La sobrespecificaci\u00f3n m\u00e1s habitual que vemos es una pieza de pl\u00e1stico presupuestada con tolerancias de metal. No es que la m\u00e1quina no pueda mantenerlas: es que el material no se quedar\u00e1 ah\u00ed despu\u00e9s.<\/p>\n\n
Los pl\u00e1sticos se dilatan con la temperatura unas diez veces m\u00e1s que el acero. Una pieza de PEEK de 200 mm cambiar\u00e1 de dimensi\u00f3n alrededor de 0,3 mm en una variaci\u00f3n de 40 C, as\u00ed que una tolerancia de m\u00e1s o menos 0,02 mm en esa distancia solo tiene sentido a una temperatura declarada. Nuestra pr\u00e1ctica por defecto es mecanizar y medir a 20 C y hacerlo constar en el informe de inspecci\u00f3n.<\/p>\n\n
Como gu\u00eda pr\u00e1ctica para elementos mecanizados: m\u00e1s o menos 0,05 mm es habitual en piezas de menos de 100 mm, m\u00e1s o menos 0,1 mm es c\u00f3modo hasta 300 mm y, m\u00e1s all\u00e1, deber\u00e1 prever especificar m\u00e1s o menos 0,3 mm o aceptar que la pieza es un ajuste y no un componente de precisi\u00f3n. En materiales higrosc\u00f3picos \u2014nailon y acetal\u2014 a\u00f1ada una tolerancia por humedad, porque una pieza de nailon mecanizada en seco crecer\u00e1 entre uno y dos por ciento al absorber la humedad ambiente. Si una tolerancia es cr\u00edtica, d\u00edganos por qu\u00e9 y le diremos si el material puede mantenerla.<\/p>\n\n","protected":false},"excerpt":{"rendered":"
Los pl\u00e1sticos no son metales, y la tabla de tolerancias que usa para el acero le meter\u00e1 en problemas. Aqu\u00ed tiene cifras realistas por material y tama\u00f1o.<\/p>\n","protected":false},"author":193679612,"featured_media":155,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_coblocks_attr":"","_coblocks_dimensions":"","_coblocks_responsive_height":"","_coblocks_accordion_ie_support":"","advanced_seo_description":"What tolerance you can realistically hold in PEEK, POM and PPS, and how temperature, wall thickness and fixturing move the number.","jetpack_seo_html_title":"CNC Tolerances in Engineering Plastics | Top Plastic","jetpack_seo_noindex":false,"jetpack_seo_schema_type":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_wpcom_ai_launchpad_first_post":false,"_tp_seo_title":"CNC Tolerances in Engineering Plastics | Top Plastic","_tp_seo_desc":"What tolerance you can realistically hold in PEEK, POM and PPS, and how temperature, wall thickness and fixturing move the number.","_tp_summary":"","_tp_updated":"","_jetpack_feature_clip_id":0,"_jetpack_hide_featured_image":false,"_jetpack_featured_image_duplicate_dismissed":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[132593],"tags":[132591],"class_list":["post-154","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-machining","tag-machining"],"jetpack_publicize_connections":[],"jetpack_likes_enabled":true,"jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pcp8Cz-2u","jetpack-related-posts":[{"id":318,"url":"https:\/\/cntopplastics.com\/es\/engineering-plastic-sheet-rod-order-spec\/","url_meta":{"origin":154,"position":0},"title":"Engineering plastic sheet and rod: how to specify an order","author":"jessemei","date":"2026-10-15","format":false,"excerpt":"Grade code, form, thickness tolerance, finish and certification: five fields that decide if your plastic order arrives usable. 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