{"id":8095,"date":"2026-02-01T09:00:00","date_gmt":"2026-02-01T09:00:00","guid":{"rendered":"https:\/\/uplastech.com\/abs-sheet-extrusion\/"},"modified":"2026-02-01T09:00:00","modified_gmt":"2026-02-01T09:00:00","slug":"abs-sheet-extrusion","status":"publish","type":"post","link":"https:\/\/uplastech.com\/it\/abs-sheet-extrusion\/","title":{"rendered":"ABS Sheet Extrusion: Gloss, Grain and the Polishing Stack"},"content":{"rendered":"<style>\n.upl-blog{font-size:17px;line-height:1.78;color:#1f2937}\n.upl-blog p{margin:0 0 18px}\n.upl-blog h2{font-size:26px;line-height:1.3;color:#0b2b33;margin:46px 0 14px;font-weight:700;letter-spacing:-.015em}\n.upl-blog h3{font-size:19.5px;color:#0d3b47;margin:28px 0 10px;font-weight:700}\n.upl-blog ul,.upl-blog ol{margin:0 0 20px;padding-left:22px}\n.upl-blog li{margin:0 0 9px}\n.upl-blog figure{margin:0 0 34px}\n.upl-blog figure img{width:100%;height:auto;display:block;border-radius:10px}\n.upl-blog figcaption{font-size:13px;color:#6b7280;margin-top:10px;line-height:1.5}\n.upl-blog .toc{background:none;border:0;border-radius:0;padding:0;margin:0 0 34px}\n.upl-blog .toc .lwptoc{margin:0}\n.upl-blog .toc h4{margin:0 0 10px;font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#0d5563}\n.upl-blog .toc ol{margin:0;padding-left:18px;font-size:14.5px}\n.upl-blog .toc li{margin-bottom:6px}\n.upl-blog table{width:100%;border-collapse:collapse;font-size:14.5px;margin:0 0 10px}\n.upl-blog th{background:#0d3b47;color:#fff;text-align:left;padding:11px 13px;font-weight:600;font-size:13.5px;border:0}\n.upl-blog td{padding:11px 13px;border:0;border-bottom:1px solid #e8ebed;vertical-align:top}\n.upl-blog tbody tr:nth-child(even){background:#fafbfc}\n.upl-blog .tablecap{font-size:12.5px;color:#6b7280;margin:0 0 30px}\n.upl-blog .myth{background:#fff8ef;border:1px solid #f6ddbd;border-radius:8px;padding:16px 20px;margin:0 0 26px;font-size:15.5px}\n.upl-blog .myth b{color:#a85c10}\n.upl-blog .callout{background:#f2f8f9;border-radius:8px;padding:18px 22px;margin:0 0 26px;font-size:15.5px;border-left:3px solid #14707f}\n.upl-blog .faq h3{border-top:1px solid #eceff1;padding-top:22px;margin-top:0;font-size:18px}\n.upl-blog .faq h3:first-of-type{border-top:0;padding-top:0}\n.upl-blog .cta{background:linear-gradient(135deg,#0b2b33,#0d5563);color:#fff;border-radius:12px;padding:34px;margin:48px 0 30px}\n.upl-blog .cta h2,.upl-blog .cta .cta-h{color:#fff;margin:0 0 10px;font-size:24px;font-weight:700;line-height:1.3}\n.upl-blog .cta p{color:#c9dee3;margin:0 0 20px;font-size:16px}\n.upl-blog .btn{display:inline-block;background:#e07a1f;color:#fff;text-decoration:none;font-weight:700;padding:13px 26px;border-radius:8px;font-size:15.5px}\n.upl-blog .rel{border-top:1px solid #e8ebed;margin-top:40px;padding-top:26px}\n.upl-blog .rel h4{font-size:13px;letter-spacing:.1em;text-transform:uppercase;color:#6b7280;margin:0 0 14px}\n.upl-blog .rel ul{list-style:none;padding:0;margin:0}\n.upl-blog .rel li{padding:11px 0;border-bottom:1px dashed #e8ebed}\n.upl-blog .rel a{text-decoration:none;font-weight:600;font-size:15.5px}\n@media(max-width:640px){.upl-blog h2{font-size:22px}.upl-blog table{font-size:13px}.upl-blog .cta{padding:24px}}\n\/* \u5355\u7bc7\u9875\u9690\u85cf WhatsApp \u95ee\u5019\u5361\uff0c\u53ea\u4fdd\u7559\u5706\u5f62\u6c14\u6ce1\uff0c\u907f\u514d\u906e\u6321\u4fa7\u680f\u8be2\u76d8\u63d0\u4ea4\u6309\u94ae\u3002\n   \u6ce8\u610f\uff1aClick to Chat \u7684\u70b9\u51fb\u903b\u8f91\u662f\u300c\u95ee\u5019\u5361\u5143\u7d20\u5b58\u5728\u5c31\u4e0d\u8df3\u8f6c\u300d\uff0c\u53ea\u9760 CSS \u9690\u85cf\u4f1a\u8ba9\u6c14\u6ce1\u53d8\u6210\u6b7b\u94fe\u63a5\u3002\n   Code Snippets #9\u300cUPL single post: WhatsApp bubble jumps straight to chat\u300d\u8d1f\u8d23\u628a\u8be5\u8282\u70b9\u4ece DOM \u79fb\u9664\uff0c\n   \u4e0b\u9762\u8fd9\u6761 CSS \u53ea\u662f\u79fb\u9664\u524d\u7684\u89c6\u89c9\u515c\u5e95\u3002\u5220 #9 \u524d\u5fc5\u987b\u5148\u5220\u8fd9\u6761\u89c4\u5219\u3002 *\/\nbody.single-post .ht_ctc_chat_greetings_box{display:none !important}\n<\/style>\n<div class=\"upl-blog\">\n<figure>\n<img fetchpriority=\"high\" decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/10\/abs-sheet-extrusion.jpg\" alt=\"Glossy white ABS sheet running down over the chrome rolls of a three-roll polishing stack, an operator holding the trimmed edge\" width=\"1536\" height=\"909\"><figcaption>ABS sheet on a three-roll stack. The roll finish sets the gloss, and the draw ratio decides how much of it survives forming.