{"id":7605,"date":"2026-10-27T01:14:24","date_gmt":"2026-10-27T01:14:24","guid":{"rendered":"https:\/\/uplastech.com\/abs-injection-molding-guide\/"},"modified":"2026-10-27T01:14:24","modified_gmt":"2026-10-27T01:14:24","slug":"abs-injection-molding-guide","status":"publish","type":"post","link":"https:\/\/uplastech.com\/fr\/abs-injection-molding-guide\/","title":{"rendered":"ABS Injection Molding: Grades, Processing and Finishing"},"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 \u81ea\u52a8\u5c55\u5f00\u7684\u95ee\u5019\u5361\uff0c\u53ea\u4fdd\u7559\u5706\u5f62\u6c14\u6ce1\uff0c\u907f\u514d\u906e\u6321\u4fa7\u680f\u8be2\u76d8\u63d0\u4ea4\u6309\u94ae *\/\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\/im-abs-part.jpg\" alt=\"Black ABS injection moulded enclosure halves on a workbench showing textured surfaces and moulded-in bosses\" width=\"1536\" height=\"909\"><figcaption>Black ABS enclosure halves straight out of the tool. The texture is in the mould, the bosses are moulded in, and the whole part is one shot \u2014 which is exactly why ABS became the default housing material.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"why\">Why ABS still wins housings<\/h2>\n<p>Acrylonitrile butadiene styrene has been the default enclosure material for fifty years and remains so for reasons that are easy to state: it is tough at room temperature, it takes a texture or a gloss directly from the tool, it can be painted, printed, hot-stamped, ultrasonically welded and electroplated, and it processes forgivingly across a wide window.<\/p>\n<p>No single property is best in class. High-impact polystyrene is cheaper. Polycarbonate is tougher and clearer. ABS+PC blends beat it on heat and impact. But ABS is the only material that is <em>good enough<\/em> on every one of those axes at a moderate price, and that combination is why it dominates consumer electronics, appliances, power tools and automotive interiors.<\/p>\n<div class=\"callout\">\n<p><strong>The number to know:<\/strong> ABS is a two-phase material \u2014 a styrene-acrylonitrile copolymer matrix with polybutadiene rubber particles dispersed in it. The rubber phase is typically 15 \u2013 25 % by weight and it is what gives the impact strength. Every property you care about (impact, gloss, weatherability, plating adhesion) is a negotiation between those two phases, which is why two \"ABS\" grades can behave completely differently.<\/p>\n<\/div>\n<h2 id=\"grades\">The grades, and what each is for<\/h2>\n<table>\n<thead>\n<tr>\n<th>Grade family<\/th>\n<th>Key property<\/th>\n<th>Typical MFR (g\/10 min)<\/th>\n<th>Used for<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>General purpose<\/td>\n<td>Balanced<\/td>\n<td>8 \u2013 20<\/td>\n<td>Generic housings, covers<\/td>\n<\/tr>\n<tr>\n<td>High impact<\/td>\n<td>Notched Izod 250 \u2013 400 J\/m<\/td>\n<td>3 \u2013 10<\/td>\n<td>Power tools, drop-tested parts<\/td>\n<\/tr>\n<tr>\n<td>High gloss<\/td>\n<td>Surface DOI, no texture<\/td>\n<td>15 \u2013 30<\/td>\n<td>Appliance fascias, cosmetic parts<\/td>\n<\/tr>\n<tr>\n<td>Matt \/ low gloss<\/td>\n<td>Low surface reflection<\/td>\n<td>8 \u2013 18<\/td>\n<td>Automotive interior, business machines<\/td>\n<\/tr>\n<tr>\n<td>Heat resistant<\/td>\n<td>HDT 95 \u2013 105 \u00b0C<\/td>\n<td>4 \u2013 12<\/td>\n<td>Appliance near heat sources<\/td>\n<\/tr>\n<tr>\n<td>Plating grade<\/td>\n<td>Controlled rubber morphology<\/td>\n<td>10 \u2013 20<\/td>\n<td>Chrome-plated trim, badges<\/td>\n<\/tr>\n<tr>\n<td>Flame retardant<\/td>\n<td>UL94 V-0<\/td>\n<td>6 \u2013 15<\/td>\n<td>Power supplies, chargers<\/td>\n<\/tr>\n<tr>\n<td>Transparent<\/td>\n<td>MBS-modified, haze 6 \u2013 12 %<\/td>\n<td>8 \u2013 15<\/td>\n<td>Light pipes, display windows<\/td>\n<\/tr>\n<tr>\n<td>Extrusion grade<\/td>\n<td>High melt strength<\/td>\n<td>1 \u2013 5<\/td>\n<td>Sheet, profile \u2014 not moulding<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 ABS grade families. The MFR ranges are indicative; each supplier's naming differs.