Enterprise Question& Answer

What are the application areas of CNC piercing machines?
CNC piercing machines are primarily used for processing wire EDM start holes, cluster holes, deep small holes, and other holes that are difficult to machine using traditional methods.
CNC piercing machines can be applied in aerospace, shipbuilding, automotive, power industries, and more.

What are the components of a CNC piercing machine?
A CNC piercing machine consists of the main unit, an electrical control cabinet, and a working fluid system.
The main unit is composed of the bed worktable, column, spindle head, and other components.
The electrical control cabinet includes the electrical box, industrial computer system, detection control unit, pulse power supply unit, and more.
The working fluid system consists of the fluid tank, pump, filtration system, deionization control system, pipelines, and other components.

What is the working principle of a CNC piercing machine?
CNC piercing machines use a continuously moving thin metal copper tube (called the electrode wire) as the electrode to perform pulse spark discharge erosion on the workpiece, shaping the metal. The electric pulse electrode is a hollow copper rod, and the medium passes through a small hole in the copper rod to serve as cooling and chip removal. The discharge between the electrode and the metal generates high temperatures that corrode the metal, enabling perforation. This process is used for machining fine holes in ultra-hard steel, hard alloys, copper, aluminum, and any conductive material.

Is it better to choose stepper or servo drive for medium wire EDM?
The drive unit of medium wire EDM includes the drive device and motor, with the main difference lying in the motor. The performance of motors from different manufacturers and models also varies.
Stepper motor: The stator has multi-phase magnetic poles and excitation windings, while the rotor has no windings. The reactive torque generated by the excited stator windings enables step-by-step operation.
Servo motor: The rotor speed of a servo motor is controlled by the input signal and can respond quickly. In automatic control systems, it is used as an actuator and features small electromechanical time constants, high linearity, and starting voltage characteristics. It converts electrical signals into angular displacement or angular velocity output on the motor shaft.
Servo motors enable precise control of speed and position accuracy, converting voltage signals into torque and speed to drive the controlled object. As a result, servo motor drives have gradually replaced stepper motors. Servo motors operate smoothly with minimal torque fluctuation, have a long overload capacity, and can quickly accelerate from very low starting frequencies to the specified speed.

How to maintain an EDM piercing machine?
The machine's lead screws, especially the Z-axis lead screw, should be oiled at least once a day or greased once a month. The rotating head of the EDM piercing machine also operates under high pressure, and its seals need to be replaced regularly. Basic 5S practices should be followed: after each use, clean the water and workpiece debris from the worktable.
In addition to cleaning the worktable after each use, maintenance of the EDM piercing machine also involves regularly cleaning the dust inside the electrical box, such as dust on the power resistors, discharge bridge stacks, and especially on the printed circuit boards. This helps improve the heat dissipation of electrical components.

What is the main transmission method of a piercing machine?
The main transmission motor of a piercing machine can use a DC motor or an AC motor. DC motors are typically directly connected to the roll via a drive shaft, while AC motors are connected to the roll through a reduction gearbox and drive shaft. The connecting shafts used in piercing machines include universal joints and crosshead joints. Crosshead joints offer excellent adjustment performance, allowing relative angular displacement in both horizontal and vertical planes.

What is an electrical control cabinet?
The electrical cabinet is primarily used to install components and control modules that manage the machine's actions. In simpler terms, it is used to control the machine to perform various tasks. For example: the electrical cabinet supports multi-card parallel operation, meaning one electrical cabinet can simultaneously control multiple machines, significantly reducing the labor intensity of workers. Additionally, the electrical cabinet has alarm settings; it will automatically sound an alarm when work is completed or if there is a malfunction, and the alarm duration can be customized. Moreover, after parts processing is completed, the electrical cabinet will automatically shut off the machine's power, greatly reducing the workload for workers. It fully replaces manual functions in many aspects.

Why does the EDM piercing process become unstable?
Unstable processing can be caused by a tilted electrode fluid outlet, non-straight fluid flow; low electrode quality; insecure clamping of the workpiece and electrode; loose discharge wire connections; or impurities in the workpiece material, leading to uneven wear at the electrode tip and resulting in electrode tilt. These situations can all cause processing instability.
Frequent short-circuit retractions during deep hole machining may be due to a non-straight electrode front end or misalignment between the drill chuck center hole and the guide center hole. If the electrode front end is not straight, change the electrode direction. If the center hole and guide are misaligned, readjust the concentricity using an adjustment mandrel.

What are the precautions for using a piercing machine?
The crankshaft inside the piercing machine pump withstands very high pressure, so the lubricating oil must be replaced promptly after a period of operation.
The rotating head of the piercing machine operates under high pressure, and its seals need to be replaced regularly.
After each use of the piercing machine, clean the water and workpiece debris from the worktable. Also, regularly clean the dust inside the electrical cabinet to improve the heat dissipation of electrical components. Dust on printed circuit boards should be removed in a timely manner.
The mechanical parts of the piercing machine (especially frequently moving parts) need to be lubricated with lubricating oil or guide rail oil as required.

How to choose a machine tool with long-term reliable accuracy?
Select precision ball screws with as large a diameter as possible, and ensure they have a fixed bearing support structure at both ends;
The transmission gears of the worktable should be minimal, ideally one pair of gears, and the position and structure of the gearbox must absolutely prevent it from being immersed in the cutting fluid;
Prefer large cross-section or high width-to-thickness ratio roller-type hardened steel rolling guides or linear guides;
Choose a five-phase ten-step stepper motor drive method. If conditions permit, a hybrid细分 drive or AC servo drive would be even more ideal.

How to improve the surface finish of wire EDM?
Appropriately reduce the pulse width and peak current to minimize the size of erosion pits; maintain the precision and smooth operation of guide wheels and bearings to reduce wire vibration and bouncing, ensuring the wire movement trajectory remains consistent and minimizing positional deviation.
Maintain appropriate wire tension, and adjust the guide wheels and power feed blocks so that the tension in the work area remains constant during wire movement up and down;
The wire should not be too tight, and the water should not be too fresh. For overly thin workpieces, add a clamping plate on both the upper and lower surfaces to buffer the reversal marks within the clamping plate area.
Ensure stable, accurate, and responsive XY motion with no stalling or crawling; maintain stable and slightly loose frequency conversion tracking; perform appropriate additional cuts or multiple cuts with minimal cutting allowance. Sweeping the cutting surface with very small cutting amounts will beneficially impact dimensional accuracy and surface finish.

How to lubricate and maintain a medium wire EDM?
Before shutting down the machine, ensure thorough cleaning. If the machine is idle for more than eight hours, wipe it clean and apply anti-rust oil to the EDM wire-cut machine. The conductive wheels and wire arranging wheels also need cleaning, but they should be wiped with kerosene. After wiping, ensure the kerosene is thoroughly cleaned and does not remain in the water tank.