🧪 PEEK
Can You Wire EDM PEEK? The Honest Answer
Let's be direct, because this is a case where the honest answer saves you money and frustration: EDM is fundamentally a process for electrically conductive materials, and PEEK is a polymer. Standard unfilled and glass-filled PEEK simply cannot be wire EDM'd or sinker EDM'd, there is no electrical path for the spark to follow. If you came here looking to EDM PEEK, the real answer is that you almost certainly want CNC machining instead, and this page explains why and what to do.
ISO 13485ISO 9001AS9100
Electrical discharge machining works by creating a spark between an electrode (the wire or the sinker tool) and an electrically conductive workpiece, eroding the workpiece thermally. The entire process depends on the workpiece completing an electrical circuit. Unfilled PEEK and glass-filled PEEK are electrical insulators, they do not conduct, so there is no spark, no erosion, and no cut. This is not a limitation of technique or parameters; it is physics. You cannot EDM an insulator.
This surprises buyers who are used to EDM as a universal precision process for difficult materials. But EDM's domain is conductive metals and conductive composites like carbide. The moment you reach for a polymer, the process simply does not apply. Glass-filled PEEK is, if anything, even more insulating, the glass fibers add no conductivity.
So for the two most common PEEK grades, unfilled and glass-filled, EDM is off the table entirely. Any shop that tells you they will wire EDM your unfilled PEEK part is mistaken. The right conversation is about which machining process to use instead, covered below.
Carbon-filled PEEK: the marginal exception
There is one nuance worth being precise about. Carbon-fiber-filled PEEK contains conductive carbon fibers, and at high enough loading some carbon-filled PEEK grades are electrically conductive to a degree. In principle, a sufficiently conductive carbon-filled PEEK could interact with an EDM spark.
In practice, this is a curiosity, not a production process. Even where carbon-filled PEEK conducts enough to spark, EDM'ing a polymer matrix raises problems that make it impractical: the thermal erosion process melts and degrades the polymer messily rather than cleanly eroding it as it does metal, the conductivity is marginal and inconsistent, and the surface quality and dimensional control are poor. No one runs production PEEK parts on an EDM, including carbon-filled.
The honest takeaway is that even the conductive PEEK grade is not a real EDM material. If you have read that carbon-filled PEEK can be EDM'd, the technically-true-but-misleading version is yes, marginally, in a lab sense, and the practical answer is no, you machine it. Do not specify EDM for any PEEK grade expecting production results.
What to actually do: CNC machining PEEK
PEEK machines very well, and CNC milling and turning are the correct processes for precision PEEK parts. PEEK has excellent machinability for a high-performance polymer; it cuts cleanly with sharp tools, holds tight tolerances, and is routinely made into intricate medical, aerospace, and semiconductor components on standard machining centers and lathes. Whatever geometry you were hoping to EDM, milling or turning will almost certainly produce it.
The machining considerations for PEEK are thermal: it has a high glass transition and can soften or stress if it overheats during cutting, so sharp tools, proper speeds and feeds, and adequate cooling matter, and annealing the stock before machining relieves internal stress for tight-tolerance parts. Glass-filled and carbon-filled PEEK are abrasive on tooling (especially glass-filled), so carbide or diamond-coated tools and tool-wear management are part of the job. For the finest features, the same fine-feature precision people associate with EDM is achievable with small-diameter end mills on a good CNC.
For implants and fluidic components in unfilled PEEK, micro-machining and laser processing are the precision routes, not EDM. The bottom line: route your PEEK part to a CNC machining shop, not an EDM shop, and you will get the precision part you actually need.
Frequently Asked Questions
For practical purposes, no. EDM erodes material by creating an electrical spark between an electrode and a conductive workpiece, so the workpiece must conduct electricity. Unfilled PEEK and glass-filled PEEK are electrical insulators, they do not conduct, so there is no spark, no erosion, and no cut. This is basic physics, not a matter of finding the right parameters or a better shop: you cannot EDM an insulator. The only nuance is carbon-fiber-filled PEEK, which contains conductive carbon fibers and at high loading can be somewhat conductive, but even there EDM is impractical because the thermal process melts and degrades the polymer messily, the conductivity is marginal and inconsistent, and surface and dimensional quality are poor. No one runs production PEEK parts, including carbon-filled, on an EDM. If a shop offers to wire EDM your unfilled or glass-filled PEEK part, they are mistaken. The correct process for precision PEEK is CNC machining, which PEEK takes very well. So treat any PEEK EDM request as a sign to switch to milling or turning, which will produce the part you actually need.
Because there is a technically-true-but-misleading kernel to it. Carbon-fiber-filled PEEK contains conductive carbon fibers, and at sufficient loading some grades are electrically conductive enough that, in principle, they could interact with an EDM spark. That fact gets repeated until it sounds like a real capability. In practice it is a laboratory curiosity, not a production process. Even where carbon-filled PEEK conducts enough to spark, the EDM thermal erosion that cleanly removes metal instead melts and chars the polymer matrix, the conductivity is marginal and varies through the part, and the resulting surface quality and dimensional control are unacceptable for real parts. So the honest answer is: yes, marginally, in a narrow lab sense, and no, not as a usable manufacturing process. Do not specify EDM for carbon-filled PEEK expecting production results, you will be disappointed. CNC machining handles carbon-filled PEEK well (with attention to the abrasive carbon fibers' effect on tooling), and that is the route to take for any conductive or non-conductive PEEK grade.
CNC machining, milling and turning, is the right answer for precision PEEK, and it handles essentially everything you might have hoped to do with EDM. PEEK has excellent machinability for a high-performance polymer: it cuts cleanly with sharp tools, holds tight tolerances, and is routinely made into intricate medical, aerospace, and semiconductor components on standard machining centers and lathes. The main considerations are thermal, PEEK can soften or build internal stress if it overheats, so sharp tooling, correct speeds and feeds, and adequate cooling matter, and annealing the stock before machining relieves stress for tight-tolerance work. Glass-filled and especially carbon-filled grades are abrasive, so carbide or diamond-coated tooling and tool-wear management are part of the job. For very fine features, small-diameter end mills on a good CNC achieve the kind of precision people associate with EDM, and for micro-scale work, laser processing and micro-machining are the specialized routes. So route your PEEK part to a CNC machining shop, not an EDM shop. Provide your tolerances and feature sizes and let the machinist select tooling and decide whether stress-relief annealing is needed for your dimensional requirements.
If what you valued about wire EDM was its ability to make intricate profiles and fine features without cutting force, the closest equivalents for PEEK are precision CNC milling with small-diameter tools, waterjet cutting for profiles in plate, and laser cutting or laser micro-machining for fine features, none of which require the workpiece to be conductive. Precision CNC milling produces intricate PEEK profiles and tight internal features with the right small tooling and careful thermal control. Waterjet cuts PEEK profiles from plate with no heat-affected zone, useful for gaskets, seals, and flat intricate shapes, though it does not match EDM's tolerance on fine internal corners. Laser processing handles very fine features and thin sections, with attention to the heat-affected and potentially charred edge that lasers leave on polymers. For most PEEK parts, plain CNC machining covers the requirement and is the default. The key mental shift is that EDM's no-contact precision is a metals capability; for PEEK you get the equivalent precision through machining, waterjet, or laser, chosen by feature size and tolerance. Tell your shop the geometry and tolerances and they will pick the right non-EDM process.
Last updated: July 2026
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