{"id":2291,"date":"2026-11-09T21:43:59","date_gmt":"2026-11-09T13:43:59","guid":{"rendered":"https:\/\/kerkepm.com\/cases\/japan-two-stage-single-screw-extruder\/"},"modified":"2026-11-09T22:20:02","modified_gmt":"2026-11-09T14:20:02","slug":"japan-two-stage-single-screw-extruder","status":"publish","type":"page","link":"https:\/\/kerkepm.com\/es\/cases\/japan-two-stage-single-screw-extruder\/","title":{"rendered":"Two stage single screw extruder that never ran"},"content":{"rendered":"<div class=\"k3\">\n<noscript><iframe loading=\"lazy\" src=\"https:\/\/www.googletagmanager.com\/ns.html?id=GTM-5JN495RG\" height=\"0\" width=\"0\" style=\"display:none;visibility:hidden\"><\/iframe><\/noscript>\n<div class=\"wrap\"><div class=\"crumbs\"><a href=\"\/\">Home<\/a><span>\/<\/span><a href=\"\/cases\/\">Case studies<\/a><span>\/<\/span>Japan<\/div><\/div><div class=\"wrap\"><div class=\"hero\">\n<p class=\"kicker\">Case study 3 \u00b7 Japan \u00b7 Waste material recycling<\/p>\n<h1>Two stage single screw extruder that never ran: one week in Japan<\/h1>\n<p class=\"dek\">The customer had run similar equipment for years, so they declined installation on their new SE-140 \/ SE-140 two stage single screw extruder. It never produced saleable pellets. We flew in, took the risk onto ourselves, and spent a week on the line \u2014 most of it on the vent, the screen and the operators.<\/p>\n<div class=\"byline\"><div><b>Line<\/b> SE-140 \/ SE-140<\/div><div><b>Material<\/b> Waste plastics<\/div><div><b>Result<\/b> stable output<\/div><div><b>On site<\/b> 1 week<\/div><div><b>Updated<\/b> 9 November 2026<\/div><\/div>\n<\/div><\/div>\n<div class=\"wrap\"><div class=\"appmedia\">\n<figure class=\"case-photo\"><img decoding=\"async\" src=\"\/wp-content\/uploads\/2026\/11\/case-japan-two-stage-single-screw-extruder.webp\" alt=\"Two stage single screw extruder line (SE-140 + SE-140) built for the Japanese recycling customer\" loading=\"eager\" fetchpriority=\"high\"><figcaption>Two stage single screw extruder line (SE-140 + SE-140) built for the Japanese recycling customer<\/figcaption><\/figure>\n<div class=\"appmedia-text\">\n<section class=\"qa\" id=\"answer\"><nav class=\"wp-block-rank-math-toc-block k3-toc\" aria-label=\"On this page\"><b>On this page:<\/b><a href=\"#rm-s1\">Quick answer<\/a><a href=\"#situation\">The situation: a line that had never made a saleable pellet<\/a><a href=\"#found\">What was wrong with the two stage single screw extruder<\/a><a href=\"#changed\">The week, day by day<\/a><a href=\"#result\">Result<\/a><\/nav><h2 id=\"rm-s1\">Quick answer<\/h2><p>A two stage single screw extruder is not a bigger single screw \u2014 the first stage plasticises and vents, the second builds pressure, and the line only runs when those two duties are balanced. Here the first-stage vent was left closed, the screen changer carried a mesh two sizes too fine, and the forced feeder was set by ear. Opening the vent, dropping to 60 mesh, matching feeder speed to screw speed and re-teaching the start-up sequence took a week and made the line saleable.<\/p><\/section>\n<\/div>\n<\/div><\/div>\n<div class=\"wrap\"><div class=\"grid\"><main>\n<div class=\"stats\"><div class=\"stat\"><b>1 week<\/b><span>on site<\/span><\/div><div class=\"stat\"><b>2 stages<\/b><span>SE-140 \/ SE-140<\/span><\/div><div class=\"stat\"><b>0<\/b><span>parts charged<\/span><\/div><\/div>\n<p class=\"note\">Photograph from the commissioning file for this project; customer names are withheld where requested.<\/p>\n\n<h2 class=\"sec\" id=\"situation\">The situation: a line that had never made a saleable pellet<\/h2>\n<p>The customer recycles post-industrial waste plastics in Japan and already owned similar equipment, so when the <a href=\"\/machines\/two-stage-single-screw\/\">SE-140 \/ SE-140 line<\/a> arrived they installed it themselves and declined commissioning support. Within two weeks the machine was producing pellets with bubbles, a burnt smell and unstable strand, and the customer's own buyers had rejected two lots. By the time we were called, the relationship on site was not good.<\/p>\n<p>We offered one thing before discussing the machine: if the line could not make product the customer accepted, we would carry the risk. An engineer was on site inside a week and stayed for seven days.