🧪 PEEK
PEEK Machining and Sourcing in San Jose, CA
PEEK sits at the top of the engineering thermoplastic ladder, and in San Jose it earns its premium price in exactly the places metals fall short: inside semiconductor process chambers where it cannot outgas, in surgical instruments where it must be biocompatible and sterilizable, and in electrical assemblies where it has to insulate. The grade you choose, unfilled, glass-filled, or carbon-filled, tunes the material toward dimensional stability, stiffness, or wear. This page covers how San Jose shops machine PEEK and how to spec it.
ISO 9001ISO 13485AS9100
PEEK, polyether ether ketone, is a semi-crystalline high-performance thermoplastic that holds its properties up to a continuous service temperature near 250 C, resists almost every solvent and chemical, and is inherently flame-retardant with very low smoke and outgassing. Those traits are exactly what San Jose's most demanding industries need, which is why buyers tolerate a material cost many times that of common engineering plastics.
In semiconductor manufacturing, PEEK is a preferred plastic for wafer-handling components, test sockets, and fixtures inside process equipment because it withstands process temperatures and aggressive chemistries without outgassing contaminants onto the wafer. In medical devices, unfilled PEEK is biocompatible, can be repeatedly steam and gamma sterilized, and is even used in implants, so it shows up in surgical instruments and device components across the Bay Area's medtech base.
PEEK is also an excellent electrical insulator and is dimensionally stable across temperature, which makes it valuable for connectors, insulators, and test fixtures in electronics. For a San Jose engineer, the decision to use PEEK is usually not about cost; it is that nothing cheaper survives the temperature, chemical, cleanliness, or biocompatibility requirement.
Choosing Between Unfilled, Glass-Filled, and Carbon-Filled
The three common PEEK grades trade off in predictable ways, and matching the grade to the function is most of getting a PEEK job right. Unfilled PEEK is the natural, tan-colored base resin. It is the most ductile, has the best elongation and impact resistance, and is the only grade used for implants and most biocompatible medical work. It is also the choice where you need the cleanest, most chemically pure material with no filler to interfere.
Glass-filled PEEK, typically 30 percent glass fiber, trades some toughness for much higher stiffness, better dimensional stability, and improved resistance to creep at temperature. It is the grade for structural brackets, fixtures, and parts that must hold tight tolerance under load and heat. The glass fibers make it more abrasive to machine and slightly less forgiving, but the rigidity is worth it for structural parts.
Carbon-filled PEEK, usually 30 percent carbon fiber, goes further on stiffness and adds two useful properties: it conducts heat better, reducing thermal expansion and hot spots, and it is dissipative rather than fully insulating, which helps in static-sensitive electronics and semiconductor handling. Carbon-filled PEEK is also the most wear-resistant grade, making it the choice for bearings, bushings, and wear surfaces. The trade-off is that it loses the electrical insulation of unfilled PEEK, so you would not use it where you need a dielectric.
Machining PEEK to Spec in the South Bay
PEEK machines well compared to metals, but it has quirks a San Jose shop has to respect to deliver dimensionally accurate parts. It is a relatively poor conductor of heat, so cutting heat builds up at the tool and can soften the material or induce internal stress if feeds and speeds are not managed. Good practice is sharp tooling, climb milling, moderate speeds, and often air or coolant to carry heat away, with the goal of keeping the part from overheating.
The bigger issue on precision PEEK parts is residual stress and machining-induced movement. PEEK can warp or shift dimension after machining as internal stresses relax, especially on thin or asymmetric parts. Shops handling tight-tolerance PEEK often stress-relieve or anneal the stock before machining and sometimes between roughing and finishing, which stabilizes the material and is the difference between a part that holds tolerance and one that creeps out of spec on the inspection bench.
For semiconductor and medical work, cleanliness is part of the spec, not just the geometry. Parts may need to be machined without certain coolants, handled to avoid contamination, and cleaned to a defined standard. When you quote PEEK work in San Jose, state the grade, the tolerance, and any cleanliness or sterilization requirement so the shop machines and handles it correctly from the start.