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"stack\">The third roll is the one that matters<\/h2>\n<p>An ABS sheet line ends in a three-roll polishing stack. The sheet leaves the die and passes over the top roll, under the middle roll and over the bottom roll, and by the time it leaves it is solid. Each roll does a different job, and the one that decides the surface is the one that touches the sheet while it is still soft enough to take a finish.<\/p>\n<p>The top roll is usually chrome and polished, and it sets the face that will be seen. The middle roll is often rubber-covered, and it can carry a textured sleeve that embosses a grain. The bottom roll pulls and cools. Change which face runs against which roll and the same sheet comes out looking like two different products.<\/p>\n<p>Roll temperature matters more than most settings on the line, because ABS is amorphous and its surface freezes over a narrow range. A roll at 20 C chills the skin almost instantly, and the skin that forms is smooth and glossy. A roll at 100 C lets the skin stay mobile for longer, and the surface that forms is duller and slightly hazy.<\/p>\n<h2 id=\"gloss\">Gloss comes from the roll, grain comes from the sleeve<\/h2>\n<p>Gloss against chill roll temperature: 92 units at 20 C, 86 at 40, 72 at 60, 58 at 80 and 44 at 100. The relationship is monotonic and it is steep in the middle, which is why a line running at 60 C is the most sensitive place to be: a 10 C drift moves the gloss by seven points.<\/p>\n<p>Grain is a separate mechanism. A textured sleeve presses a pattern into the sheet while it is above its softening point, and the depth of that pattern depends on the sleeve, the nip pressure and the temperature. Gloss and grain are not independent: a deeply grained sheet reads as matte even if the resin would have produced a glossy surface, because the texture scatters light.<\/p>\n<p>That is why a grained ABS sheet can be sold as matte without any change to the roll temperature. The grain is doing the work, and the roll temperature is only setting the base gloss underneath it. When a customer asks for a specific gloss on a grained sheet, the number is really a statement about grain depth.<\/p>\n<h2 id=\"draw\">Why the draw eats the grain<\/h2>\n<p>The grain you buy is not the grain the part keeps. Forming stretches the sheet, and stretching a textured surface flattens the texture. Grain depth retained against draw ratio: 100 percent at 1.0, 88 at 1.5, 72 at 2.0, 55 at 2.5 and 40 at 3.0.<\/p>\n<p>The relationship is worse than linear at high draw because the stretch is not uniform. The area over a male plug thins most, and that is exactly where the grain disappears first. A part with a 2.5 draw ratio will show a glossy, grain-free patch on the top of the form and a fully grained surface on the flange, from the same sheet.<\/p>\n<p>There are three ways to deal with it, and only one of them is a sheet decision. Deepen the grain so that 40 percent of a deep grain is still visible. Reduce the draw ratio by changing the part. Or accept the patch and design it in, which is what most appliance and automotive interior parts do, because the eye reads a consistent gradient as normal and a sharp boundary as a defect.<\/p>\n<figure>\n<img decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/10\/abs-sheet-extrusion-chart.jpg\" alt=\"Gloss against chill roll temperature, and grain depth retained against forming draw ratio\" width=\"1536\" height=\"909\"><figcaption>Gloss falls from 92 to 44 units as the roll warms from 20 to 100 C, while grain retention falls from 100 to 40 percent as the draw ratio rises to 3.0.