{"id":397,"date":"2026-11-06T21:32:00","date_gmt":"2026-11-06T13:32:00","guid":{"rendered":"https:\/\/kerkepm.com\/knowledge\/twin-screw-extruder-troubleshooting\/"},"modified":"2026-11-08T20:42:55","modified_gmt":"2026-11-08T12:42:55","slug":"twin-screw-extruder-troubleshooting","status":"publish","type":"page","link":"https:\/\/kerkepm.com\/es\/knowledge\/twin-screw-extruder-troubleshooting\/","title":{"rendered":"Twin Screw Extruder Troubleshooting"},"content":{"rendered":"<div class=\"k3\">\n<div class=\"wrap\"><div class=\"crumbs\"><a href=\"\/\">Home<\/a><span>\/<\/span><a href=\"\/knowledge\/\">Knowledge<\/a><span>\/<\/span>Twin Screw Extruder Troubleshooting<\/div><\/div><div class=\"wrap\"><div class=\"hero\">\n<p class=\"kicker\">Service \u00b7 9 min read<\/p>\n<h1>Twin Screw Extruder Troubleshooting: Nine Symptoms, Nine Causes<\/h1>\n<p class=\"dek\">Most faults reported as 'the machine is not working' resolve to feeding, vacuum, temperature or wear. This is the tree we use on the phone before anyone books a flight. A reference twin screw extruder troubleshooting page from Kerke.<\/p>\n<div class=\"byline\"><div><b>Updated<\/b> 6 November 2026<\/div><div><b>Reviewed by<\/b> Kerke process team<\/div>\n<div><b>Basis<\/b> commissioning records, parameter table<\/div><\/div>\n<\/div><\/div>\n<div class=\"wrap\"><div class=\"grid\"><main>\n\n<p class=\"lead\">Diagnose in the order the material travels: feeder \u2192 feed zone \u2192 melting \u2192 vent \u2192 die \u2192 pelletizer. A symptom that appears at the die is usually caused two metres upstream.<\/p>\n\n<nav class=\"wp-block-rank-math-toc-block k3-toc\" aria-label=\"On this page\"><b>On this page:<\/b><a href=\"#rm-s1\">Symptom \u2192 cause \u2192 action<\/a><a href=\"#rm-s2\">When it is wear, not settings<\/a><a href=\"#rm-s3\">What to send us<\/a><a href=\"#rm-s4\">FAQ<\/a><a href=\"#rm-s5\">Where these numbers come from<\/a><\/nav><h2 class=\"sec\" id=\"table\" id=\"rm-s1\">Symptom \u2192 cause \u2192 action<\/h2>\n<div class=\"tw\"><table>\n<caption><b>Table 1.<\/b> Nine common faults on co-rotating twin screw compounding lines.<\/caption>\n<thead><tr><th scope=\"col\">Symptom<\/th><th scope=\"col\">Most likely cause<\/th><th scope=\"col\">Check first<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>Output falls with no change in settings<\/td><td>Wear on screw elements or liner, or feeder drift<\/td><td>Weigh a 60-second sample at the die; compare with the feeder setpoint and with the commissioning record.<\/td><\/tr>\n<tr><td>Torque high, output low<\/td><td>Cold barrel zone, blocked die hole, or over-long mixing section<\/td><td>Zone-by-zone temperature against the profile; die pressure; last screw configuration change.<\/td><\/tr>\n<tr><td>Melt temperature runs away<\/td><td>Screw speed too high for the formulation, or worn elements generating shear without conveying<\/td><td>Reduce rpm 10% and watch the trend. If temperature follows rpm linearly, the screw is doing shear work instead of conveying.<\/td><\/tr>\n<tr><td>Vent spitting melt<\/td><td>Melt seal not established, vacuum too high, or vent insert worn<\/td><td>Vacuum level (\u22120.06 to \u22120.09 MPa), feed rate stability, vent insert clearance.<\/td><\/tr>\n<tr><td>Black specks in natural product<\/td><td>Degraded material on the screw, dead spots behind the die, or a worn screw flight<\/td><td>Purge and inspect; check the die plate radius and the last 3D element.<\/td><\/tr>\n<tr><td>Strands break in the water bath<\/td><td>Die hole count too high for the polymer, water too warm, or filler loading too high for strand cutting<\/td><td>Water temperature (15\u201325 \u00b0C), bath length, and whether loading has moved above 50%.<\/td><\/tr>\n<tr><td>Pellets with tails or twins<\/td><td>Blunt pelletizer blades, wrong blade clearance, or die face temperature too low<\/td><td>Blade gap (0.05\u20130.1 mm), blade wear, die heater band.