<\/p>\n\n<h2 class=\"sec\" id=\"found\">What was wrong with the two stage single screw extruder<\/h2>\n<p>Nothing was broken on the two stage single screw extruder. It was being run as if the second stage were a metering section of a single screw, which is the standard mistake with this architecture: the two stages have to be balanced by pressure and by venting, not by one speed dial.<\/p>\n<div class=\"tw\"><table><caption><b>Table 1.<\/b> What the line was doing, and what a balanced SE\/SE line has to do.<\/caption>\n<thead><tr><th scope=\"col\">Item<\/th><th scope=\"col\">On arrival<\/th><th scope=\"col\">Correct for this feed<\/th><th scope=\"col\">Effect<\/th><\/tr><\/thead><tbody>\n<tr><td><b>Stage-1 vent<\/b><\/td><td>Closed, plugged with a blind flange<\/td><td>Open to atmosphere, then \u22120.05 MPa on the second vent<\/td><td>Moisture and volatiles had nowhere to go; that is the bubble and the smell.<\/td><\/tr>\n<tr><td><b>Screen changer<\/b><\/td><td>120 mesh<\/td><td>60 mesh, 40 \u00b5m only for clean rigid scrap<\/td><td>Fine mesh on contaminated film raises head pressure until the safety valve lifts and output collapses.<\/td><\/tr>\n<tr><td><b>Forced feeder<\/b><\/td><td>Set by ear, no catch sample<\/td><td>Matched to stage-1 amps, verified by 10-minute catch<\/td><td>Starving then flooding: the stage-1 screw never ran full, so it never vented properly.<\/td><\/tr>\n<tr><td><b>Stage-1 profile<\/b><\/td><td>230 \u00b0C flat<\/td><td>180\u2013200 \u00b0C, rising only at the last zone<\/td><td>Film scrap needs gentle melting; 230 \u00b0C degraded the polymer before the vent.<\/td><\/tr>\n<tr><td><b>Stage-2 profile<\/b><\/td><td>Same as stage 1<\/td><td>190\u2013205 \u00b0C with the die 10 \u00b0C above stage 2<\/td><td>Pressure build-up without re-melting what stage 1 had already controlled.<\/td><\/tr>\n<tr><td><b>Strand cooling<\/b><\/td><td>Bath 1.2 m from the die<\/td><td>0.3\u20130.5 m, water 30\u201340 \u00b0C<\/td><td>Long air gap let the strand sag and stick before it hit water.<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>Two of these are worth dwelling on. The closed vent is the one that reads as \"cheap machine\" to a buyer: pellets with bubbles look like a dispersion failure, but on a recycling line they are almost always a venting failure. And the 120 mesh screen is the classic self-inflicted wound \u2014 a finer screen feels like better filtration until the pressure spike costs you a shift.<\/p>\n\n<h2 class=\"sec\" id=\"changed\">The week, day by day<\/h2>\n<ol class=\"flow\">\n<li><b>Day 1 \u2014 read, don't touch.<\/b> Panel log, ampere readings on both stages, catch samples of feed and product. The line was cycling: 12 minutes full, 4 minutes starved.<\/li>\n<li><b>Day 2 \u2014 venting.<\/b> Blind flange off, stage-1 vent opened, second vent pulled to \u22120.05 MPa. Bubbles gone by the afternoon; smell reduced but still present, which pointed at temperature.<\/li>\n<li><b>Day 3 \u2014 screening and pressure.<\/b> 120 \u2192 60 mesh; head pressure dropped from 21 MPa to 14 MPa and the safety valve stopped lifting.<\/li>\n<li><b>Day 4 \u2014 feeder and stage balance.<\/b> Forced feeder matched to stage-1 amps; stage-2 speed set from the pressure the die needs, not from the output the customer wanted.<\/li>\n<li><b>Day 5\u20136 \u2014 profile and strand.<\/b> Both stages re-profiled for film scrap; bath moved to 0.4 m from the die, water to 35 \u00b0C.<\/li>\n<li><b>Day 7 \u2014 training.<\/b> The 9-step start-up sequence written on the wall in Japanese and English, with the three readings the operator is allowed to change and the three they are not.<\/li>\n<\/ol>\n\n<h2 class=\"sec\" id=\"result\">Result<\/h2>\n<p>Pellets came out clear of bubbles and odour, strand ran without breaks for a full shift, and the customer's buyer accepted the third lot. Output settled at the low end of the SE-140 \/ SE-140 band \u2014 the line is sized by the feed's bulk density, and this feed is light.<\/p>\n<div class=\"quoteband\"><b>The lesson the customer wrote back:<\/b> the machine was not the problem, the way we started it was. They now train every new operator on the vent before they let them touch the speed dial.