{"id":17421,"date":"2021-07-21T16:07:14","date_gmt":"2021-07-21T14:07:14","guid":{"rendered":"http:\/\/s522541291.online.de\/?p=17421"},"modified":"2024-10-25T15:00:58","modified_gmt":"2024-10-25T13:00:58","slug":"europlast-in-plastverarbeiter-ausgabe-06-02","status":"publish","type":"post","link":"https:\/\/ep-kunststofftechnik.de\/en\/europlast-in-plastverarbeiter-ausgabe-06-02\/","title":{"rendered":"EUROplast in \u201cPlast\u00adver\u00adar\u00adbeiter\u201d issue 06\/02"},"content":{"rendered":"

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Polyamide for the aviation industry \u2013 fire protection in sight
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Print version in Acrobat Reader format<\/a><\/strong><\/u><\/a>

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The problem with components with aviation approval according to ABD and FAR is, on the one hand, the low flammability required, and on the other hand, no toxic fumes must be produced in the event of a fire. A polyamide rises to the challenge.<\/h5>\n\n\n\n

To date, polycar\u00adbo\u00adnate (PC) has often been used for aviation appli\u00adca\u00adtions. However, this amorphous material causes problems because of its relatively poor resis\u00adtance to stress cracking. There is a risk that cracks can be triggered by a super\u00adpo\u00adsi\u00adtion of stresses in conjunc\u00adtion with a chemical attack.<\/p>\n\n\n\n

Stresses arise on plastic parts during the manufac\u00adtu\u00adring process, for example during injec\u00adtion molding or deep drawing \u2014 with good workman\u00adship and a plastic-friendly design of the compon\u00adents reducing the stress level. Depen\u00adding on the appli\u00adca\u00adtion, the compon\u00adents can also experi\u00adence considerable stress in the later instal\u00adla\u00adtion situa\u00adtion due to the use of thread-forming screws instead of thread-cutting screws or incor\u00adrectly designed snap hooks.<\/p>\n\n\n\n

The compon\u00adents required are technical functional parts of the seat mecha\u00adnism. When installed, these are exposed to certain stresses and are conta\u00admi\u00adnated with substances that trigger stress cracks, such as grease, but also food, hand creams or cleaning agents. After every long flight there is a cleaning, which is sometimes carried out in the most remote places in the world. This makes it diffi\u00adcult to specify the substances with which plastic parts may be treated. However, the use of polycar\u00adbo\u00adnate, a material with high impact strength and the possi\u00adbi\u00adlity of flame retar\u00addancy, poses the risk of stress cracking with almost every commer\u00adci\u00adally available cleaning agent.<\/p>\n\n\n\n

The property profile of the material that is approved for the aviation industry must meet certain requi\u00adre\u00adments:<\/p>\n\n\n\n

    \n
  • Flamma\u00adbi\u00adlity on horizontal test (15s) accor\u00adding to App.F to part 25 part I \u00a7 (a),(1),(v)<\/li>\n\n\n\n
  • Smoke density per FAR 25.853 (d)<\/li>\n\n\n\n
  • Smoke density accor\u00adding to ABD 0031<\/li>\n\n\n\n
  • Toxicity accor\u00adding to ABD 0031<\/li>\n\n\n\n
  • Chemical resis\u00adtance<\/li>\n\n\n\n
  • Defined strength and elonga\u00adtion values<\/li>\n<\/ul>\n\n\n\n

    After various tests, a dry impact-resistant PA6 GF 15 FR (Foramid GM 96\/30\u20131) was created that was suitable for the aviation industry. The polymer matrix of this material consists of polyamide 6, a semi-crystal\u00adline material with suffi\u00adcient strength and elonga\u00adtion values as well as high chemical resis\u00adtance. To achieve the flame-retar\u00addant proper\u00adties, signi\u00adfi\u00adcant amounts of a phosphate- and heavy-metal-free flame retar\u00addant system were added. Further\u00admore, around 15% glass fiber was compounded to increase strength and rigidity. With a propor\u00adtion of 30%, the material was too brittle due to the high flame retar\u00addant content. An added rubber-based impact modifier helped to increase the dry impact strength.<\/p>\n\n\n\n

    Processing aspects<\/h5>\n\n\n\n

    The material can be processed like a normal PA 6 \u2013 GF15. To ensure colora\u00adbi\u00adlity, the color must be adjusted exactly to the base material. However, it should be noted that colora\u00adbi\u00adlity is only possible to a limited extent due to the high flame retar\u00addant content.<\/p>\n\n\n\n

    The plasti\u00adci\u00adzing and injec\u00adtion condi\u00adtions must be adjusted so that the blend does not separate. The parame\u00adters were deter\u00admined empiri\u00adcally.<\/p>\n\n\n\n

    Despite the dry impact modifi\u00adca\u00adtion, the finished injec\u00adtion molded parts should still be condi\u00adtioned with 2\u20133 % distilled water after comple\u00adtion. This increases the impact strength of the relatively brittle polyamide compound due to the high flame retar\u00addant content.<\/p>\n\n\n\n

    The injec\u00adtion mold is equipped with hard inserts made of hot-work steel (1.2344) and has optimal tempe\u00adra\u00adture control. Due to the relatively low volumes in the aviation industry, the injec\u00adtion is carried out using a rod and distri\u00adbutor without hot runner techno\u00adlogy. Care was taken to ensure that the tunnel gate connec\u00adtion was suffi\u00adci\u00adently thick. This is important for low shear and suffi\u00adcient pressure supply to the semi-crystal\u00adline material. The weld lines were placed in non-critical areas. Demoul\u00adding is carried out using flat and round ejectors and, in some cases, using complex slide techno\u00adlogy.<\/p>\n\n\n\n