<\/td><\/tr>\n<tr><td>Fines above 2%<\/td><td>Brittle melt, blade speed too high, or water ring nozzle misalignment<\/td><td>Pelletizer rpm, water flow and angle, melt temperature at the die.<\/td><\/tr>\n<tr><td>Gearbox oil temperature alarm<\/td><td>Blocked oil cooler, low oil level, or sustained torque above rating<\/td><td>Cooler water flow, oil level and colour, torque history for the last 24 h.<\/td><\/tr>\n<\/tbody><\/table><\/div>\n\n<h2 class=\"sec\" id=\"wear\" id=\"rm-s2\">When it is wear, not settings<\/h2>\n<p>Screw and liner wear is progressive and silent. Two measurements catch it early: <strong>output at fixed rpm and feeder setting<\/strong> (falls 5\u201310% before the operator notices anything) and <strong>clearance between screw flight and liner<\/strong> at the wear zone. For 85% CaCO<sub>3<\/sub>, plan on a wear inspection at 4,000\u20136,000 hours; for glass fibre, at 3,000\u20134,000.<\/p>\n<div class=\"call rule\"><h4>Rule of thumb<\/h4><p>If a change of settings fixes the symptom within one shift, it was a setting. If the symptom returns within a week at the same settings, it is wear, feeding or material \u2014 stop adjusting and start measuring.<\/p><\/div>\n\n<h2 class=\"sec\" id=\"escalate\" id=\"rm-s3\">What to send us<\/h2>\n<ul>\n<li>Barrel profile, screw speed, feeder rates, vacuum, die pressure and torque at the moment of the fault<\/li>\n<li>Photos of the extrudate and of the die face<\/li>\n<li>Material batch, filler grade and any change in supplier<\/li>\n<li>Hours run since the last screw inspection<\/li>\n<\/ul>\n<p>With those four items we can usually name the cause before a technician leaves Nanjing.<\/p>\n\n<h2 class=\"sec\" id=\"faq\" id=\"rm-s4\">FAQ<\/h2>\n<details open><summary>Output dropped 15% overnight \u2014 where do I look?<\/summary><p>First the feeder: weigh a timed sample at the die. If the feeder is delivering what it should, check die pressure and the last barrel zone temperature, then screw wear. A 15% overnight drop is almost never wear \u2014 wear is gradual.<\/p><\/details><details><summary>Why does the vent spit only at high output?<\/summary><p>The melt seal is being pushed downstream by the higher fill ratio. Either lower the vacuum slightly, move the vent one barrel back, or add a reverse-flight element before the vent.<\/p><\/details><details><summary>How often should screws be inspected?<\/summary><p>Every 2,500 hours for abrasive filler, every 4,000 for general compounding. Inspection means measuring flight width and liner clearance, not looking at the screw.<\/p><\/details>\n<div class=\"method\"><h2 id=\"rm-s5\">Where these numbers come from<\/h2>\n<p>Values are drawn from the Kerke parameter table, commissioning records and service reports from lines in the field. Temperature windows and consumption figures are typical ranges \u2014 confirm on your own material before they become a production setpoint.<\/p><\/div>\n<div class=\"related\"><h2 id=\"rm-s6\">Related reading<\/h2><div class=\"rel-grid\"><a class=\"rel\" href=\"\/knowledge\/twin-screw-extruder-startup\/\"><span>Knowledge<\/span>Twin Screw Extruder Startup: The 9-Step Sequence That Protects the Screw<\/a><a class=\"rel\" href=\"\/knowledge\/extruder-maintenance-schedule\/\"><span>Knowledge<\/span>Extruder Maintenance Schedule: 250 \/ 2,500 \/ 5,000 \/ 10,000 Hours<\/a><\/div><\/div>\n<div class=\"cta\"><div><b>Tell us your material \u2014 we will tell you the line<\/b><p>Send 25\u201350 kg and we run it on our lab extruder: pellets, running video and a capacity report back in 3\u20137 days.<\/p><\/div>\n<div class=\"acts\"><a href=\"\/get-a-quote\/\">Get a quote<\/a>\n<a class=\"alt\" href=\"\/get-a-quote\/#trial\">Send material for trial<\/a><\/div><\/div>\n<\/main>\n<aside><h5>On this page<\/h5><ol><li><a href=\"#table\">Symptom \u2192 cause \u2192 action<\/a><\/li><li><a href=\"#wear\">When it is wear, not settings<\/a><\/li><li><a href=\"#escalate\">What to send us<\/a><\/li><li><a href=\"#faq\">FAQ<\/a><\/li><\/ol>\n<div class=\"sidecard\"><b>Question not covered?