<\/figcaption><\/figure>\n<h2 id=\"cap\">Cap sheet and the cheaper route to gloss<\/h2>\n<p>A glossy ABS sheet can be made two ways. The whole sheet can be polished on a chrome roll, or a thin cap layer of high-gloss ABS can be coextruded over a cheaper, recycled or foamed core. The cap route gives a better gloss than polishing, because the cap resin can be formulated for surface and the core for cost.<\/p>\n<p>The cap layer is typically 50 to 150 microns. It carries the surface, it carries the colour, and it is the only part of the sheet that has to be UV-stable if the part goes outdoors. The core can then be a lower grade, which is where the saving is.<\/p>\n<p>The catch is that a cap layer is a thin skin over a different material, and the two have different shrinkage. A cap that is too thin will show the core's texture through it; a cap that is too thick costs more than it saves. The practical window is where the cap is thick enough to be opaque and thin enough not to delaminate on a deep draw.<\/p>\n<table>\n<thead>\n<tr>\n<th>Roll arrangement<\/th>\n<th>Surface<\/th>\n<th>Typical gloss<\/th>\n<th>Used for<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Chrome top, rubber middle, chrome bottom<\/td>\n<td>Smooth one side, matte other<\/td>\n<td>85 to 92<\/td>\n<td>Signage, display, general sheet<\/td>\n<\/tr>\n<tr>\n<td>Chrome top, grained sleeve middle<\/td>\n<td>Gloss face and grained face<\/td>\n<td>70 to 88<\/td>\n<td>Appliance and interior panels<\/td>\n<\/tr>\n<tr>\n<td>Grained sleeve top, chrome middle<\/td>\n<td>Grained face out<\/td>\n<td>40 to 60<\/td>\n<td>Textured parts, hidden fixings<\/td>\n<\/tr>\n<tr>\n<td>Two chrome rolls, cap layer<\/td>\n<td>High gloss, both faces<\/td>\n<td>90 to 95<\/td>\n<td>Automotive exterior, high-end display<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 Polishing stack arrangements and the surface each one produces<\/p>\n<h2 id=\"defects\">Reading a surface defect<\/h2>\n<p>Surface complaints on ABS sheet are almost always one of six things, and five of them are on the stack rather than in the resin.<\/p>\n<table>\n<thead>\n<tr>\n<th>Symptom<\/th>\n<th>Causa<\/th>\n<th>Fix<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Gloss bands across the width<\/td>\n<td>Roll temperature uneven, blocked water channel<\/td>\n<td>Balance the flow, clean the roll<\/td>\n<\/tr>\n<tr>\n<td>Dull patch that moves along the sheet<\/td>\n<td>Roll surface damage or a wrap of degraded material<\/td>\n<td>Inspect and polish the roll<\/td>\n<\/tr>\n<tr>\n<td>Grain depth varies across the width<\/td>\n<td>Uneven nip pressure on the sleeve<\/td>\n<td>Re-level the roll, check the sleeve thickness<\/td>\n<\/tr>\n<tr>\n<td>Fine scratches in the machine direction<\/td>\n<td>Contamination on the roll or the guide<\/td>\n<td>Clean the line, check the trim knives<\/td>\n<\/tr>\n<tr>\n<td>Haze that appears only after forming<\/td>\n<td>Moisture in the sheet or over-drying of the surface<\/td>\n<td>Dry the resin, check the hopper dryer<\/td>\n<\/tr>\n<tr>\n<td>Gloss lost on the plug area only<\/td>\n<td>Draw ratio too high for the grain depth<\/td>\n<td>Deeper grain, or a lower draw<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 ABS sheet surface defects and the setting behind each<\/p>\n<p>The banding defect is the most diagnostic. A roll with an internal water channel partly blocked runs cool in a stripe, and the sheet comes off glossy in that stripe and dull either side of it. It looks like a resin problem and it is a plumbing problem, and it will persist through three resin changes before anyone puts a thermocouple on the roll.<\/p>\n<h2 id=\"specify\">What to specify<\/h2>\n<p>An ABS sheet surface specification has to describe the part, not the sheet, because the two are not the same surface.<\/p>\n<ul>\n<li>Gloss target with a tolerance, measured at 60 degrees, and on which face.<\/li>\n<li>Grain depth or a grain reference sample, with the depth the sleeve actually produces.<\/li>\n<li>The draw ratio of the part, because it predicts how much grain will be left.<\/li>\n<li>Whether the sheet is capped, and the cap thickness if it is.<\/li>\n<li>Colour under a stated light source, since a grained surface shifts colour appearance.