{"id":13385,"date":"2022-10-21T16:38:38","date_gmt":"2022-10-21T08:38:38","guid":{"rendered":"https:\/\/zetarmold.com\/?p=13385"},"modified":"2026-04-04T11:21:07","modified_gmt":"2026-04-04T03:21:07","slug":"encolhimento-de-pecas-de-plastico-produtos-de-moldagem-por-injecao-de-precisao","status":"publish","type":"post","link":"https:\/\/zetarmold.com\/pt\/encolhimento-de-pecas-de-plastico-produtos-de-moldagem-por-injecao-de-precisao\/","title":{"rendered":"Como evitar a flutua\u00e7\u00e3o da contra\u00e7\u00e3o das pe\u00e7as de pl\u00e1stico para produtos de moldagem por inje\u00e7\u00e3o de precis\u00e3o?"},"content":{"rendered":"<p><strong>A moldagem por inje\u00e7\u00e3o de precis\u00e3o baseia-se na premissa de que o molde pode ser fabricado com o tamanho pretendido. No entanto, mesmo que a dimens\u00e3o do molde seja certa, a dimens\u00e3o real do produto varia consoante a contra\u00e7\u00e3o real. Por conseguinte, o controlo da retra\u00e7\u00e3o \u00e9 muito importante na moldagem por inje\u00e7\u00e3o de precis\u00e3o.<\/strong><\/p>\n<p>A taxa de contra\u00e7\u00e3o \u00e9 regida pela adequa\u00e7\u00e3o do desenho do molde e tamb\u00e9m varia consoante o lote de resina e, se o pigmento for alterado, a taxa de contra\u00e7\u00e3o tamb\u00e9m varia.<\/p>\n<p>O controlo da retra\u00e7\u00e3o \u00e9 dif\u00edcil porque a fixa\u00e7\u00e3o e a reprodutibilidade da <a href=\"https:\/\/zetarmold.com\/pt\/\" data-type=\"URL\" data-id=\"https:\/\/zetarmold.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">moldagem por inje\u00e7\u00e3o<\/a> As condi\u00e7\u00f5es do processo de fabrico e a a\u00e7\u00e3o de cada ciclo de moldagem por inje\u00e7\u00e3o de pl\u00e1stico variam consoante a m\u00e1quina de moldagem, e a taxa de contra\u00e7\u00e3o real varia.<\/p>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-1 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Molding.jpg\" alt=\"\" class=\"wp-image-13389\" height=\"360\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Molding.jpg 564w, https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Molding-300x200.jpg 300w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<h2 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">1. Os principais factores que afectam a taxa de retra\u00e7\u00e3o<\/span><\/h2>\n<p>A dimens\u00e3o do molde pode ser obtida adicionando a taxa de retra\u00e7\u00e3o \u00e0 dimens\u00e3o do produto, pelo que os principais factores da taxa de retra\u00e7\u00e3o devem ser considerados durante a conce\u00e7\u00e3o do molde.<\/p>\n<ul>\n<li>Press\u00e3o da resina<\/li>\n<li>Temperatura da resina<\/li>\n<li>Temperatura do molde<\/li>\n<li>\u00c1rea da sec\u00e7\u00e3o transversal do port\u00e3o<\/li>\n<li>Tempo de inje\u00e7\u00e3o<\/li>\n<li>Tempo de arrefecimento<\/li>\n<li>Espessura da parede do produto<\/li>\n<li>Material de refor\u00e7o<\/li>\n<li>Orientabilidade<\/li>\n<\/ul>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-2 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Injection-Molding2.jpg\" alt=\"\" class=\"wp-image-13390\" height=\"300\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Injection-Molding2.jpg 564w, https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Precision-Injection-Molding2-300x150.jpg 300w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Velocidade de inje\u00e7\u00e3o<\/span><\/h3>\n<p><span class=\"has-inline-color has-black-color\"><strong>Press\u00e3o da resina\u00a0\u00a0<\/strong><\/span><\/p>\n<p>A press\u00e3o da resina tem uma grande influ\u00eancia na taxa de retra\u00e7\u00e3o. Se a press\u00e3o da resina for grande, a taxa de retra\u00e7\u00e3o torna-se menor e o tamanho do produto \u00e9 maior.