{"id":490,"date":"2022-04-11T08:56:41","date_gmt":"2022-04-11T00:56:41","guid":{"rendered":"https:\/\/www.fuhrung.com\/technical-blog\/?p=490"},"modified":"2022-04-11T08:57:21","modified_gmt":"2022-04-11T00:57:21","slug":"causes-and-solutions-for-cracking-or-breakage-of-injection-products%ef%bf%bc","status":"publish","type":"post","link":"https:\/\/www.fuhrung.com\/technical-blog\/causes-and-solutions-for-cracking-or-breakage-of-injection-products%ef%bf%bc.html","title":{"rendered":"Causes and solutions for cracking or breakage of injection products"},"content":{"rendered":"\n

Product cracking, including surface filiform crack, micro crack, top white, crack and trauma crisis caused by part mucosa and runner mucosa. The cracking is divided into demoulding cracking and application cracking according to time. Crack refers to the fracture of formed products during mold opening or ejection. Cracks sometimes occur when the product is brittle or demoulded poorly. The speed of the ejector pin will also lead to cracks. The faster the speed, the more likely it is to crack.<\/p>\n\n\n\n

The causes of product cracking are roughly analyzed as follows:<\/p>\n\n\n\n

1. Processing aspect<\/p>\n\n\n\n

\u2460 Excessive processing pressure, too fast speed, more filling, and too long injection and pressure holding time will cause excessive internal stress and cracking.<\/p>\n\n\n\n

\u2461 Strong pulling products are easy to cause demoulding cracking, so the mold opening speed and pressure should be adjusted appropriately.<\/p>\n\n\n\n

\u2462 Appropriately increase the mold temperature to make the products easy to demould, and appropriately reduce the material temperature to prevent decomposition.<\/p>\n\n\n\n

\u2463 Prevent cracking due to low mechanical strength caused by fusion marks and plastic degradation.<\/p>\n\n\n\n

Proper use of mold release agent and frequent removal of aerosol and other substances on mold surface.<\/p>\n\n\n\n

\u2465 The residual stress of the product causes cracking. Internal stress can be eliminated and cracking can be prevented by annealing heat treatment immediately after product forming.<\/p>\n\n\n\n

2. Mold aspect<\/p>\n\n\n\n

(1) the ejection must be balanced, for example, the number of ejector pins and the area of cross section shall be sufficient. The inclination of the ejection must be enough, and the cavity surface must be smooth enough, so as to prevent cracking due to the external force leading to the residual stress concentration.<\/p>\n\n\n\n

\u2461 The product structure shall not be too thin, and the transition part shall adopt circular arc transition as far as possible to avoid stress concentration caused by sharp corners and chamfering.<\/p>\n\n\n\n

\u2462 Metal inserts shall be used as little as possible to prevent excessive internal stress caused by different shrinkage between inserts and products.<\/p>\n\n\n\n

\u2463 The sprue is enough to release the gate material in the future and during curing, which is easy to release.<\/p>\n\n\n\n

\u2464 Demoulding air inlet holes shall be properly set for deep bottom products to prevent the formation of vacuum negative pressure.<\/p>\n\n\n\n

\u2465 The connection between the sprue bushing and the nozzle shall prevent the product from sticking to the fixed mold due to the drag of cold and hard materials.<\/p>\n\n\n\n

3. Material aspect<\/p>\n\n\n\n

\u2460 The recycled material content is too high and the product strength is too low, which is easy to cause cracking.<\/p>\n\n\n\n

\u2461 Excessive humidity will cause chemical reaction between plastic and water vapor, reduce strength and cause ejection cracking. The molding temperature of each material shall be observed, the residence time shall be shortened to reduce the decomposition and aging of resin, and the drying conditions shall be strengthened to inhibit the decomposition of water. The crystallinity of the product can also be improved by increasing the mold temperature and prolonging the cooling time.<\/p>\n\n\n\n

\u2462 The material itself is not suitable for processing environment or poor quality, and will cause cracking if polluted.<\/p>\n\n\n\n

4. Machine<\/p>\n\n\n\n

The plasticizing capacity of the injection molding machine <\/a><\/strong>should be appropriate. If it is too small, the plasticizing is not sufficient, it will become brittle due to incomplete mixing, and it will decompose if it is too large.<\/p>\n\n\n\n

Slow down the mold opening speed and ejection speed to reduce the load on the molded product and reduce cracks.<\/p>\n\n\n\n

Add rounded corners to the corners of formed products to prevent cracking.<\/p>\n\n\n\n

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Product cracking, inclu…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"aside","meta":{"footnotes":""},"categories":[1],"tags":[28],"class_list":["post-490","post","type-post","status-publish","format-aside","hentry","category-technical","tag-injection-molding-machine","post_format-post-format-aside"],"_links":{"self":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/490","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/comments?post=490"}],"version-history":[{"count":2,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/490\/revisions"}],"predecessor-version":[{"id":493,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/posts\/490\/revisions\/493"}],"wp:attachment":[{"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/media?parent=490"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/categories?post=490"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fuhrung.com\/technical-blog\/wp-json\/wp\/v2\/tags?post=490"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}