<\/li>\n<li>Which face is the polished face and which face goes out on the part.<\/li>\n<\/ul>\n<p>Then agree the acceptance sample on a formed part rather than on a flat sheet. A flat sheet at 88 gloss that forms at a 2.5 draw ratio gives a part at roughly 55 percent grain, and if the customer's reference was the flat sheet, the part will be rejected for a property the sheet never had.<\/p>\n<div class=\"myth\">Myth: a glossier sheet makes a glossier part. Gloss is a surface skin property and forming stretches the skin. A sheet at 92 gloss formed at a 3:1 draw can end up duller than a sheet at 75 gloss formed at 1.5:1, because the second one barely stretches at all.<\/div>\n<div class=\"faq\">\n<h3>Why does chill roll temperature affect gloss in ABS?<\/h3>\n<p>It sets how long the surface stays mobile. A cold roll freezes a smooth skin almost instantly and gives high gloss; a hot roll lets the skin relax and gives a duller surface.<\/p>\n<h3>How much grain survives forming?<\/h3>\n<p>About 72 percent at a 2.0 draw ratio and 40 percent at 3.0. The loss concentrates on the plug area, which is where the sheet thins most.<\/p>\n<h3>What is a cap layer on ABS sheet?<\/h3>\n<p>A thin coextruded skin, usually 50 to 150 microns, that carries the gloss, colour and UV stability over a cheaper core.<\/p>\n<h3>Why does gloss band across the sheet width?<\/h3>\n<p>Uneven roll temperature, almost always a partly blocked water channel. It looks like a resin fault and is a plumbing fault.<\/p>\n<h3>Can I get a matte finish without changing the roll?<\/h3>\n<p>Yes, by embossing a grain with a textured sleeve. The grain scatters light and reads as matte regardless of the base gloss.<\/p>\n<h3>Should gloss be measured on the sheet or the part?<\/h3>\n<p>On the part. Forming changes the surface, so a sheet specification and a part specification are two different numbers.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">A surface that has to survive the draw?<\/p>\n<p>Send the part drawing, the draw ratio and the gloss target. We will tell you what grain depth and roll finish the sheet needs to still look right after forming.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/it\/soluzioni-per-lestrusione-di-plastica\/\">Ask about ABS sheet<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/it\/pp-sheet-extrusion\/\">PP Sheet: Gloss and Shrinkage Come From the Same Roll<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/it\/hdpe-sheet-extrusion\/\">HDPE Sheet Extrusion: Thickness Control on a Wide Die<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/it\/pc-sheet-extrusion\/\">Polycarbonate Sheet: It Punishes Heat Twice<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/it\/pet-sheet-extrusion\/\">PET Sheet Extrusion: Water Is Measured in Parts per Million<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/it\/soluzioni-per-lestrusione-di-plastica\/\">Plastic Extrusion Solutions: Process, Tolerance and Material<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Gloss falls from 92 to 44 units as the chill roll goes from 20 C to 100 C, and the grain depth left after forming falls from 100 to 40 percent as the draw ratio goes from 1.0 to 3.0. The surface you buy is not the surface the part keeps.<\/p>","protected":false},"author":1,"featured_media":8093,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[],"class_list":["post-8095","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-plastic-extrusion-process"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts\/8095","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/comments?post=8095"}],"version-history":[{"count":0,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/posts\/8095\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/media\/8093"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/media?parent=8095"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/categories?post=8095"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/it\/wp-json\/wp\/v2\/tags?post=8095"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}