<\/b><p>Send the material, the machine model and the symptom. We answer with a parameter sheet, not a brochure.<\/p>\n<a class=\"btn\" href=\"\/get-a-quote\/\">Ask an engineer<\/a>\n<a class=\"btn ghost\" href=\"\/knowledge\/\">All articles<\/a><\/div><\/aside><\/div><\/div>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@graph\": [{\"@type\": \"TechArticle\", \"headline\": \"Twin Screw Extruder Troubleshooting: Nine Symptoms, Nine Causes\", \"description\": \"Most faults reported as 'the machine is not working' resolve to feeding, vacuum, temperature or wear. 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Either lower the vacuum slightly, move the vent one barrel back, or add a reverse-flight element before the vent.\"}}, {\"@type\": \"Question\", \"name\": \"How often should screws be inspected?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Every 2,500 hours for abrasive filler, every 4,000 for general compounding. Inspection means measuring flight width and liner clearance, not looking at the screw.\"}}]}]}<\/script>\n<div class=\"wrap\"><section class=\"k3-more\" id=\"rm-more\"><h2>Twin screw extruder troubleshooting \u2014 the short version<\/h2><figure class=\"k3-fig\"><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/11\/kte-65b-co-rotating-twin-screw-extruder-01-1200.webp\" alt=\"twin screw extruder troubleshooting\" loading=\"lazy\" width=\"1200\" height=\"675\"><figcaption>Kerke test line, Nanjing \u2014 where the figures on this page were measured<\/figcaption><\/figure><p>Note on Twin screw extruder troubleshooting: every figure on this page is a reference range measured on Kerke's own test line in Nanjing, not a catalogue maximum. If your material differs from the one in the table, send 25\u201350 kg and we will replace the range with a measured number.<\/p><p>Planning a twin screw extruder troubleshooting upgrade this quarter? Send the material and the target output \u2014 the configuration comes back within one working day.<\/p><p class=\"k3-rel\"><b>Related on this site:<\/b> <a href=\"\/machines\/co-rotating-twin-screw-extruder\/\">Twin screw extruder range<\/a> \u00b7 <a href=\"\/applications\/\">Extrusion lines by application<\/a> \u00b7 <a href=\"\/get-a-quote\/\">free extrusion line quotation<\/a> \u00b7 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Pelletizing\" target=\"_blank\" rel=\"noopener\">Wikipedia: Pelletizing<\/a><\/p><\/section><\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Home\/Knowledge\/Twin Screw Extruder Troubleshooting Service \u00b7 9 min read Twin Screw Extruder Troubleshooting: Nine Symptoms, Nine Causes Most faults reported as &#8216;the machine is not working&#8217; resolve to feeding, vacuum, temperature or wear. This is the tree we use on the phone before anyone books a flight. A reference twin screw extruder troubleshooting page from [&#8230;]\n","protected":false},"author":1,"featured_media":0,"parent":63,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-blank.php","meta":{"footnotes":""},"application":[],"app_group":[],"class_list":["post-397","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/397","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/comments?post=397"}],"version-history":[{"count":0,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/397\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/63"}],"wp:attachment":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/media?parent=397"}],"wp:term":[{"taxonomy":"application","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/application?post=397"},{"taxonomy":"app_group","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/app_group?post=397"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}