved surfaces, methods such as contour line machining and spiral machining can be used to reduce tool idle travel and improve machining efficiency. At the same time, cutting parameters such as spindle speed, feed rate, and cutting depth should be set reasonably to ensure machining quality and tool life.
Tool compensation:
Tool compensation is an important means to improve machining accuracy. During the processing process, due to tool wear and replacement, the machining size will change. Through the tool compensation function, the radius and length of the tool can be adjusted in time to ensure the accuracy of the machining size. At the same time, tool compensation can also be used to compensate for the errors of the machine tool and improve machining accuracy.
Accuracy detection:
During the processing process, the mold should be inspected for accuracy regularly. Detection can be carried out using equipment such as three-coordinate measuring instruments and projectors to detect the size, shape, and position accuracy of the mold. Through detection, problems in the processing process can be found in time, and corresponding measures can be taken for adjustment to ensure machining accuracy.
IV. Safety operation precautions
Operator training:
Operators of CNC machining centers should undergo professional training and be familiar with the operation methods and safety precautions of the machine tool. The training content includes the structure, performance, operation methods, programming skills, and safety operation procedures of the machine tool. Only personnel who have passed training and passed the assessment can operate the CNC machining center.
Safety protection devices:
CNC machining centers should be equipped with complete safety protection devices such as protective doors, shields, and emergency stop buttons. When operating the machine tool, the operator should use safety protection devices correctly to avoid safety accidents.
Tool installation and replacement:
When installing and replacing tools, the power of the machine tool should be turned off first and ensure that the tool is installed firmly. When installing tools, special tool wrenches should be used. Avoid using tools such as hammers to strike the tool to avoid damaging the tool and the machine tool spindle.
Safety precautions during the processing process:
During the processing process, the operator should closely monitor the operating status of the machine tool. If any abnormal situation is found, the machine should be stopped for inspection immediately. At the same time, avoid touching the tool and workpiece during the processing process to avoid safety accidents.
Operator training:
Operators of CNC machining centers should undergo professional training and be familiar with the operation methods and safety precautions of the machine tool. The training content includes the structure, performance, operation methods, programming skills, and safety operation procedures of the machine tool. Only personnel who have passed training and passed the assessment can operate the CNC machining center.
Safety protection devices:
CNC machining centers should be equipped with complete safety protection devices such as protective doors, shields, and emergency stop buttons. When operating the machine tool, the operator should use safety protection devices correctly to avoid safety accidents.
Tool installation and replacement:
When installing and replacing tools, the power of the machine tool should be turned off first and ensure that the tool is installed firmly. When installing tools, special tool wrenches should be used. Avoid using tools such as hammers to strike the tool to avoid damaging the tool and the machine tool spindle.
Safety precautions during the processing process:
During the processing process, the operator should closely monitor the operating status of the machine tool. If any abnormal situation is found, the machine should be stopped for inspection immediately. At the same time, avoid touching the tool and workpiece during the processing process to avoid safety accidents.
In conclusion, when using a CNC machining center for mold processing, attention should be paid to tool selection and use, precautions during the processing process, measures to improve machining accuracy, and safety operation precautions. Only by strictly following the operating procedures can machining quality and safety be guaranteed and production efficiency be improved.