{"id":2997,"date":"2026-10-13T14:36:48","date_gmt":"2026-10-13T06:36:48","guid":{"rendered":"https:\/\/www.jccncmachining.com\/?p=2997"},"modified":"2026-10-15T09:36:23","modified_gmt":"2026-10-15T01:36:23","slug":"peek-vs-ultem-cnc-machining","status":"publish","type":"post","link":"https:\/\/www.jccncmachining.com\/it\/blog\/peek-vs-ultem-cnc-machining\/","title":{"rendered":"La selezione dei polimeri ad alta temperatura \u00e8 pi\u00f9 di una semplice classificazione termica"},"content":{"rendered":"<article>PEEK and Ultem (PEI) are often shortlisted for demanding CNC-machined plastic parts, but selecting the polymer by a headline temperature rating can miss the real design limit. The part may fail through creep, chemical exposure, dimensional drift, stress at a fastener, or an incompatible cleaning process before it reaches a nominal thermal limit. Compare PEEK vs Ultem by the exact grade, sustained load, temperature duration, chemical contact, fit, electrical or optical function, stock form, and evidence required for release.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.jccncmachining.com\/wp-content\/uploads\/2026\/10\/2997-cover.webp\" alt=\"PEEK Ultem machined high temperature parts\" >\n<nav class=\"article-toc\" aria-label=\"Indice\"><strong>Indice dei contenuti<\/strong><\/p>\n<ol>\n<li><a href=\"#duty-profile\">Write the duty profile before ranking polymers<\/a><\/li>\n<li><a href=\"#tradeoffs\">PEEK and Ultem: different trade-offs<\/a><\/li>\n<li><a href=\"#temperature-load\">Temperature and load must be considered together<\/a><\/li>\n<li><a href=\"#machining-evidence\">Machining and verification affect the result<\/a><\/li>\n<li><a href=\"#selection-sequence\">A shortlist that can be defended<\/a><\/li>\n<li><a href=\"#faqs\">PEEK and Ultem FAQs<\/a><\/li>\n<\/ol>\n<\/nav>\n<section id=\"duty-profile\">\n<h2>Write the duty profile before ranking polymers<\/h2>\n<p>Start with the part\u2019s function and the conditions that threaten it. Record peak and continuous temperature separately, load and duration, chemical exposure, cleaning agents, humidity, contact surface, allowed deflection, and critical fits. If the part is an insulator, spacer, manifold, guide, or structural bracket, identify which performance requirement is mandatory and which is only preferred.<\/p>\n<p>Do not use melting point, heat-deflection temperature, and long-term service temperature as interchangeable numbers. They describe different conditions. A short exposure without load is not equivalent to a component holding preload for months at elevated temperature. Ask which test, grade, and condition supports any number that enters the design decision.<\/p>\n<\/section>\n<section id=\"tradeoffs\">\n<h2>PEEK and Ultem: different trade-offs<\/h2>\n<table>\n<thead>\n<tr>\n<th>Selection issue<\/th>\n<th>PEEK screening question<\/th>\n<th>Ultem \/ PEI screening question<\/th>\n<th>Evidence to request<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Thermal duty<\/td>\n<td>Does the selected grade retain required properties at the sustained load and duration?<\/td>\n<td>Does the grade meet the same load, temperature, and exposure combination?<\/td>\n<td>Grade-specific long-term data and project test conditions<\/td>\n<\/tr>\n<tr>\n<td>Chemical contact<\/td>\n<td>Is the exact fluid, concentration, temperature, and duration compatible?<\/td>\n<td>Could the same exposure cause property change or stress cracking?<\/td>\n<td>Supplier data or a representative compatibility test<\/td>\n<\/tr>\n<tr>\n<td>Mechanical fit<\/td>\n<td>Will creep, deflection, or wear consume the clearance?<\/td>\n<td>Will stiffness and relaxation behavior preserve the interface?<\/td>\n<td>Allowable movement, load duration, and dimensional acceptance state<\/td>\n<\/tr>\n<tr>\n<td>Electrical \/ optical need<\/td>\n<td>Does the grade provide the required insulation or appearance?<\/td>\n<td>Is a particular dielectric, color, or appearance requirement central?<\/td>\n<td>Exact grade and the applicable test method<\/td>\n<\/tr>\n<tr>\n<td>Economics and sourcing<\/td>\n<td>Does the performance benefit justify stock and machining cost?<\/td>\n<td>Can the grade satisfy the function at a lower total project cost?<\/td>\n<td>Stock form, quantity, yield, machining route, and approval requirements<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.jccncmachining.com\/wp-content\/uploads\/2026\/10\/2997-h2-1.webp\" alt=\"PEEK Ultem polymer comparison samples\" >\n<p>These families contain multiple grades and reinforced variants. Fillers can change stiffness, wear, thermal expansion, electrical behavior, and machinability. Do not transfer an unfilled-resin property to a carbon- or glass-reinforced grade. A supplier\u2019s <a href=\"https:\/\/www.jccncmachining.com\/it\/blog\/lavorazione-meccanica-del-peek-vergine-per-risolvere-problemi-di-precisione-legati-a-deformazioni-e-usura-degli-utensili\/\">PEEK machining guide<\/a> che <a href=\"https:\/\/www.jccncmachining.com\/it\/blog\/the-complete-ultem-machining-guide-properties-grades-cnc-best-practices\/\">Ultem machining guide<\/a> discuss material-specific processing; a particular grade still needs to be verified against the part duty.