The processing performance of cnc numerical control machining centers is very powerful and their application range is wide. However, there are some detailed knowledge that our processing personnel need to master when using CNC machining centers to Custom Machined Metal Parts. We have summarized a large amount of data and will analyze in detail the eight major steps that need to be familiar with when using CNC machining centers for everyone. Let's take a look together and see if you have overlooked these:
I. Preparations before Starting the Machine Tool
After each startup of the machine tool or after the feed stops or resets, the reference of the machine tool should first be reset to zero to provide a reference position for subsequent operations.
II. Custom Machined Metal Parts Clamping
Before clamping the Custom Machined Metal Parts, each surface must be cleaned thoroughly to ensure it is free of iron filings, dust and oil stains. Use a file or oilstone to remove burrs from the surface of the workpiece. The high-speed iron used for clamping must be ground flat on each surface by a grinding machine to make it smooth and stable. The weights and nuts must be fixed to ensure reliable clamping of the processed parts. For some difficult-to-clamp parts, they can be directly clamped onto the vise. The worktable of the machine tool needs to be kept clean, free of iron filings, oil stains and dust. Iron pads are generally placed at the four corners of the Custom Machined Metal Parts. For parts with large spans, they must be placed in the middle.
According to the dimensions on the drawing, use a straightedge to check whether the length, width and height of the workpiece are qualified. When clamping the Custom Machined Metal Parts, follow the clamping and placement method in the programming operation manual, and avoid the situation where the cutting head may touch the fixture during processing. After the workpiece is placed on the iron pad, the reference surface of the workpiece should be pulled according to the requirements of the drawing. For those already ground workpieces, it is necessary to check whether their verticality is qualified. After the workpiece is pulled out, the nut must be tightened to prevent the clamping from being unreliable and causing the Custom Machined Metal Parts to have a unique phenomenon during processing. Pull the gauge again to ensure that the error does not exceed the specified value after the clamping is completed.
III. Colliding data of Custom Machined Metal Parts
For the clamped parts, the centering bar can be used for alignment to determine the processing coordinate position. The medium rods can be of two types: mechanical and photoelectric. In the middle division, the number of single-sided touches and the number of double-sided touches can be adopted. The steps for center touch count are roughly as follows:
The photoelectric type is stationary, while the mechanical type rotates 450-600 IPm. Manually move the X-axis of the worktable in the middle to let the impact head touch the side of the Custom Machined Metal Parts. When the impact head just touches the workpiece and the red light is on, set the relative coordinate value at this point to 0. Then manually move the X-axis of the worktable to let the impact head touch the other side of the Custom Machined Metal Parts. When the collision head touches the parts, record the relative coordinates at this time. Subtract the diameter of the collision head from its relative value and check whether the length of the workpiece meets the requirements on the drawing.
Divide this relative coordinate number by 2, and the resulting value is the middle value of the workpiece's X-axis. Then move the worktable to the middle value above the X-axis, setting the relative coordinate value of the X-axis at this point to 0. This point is the zero point on the workpiece's X-axis. Carefully record the mechanical coordinate value of the zero point on the workpiece's X-axis in one of G54-G59. Let the machine tool determine the 0 point on the workpiece and check the correctness of the data again. The steps for setting the 0 point on the Y-axis of the workpiece are the same as the operation method on the X-axis.
IV. CAM Software Programming for Custom Machined Metal Parts
Programmers select the parts to be processed, program them through the CAM software UG to generate tool paths, conduct interference checks through the UG simulation module, process after the interference checks to generate safe and stable NC codes, which are transmitted to the workshop and then put on the machine.
V. Prepare all the tools according to the programming operation manual
According to the tool data in the programming operation manual, replace the tool to be processed with the one to be used. Let the tool touch the height gauge placed on the reference surface. When the red light of the gauge is on, set the relative coordinate value of this point to zero. Move the tool to a safe place, manually move the tool down by 50mm, and set the relative coordinate value of this point to zero again. This point is the zero position of the Z-axis.
Record the mechanical coordinate Z value of this point in one of G54 to G59. This completes the zero position setting of the X, Y and Z axes of the workpiece. Check the correctness of the data carefully once again
For the single-sided impact number, also follow the above method to impact one side of the X and Y axes of the Custom Machined Metal Parts. Offset the relative coordinate values of the X and Y axes at this point. The radius of the impact number head is the zero position of the X and Y axes. Finally, mark the mechanical coordinate of the X and Y axes at this point in one of the positions G54 to G59. Check the correctness of the data carefully once again.
Check the correctness of the zero point. Move the X and Y axes to the edge of the workpiece, and visually inspect the correctness of the zero point based on the size of the workpiece. Copy the program file to the computer according to the file path in the programming operation instruction manual.