<\/div>\n\n<h2 class=\"sec\" id=\"line\">Line configuration<\/h2>\n<div class=\"tw\"><table><caption><b>Table 2.<\/b> SE\/SE two-stage range, for comparison with this build.<\/caption>\n<thead><tr><th scope=\"col\">Configuration<\/th><th scope=\"col\">Stage 1<\/th><th scope=\"col\">Stage 2<\/th><th scope=\"col\">Output (kg\/h)<\/th><th scope=\"col\">Feed<\/th><\/tr><\/thead><tbody>\n<tr><td><b>SE-120 \/ SE-120<\/b><\/td><td>120 mm<\/td><td>120 mm<\/td><td>200\u2013400<\/td><td>Film, bag, rigid regrind<\/td><\/tr>\n<tr><td><b>SE-140 \/ SE-140<\/b> (this line)<\/td><td>140 mm<\/td><td>140 mm<\/td><td>between the 120 and 150 builds<\/td><td>Post-industrial film and mixed scrap<\/td><\/tr>\n<tr><td><b>SE-150 \/ SE-150<\/b><\/td><td>150 mm<\/td><td>150 mm<\/td><td>400\u2013800<\/td><td>Film, woven bag<\/td><\/tr>\n<tr><td><b>SE-180 \/ SE-180<\/b><\/td><td>180 mm<\/td><td>180 mm<\/td><td>800\u20132,000<\/td><td>Woven bag, heavy film<\/td><\/tr>\n<\/tbody><\/table><\/div>\n\n<h2 class=\"sec\" id=\"transfer\">What transfers to your line<\/h2>\n<p>If you are installing a two stage single screw extruder without support because you have run single screws before, check these three before you call anyone \u2014 they are what a commissioning week actually buys:<\/p>\n<div class=\"call warn\"><h4>Vent, screen, feed \u2014 in that order<\/h4>\n<p><b>Vent open and pulling.<\/b> A closed first-stage vent turns moisture into bubbles and bubbles into a quality complaint. <b>Mesh matched to contamination<\/b>, not to ambition: 60 mesh on film, finer only on clean rigid scrap. <b>Feeder matched to stage-1 amps<\/b> \u2014 a starved first stage cannot vent, and a flooded one cannot melt.<\/p><\/div>\n<p>Every two stage single screw extruder leaves with that sequence; the version on the wall is the same one in our <a href=\"\/knowledge\/twin-screw-extruder-startup\/\">9-step start-up article<\/a>; the venting and screening logic applies to twin screws as well.<\/p>\n\n<h2 class=\"sec\" id=\"faq\">FAQ<\/h2>\n<details open><summary>Why would a two stage single screw extruder be chosen over a twin screw for recycling?<\/summary><p>Cost per kg\/h on light, contaminated feed, and the fact that a two stage single screw extruder separates venting from pressure build-up. A single screw with forced feeding handles film and woven bag at a lower capital cost, and the second stage gives you a dedicated pressure-building section that does not compete with mixing. A twin screw wins when the scrap needs compounding or heavy filling.<\/p><\/details><details><summary>Can the customer&#x27;s own team install the line?<\/summary><p>Mechanically yes \u2014 this two stage single screw extruder was installed correctly. The failure was in commissioning: venting, screening, feeder balance and the start-up sequence. Those are the four things a commissioning visit actually delivers, and they are the reason the machine is sold with one.<\/p><\/details><details><summary>What mesh should a recycling line run?<\/summary><p>60 mesh as a default for film and mixed scrap, 40 \u00b5m only where the feed is clean rigid regrind and the product needs it. Finer mesh raises head pressure, and on a two-stage line that pressure has to be carried by the second stage \u2014 which then has nothing left for the die.<\/p><\/details><details><summary>How much output is lost by running the vent closed?<\/summary><p>Not output directly \u2014 quality first. The line keeps running and keeps making pellets nobody will buy. In this case the visible symptom was bubbles, and the invisible one was a burnt smell that came from the 230 \u00b0C profile, not from the vent.<\/p><\/details>\n<div class=\"method\"><h2 id=\"rm-s2\">Where this record comes from<\/h2>\n<p>Commissioning reports, service logs and the parameter sheet issued with the line. Machine figures are the quoted bands for the model; process windows follow the Kerke parameter table and are confirmed on a material trial before they become a production setpoint. Where the customer asked not to be named, the country and the application are kept and the company name is not.<\/p>\n<p>Reviewed by the Kerke process team, Nanjing. Case published 9 November 2026.