{"id":2303,"date":"2026-11-09T21:44:07","date_gmt":"2026-11-09T13:44:07","guid":{"rendered":"https:\/\/kerkepm.com\/cases\/korea-tpe-underwater-pelletizing\/"},"modified":"2026-11-09T22:20:08","modified_gmt":"2026-11-09T14:20:08","slug":"korea-tpe-underwater-pelletizing","status":"publish","type":"page","link":"https:\/\/kerkepm.com\/es\/cases\/korea-tpe-underwater-pelletizing\/","title":{"rendered":"TPE underwater pelletizing on a first-build line"},"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>Korea<\/div><\/div><div class=\"wrap\"><div class=\"hero\">\n<p class=\"kicker\">Case study 10 \u00b7 Korea \u00b7 TPE elastomer<\/p>\n<h1>TPE underwater pelletizing on a first-build line: KTE-85B in Korea<\/h1>\n<p class=\"dek\">Underwater pelletizing lines are expensive, and this one was our first build of its size. It ran on the first production campaign, paid for itself in three months, and the customer ordered a second machine six months later. TPE underwater pelletizing is decided by water temperature, die freeze-off and oil absorption \u2014 not by the pelletizer's price tag.<\/p>\n<div class=\"byline\"><div><b>Line<\/b> KTE-85B + underwater<\/div><div><b>Material<\/b> TPE<\/div><div><b>Result<\/b> first build accepted<\/div><div><b>Repeat<\/b> 6 months later<\/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-korea-tpe-underwater-pelletizing.webp\" alt=\"TPE underwater pelletizing line for the Korea customer \u2014 first article pellets at run-in\" loading=\"eager\" fetchpriority=\"high\"><figcaption>TPE underwater pelletizing line for the Korea customer \u2014 first article pellets at run-in<\/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 first build, bought on specification<\/a><a href=\"#found\">What decides TPE underwater pelletizing<\/a><a href=\"#changed\">How the line was proven before shipment<\/a><a href=\"#result\">Result<\/a><\/nav><h2 id=\"rm-s1\">Quick answer<\/h2><p>TPE is pelletised underwater because the pellet shape is what the customer sells: round, free-flowing, no blocking in the bag. On this KTE-85B line (85 mm, 2\u00d72,100 N\u00b7m, 550\u20131,000 kg\/h) the die face runs in water at 40\u201355 \u00b0C with flow high enough to carry pellets away before they touch each other, and the die is heated to prevent freeze-off at start-up. On a TPE underwater pelletizing line the compounding side is oil absorption \u2014 SEBS takes 2\u20135 times its own weight, injected in stages, not all at once.<\/p><\/section>\n<\/div>\n<\/div><\/div>\n<div class=\"wrap\"><div class=\"grid\"><main>\n<div class=\"stats\"><div class=\"stat\"><b>3 months<\/b><span>payback reported<\/span><\/div><div class=\"stat\"><b>550\u20131,000<\/b><span>kg\/h band<\/span><\/div><div class=\"stat\"><b>+1<\/b><span>machine ordered<\/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 first build, bought on specification<\/h2>\n<p>The customer makes TPE compounds in Korea for consumer and automotive parts, Shore 30A to 90A, mostly SEBS-based with oil, PP and filler. The line is a <a href=\"\/machines\/co-rotating-twin-screw-extruder\/\">KTE-85B<\/a> \u2014 85 mm, 2\u00d72,100 N\u00b7m, 220\u2013315 kW, 550\u20131,000 kg\/h \u2014 with an underwater die-face pelletizing system built in our own workshop.<\/p>\n<p>A TPE underwater pelletizing line is the most expensive pelletizing option, and buyers rightly ask why. The answer is pellet geometry: TPE sold into injection moulding has to be round, free-flowing and non-blocking, and a strand line gives neither the shape nor the consistency. This was our first build of the system at this size, which is exactly the kind of order where the risk sits with the supplier \u2014 so it was tested before it shipped, and it ran on the first campaign.<\/p>\n\n<h2 class=\"sec\" id=\"found\">What decides TPE underwater pelletizing<\/h2>\n<p>Two separate problems that meet at the die: what the compound is, and what the water does to it.<\/p>\n<div class=\"tw\"><table><caption><b>Table 1.<\/b> The settings that decide whether TPE pellets come out round and free-flowing.<\/caption>\n<thead><tr><th scope=\"col\">Variable<\/th><th scope=\"col\">Setting on this line<\/th><th scope=\"col\">Failure mode if wrong<\/th><\/tr><\/thead><tbody>\n<tr><td><b>Oil absorption<\/b><\/td><td>SEBS oil at 2\u20135\u00d7 rubber weight, injected in two stages<\/td><td>One-shot injection makes the melt slip; the compound never homogenises and the pellet surface is oily.