<\/p>\n<p>Mesmo na mesma cavidade do molde, a press\u00e3o da resina varia consoante a forma do produto, pelo que a taxa de contra\u00e7\u00e3o varia.<\/p>\n<p>No caso de uma multi-cavidade<a href=\"https:\/\/zetarmold.com\/pt\/\" data-type=\"URL\" data-id=\"https:\/\/zetarmold.com\/\" target=\"_blank\" rel=\"noreferrer noopener\"> molde de inje\u00e7\u00e3o<\/a>A press\u00e3o da resina em cada cavidade \u00e9 f\u00e1cil de produzir diferen\u00e7as e, como resultado, a taxa de contra\u00e7\u00e3o de cada cavidade n\u00e3o \u00e9 a mesma.\u00a0\u00a0<\/p>\n<p><span class=\"has-inline-color has-black-color\"><strong>Temperatura do molde\u00a0<\/strong><\/span>\u00a0<\/p>\n<p>Quer se trate de uma resina n\u00e3o cristalina ou de uma resina cristalina, se a temperatura do molde for elevada, a taxa de contra\u00e7\u00e3o ser\u00e1 maior.<\/p>\n<p><a href=\"https:\/\/zetarmold.com\/pt\/\" data-type=\"URL\" data-id=\"https:\/\/zetarmold.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">Moldagem por inje\u00e7\u00e3o de precis\u00e3o<\/a> para manter a temperatura do molde a uma temperatura espec\u00edfica. Na conce\u00e7\u00e3o do molde, deve prestar-se aten\u00e7\u00e3o \u00e0 conce\u00e7\u00e3o do circuito de arrefecimento.\u00a0\u00a0<\/p>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">\u00c1rea da sec\u00e7\u00e3o transversal do port\u00e3o<\/span><\/h3>\n<p>De um modo geral, a taxa de retra\u00e7\u00e3o muda quando a \u00e1rea da sec\u00e7\u00e3o transversal da porta \u00e9 alterada. A taxa de retra\u00e7\u00e3o torna-se menor \u00e0 medida que o tamanho da porta aumenta, o que est\u00e1 relacionado com a fluidez da resina.&nbsp;&nbsp;<\/p>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Espessura da parede do produto&nbsp;&nbsp;<\/span><\/h3>\n<p>A espessura da parede da cavidade da parede do produto tamb\u00e9m afecta o rendimento. Para resinas n\u00e3o cristalinas, como a resina tem uma tend\u00eancia diferente para afetar a taxa de retra\u00e7\u00e3o da espessura da parede, a espessura da parede \u00e9 grande, a taxa de retra\u00e7\u00e3o tamb\u00e9m \u00e9 grande, e vice-versa, a taxa de retra\u00e7\u00e3o torna-se menor.<\/p>\n<p>Para resinas cristalinas, \u00e9 importante evitar varia\u00e7\u00f5es particularmente grandes na espessura da parede. No caso de um molde com v\u00e1rias cavidades, se houver uma diferen\u00e7a na espessura da parede da cavidade do molde, a taxa de retra\u00e7\u00e3o tamb\u00e9m ser\u00e1 diferente.\u00a0\u00a0<\/p>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-3 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"564\" height=\"357\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/injection-molding-wall-thickness.jpg\" alt=\"\" class=\"wp-image-13408\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/injection-molding-wall-thickness.jpg 564w, https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/injection-molding-wall-thickness-300x190.jpg 300w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Refor\u00e7o do conte\u00fado material&nbsp;&nbsp;<\/span><\/h3>\n<p>Ao utilizar resina refor\u00e7ada com fibra de vidro, quanto mais fibra de vidro for adicionada, menor ser\u00e1 a taxa de retra\u00e7\u00e3o e a taxa de retra\u00e7\u00e3o na dire\u00e7\u00e3o do fluxo \u00e9 menor do que a taxa de retra\u00e7\u00e3o transversal.<\/p>\n<p>De acordo com a resina, a sua diferen\u00e7a \u00e9 maior, para evitar a deforma\u00e7\u00e3o da mosca de distor\u00e7\u00e3o, deve ter-se em conta a forma do port\u00e3o, a posi\u00e7\u00e3o da boca da mosca voadora e o n\u00famero de port\u00f5es.