<\/p>\n<\/section>\n<section id=\"temperature-load\">\n<h2>Temperature and load must be considered together<\/h2>\n<p>A polymer can tolerate a temperature in one test and still be unsuitable under sustained stress at that temperature. Load creates deflection; time may increase deformation; temperature can accelerate movement; and the geometry determines how that movement affects the assembly. Define the maximum permitted movement at the functional interface rather than choosing a resin based on the highest published temperature.<\/p>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.jccncmachining.com\/wp-content\/uploads\/2026\/10\/2997-h2-2.webp\" alt=\"Polymer component under thermal load\" >\n<p>Fasteners and press fits deserve early review. A high clamp force around a machined hole can create local stress. A threaded insert may spread load differently from a screw in plastic. At elevated temperature, preload retention and creep can govern the design. Test the assembly or model the load path with grade-specific inputs when the function is critical.<\/p>\n<p>Chemicals and cleaning add another interaction. A part may be exposed to a fluid while stressed, or cleaned with a solvent between cycles. Compatibility data should match the exact medium and exposure condition; broad labels such as \u201cchemical resistant\u201d do not establish that a finished, machined part will retain its properties.<\/p>\n<\/section>\n<section id=\"machining-evidence\">\n<h2>Machining and verification affect the result<\/h2>\n<p>High-performance resin stock can still move during machining. Internal stress, stock form, material removal sequence, clamping pressure, cutting heat, and wall thickness can affect flatness and fit. A design that leaves a narrow wall after a large pocket is cut may need staged roughing, support, rest time, or a verification step. This should be planned for the actual geometry, not assumed from the resin name.<\/p>\n<p>Inspection also depends on state. Identify the datum scheme, free-state or fixtured measurement, temperature condition, and the method for checking critical profiles. If the part will operate hot or under load, room-temperature dimensions alone may not prove functional fit. When electrical, chemical, or thermal performance is critical, decide whether the evidence is a material certificate, a test coupon, or a representative assembly validation.<\/p>\n<\/section>\n<section id=\"selection-sequence\">\n<h2>A shortlist that can be defended<\/h2>\n<ol>\n<li>Eliminate grades that cannot meet a mandatory chemical, thermal, electrical, or regulatory requirement.<\/li>\n<li>Compare long-term load, creep, stiffness, and dimensional allowance at the actual operating condition.<\/li>\n<li>Review the mating surface, wear mode, fasteners, and cleaning method.<\/li>\n<li>Ask whether the geometry is machinable and inspectable with the intended stock form and quantity.<\/li>\n<li>Compare total cost, including material, machining, finishing, inspection, scrap exposure, and validation\u2014not resin price alone.<\/li>\n<li>Record the selected grade and approval evidence on the drawing or controlled specification.<\/li>\n<\/ol>\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.jccncmachining.com\/wp-content\/uploads\/2026\/10\/2997-h2-3.webp\" alt=\"High performance polymer inspection\" >\n<p>If neither material clearly passes, broaden the shortlist only after identifying the unmet requirement. A higher material category is not automatically a safer design choice; over-specification adds cost and can introduce machining or sourcing constraints without improving the component\u2019s governing failure mode.<\/p>\n<\/section>\n<section id=\"faqs\">\n<h2>PEEK and Ultem FAQs<\/h2>\n<h3>Is PEEK always better for higher temperature?<\/h3>\n<p>No universal grade ranking replaces the actual load, exposure duration, chemical environment, stock form, and test condition. Compare the property relevant to the part\u2019s duty.<\/p>\n<h3>Can a reinforced grade use the same data as an unfilled polymer?<\/h3>\n<p>No. Reinforcement can change mechanical, thermal, electrical, and machining behavior. Verify the exact formulation and directionality where relevant.<\/p>\n<h3>Which polymer is less expensive?<\/h3>\n<p>Price depends on grade, form, size, availability, quantity, and waste. Compare total part cost and qualification burden rather than assuming one family is always less expensive.<\/p>\n<\/section>\n<\/article>","protected":false},"excerpt":{"rendered":"<p>PEEK and Ultem (PEI) are often shortlisted for demanding CNC-machined plastic parts, but selecting the polymer by a headline temperature rating can miss the real design limit. The part may fail through creep, chemical exposure, dimensional drift, stress at a fastener, or an incompatible cleaning process before it reaches a nominal thermal limit. Compare PEEK [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2997","post","type-post","status-publish","format-standard","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/posts\/2997","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/comments?post=2997"}],"version-history":[{"count":2,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/posts\/2997\/revisions"}],"predecessor-version":[{"id":3037,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/posts\/2997\/revisions\/3037"}],"wp:attachment":[{"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/media?parent=2997"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/categories?post=2997"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jccncmachining.com\/it\/wp-json\/wp\/v2\/tags?post=2997"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}