<\/td><\/tr>\n<tr><td><b>L\/D and mixing<\/b><\/td><td>44\u201352, toothed and narrow kneading elements<\/td><td>All-90\u00b0 geometry degrades SEBS; too short a screw leaves oil pockets.<\/td><\/tr>\n<tr><td><b>Die temperature<\/b><\/td><td>Heated die, held above the melt freeze point<\/td><td>Freeze-off at start-up: holes block before the cutter reaches speed.<\/td><\/tr>\n<tr><td><b>Water temperature<\/b><\/td><td>40\u201355 \u00b0C<\/td><td>Cold water quenches the skin and gives tails and angel hair; hot water gives flat, deformed pellets.<\/td><\/tr>\n<tr><td><b>Water flow<\/b><\/td><td>High enough to carry pellets clear of the die face<\/td><td>Pellets recirculate, stick together, and block the cutting chamber.<\/td><\/tr>\n<tr><td><b>Cutting speed<\/b><\/td><td>Matched to throughput per hole<\/td><td>Slow cutter gives long pellets; fast cutter gives fines and heat at the die.<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>The oil side is where most TPE lines are lost. SEBS absorbs oil slowly, and a single injection point at full rate produces a melt that slips in the feed zone and a pellet that sweats oil in the bag three days later. Two injection points, spaced along a dedicated absorption zone, are the difference between a compound and a mixture.<\/p>\n\n<h2 class=\"sec\" id=\"changed\">How the line was proven before shipment<\/h2>\n<ol class=\"flow\">\n<li><b>Die and cutter tested as a subassembly.<\/b> Freeze-off behaviour checked at start-up, which is the failure that ruins the first hour of every underwater line.<\/li>\n<li><b>Compound run at three hardnesses.<\/b> Shore 40A, 60A and 85A, with water temperature and cutter speed recorded for each \u2014 the settings shipped with the machine are the ones that produced acceptable pellets.<\/li>\n<li><b>Oil injection split into two points<\/b> and the absorption zone length confirmed on the trial, not on the drawing.<\/li>\n<li><b>Installation and start-up support<\/b> at the customer's plant, including the shutdown and restart sequence, because an underwater line that is restarted cold will block.<\/li>\n<\/ol>\n\n<h2 class=\"sec\" id=\"result\">Result<\/h2>\n<p>The first production campaign on this TPE underwater pelletizing line produced pellets inside the customer's specification, and the customer reported recovering the machine cost within three months of running. Six months later they ordered a second machine, and during that installation the first line was running without attention \u2014 which is the most useful thing a supplier can see on a repeat visit.<\/p>\n<div class=\"quoteband\"><b>What this case says about first builds:<\/b> an underwater system is not a commodity add-on. If a supplier cannot show you the die and cutter running before shipment, with the water temperature and cutter speed written down, the first build is being debugged in your plant instead of theirs.<\/div>\n\n<h2 class=\"sec\" id=\"line\">Line configuration<\/h2>\n<div class=\"tw\"><table><caption><b>Table 2.<\/b> KTE-85B with underwater pelletizing, as built.<\/caption>\n<thead><tr><th scope=\"col\">Item<\/th><th scope=\"col\">Specification<\/th><\/tr><\/thead><tbody>\n<tr><td>Model<\/td><td>KTE-85B, 85 mm, 2\u00d72,100 N\u00b7m, 220\u2013315 kW<\/td><\/tr>\n<tr><td>Output band<\/td><td>550\u20131,000 kg\/h (application dependent)<\/td><\/tr>\n<tr><td>L\/D<\/td><td>44\u201352<\/td><\/tr>\n<tr><td>Oil injection<\/td><td>Two points in a dedicated absorption zone, up to 3\u00d7 rubber weight<\/td><\/tr>\n<tr><td>Pelletizing<\/td><td>Underwater die-face, water 40\u201355 \u00b0C, heated die<\/td><\/tr>\n<tr><td>Downstream<\/td><td>Centrifugal dryer, vibrating screen, bagging<\/td><\/tr>\n<\/tbody><\/table><\/div>\n\n<h2 class=\"sec\" id=\"transfer\">What transfers to your line<\/h2>\n<div class=\"call warn\"><h4>Ask these three questions about any underwater line<\/h4>\n<p><b>Is the die heated and how is freeze-off handled at start-up?<\/b> <b>What water temperature and flow are specified for my hardness?<\/b> <b>Was the die and cutter run as a subassembly before shipment?<\/b> A supplier who answers all three has built one before; a supplier who answers none is learning on your order.<\/p><\/div>\n<p>The compounding side is on the <a href=\"\/applications\/tpe-tpu-tpr-pelletizing\/\">TPE \/ TPU \/ TPR page<\/a>; the seven cutting methods, including where underwater wins and where it does not, are compared in <a href=\"\/knowledge\/pelletizing-methods-compared\/\">this article<\/a>.