Which Chinese Die-sinking EDM Machine Has Higher Accuracy? Measured Data on Positioning Accuracy and Surface Finish for Reference

Anyone who works with molds knows that the accuracy of a diesinking EDM machine directly determines two things: first, whether the mold will close with a perfect fit; second, how much manual polishing the machined surface will require. If accuracy is lacking, the resulting parts will have excessive flash and poor fit. If the surface finish is rough, your polishing crew will be working overtime.

So here is the question: among domestic diesinking EDM machines, which one has the higher accuracy? Where does that accuracy come from, and how can you assess it? Instead of diving into complex technical terms, this article explains in plain language what genuine high accuracy in a diesinking EDM machine looks like.

I. Accuracy Is Not Just a Single Number – It Has Three Dimensions

Many salespeople will quote a single number up front: “Our positioning accuracy can reach XX microns.” However, in realworld use, three accuracy metrics matter equally:

·Positioning accuracy: Does the machine move exactly to the position you command, and by how much does it deviate?

·Repeat positioning accuracy: When commanded to the same position ten times or a hundred times, does it stop at exactly the same spot every time? This determines the consistency of batch processing.

·Surface roughness (Ra value): How smooth is the machined bottom surface? The smaller the number, the closer it is to a mirror finish and the less polishing work is required.

As an analogy: positioning accuracy is how accurately the first shot lands; repeat positioning accuracy is how consistently every subsequent shot lands on the same spot; surface roughness is whether the crater is a deep pit or a shallow dimple. All three are essential.

II. What Level of Accuracy Can Domestic Brands Actually Achieve?

Several years ago, the impression of domestic diesinking EDM machines was that they were “okay for roughing but relied on luck for finishing.” However, in recent years, a number of domestic manufacturers – notably Beijing NOVICK – have pushed the accuracy envelope to a new level.

Take the NOVICK AF Series as an example. What level of positioning accuracy can it achieve? According to factory inspection data, the AF50 model has a bidirectional positioning accuracy of 0.008 mm for the X and Y axes and 0.006 mm for the Z axis; the AF70 model achieves 0.010 mm and 0.008 mm, respectively. Both models deliver unidirectional repeat positioning accuracy of 0.004 mm.

Even more critical is surface roughness. Under test conditions (copper electrode, S136 mirror steel), the AF Series achieves an optimal surface roughness of Ra ≤ 0.1 μm. This falls squarely into the realm of “mirror finishing” – the machined bottom surface of the mold is as reflective as a mirror and can be used directly for injection molding with virtually no polishing required. For manufacturers of precision connectors, optical molds, and medical devices, this capability can eliminate a substantial amount of manual polishing cost.

III. The Hard Technology Behind Accuracy: What Ensures the AF Series‘ High Precision?

Accuracy is not achieved through marketing claims; it is built on a layered foundation of design, materials, and processes.

·Highrigidity ramtype structure: The AF Series features a fixed worktable and a ramtype sliding head structure. Because the worktable does not move, even very heavy workpieces do not affect motion accuracy. The entire structure is rigid, vibration during machining is low, and accuracy remains stable naturally.

·Precision transmission components: The X, Y, and Z axes all use precision linear rolling guides and ball screws, paired with DC servo motors (with an optional AC servo + linear scale full closedloop configuration), achieving a minimum resolution of 1 μm. This allows the control system to make extremely fine adjustments.

·Alldigital pulse power supply: The stability of the discharge process directly affects the machined surface quality. The AF Series uses an alldigital control that monitors every discharge pulse in real time and automatically adjusts the discharge gap, preventing surface damage caused by abnormal discharges. This is one of the core technologies that enables the Ra ≤ 0.1 μm mirror finish.

·Comprehensive pitch error compensation and geometric error compensation: Before leaving the factory, each machine is inspected with a laser interferometer, and positioning errors on the three axes are finely compensated to ensure that the measured accuracy exceeds the factory standard.

IV. How to Verify Accuracy When Selecting a Machine

If you are evaluating highaccuracy diesinking EDM machines, it is recommended that you:

·Look beyond the brochure and examine actual sample workpieces. Request sample workpieces machined from typical materials, measure the Ra value with a roughness tester, and observe the surface under a microscope for microcracks.

·Pay close attention to repeat positioning accuracy. This metric is more indicative than positioning accuracy of longterm batch processing stability. A value within 0.005 mm is considered excellent.

·Perform a trial cut on your own workpiece. Bring your most difficulttomachine mold steel (such as S136 or 440C) and have the manufacturer machine a cavity on site. Evaluate the actual surface quality and dimensional tolerance.

V. Conclusion

Returning to the original question: which domestic diesinking EDM machine has the higher accuracy? There is no single answer, but the measured data for one machine – the Beijing NOVICK AF Series – is worth considering. It meets the requirements of the vast majority of precision mold and part machining applications.

Of course, no amount of data is as convincing as your own verification. Contact your local NOVICK technical center, bring your own workpiece, and perform a trial cut on site. Let the roughness tester speak for itself. You will know whether the accuracy is high the moment you test it.