<\/p>\n<p>Two selection traps. First, <strong>MFR is not quality<\/strong> \u2014 a high MFR grade fills a thin wall more easily but has lower impact and worse weld-line strength, because the same molecular weight reduction that improves flow reduces entanglement. Second, <strong>high impact and high gloss fight each other<\/strong>: large rubber particles give impact but scatter light at the surface, so a high-impact grade cannot give a Class A gloss without a cap layer or a paint film.<\/p>\n<h2 id=\"properties\">The property table you will actually use<\/h2>\n<table>\n<thead>\n<tr>\n<th>Propri\u00e9t\u00e9<\/th>\n<th>Typical value<\/th>\n<th>What it means for design<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Densit\u00e9<\/td>\n<td>1.04 \u2013 1.07 g\/cm\u00b3<\/td>\n<td>Part weight is predictable; ABS is not a lightweighting material<\/td>\n<\/tr>\n<tr>\n<td>Tensile strength<\/td>\n<td>38 \u2013 50 MPa<\/td>\n<td>Adequate for snap fits and screws, not for structural loads<\/td>\n<\/tr>\n<tr>\n<td>Flexural modulus<\/td>\n<td>2.0 \u2013 2.8 GPa<\/td>\n<td>Stiff enough for walls of 2 mm on a 150 mm part<\/td>\n<\/tr>\n<tr>\n<td>Notched Izod, 23 \u00b0C<\/td>\n<td>100 \u2013 400 J\/m<\/td>\n<td>Grade-dependent by 4\u00d7 \u2014 specify it, do not assume<\/td>\n<\/tr>\n<tr>\n<td>Notched Izod, \u221220 \u00b0C<\/td>\n<td>40 \u2013 120 J\/m<\/td>\n<td>Drops sharply; cold-climate parts need a high-impact grade<\/td>\n<\/tr>\n<tr>\n<td>HDT at 1.82 MPa<\/td>\n<td>80 \u2013 105 \u00b0C<\/td>\n<td>Below 100 \u00b0C the part creeps under load<\/td>\n<\/tr>\n<tr>\n<td>Vicat softening<\/td>\n<td>95 \u2013 108 \u00b0C<\/td>\n<td>Limits near-heat applications<\/td>\n<\/tr>\n<tr>\n<td>Linear shrinkage<\/td>\n<td>0.4 \u2013 0.7 %<\/td>\n<td>Predictable \u2014 ABS is one of the easiest materials to hold tolerance in<\/td>\n<\/tr>\n<tr>\n<td>Water absorption, 24 h<\/td>\n<td>0.2 \u2013 0.4 %<\/td>\n<td>Dryable in 2 \u2013 3 h; not a moisture-critical material<\/td>\n<\/tr>\n<tr>\n<td>Coefficient of thermal expansion<\/td>\n<td>70 \u2013 90 \u00d7 10\u207b\u2076 \/K<\/td>\n<td>2.5\u00d7 aluminium \u2014 matters for metal inserts<\/td>\n<\/tr>\n<tr>\n<td>UL94<\/td>\n<td>HB as standard<\/td>\n<td>V-0 requires a specific FR grade<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 ABS properties. Note how wide the impact range is; that single number drives most grade selection.<\/p>\n<h2 id=\"processing\">The processing window<\/h2>\n<table>\n<thead>\n<tr>\n<th>Param\u00e8tres<\/th>\n<th>Typical setting<\/th>\n<th>Effect of running outside<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Drying<\/td>\n<td>80 \u00b0C, 2 \u2013 3 h<\/td>\n<td>Below 0.1 % moisture; wet resin gives silver streaks<\/td>\n<\/tr>\n<tr>\n<td>Barrel, feed zone<\/td>\n<td>180 \u2013 200 \u00b0C<\/td>\n<td>Too cold: feed slip. Too hot: bridging in the hopper<\/td>\n<\/tr>\n<tr>\n<td>Barrel, compression<\/td>\n<td>200 \u2013 220 \u00b0C<\/td>\n<td>Melting and homogenising<\/td>\n<\/tr>\n<tr>\n<td>Barrel, metering<\/td>\n<td>210 \u2013 230 \u00b0C<\/td>\n<td>Sets melt viscosity and therefore fill pressure<\/td>\n<\/tr>\n<tr>\n<td>Nozzle<\/td>\n<td>210 \u2013 225 \u00b0C<\/td>\n<td>Cold nozzle = cold slug in the gate<\/td>\n<\/tr>\n<tr>\n<td>Melt temperature (measured)<\/td>\n<td>220 \u2013 250 \u00b0C<\/td>\n<td>Above 260 \u00b0C butadiene degrades \u2014 yellowing and odour<\/td>\n<\/tr>\n<tr>\n<td>Mould temperature<\/td>\n<td>40 \u2013 70 \u00b0C<\/td>\n<td>Below 40: weld lines and stress. Above 80: long cycle, sink<\/td>\n<\/tr>\n<tr>\n<td>Injection