<\/p>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Orienta\u00e7\u00e3o&nbsp;&nbsp;<\/span><\/h3>\n<p>No entanto, embora existam grandes diferen\u00e7as na orienta\u00e7\u00e3o, esta existe para todas as resinas. A orienta\u00e7\u00e3o das resinas cristalinas \u00e9 particularmente grande e varia devido \u00e0 espessura da parede e \u00e0s condi\u00e7\u00f5es de moldagem.<\/p>\n<p>Al\u00e9m disso, existe a gera\u00e7\u00e3o de retra\u00e7\u00e3o p\u00f3s-moldagem, cujos principais factores s\u00e3o:<\/p>\n<ul>\n<li><strong>Al\u00edvio do stress interno<\/strong><\/li>\n<li><strong>Cristaliza\u00e7\u00e3o<\/strong><\/li>\n<li><strong>Temperatura<\/strong><\/li>\n<li><strong>Humidade<\/strong><\/li>\n<\/ul>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-4 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"564\" height=\"282\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/05\/injection_molding_material_shrinkage.jpg\" alt=\"\" class=\"wp-image-9228\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/05\/injection_molding_material_shrinkage.jpg 564w, https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/05\/injection_molding_material_shrinkage-300x150.jpg 300w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<h2 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">2. Medidas que podem ser adoptadas\u00a0<\/span><\/h2>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Canal de fluxo, balan\u00e7a de porta\u00a0<\/span><\/h3>\n<p>Como j\u00e1 foi referido, a taxa de contra\u00e7\u00e3o varia em fun\u00e7\u00e3o da press\u00e3o da resina. No caso de moldes de cavidade \u00fanica com m\u00faltiplas portas e no caso de moldes de m\u00faltiplas cavidades.<\/p>\n<p>Para encher o molde de forma igual, \u00e9 necess\u00e1rio efetuar o equil\u00edbrio da comporta. O fluxo de resina est\u00e1 relacionado com a resist\u00eancia ao fluxo no canal, pelo que \u00e9 melhor equilibrar o canal antes de efetuar o equil\u00edbrio do port\u00e3o.<\/p>\n<h3 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">Disposi\u00e7\u00e3o da cavidade do molde<\/span><\/h3>\n<p>Para que as condi\u00e7\u00f5es de moldagem sejam f\u00e1ceis de definir, \u00e9 necess\u00e1rio prestar aten\u00e7\u00e3o \u00e0 disposi\u00e7\u00e3o das cavidades.<\/p>\n<p>Uma vez que a resina fundida ser\u00e1 tropicalizada no molde, a distribui\u00e7\u00e3o da temperatura do molde ser\u00e1 em c\u00edrculos conc\u00eantricos centrados na porta numa disposi\u00e7\u00e3o geral da cavidade.<\/p>\n<p>Por conseguinte, quando se escolhe a disposi\u00e7\u00e3o das cavidades para a <a href=\"https:\/\/zetarmold.com\/pt\/\" data-type=\"URL\" data-id=\"https:\/\/zetarmold.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">moldes de inje\u00e7\u00e3o<\/a>Se a porta de entrada for o centro do canal de fluxo, \u00e9 f\u00e1cil obter o equil\u00edbrio do canal de fluxo e a disposi\u00e7\u00e3o do c\u00edrculo conc\u00eantrico.<\/p>\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-5 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:100%\">\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"564\" height=\"376\" src=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Shrink-on-Your-Plastic-Parts.jpg\" alt=\"\" class=\"wp-image-13391\" srcset=\"https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Shrink-on-Your-Plastic-Parts.jpg 564w, https:\/\/zetarmold.com\/wp-content\/uploads\/2022\/10\/Shrink-on-Your-Plastic-Parts-300x200.jpg 300w\" sizes=\"(max-width: 564px) 100vw, 564px\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<h2 class=\"wp-block-heading\"><span class=\"has-inline-color has-vivid-cyan-blue-color\">3. Evitar a deforma\u00e7\u00e3o do molde<\/span><\/h2>\n<p>A raz\u00e3o para a deforma\u00e7\u00e3o \u00e9 a exist\u00eancia de tens\u00f5es internas devido \u00e0 contra\u00e7\u00e3o desigual, pelo que \u00e9 necess\u00e1rio evitar a contra\u00e7\u00e3o desigual.