How to determine the performance and quality of a used spark machine
The performance and quality of a used spark machine is mainly judged from the following aspects:
1. Assessment of machining accuracy
Worktable flatness check: Use a level to place on the surface of the worktable to check the levelness of the worktable at different positions. The smaller the flatness error, the better the equipment can ensure the relative positional accuracy between the workpiece and the electrode during the machining process. For example, high-precision spark machine table flatness error can be controlled within ± 0.01mm.
Electrode fixture perpendicularity detection: use a ruler against the electrode fixture, observe the degree of fit between the two, or use a percentage meter to measure the deviation of the electrode fixture in the vertical direction. If the perpendicularity is not good, the angle between the electrode and the workpiece will be deviated during the machining process, which will affect the machining accuracy, especially when machining the molds with perpendicularity requirements.
Positioning accuracy test: Evaluated by performing multiple positioning machining on a standard workpiece. For example, install a positioning block with a precise scale on the table, set the positioning program of the spark machine, carry out multiple repetitions of positioning processing, and measure the deviation of each processing position from the set position. The deviation of a spark machine with high positioning accuracy is usually within a few micrometers, which can meet the needs of precision machining.
2. Discharge performance test
Observation of discharge stability: Let the spark machine run under normal processing parameters for a period of time, and observe the spark status during the discharge process. Stable discharge process, the spark should be evenly distributed, no frequent arc interruptions or abnormal discharge phenomenon. Can be initially judged by observing the spark color and sound, the normal discharge spark is blue-white and sound uniform. If there is a yellow spark or discharge sound at times, it may indicate that the discharge is not stable, which will affect the processing surface quality and processing speed.
Electrode loss measurement: After processing a certain number of workpieces, measure the degree of electrode loss. You can choose a simple geometry electrode, such as a cylindrical electrode, and use a micrometer to measure the size change of the electrode before and after machining to calculate the electrode loss rate. Generally speaking, the electrode loss rate of a good performance spark machine is low, for example, the electrode loss rate of some advanced CNC spark machines can be controlled in the range of 0.1% - 0.3%, lower electrode loss helps to reduce the machining cost and improve the machining accuracy.
Machining speed test: According to the specification and application range of the spark machine, select the appropriate workpiece material and processing parameters for machining speed test. For example, for copper electrode machining mold steel workpiece, set certain parameters such as discharge current, pulse width and pulse interval, and record the time required to process a certain depth or volume of workpiece. Different brands and models of spark machine processing speed varies greatly, efficient spark machine can complete the processing task in a shorter period of time, improve productivity.
3. Equipment Stability Considerations
Running noise and vibration check: in the no-load and loaded (processing) state of the equipment, respectively, listen to the sound emitted by the equipment and feel the vibration situation. Normal operation of the spark machine should be only a slight motor running sound and discharge sound, no abnormal friction, impact or whistling sound. At the same time, touch the equipment shell, feel the degree of vibration, if the vibration is too large, it may indicate that the internal mechanical parts of the equipment there are loose, wear and tear or imbalance, etc., which will affect the machining accuracy and equipment life.
Long-time running test: If conditions permit, let the spark machine run continuously for several hours or even a day, to observe whether the equipment will appear overheating, alarms, precision degradation and other problems. During long time running, the electrical system, cooling system and mechanical parts of the equipment can be fully tested. Stable equipment can maintain good performance status and will not break down due to long time working.
Check the maintenance records: Ask the seller for the maintenance records of the equipment, to understand the equipment's past failures, maintenance content and maintenance frequency. If the equipment often breaks down and has frequent repairs, it may indicate that the equipment has potential quality problems or is used in a poor environment.
4. Key Component Inspection
Condition of electrode clamps: Check whether the clamping force of the electrode clamps is sufficient and uniform, and whether the mechanical structure of the clamps is intact, with no damaged or deformed parts. You can manually operate the fixture to clamp and loosen the electrode, feel whether its strength is appropriate, and observe whether the fixture opening and closing action is smooth. If the clamping force of the fixture is insufficient, the electrode may loosen during the machining process, affecting the machining accuracy.
Working fluid system function: The working fluid system is crucial to the machining performance of the spark machine. Check whether there is any leakage in the working fluid tank and whether the working fluid pump is in normal working condition, including whether the flow rate and pressure meet the requirements. You also need to check whether the filter is clogged. A good filtration system can ensure the cleanliness of the working fluid and prevent impurities from entering the machining area and affecting the machining quality. For example, the flow rate of the working fluid should be able to meet the discharge cooling demand between the electrode and the workpiece; insufficient flow rate may lead to unstable discharge.
CNC system evaluation: For CNC spark machines, check whether the display of the CNC system is clear, whether the buttons are sensitive, and whether the operation interface is friendly. Test the programming function of the CNC system, input some simple machining instructions and observe whether the system can recognize and execute them correctly. At the same time, check whether the storage function and communication function (such as data transmission with external devices) of the CNC system are normal. A stable and fully functional CNC system can realize more complex machining tasks and improve machining accuracy and efficiency.
Screw and guide rail wear check: The precision of the screw and guide rail directly affects the movement precision of the spark machine electrode. Check for wear, scratches or corrosion by observing the surface of the screw and guide rail. Slight wear can be solved by adjusting the compensation, but if the wear is serious, it will cause the electrode movement precision to decrease and affect the machining quality. You can use a micrometer to measure the straightness and motion accuracy of the screw and guideway to assess the degree of wear.
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