VI. Setting of Processing Parameters
The setting of the spindle speed during processing: N=1000×V/ (3.14×D)
N: Spindle speed (rpm/min)
V: Cutting speed (m/min)
D: Tool diameter (mm)
The feed rate setting for processing: F=N×M×Fn
F: Feed rate (mm/min)
M: Number of cutting edges of the tool
Fn: Cutting capacity of the tool (mm/ revolutions)
The cutting allowance per edge is set as: Fn=Z×Fz
Z: The number of cutting edges of the tool
Fz: Cutting allowance per edge of the tool (mm/ turn)
VII. Start processing
At every stage of the process, it is necessary to carefully check whether the tool to be used is the one set in the programming manual. When starting the processing, the feed rate should be adjusted to the minimum. When performing rapid positioning tool drop and tool feed in a single section, one should concentrate and place the hand on the stop button. If any abnormality occurs, stop immediately. It is necessary to observe the movement direction of the tool and ensure safe feed. Then, gradually increase the feed rate to an appropriate position. At the same time, coolant or cold air should be added to the tool and the workpiece. When performing rough machining, the workpiece should not be too far from the control panel. If any abnormal phenomenon occurs, the machine should be stopped immediately for inspection. After rough machining, pull the gauge once to ensure that the workpiece is not loose. If it is, the number of follow-up touches needs to be recalibated. During the machining process, continuously optimize the machining parameters to achieve a better machining effect.
Since this process is a crucial one, after the custom machined metal parts is processed, it is necessary to measure whether its main dimensional values are consistent with the requirements of the drawings. If there are any problems, they should be reported to the on-duty leader or the program editor in a timely manner for inspection and resolution. Only after self-inspection and passing can it be removed, and it must be sent to the inspector for special inspection.
Processing type
Hole processing: Before drilling holes on the machining center, it is essential to use a center drill for positioning first. Then, use a drill bit that is 0.5 to 2mm smaller than the drawing size for drilling. Finally, use an appropriate drill bit for fine processing.
Boring processing: When boring a workpiece, a center drill should be used for positioning first. Then, a drill bit 1 to 2mm smaller than the drawing size should be used for drilling. Next, a rough boring tool (or milling cutter) should be used to process until only about 0.3mm of machining allowance is left on one side. Finally, a precision boring tool with pre-adjusted dimensions should be used for precision boring. The allowance for the last precision boring should not be less than 0.1mm.
Reaming processing: When performing reaming processing on a custom machined metal parts, it is necessary to first position it with a center drill, then drill a hole with a drill bit 0.5 to 0.3mm smaller than the drawing size, and finally use a reamer to reaming the hole. During reaming processing, pay attention to controlling the spindle speed within 70 to 180rpm/min.
Direct numerical control (DNC) operation: Before DNC numerical control processing, the machined metal parts should be clamped properly, the zero position set, and the parameters set. Open the processing program to transfer data in the computer for inspection, then let the computer enter the DNC state and input the file name of the correct processing program. Press the TAPE key and the program start key on the processing machine tool. At this time, the machine tool controller will display the flashing LSK words. Press the Enter key on the computer to perform DNC data transmission processing.
VIII. Scope and Contents of Self-inspection by Processing personnel
Before processing, the processing personnel must carefully read the contents on the process card, know the parts and shapes of the workpiece that need to be processed, as well as all the dimensions marked on the drawing, and be aware of the processing content of the next procedure.
Before the workpiece is clamped, it is necessary to measure whether the size of the blank material meets the requirements of the drawing. When the workpiece is clamped, it is necessary to check whether its placement is consistent with the programming operation instruction manual.
After the rough machining is completed, self-inspection should be carried out. This way, the data with errors can be adjusted in a timely manner. The main content of the self-inspection is the position and size of the machining fill.
After rough machining and self-inspection, precision machining can be carried out. After precision machining, the operator should conduct self-inspection on the shape and size of the machining complement. For the machining complement of vertical surfaces, the basic length and width dimensions should be inspected. For the machining complement of inclined surfaces, the dimensions marked on the drawing should be inspected. After the machining personnel complete the self-inspection, The machined metal parts can be removed and sent to the inspector for special inspection only after it is confirmed to be in compliance with the drawings and process requirements.
The above are the eight basic steps for using a cnc numerical control machining center. Let's summarize them together. They mainly include the preparatory work before starting up, the clamping of the machined meatal parts, the number of contacts of the machined metal parts, the programming of the machined metal parts CAM software, the preparation of relevant tools according to the operation manual, the setting of processing parameters, the start of processing, and the self-inspection work after processing completion. I hope it can be helpful to you!
Xi an Hi-Precision Machinery Co., Ltd is located in famous ancient capital Xi'an China, with over 15 Years of experience in precision machining area. We provide high quality global manufacturing solutions and one-stop supply chain management solutions. Please feel free to contact us : jovis@lhcncparts.com