Frequently Asked Questions
Choose PEEK when the application crosses a threshold that cheaper plastics cannot meet and where metal causes a different problem. PEEK holds its mechanical properties up to about 250 C continuous, resists nearly all solvents and chemicals, is inherently flame-retardant with very low outgassing, and is biocompatible and sterilizable in its unfilled form. So if your part sees high temperature, aggressive chemistry, a clean semiconductor process environment, or a medical sterilization cycle, common engineering plastics like acetal or nylon will not survive and PEEK is justified despite its much higher cost. PEEK is chosen over aluminum or steel when you need electrical insulation, chemical inertness, low outgassing, biocompatibility, or simply a non-metallic part that will not contaminate or scratch a wafer or mating surface. If your part lives at room temperature in benign conditions and does not need those properties, PEEK is overkill and a cheaper plastic or aluminum will do. The decision in San Jose is almost always driven by a hard requirement, temperature, chemistry, cleanliness, or biocompatibility, rather than by preference.
The filler tunes PEEK toward different priorities. Unfilled PEEK is the natural base resin, the most ductile and impact-resistant grade, the best electrical insulator, and the only grade used for implants and most biocompatible medical work because it has no filler to interfere; it is the purest and most forgiving choice. Glass-filled PEEK, usually 30 percent glass fiber, trades some toughness for substantially higher stiffness, better dimensional stability, and improved creep resistance under load and heat, making it the grade for structural fixtures and brackets that must hold tolerance. Carbon-filled PEEK, usually 30 percent carbon fiber, pushes stiffness even higher, conducts heat better to reduce thermal expansion, offers the best wear resistance for bearings and bushings, and is electrically dissipative rather than insulating, which helps in static-sensitive electronics but means you cannot use it where you need a dielectric. For a San Jose buyer, the short guide is unfilled for medical and electrical insulation, glass-filled for stiff structural parts, and carbon-filled for wear surfaces and static-sensitive applications.
PEEK can move dimensionally after machining because of residual internal stress in the stock and stress induced by the cutting process. Extruded and molded PEEK shapes carry locked-in stresses from how they were made, and when you machine away material, especially on thin or asymmetric parts, those stresses redistribute and the part can warp or shift size after it comes off the machine. PEEK also conducts heat poorly, so if a shop runs it too hard the cutting heat builds at the tool and adds thermal stress that compounds the problem. The standard fix used by San Jose shops doing tight-tolerance PEEK work is to anneal or stress-relieve the stock before machining, and sometimes again between roughing and finishing passes, which relaxes the internal stress so the finished part stays stable. Good machining practice, sharp tools, moderate speeds, and heat management, prevents adding new stress. If your PEEK part has tight tolerances or a thin or asymmetric geometry, tell the shop up front so they can plan the annealing steps rather than discovering the movement at final inspection.
Yes, PEEK is one of the preferred high-performance plastics for both industries, which is a big reason it sees steady demand in the South Bay. In medical devices, unfilled PEEK is biocompatible, can withstand repeated steam, gamma, and ethylene oxide sterilization, and is even used in long-term implants, so it appears in surgical instruments and device components, and shops serving that market machine it under ISO 13485 quality systems. In semiconductor manufacturing, PEEK is favored for wafer-handling components, test sockets, and fixtures inside process equipment because it tolerates process temperatures and aggressive chemistries without outgassing contaminants that would ruin a wafer, and carbon-filled or specially formulated antistatic grades help in static-sensitive handling. The key for both applications is that cleanliness and material grade are part of the specification, not just the geometry. When you source PEEK for medical or semiconductor use in San Jose, specify the exact grade, any sterilization or cleanliness requirement, and the quality system you need, and choose a shop that already serves that industry so the handling and documentation match the application.
Last updated: July 2026
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