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CNC wire-cut Machining aluminum-common problems and solving methods
Dec 07, 2016

EDM machine by the bed, table, and column spindle head, fluid and liquid filtration systems, pulse power supplies, servo feed, spindle head and table accessories, and other components.

(1) bed and column
Bed and post is infrastructure, by ensuring mutual position between the electrodes with the pallet and workpiece. The level of location accuracy has a direct effect on machining, machine tool accuracy is not high, the accuracy is difficult to control. Therefore, the bed and column structure should be not only reasonable, has high rigidity, can withstand the spindle load suddenly accelerated motion of the inertia force and moving parts, but also can reduce deformations caused by temperature change.

(2) table
Table is mainly used for supporting and clamping the workpiece. In the actual processing, by turning a vertical screw to change the relative position of the electrode and the workpiece. Work table fitted with tank, to accommodate the working fluid, in the electrode and the workpiece is immersed in working fluid, play a role in cooling and chip. Workbench is the operator when the clamp is often moving parts, by moving up and down slide, change the vertical position, to the relative position of the electrodes and the tools required.

(3) the spindle head
Spindle head is a key component of EDM machine tools, servo mechanism in the structure, guidance and anti-torque institution, subsidiary body consists of three parts. To control the discharge gap between the workpiece and electrode.
Spindle directly influence processing of process indicators, such as productivity, geometric accuracy and surface roughness on the spindle head has the following requirements:
1) have a certain axial and lateral stiffness and precision;
2) had enough feed and pick up speed;
3) spindle straightness and torsion-proof performance;
4) high sensitivity, without crawling phenomenon;
5) has a reasonable load-carrying capacity of electrode quality.
Early in the 20th century, 60-70 's extensive use of hydraulic servo spindle head like a DYT-l type, DYT-2 type, and are now generally used stepper motors, DC or AC servo motor to the driving spindle head.

(4) EDM machine fluids and filtering system
EDM fluid when the function has the following aspects:
1) after discharge recovery insulation State of discharge gap (deionization) so that the next pulse forming spark again. Calls in this regard for working fluid has some insulation, between the resistivity in L03~106 ω · cm.
2) make it easier for galvanic corrosion product of suspension, discharge from the discharge gap, lest serious pollution discharge gap, leading to harmful arc discharge points are not separated and formed discharge.

3) cooled electrode and reduce high instantaneous discharge of local surface temperature, surface caused by overheating or coke, burns and the formation of the arc discharge.
4) working fluid or compressible spark discharge channels, increase the expansion of channels of compressed gases, plasmas and the force of the explosion, to throw more melted and vaporized metal, increase the amount of erosion.
Currently using kerosene as a working solution of EDM, because new resistivity 106 ω • cm of kerosene, used between l05~104 ω • cm, and relatively stable, its viscosity, density, surface tension, also fully meets the requirements of electrical discharge machining performance. But kerosene fire. So when the heavy normalized process, should use the liquid oil or mixed with oil.

(5) the pulse power supply for electrical discharge machine
Pulse power supply converts AC power frequency is the role of the energy supply needed to spark gap to ablation of metals. Pulse power of EDM machining productivity, surface quality, process speed, process stability and technical and economic indicators such as tool electrode wear has a great impact.
Now universal
(Budget) EDM pulsed power supply for high voltage composite transistors are used, medium and high-end EDM machine tool by computer numerical control pulse power supply and internal EDM normalized database, can be invoked through computer settings and the coarse, medium and fine processing rule parameter.

(6) electrical discharge machining machine tool servo
Electric spark machining and machining different, belonging to the "no touch processing". When normal electrical discharge machining, there is a gap between the tool and the workpiece, s. If the gap is too large, strike put the gap between impulse voltage of the insulating fluid, no spark, you must feed the electrode tool down until clearance s equal to or less than a certain value (usually S=0.1~0.01mm, and processing rule), to penetrate and generate spark discharges. When normal electrical discharge machining workpiece
Increasingly ablation w, s will gradually expand the gap, you must make the electrode tool to speed compensation d feed in order to maintain the required gap. Feed d is greater than the workpiece removal rate

W, s gap will gradually become smaller, or equal to zero, form a short circuit. When the gap is too small, you must reduce the feed rate d. If the tool between the workpiece once the short circuit (S=0), the tools must be made with greater speed d