pressure<\/td>\n<td>60 \u2013 120 MPa<\/td>\n<td>Depends on wall thickness and flow length<\/td>\n<\/tr>\n<tr>\n<td>Holding pressure<\/td>\n<td>40 \u2013 70 % of injection<\/td>\n<td>Too low: sink. Too high: flash and stress<\/td>\n<\/tr>\n<tr>\n<td>Back pressure<\/td>\n<td>0.3 \u2013 0.8 MPa<\/td>\n<td>Too low: unmelted pellets and air. Too high: over-heating<\/td>\n<\/tr>\n<tr>\n<td>Vitesse de la vis<\/td>\n<td>40 \u2013 80 rpm<\/td>\n<td>Keep peripheral speed below 0.2 m\/s for shear-sensitive FR grades<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 3 \u2014 A starting window for general-purpose ABS. Every grade's datasheet overrides this.<\/p>\n<p>The single most common processing error with ABS is running the melt too hot to solve a fill problem that is really a wall-thickness problem. At 265 \u00b0C the butadiene phase starts to crosslink and oxidise: the part comes out slightly yellow, smells faintly of burnt rubber, and \u2014 more importantly \u2014 the impact strength quietly drops by a third. You cannot see the loss of impact until the part fails in the field.<\/p>\n<div class=\"myth\">\n<p><b>Myth: \"ABS does not need drying.\"<\/b> ABS absorbs 0.2 \u2013 0.4 % moisture in 24 hours of exposure to normal air. At 0.2 % you get faint silver streaking on a gloss surface; at 0.35 % you get visible bubbles and a rough patch near the gate. Two hours at 80 \u00b0C costs almost nothing; a rejected batch costs a shift.<\/p>\n<\/div>\n<h2 id=\"design\">Design rules specific to ABS<\/h2>\n<table>\n<thead>\n<tr>\n<th>Fonctionnalit\u00e9<\/th>\n<th>Rule<\/th>\n<th>Why ABS is different<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Wall thickness<\/td>\n<td>1.8 \u2013 3.0 mm; keep variation within 25 %<\/td>\n<td>Thick sections sink visibly on a gloss surface<\/td>\n<\/tr>\n<tr>\n<td>Ribs<\/td>\n<td>0.5 \u2013 0.6 \u00d7 wall, spacing \u2265 2 \u00d7 wall<\/td>\n<td>ABS sinks readily; thin ribs hide it<\/td>\n<\/tr>\n<tr>\n<td>Bosses<\/td>\n<td>OD = 2 \u00d7 ID; wall 0.6 \u00d7 nominal<\/td>\n<td>Bosses are the classic sink location<\/td>\n<\/tr>\n<tr>\n<td>Draft<\/td>\n<td>1\u00b0 minimum, 1.5\u00b0 on textured faces<\/td>\n<td>Texture adds 1\u00b0 per 0.025 mm depth<\/td>\n<\/tr>\n<tr>\n<td>Snap fit undercut<\/td>\n<td>0.5 \u2013 1.0 mm; strain \u2264 1.5 %<\/td>\n<td>ABS tolerates repeated flexing better than PS<\/td>\n<\/tr>\n<tr>\n<td>Living hinge<\/td>\n<td>Not recommended<\/td>\n<td>ABS fatigues; use PP for hinges<\/td>\n<\/tr>\n<tr>\n<td>Screw boss<\/td>\n<td>Pilot 0.8 \u00d7 screw minor diameter<\/td>\n<td>ABS cuts threads well but cracks if the boss is thin<\/td>\n<\/tr>\n<tr>\n<td>Sharp corners<\/td>\n<td>Internal R \u2265 0.5 \u00d7 wall<\/td>\n<td>Stress concentration plus flow hesitation<\/td>\n<\/tr>\n<tr>\n<td>Gate location<\/td>\n<td>Away from cosmetic faces<\/td>\n<td>Gate blush is very visible on gloss ABS<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 4 \u2014 ABS design rules. The living hinge row is the one designers most often ignore.<\/p>\n<h2 id=\"finishing\">Finishing: where ABS earns its place<\/h2>\n<p>ABS is the easiest engineering plastic to decorate, and this is a large part of why it is specified.<\/p>\n<table>\n<thead>\n<tr>\n<th>Processus<\/th>\n<th>What it needs<\/th>\n<th>Adhesion \/ result<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Spray painting<\/td>\n<td>Isopropanol wipe; no primer on most grades<\/td>\n<td>Excellent; ABS dissolves slightly in solvent-based paints, giving a chemical bond<\/td>\n<\/tr>\n<tr>\n<td>Pad printing<\/td>\n<td>Flame or plasma pre-treatment for durability<\/td>\n<td>Good; untreated prints wear off<\/td>\n<\/tr>\n<tr>\n<td>Laser marking<\/td>\n<td>Light or dark pigment contrast<\/td>\n<td>Good; requires a laser-markable grade for high contrast<\/td>\n<\/tr>\n<tr>\n<td>Ultrasonic