<\/p><\/div>\n<div class=\"related\"><h2 id=\"rm-s3\">Related<\/h2><div class=\"rel-grid\"><a class=\"rel\" href=\"\/applications\/recycled-plastic-pelletizing\/\"><span>Application<\/span>Waste Plastic Recycling Pelletizing Line<\/a><a class=\"rel\" href=\"\/machines\/two-stage-single-screw\/\"><span>Machine<\/span>Two-Stage Single Screw Line SE\/SE<\/a><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=\"\/cases\/\"><span>Case studies<\/span>All eight field cases<\/a><\/div><\/div>\n<div class=\"pager\"><a href=\"\/cases\/dubai-filler-masterbatch-extruder\/\"><span>Previous case<\/span>Dubai, UAE \u00b7 Filler masterbatch<\/a><a href=\"\/cases\/cambodia-pet-flake-pelletizing-line\/\"><span>Next case<\/span>Cambodia \u00b7 PET bottle flake<\/a><\/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=\"#situation\">The situation: a line that had never made a saleable pellet<\/a><\/li><li><a href=\"#found\">What was wrong with the two stage single screw extruder<\/a><\/li><li><a href=\"#changed\">The week, day by day<\/a><\/li><li><a href=\"#result\">Result<\/a><\/li><li><a href=\"#line\">Line configuration<\/a><\/li><li><a href=\"#transfer\">What transfers to your line<\/a><\/li><li><a href=\"#faq\">FAQ<\/a><\/li><\/ol>\n<div class=\"sidecard\"><b>Installing it yourself?<\/b>\n<p>Send the feed type, bulk density and contamination level. We will send the vent, screen and feeder settings before the machine ships, so the first shift is not the learning curve.<\/p>\n<a class=\"btn\" href=\"\/get-a-quote\/\">Ask an engineer<\/a>\n<a class=\"btn ghost\" href=\"\/cases\/\">All case studies<\/a><\/div>\n<\/aside><\/div><\/div>\n<script type=\"application\/ld+json\">{\"@context\": \"https:\/\/schema.org\", \"@graph\": [{\"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Why would a two stage single screw extruder be chosen over a twin screw for recycling?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Cost per kg\/h on light, contaminated feed, and the fact that a two stage single screw extruder separates venting from pressure build-up. A single screw with forced feeding handles film and woven bag at a lower capital cost, and the second stage gives you a dedicated pressure-building section that does not compete with mixing. 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Treat them as a starting point for your own material, not as a guarantee \u2014 the same correction on a different filler grade or carrier ends in a different number.<\/p><p class=\"k3-rel\"><b>Related on this site:<\/b> <a href=\"\/applications\/\">Extrusion lines by application<\/a> \u00b7 <a href=\"\/machines\/\">Twin screw extruder types<\/a> \u00b7 <a href=\"\/get-a-quote\/\">free extrusion line quotation<\/a> \u00b7 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Extrusion\" target=\"_blank\" rel=\"noopener\">Wikipedia: Extrusion<\/a><\/p><\/section><\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Home\/Case studies\/Japan Case study 3 \u00b7 Japan \u00b7 Waste material recycling Two stage single screw extruder that never ran: one week in Japan The customer had run similar equipment for years, so they declined installation on their new SE-140 \/ SE-140 two stage single screw extruder. It never produced saleable pellets. We flew in, took [&#8230;]\n","protected":false},"author":0,"featured_media":2356,"parent":2288,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-blank.php","meta":{"footnotes":""},"application":[],"app_group":[],"class_list":["post-2291","page","type-page","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/2291","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"}],"replies":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/comments?post=2291"}],"version-history":[{"count":0,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/2291\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/2288"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/media\/2356"}],"wp:attachment":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/media?parent=2291"}],"wp:term":[{"taxonomy":"application","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/application?post=2291"},{"taxonomy":"app_group","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/app_group?post=2291"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}