{"id":4980,"date":"2026-09-10T10:26:45","date_gmt":"2026-09-10T08:26:45","guid":{"rendered":"https:\/\/hamco-germany.com\/?post_type=fachbegriff&#038;p=4980"},"modified":"2026-09-10T10:42:48","modified_gmt":"2026-09-10T08:42:48","slug":"compression-set","status":"publish","type":"fachbegriff","link":"https:\/\/hamco-germany.com\/en\/fachbegriff\/druckverformungsrest\/","title":{"rendered":"Compression set"},"content":{"rendered":"<h2>That really takes the biscuit!<\/h2>\n<p>Our sofa used to be really lovely. The seat was firm, the cushions were high and completely wrinkle-free.<\/p>\n<p>Then, after sitting there for a few minutes, we talked about the <a href=\"https:\/\/hamco-germany.com\/en\/technical-term\/creep-behaviour\/\">Creeper behaviour<\/a> I gave some thought to plastics. After that, the sofa looked just as it did in the catalogue.<\/p>\n<p>After a few years, our sofa had a pretty good idea of where our favourite spot was. The seat had sagged permanently \u2013 even though our own weight hadn\u2019t increased by any significant amount.<\/p>\n<p>What we can observe here is a <strong>Compression set<\/strong>. It describes the proportion of a previously induced deformation that remains permanently after the load has been removed and a defined recovery period has elapsed.<\/p>\n<p><strong>The three heights of our sofa<\/strong><\/p>\n<p>And that is precisely why we need three height measurements:<\/p>\n<ul>\n<li>which <strong>original height H0<\/strong>: the seat height of the new sofa, which is stated as 45 cm in the catalogue,<\/li>\n<li>which <strong>Height under load H1<\/strong>: the seat height, which is still 35 cm when we are sitting on it,<\/li>\n<li>which <strong>Height H2 after relaxation<\/strong>: the seat height, which is still 42 cm after the load has been removed and a sufficient recovery period has elapsed.<\/li>\n<\/ul>\n<p>So, when the sofa was in use, the seat was compressed by 10 cm. After getting up, 3 cm of this compression remained permanently.<\/p>\n<p>The residual compression deformation can be calculated as follows:<\/p>\n<p>(H0\u2013H2)\/(H0\u2013H1) \u00d7 100<\/p>\n<p>In this example, our sofa has a <strong>Compression set of 30 %<\/strong>.<\/p>\n<p>The higher this value, the greater the proportion of the original deformation that remains after the load is removed. <strong>But bigger isn\u2019t always better \u2013 that\u2019s exactly the point!<\/strong><\/p>\n<p><strong>The technical background<\/strong><\/p>\n<p>If an injection-moulded seal is made from a <a href=\"https:\/\/hamco-germany.com\/en\/material\/tpe-thermoplastic-elastomers\/\">thermoplastic elastomer<\/a> If subjected to stress over a prolonged period, it may, depending on the material, temperature and load, <strong>to become increasingly permanently deformed<\/strong>. Some of the deformation reverts to its original state once the load is removed, whilst the rest remains.<\/p>\n<p><strong>What the figure indicates<\/strong><\/p>\n<p>The compression set is an important parameter, particularly for soft, elastic materials. <strong>The lower the value, the better the material\u2019s resilience.<\/strong><\/p>\n<p>The magnitude of the compression set depends, amongst other things, on <strong>Material, temperature, duration of loading, degree of compression and recovery time<\/strong> . A percentage figure must therefore always be considered in conjunction with the underlying test conditions.<\/p>\n<p>Our sofa merely illustrates the principle \u2013 it is, of course, not a test carried out in accordance with the relevant standards.<\/p>\n<p>For a technical plastic component, however, such a degree of permanent deformation can be crucial: if a component does not sufficiently regain its original shape after prolonged loading, its function may also be impaired.<\/p>","protected":false},"featured_media":4981,"parent":0,"template":"","class_list":["post-4980","fachbegriff","type-fachbegriff","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/hamco-germany.com\/en\/wp-json\/wp\/v2\/fachbegriff\/4980","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hamco-germany.com\/en\/wp-json\/wp\/v2\/fachbegriff"}],"about":[{"href":"https:\/\/hamco-germany.com\/en\/wp-json\/wp\/v2\/types\/fachbegriff"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hamco-germany.com\/en\/wp-json\/wp\/v2\/media\/4981"}],"wp:attachment":[{"href":"https:\/\/hamco-germany.com\/en\/wp-json\/wp\/v2\/media?parent=4980"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}