welding<\/td>\n<td>Joint design with an energy director<\/td>\n<td>Excellent \u2014 ABS welds to ABS at 80 \u2013 90 % of parent strength<\/td>\n<\/tr>\n<tr>\n<td>Solvent bonding<\/td>\n<td>Methylene chloride or ABS cement<\/td>\n<td>Excellent; produces a near-invisible joint<\/td>\n<\/tr>\n<tr>\n<td>Hot stamping<\/td>\n<td>Foils formulated for styrenics<\/td>\n<td>Bon<\/td>\n<\/tr>\n<tr>\n<td>Electroplating<\/td>\n<td>Plating-grade ABS only; chrome etch<\/td>\n<td>Excellent on the right grade, impossible on the wrong one<\/td>\n<\/tr>\n<tr>\n<td>In-mould decoration<\/td>\n<td>Film with a styrene-compatible tie layer<\/td>\n<td>Good; watch film stretch in deep draws<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 5 \u2014 ABS finishing routes. Electroplating is the one that absolutely requires a specific grade.<\/p>\n<p>The plating point deserves emphasis because it is a frequent and expensive mistake. Electroplating ABS works by etching the butadiene particles out of the surface with chromic acid, leaving microscopic pores that the electroless nickel anchors into. That only works if the rubber particles are the right size and evenly distributed at the surface \u2014 which is a property of the <em>plating grade<\/em>, not of ABS in general. Plate a general-purpose grade and you get patchy adhesion and blistering after thermal cycling.<\/p>\n<h2 id=\"defects\">Defects and their ABS-specific causes<\/h2>\n<table>\n<thead>\n<tr>\n<th>D\u00e9faut<\/th>\n<th>Likely cause in ABS<\/th>\n<th>Fix<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Silver streaks<\/td>\n<td>Moisture above 0.1 %<\/td>\n<td>Dry 80 \u00b0C \/ 3 h; check dryer dew point<\/td>\n<\/tr>\n<tr>\n<td>Yellowing \/ burnt smell<\/td>\n<td>Melt above 255 \u00b0C, or long residence time<\/td>\n<td>Lower melt; reduce shot size relative to barrel capacity<\/td>\n<\/tr>\n<tr>\n<td>Weld line visible or weak<\/td>\n<td>Low mould temperature, low injection speed at the weld<\/td>\n<td>Raise mould to 60 \u2013 70 \u00b0C; increase speed through the weld<\/td>\n<\/tr>\n<tr>\n<td>Gate blush<\/td>\n<td>High shear at the gate, or a cold gate<\/td>\n<td>Larger gate; raise gate temperature; slow the first stage<\/td>\n<\/tr>\n<tr>\n<td>Sink over bosses<\/td>\n<td>Boss wall too thick, insufficient hold<\/td>\n<td>Reduce boss wall to 0.6 \u00d7 nominal; extend hold time<\/td>\n<\/tr>\n<tr>\n<td>Stress cracking<\/td>\n<td>Moulded-in stress plus solvent contact<\/td>\n<td>Raise mould temperature; anneal at 70 \u00b0C \/ 2 h; avoid solvent contact<\/td>\n<\/tr>\n<tr>\n<td>Delamination<\/td>\n<td>Incompatible regrind or contamination<\/td>\n<td>Segregate regrind; limit to 20 % and same grade<\/td>\n<\/tr>\n<tr>\n<td>Brittle parts<\/td>\n<td>Over-dried, over-heated, or high regrind ratio<\/td>\n<td>Check melt temp and regrind content; verify grade<\/td>\n<\/tr>\n<tr>\n<td>Poor plating adhesion<\/td>\n<td>Wrong grade, or mould release agent on the surface<\/td>\n<td>Use plating grade; no silicone release agent<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 6 \u2014 ABS defects. Note that \"brittle parts\" has three completely different causes that look identical.<\/p>\n<h2 id=\"regrind\">Regrind: the silent variable<\/h2>\n<p>ABS regrind is routinely reused at 20 \u2013 30 % and this is normally fine. It stops being fine when the regrind has been through the machine more than twice, when it is mixed across colours, or when it is mixed with ABS\/PC.