    Compound production<\/h5>\n\n\n\n

    Due to its versa\u00adti\u00adlity, the polyamide polymer group has estab\u00adlished itself as one of the most important and versa\u00adtile thermo\u00adpla\u00ads\u00adtics in the field of injec\u00adtion molding granules. The macro\u00admole\u00adcule is made up of one or two diffe\u00adrent monomers. A distinc\u00adtion is made between PA 6 (but also PA 11 and PA 12) and PA 6.6 (but also PA 4.6 and PA 6.9). The number indicates the number of carbon atoms in the molecule.<\/p>\n\n\n\n

    The combi\u00adna\u00adtion of halogen- and phosphate-free flame retar\u00addancy, glass fiber reinforce\u00adment and impact modifi\u00adca\u00adtion required for the intended purpose repres\u00adents a parti\u00adcular chall\u00adenge for the compounder. The aspects of polymer compa\u00adti\u00adbi\u00adlity, coordi\u00adna\u00adtion of the mecha\u00adnisms of action, safety of the process, environ\u00admental compa\u00adti\u00adbi\u00adlity and good econo\u00admics must be taken into account.<\/p>\n\n\n\n

    Based on many years of experi\u00adence, a flame retar\u00addant system based on melamine cyanurate ( melapur MC 25 from DSM ) proved to be suitable.<\/p>\n\n\n\n

    It is clear that in PA 6 the end groups NH2 and COOH form a bond with those of MCU, with the forma\u00adtion reaction taking place through opening of the rings and attach\u00adment. Cyanuric acid is broken down, which at the same time leads to the break\u00addown of Polymaid and thus to a lower smoke gas density. However, it has been shown that the dosage of melamine cyanurate in order to achieve the respec\u00adtive fire class must be set much higher than speci\u00adfied by the manufac\u00adturer.<\/p>\n\n\n\n

    While 8 weight of % was enough for the MCU 25 product from Chemie Linz in 1992 to achieve V 0 accor\u00adding to UL 94 (1.6 mm) for unrein\u00adforced PA 6, at least 12.5 weight of % is required with the afore\u00admen\u00adtioned product .<\/p>\n\n\n\n

    The fire behavior of PA 6 with glass fiber was there\u00adfore only influenced by the flame retar\u00addant system to the extent that V 2 accor\u00adding to UL 94 (1.6 mm) was achieved. Since the compon\u00adents have a wall thick\u00adness of 3 mm, the flamma\u00adbi\u00adlity drops to V 1 accor\u00adding to UL 94 and thus meets the flame retar\u00addancy tests of the aviation industry, which differ from the tests of Under\u00adwri\u00adters Labora\u00adto\u00adries.<\/p>\n\n\n\n

    By adding the impact modifier, in this case an ethylene propy\u00adlene rubber (EPM), to the already high flame retar\u00addant content, a compli\u00adcated mixture is created that places high demands on the techno\u00adlo\u00adgical process of compoun\u00adding. Without three gravi\u00adme\u00adtric dosing units on the one hand and the correct choice of visco\u00adsity as a quotient of shear rate and shear stress on the other hand, consis\u00adtent quality cannot be guaran\u00adteed.<\/p>\n\n\n\n

    Technical functional parts of the seat mecha\u00adnics for the aviation industry<\/span><\/figcaption><\/figure>\n\n\n\n
    Proces\u00adsing the polyamide on the injec\u00adtion molding machine<\/span><\/figcaption><\/figure>\n\n\n\n
    Tool techno\u00adlogy for produ\u00adcing the functional parts<\/span><\/figcaption><\/figure>\n\n\n\n

    Images: EP Kunst\u00adstoff\u00adtechnik <\/p>\n\n\n\n

    Authors<\/h5>\n\n\n\n

    Dr. Gerhard Pohl, owner of Carl Pohl textile and thermo\u00adpla\u00adstic produc\u00adtion Forst \/ Lausitz and managing director of Dr. Pohl-Textil- und Thermo\u00adplast GmbH, Forst \/ Lausitz<\/p>\n\n\n\n

    Dipl.-Ing. Elmar Nachts\u00adheim, Managing Director of Europlast, EP Kunst\u00adstoff\u00adtechnik GmbH, Ilsfeld<\/p>","protected":false},"excerpt":{"rendered":"

    Our specia\u00adlist article on the use of polyamide in the aviation industry was published in the trade magazine Plast\u00adver\u00adar\u00adbeiter (issue 06\/02).<\/p>","protected":false},"author":1,"featured_media":17391,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"brizy-blank-template.php","format":"standard","meta":{"wp_typography_post_enhancements_disabled":false,"footnotes":""},"categories":[10,8],"tags":[17,19,16],"class_list":["post-17421","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-aktuelles","category-presse","tag-innovation-2","tag-presse","tag-technologie-2"],"brizy_media":[],"_links":{"self":[{"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/posts\/17421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/comments?post=17421"}],"version-history":[{"count":10,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/posts\/17421\/revisions"}],"predecessor-version":[{"id":24450,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/posts\/17421\/revisions\/24450"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/media\/17391"}],"wp:attachment":[{"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/media?parent=17421"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/categories?post=17421"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ep-kunststofftechnik.de\/en\/wp-json\/wp\/v2\/tags?post=17421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}