<\/p>\n\n<h2 class=\"sec\" id=\"faq\">FAQ<\/h2>\n<details open><summary>Why does TPE need underwater pelletizing instead of strand cutting?<\/summary><p>Because on a TPE underwater pelletizing line the pellet shape is the product. TPE for injection moulding has to be round and free-flowing; strand cutting gives a cylindrical pellet that blocks in the bag at higher hardness and deforms at lower hardness. Underwater die-face cutting gives round pellets with a controlled size.<\/p><\/details><details><summary>What water temperature does TPE underwater pelletizing need?<\/summary><p>40\u201355 \u00b0C on this line, set by hardness and by the die. Too cold and the skin quenches into tails and angel hair; too hot and the pellets flatten and stick in the dryer.<\/p><\/details><details><summary>How is oil loaded into a TPE compound?<\/summary><p>At two injection points along a dedicated absorption zone, up to 3\u00d7 the rubber weight for SEBS. One-shot injection makes the melt slip in the feed zone and leaves oil pockets that sweat out of the pellet days later.<\/p><\/details><details><summary>Can a first-build underwater line be trusted?<\/summary><p>Only if the die and cutter were run as a subassembly before shipment, with water temperature and cutter speed recorded. That test is what turns a first build into a specification \u2014 and it is a fair thing to ask any supplier for.<\/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\/tpe-tpu-tpr-pelletizing\/\"><span>Application<\/span>TPE \/ TPU \/ TPR Elastomer Line<\/a><a class=\"rel\" href=\"\/machines\/co-rotating-twin-screw-extruder\/\"><span>Machine<\/span>Co-Rotating Twin Screw Extruder (KTE-50B to KTE-135D)<\/a><a class=\"rel\" href=\"\/knowledge\/pelletizing-methods-compared\/\"><span>Knowledge<\/span>Seven Pelletizing Methods Compared: Strand, Water Ring, Underwater, Hot Face<\/a><a class=\"rel\" href=\"\/cases\/\"><span>Case studies<\/span>All eight field cases<\/a><\/div><\/div>\n<div class=\"pager\"><a href=\"\/cases\/mexico-pa-glass-fiber-compounding\/\"><span>Previous case<\/span>Mexico \u00b7 PA + short glass fibre<\/a><span><\/span><\/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 first build, bought on specification<\/a><\/li><li><a href=\"#found\">What decides TPE underwater pelletizing<\/a><\/li><li><a href=\"#changed\">How the line was proven before shipment<\/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>TPE, Shore 30A\u201390A?<\/b>\n<p>Send the hardness, the oil phr and the pellet size you sell. Water temperature and cutter speed follow from those three, and we will send them before the machine ships.<\/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 does TPE need underwater pelletizing instead of strand cutting?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Because on a TPE underwater pelletizing line the pellet shape is the product. TPE for injection moulding has to be round and free-flowing; strand cutting gives a cylindrical pellet that blocks in the bag at higher hardness and deforms at lower hardness. 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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\/Korea Case study 10 \u00b7 Korea \u00b7 TPE elastomer TPE underwater pelletizing on a first-build line: KTE-85B in Korea Underwater pelletizing lines are expensive, and this one was our first build of its size. It ran on the first production campaign, paid for itself in three months, and the customer ordered a second machine [&#8230;]\n","protected":false},"author":0,"featured_media":2362,"parent":2288,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"page-blank.php","meta":{"footnotes":""},"application":[],"app_group":[],"class_list":["post-2303","page","type-page","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/2303","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=2303"}],"version-history":[{"count":0,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/pages\/2303\/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\/2362"}],"wp:attachment":[{"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/media?parent=2303"}],"wp:term":[{"taxonomy":"application","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/application?post=2303"},{"taxonomy":"app_group","embeddable":true,"href":"https:\/\/kerkepm.com\/es\/wp-json\/wp\/v2\/app_group?post=2303"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}