<\/p>\n<table>\n<thead>\n<tr>\n<th>Regrind content<\/th>\n<th>Impact retention<\/th>\n<th>Colour shift<\/th>\n<th>Verdict<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>0 %<\/td>\n<td>100 %<\/td>\n<td>None<\/td>\n<td>Reference<\/td>\n<\/tr>\n<tr>\n<td>20 %<\/td>\n<td>92 \u2013 96 %<\/td>\n<td>Barely measurable<\/td>\n<td>Standard practice<\/td>\n<\/tr>\n<tr>\n<td>30 %<\/td>\n<td>85 \u2013 92 %<\/td>\n<td>Slight yellowing<\/td>\n<td>Acceptable for non-cosmetic<\/td>\n<\/tr>\n<tr>\n<td>50 %<\/td>\n<td>70 \u2013 80 %<\/td>\n<td>Visible<\/td>\n<td>Hidden parts only<\/td>\n<\/tr>\n<tr>\n<td>100 % (once)<\/td>\n<td>55 \u2013 70 %<\/td>\n<td>Clear yellow shift<\/td>\n<td>Not recommended<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 7 \u2014 Regrind effects on ABS. The impact loss is the hidden cost, not the colour.<\/p>\n<p>Regrind that has been through the machine twice has been at 230 \u00b0C for a cumulative 10 \u2013 20 minutes. The butadiene has partly crosslinked, so the rubber particles no longer cavitate on impact and the material behaves more like polystyrene. The part looks identical and fails the drop test.<\/p>\n<h2 id=\"cost\">Where the money goes<\/h2>\n<table>\n<thead>\n<tr>\n<th>Cost element<\/th>\n<th>Share of part price<\/th>\n<th>Lever<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Mat\u00e9riau<\/td>\n<td>35 \u2013 50 %<\/td>\n<td>Wall thickness; grade; regrind ratio<\/td>\n<\/tr>\n<tr>\n<td>Machine time<\/td>\n<td>20 \u2013 30 %<\/td>\n<td>Cycle time; cavitation<\/td>\n<\/tr>\n<tr>\n<td>Tooling amortisation<\/td>\n<td>10 \u2013 20 %<\/td>\n<td>Volume; cavity count<\/td>\n<\/tr>\n<tr>\n<td>Labour and overhead<\/td>\n<td>10 \u2013 15 %<\/td>\n<td>Automation; part handling<\/td>\n<\/tr>\n<tr>\n<td>Finition<\/td>\n<td>0 \u2013 25 %<\/td>\n<td>Paint and print are often the largest single line<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 8 \u2014 Cost structure for a typical ABS housing. Painting can double the piece price.<\/p>\n<p>Because ABS is cheap relative to PC or PBT, material is a smaller share and cycle time is a larger one. A 2 mm wall in a 4-cavity tool on a 25-second cycle will usually beat a 2.5 mm wall in a 2-cavity tool on a 20-second cycle, because the machine rate is amortised over twice as many parts.<\/p>\n<h2 id=\"alternatives\">When to move off ABS<\/h2>\n<table>\n<thead>\n<tr>\n<th>Requirement<\/th>\n<th>Move to<\/th>\n<th>Penalty<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Higher impact, cold climate<\/td>\n<td>ABS\/PC blend<\/td>\n<td>+20 \u2013 40 % material cost; needs drying at 100 \u00b0C<\/td>\n<\/tr>\n<tr>\n<td>Transparence<\/td>\n<td>PC or PMMA<\/td>\n<td>Much higher processing temperature<\/td>\n<\/tr>\n<tr>\n<td>Continuous use above 100 \u00b0C<\/td>\n<td>PC, PBT, or PA<\/td>\n<td>Higher cost; different tooling steel<\/td>\n<\/tr>\n<tr>\n<td>Chemical resistance<\/td>\n<td>PP, PE, or PA<\/td>\n<td>Lower stiffness; different finish<\/td>\n<\/tr>\n<tr>\n<td>Outdoor UV exposure<\/td>\n<td>ASA or PC\/ASA<\/td>\n<td>+30 \u2013 60 % material cost<\/td>\n<\/tr>\n<tr>\n<td>Cost reduction<\/td>\n<td>HIPS<\/td>\n<td>Much lower impact; cannot be plated<\/td>\n<\/tr>\n<tr>\n<td>Living hinge<\/td>\n<td>PP<\/td>\n<td>Lower stiffness; different texture<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 9 \u2014 Substitution map. ASA is the direct UV-stable swap and is the most common one we quote.<\/p>\n<p>The UV substitution is worth knowing precisely: ABS yellows and chalks within one to two summers outdoors because the butadiene double bonds oxidise. ASA replaces the butadiene with an acrylate rubber that has no double bonds, so it does not have the failure mechanism. Chemically it is the same family, it processes the same way, and it costs 30 \u2013 60 % more. Any outdoor ABS part is a design error, not a material choice.<\/p>\n<h2 id=\"cycletime\">Cycle time: where the seconds actually go<\/h2>\n<p>An ABS housing on a 25-second cycle spends most of that time waiting for the plastic to cool enough to eject. Understanding the split tells you which lever is worth pulling.