<\/p>\n<p>No caso de um produto redondo com um orif\u00edcio no centro da engrenagem, deve ser colocada uma porta no centro.<\/p>\n<p>No entanto, quando existe uma grande diferen\u00e7a de retra\u00e7\u00e3o entre a dire\u00e7\u00e3o do fluxo da resina e a dire\u00e7\u00e3o vertical, existe uma desvantagem da forma oval, pelo que, quando \u00e9 necess\u00e1ria uma circularidade de alta precis\u00e3o, \u00e9 necess\u00e1ria uma classifica\u00e7\u00e3o de 3 ou 6 pontos.<\/p>\n<p>No entanto, \u00e9 necess\u00e1rio prestar aten\u00e7\u00e3o suficiente ao equil\u00edbrio de cada porta. Quando se utilizam port\u00f5es laterais, os port\u00f5es de 3 pontos aumentar\u00e3o o di\u00e2metro interior dos produtos cil\u00edndricos.<\/p>\n<p>No caso de n\u00e3o serem permitidas marcas de porta nas superf\u00edcies exterior e final, podem ser obtidos bons resultados utilizando menos portas uniformes internas de v\u00e1rios pontos.<\/p>\n<div style=\"background:#f0f4f8;padding:20px;border-radius:8px;margin-top:30px;\">\n<p style=\"margin:0 0 10px;font-size:18px;\"><strong>Need a Quote for Your Injection Molding Project?<\/strong><\/p>\n<p style=\"margin:0 0 10px;\">Get competitive pricing, DFM feedback, and production timeline from ZetarMold&#8217;s engineering team.<\/p>\n<p style=\"margin:0;\"><a href=\"https:\/\/zetarmold.com\/pt\/contactar-nos\/\" style=\"background:#2563eb;color:white;padding:12px 24px;border-radius:6px;text-decoration:none;font-weight:bold;\">Request a Free Quote \u2192<\/a> See our <a href=\"https:\/\/zetarmold.com\/pt\/injection-mold-complete-guide\/\">Injection Mold Complete Guide<\/a> for a comprehensive overview.<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Precision injection molding is based on the premise that the mold can be made to the desired size. However, even if the mold size is certain, the actual size of the product varies depending on the actual shrinkage. Therefore, the control of shrinkage is very important in precision injection molding. The shrinkage rate is governed [&hellip;]<\/p>","protected":false},"author":1,"featured_media":5429,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"none","_seopress_titles_title":"How to prevent shrinkage fluctuation of plastic | ZetarMold","_seopress_titles_desc":"Explore the properties and applications of shrinkage plastic parts precision injection molding products. ZetarMold helps you select the right plastic resin for","_seopress_robots_index":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[52],"tags":[202],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/posts\/13385"}],"collection":[{"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/comments?post=13385"}],"version-history":[{"count":0,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/posts\/13385\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/media\/5429"}],"wp:attachment":[{"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/media?parent=13385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/categories?post=13385"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zetarmold.com\/pt\/wp-json\/wp\/v2\/tags?post=13385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}