<\/p>\n<table>\n<thead>\n<tr>\n<th>Phase<\/th>\n<th>Typical share<\/th>\n<th>What controls it<\/th>\n<th>Can you shorten it?<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Injection<\/td>\n<td>8 \u2013 15 %<\/td>\n<td>Wall thickness, flow length, injection speed<\/td>\n<td>Yes \u2014 faster fill, better gate<\/td>\n<\/tr>\n<tr>\n<td>Hold \/ packing<\/td>\n<td>15 \u2013 25 %<\/td>\n<td>Gate freeze time, wall thickness at the gate<\/td>\n<td>Yes \u2014 find the gate-seal time<\/td>\n<\/tr>\n<tr>\n<td>Refroidissement<\/td>\n<td>45 \u2013 65 %<\/td>\n<td>Wall thickness squared, mould temperature, cooling channel design<\/td>\n<td>Yes \u2014 but the biggest lever is wall thickness<\/td>\n<\/tr>\n<tr>\n<td>Mould open \/ eject<\/td>\n<td>5 \u2013 10 %<\/td>\n<td>Machine, robot, ejection stroke<\/td>\n<td>Marginally<\/td>\n<\/tr>\n<tr>\n<td>Mould close<\/td>\n<td>3 \u2013 6 %<\/td>\n<td>Clamp speed<\/td>\n<td>Marginally<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 10 \u2014 Cycle time breakdown for a 2 mm ABS housing. Cooling dominates, and cooling time scales with the square of wall thickness.<\/p>\n<p>The practical consequence: reducing a wall from 2.5 mm to 2.0 mm cuts cooling time by about 36 %, which is 8 \u2013 12 seconds on a typical housing. Reducing mould temperature from 60 \u00b0C to 50 \u00b0C cuts cooling time by perhaps 15 %, but costs surface quality and increases stress. The wall is the better lever, and it is a design decision rather than a process one.<\/p>\n<p>Gate seal is the other easy win. ABS gates freeze quickly \u2014 usually 1.5 \u2013 3 seconds after the cavity fills. Holding for six seconds wastes four seconds per shot, which on a 25-second cycle is 16 % of capacity. Run a hold-time study: mould parts at 2, 3, 4, 5 and 6 seconds of hold, weigh them, and find the point where weight stops increasing. That is your gate-seal time.<\/p>\n<h2 id=\"paint\">Paint adhesion failures, and how to fix them<\/h2>\n<p>ABS is painted more than any other engineering plastic, and paint adhesion is the most common finishing complaint. Almost every failure has one of five causes.<\/p>\n<table>\n<thead>\n<tr>\n<th>Failure<\/th>\n<th>Apparence<\/th>\n<th>Cause<\/th>\n<th>Fix<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Poor initial adhesion<\/td>\n<td>Paint lifts with tape test<\/td>\n<td>Mould release agent or oil on the surface<\/td>\n<td>Isopropanol wipe; specify no silicone release<\/td>\n<\/tr>\n<tr>\n<td>Adhesion loss after humidity<\/td>\n<td>Blistering or peeling at edges<\/td>\n<td>Moisture in the moulded part migrating to the interface<\/td>\n<td>Dry the parts at 70 \u00b0C before painting<\/td>\n<\/tr>\n<tr>\n<td>Cracking on flex<\/td>\n<td>Fine cracks in the paint film<\/td>\n<td>Paint too hard for the substrate<\/td>\n<td>Use a flexible primer or a softer topcoat<\/td>\n<\/tr>\n<tr>\n<td>Solvent attack<\/td>\n<td>Etched or crazed surface under the paint<\/td>\n<td>Aggressive solvent in the paint attacking stressed ABS<\/td>\n<td>Reduce moulded-in stress; use a milder solvent system<\/td>\n<\/tr>\n<tr>\n<td>Colour variation<\/td>\n<td>Patchy or mottled finish<\/td>\n<td>Uneven surface texture, or flow marks under the paint<\/td>\n<td>Fix the moulding first; paint hides nothing on gloss<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 11 \u2014 Paint adhesion failures. The first row accounts for the majority of them.<\/p>\n<p>The one that surprises people is the fourth: a solvent-based paint can stress-crack an ABS part that has high moulded-in stress. The paint is not defective and the plastic is not defective \u2014 the combination is. Raising the mould temperature from 40 \u00b0C to 60 \u00b0C is usually enough to fix it, because it lets the stress relax before the part ejects.<\/p>\n<h2 id=\"qc\">Quality checks specific to ABS<\/h2>\n<table>\n<thead>\n<tr>\n<th>Check<\/th>\n<th>M\u00e9thode<\/th>\n<th>Frequency<\/th>\n<th>Rejects if<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Colour<\/td>\n<td>Spectrophotometer against a master<\/td>\n<td>Start of run, per batch<\/td>\n<td>&Delta;E &gt; 1.0<\/td>\n<\/tr>\n<tr>\n<td>Gloss<\/td>\n<td>Gloss meter at 60\u00b0<\/td>\n<td>Start of run<\/td>\n<td>Outside the specified band &plusmn;5 units<\/td>\n<\/tr>\n<tr>\n<td>Impact<\/td>\n<td>Drop test or Izod on a moulded bar<\/td>\n<td>Per shift<\/td>\n<td>Below the agreed value<\/td>\n<\/tr>\n<tr>\n<td>Weld line<\/td>\n<td>Visual against a limit sample, plus a bend test<\/td>\n<td>Per shift<\/td>\n<td>Visible on a cosmetic face, or breaks at the weld<\/td>\n<\/tr>\n<tr>\n<td>Dimensions<\/td>\n<td>Caliper \/ gauge<\/td>\n<td>Hourly<\/td>\n<td>Outside drawing<\/td>\n<\/tr>\n<tr>\n<td>Plating adhesion<\/td>\n<td>Thermal cycle \u221240 to +80 \u00b0C, 3 cycles, then tape<\/td>\n<td>Per batch, plated parts<\/td>\n<td>Any blistering<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 12 \u2014 ABS inspection. Gloss is worth measuring \u2014 the eye is unreliable and customers are not.<\/p>\n<h2 id=\"faq\">Frequently asked questions<\/h2>\n<div class=\"faq\">\n<h3>What is the difference between ABS and ABS\/PC?<\/h3>\n<p>ABS\/PC is a blend, typically 50 \u2013 70 % PC. It roughly doubles the impact strength and raises the heat deflection temperature by 15 \u2013 25 \u00b0C, at 20 \u2013 40 % higher material cost and a much tighter drying requirement (100 \u00b0C for 4 h). It also has poorer flow, so walls and ribs need re-checking.<\/p>\n<h3>Can ABS be sterilised?<\/h3>\n<p>Only with ethylene oxide or gamma at low dose. Autoclaving at 121 \u00b0C exceeds the heat deflection temperature and the part will distort. For repeated autoclave cycles, use PPSU or PEI.<\/p>\n<h3>Why do my ABS parts crack around screw bosses?<\/h3>\n<p>Three causes, in order of frequency: the boss wall is too thick so the core is still molten when the surface freezes, creating a shrink stress ring; the screw is over-torqued; or the part is assembled with a solvent-based adhesive that stress-cracks the moulded-in stress. Measure the boss wall \u2014 it should be about 0.6 \u00d7 the nominal wall, not 1.0 \u00d7.<\/p>\n<h3>What mould temperature should I use for a gloss finish?<\/h3>\n<p>60 \u2013 70 \u00b0C for high gloss. Below 50 \u00b0C the surface replicates the tool poorly and you get a dull, slightly hazy finish that cannot be polished out. Above 80 \u00b0C the cycle lengthens significantly and sink becomes more likely.<\/p>\n<h3>Is ABS food safe?<\/h3>\n<p>Standard ABS is not suitable for direct food contact in the EU or US without a specific food-contact-compliant grade. Many suppliers offer them; they use the same polymer with compliant additives and are certified to EU 10\/2011 or FDA 21 CFR 177.1020. Do not assume a general-purpose grade qualifies.<\/p>\n<h3>Can ABS be glued?<\/h3>\n<p>Yes, better than almost any other engineering plastic. Solvent cements based on methyl ethyl ketone or dichloromethane produce a joint that is nearly as strong as the parent material, because ABS dissolves in them and the two surfaces merge. This is why ABS is the standard material for bonded enclosures and prototypes.<\/p>\n<h3>Why does my black ABS part look grey around the gate?<\/h3>\n<p>Gate blush. High shear at the gate orients the rubber particles and scatters light. Fix it with a larger gate, a slower first-stage fill through the gate, or a higher gate temperature. On a textured part, move the gate to a non-visible face.<\/p>\n<h3>What is the shrinkage, and how do I design for it?<\/h3>\n<p>0.4 \u2013 0.7 %, with the higher figure for high-impact grades and thick walls. Design the tool steel to the nominal plus shrinkage and correct after the first shot. ABS is one of the most predictable materials to tool, which is part of why it is popular for tight-tolerance work.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">Moulding an ABS housing? Send the drawing and the drop-test requirement<\/p>\n<p>We will tell you which ABS grade meets the impact target, where the tool needs to change to avoid sink and weld lines, and what the part costs at your volume.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/fr\/abs-injection-molding\/\">Talk to an ABS moulding engineer<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/fr\/injection-molding-material-selection\/\">Injection Molding Material Selection: 14 Plastics Compared<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/fr\/injection-molding-design-guidelines\/\">Injection Molding Design Guidelines: 12 Rules That Cut Part Cost<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/fr\/pc-injection-molding-guide\/\">PC Injection Molding: Drying, Melt Temperature and Stress Cracking<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/fr\/injection-molding-defects\/\">Injection Molding Defects: 12 Problems, Causes and Fixes<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/fr\/custom-injection-molding-guide\/\">Custom Injection Molding Guide: Process, Cost &amp; Tolerances<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>ABS moulding in practice: the nine grade families, the processing window, design rules, finishing routes including plating, regrind limits and the defects specific to ABS.<\/p>","protected":false},"author":1,"featured_media":7597,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_seopress_titles_title":"ABS Injection Molding: Grades, Processing & Finishing","_seopress_titles_desc":"ABS moulding in practice: nine grade families, the processing window, design rules, finishing routes including plating, regrind limits and ABS-specific defects.","_seopress_robots_index":"1","_seopress_robots_follow":"1","_seopress_robots_imageindex":"","_seopress_robots_snippet":"","_seopress_robots_primary_cat":"35","_seopress_robots_breadcrumbs":"","_seopress_robots_freeze_modified_date":"","_seopress_robots_custom_modified_date":"","_seopress_robots_canonical":"https:\/\/uplastech.com\/abs-injection-molding-guide\/","_seopress_social_fb_title":"","_seopress_social_fb_desc":"","_seopress_social_fb_img":"","_seopress_social_fb_img_attachment_id":0,"_seopress_social_fb_img_width":0,"_seopress_social_fb_img_height":0,"_seopress_social_twitter_title":"","_seopress_social_twitter_desc":"","_seopress_social_twitter_img":"","_seopress_social_twitter_img_attachment_id":0,"_seopress_social_twitter_img_width":0,"_seopress_social_twitter_img_height":0,"_seopress_redirections_value":"","_seopress_redirections_enabled":"","_seopress_redirections_enabled_regex":"","_seopress_redirections_logged_status":"","_seopress_redirections_param":"","_seopress_redirections_type":0,"_seopress_analysis_target_kw":"abs injection molding","footnotes":""},"categories":[35],"tags":[],"class_list":["post-7605","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-injection-molding"],"meta_box":{"post-to-quiz_to":[]},"_links":{"self":[{"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/posts\/7605","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/comments?post=7605"}],"version-history":[{"count":0,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/posts\/7605\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/media\/7597"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/media?parent=7605"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/categories?post=7605"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/fr\/wp-json\/wp\/v2\/tags?post=7605"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}