{"id":8285,"date":"2026-04-01T09:00:00","date_gmt":"2026-04-01T08:00:00","guid":{"rendered":"https:\/\/uplastech.com\/mold-tool-life\/"},"modified":"2026-04-01T09:00:00","modified_gmt":"2026-04-01T08:00:00","slug":"mold-tool-life","status":"publish","type":"post","link":"https:\/\/uplastech.com\/ja\/mold-tool-life\/","title":{"rendered":"Mould Tool Life: What Actually Wears Out and What Only Looks Worn"},"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\/mold-tool-life.jpg\" alt=\"An injection mould insert on a toolroom bench with a visibly washed out and rounded gate area, a magnifier and pin gauge beside it\" width=\"1536\" height=\"909\"><figcaption>A gate that has grown. The cavity still looks fine, which is why the drift is found on the part rather than on the tool.<\/figcaption><\/figure>\n<div class=\"toc\"><\/div>\n<h2 id=\"distribution\">Where tools actually fail<\/h2>\n<p>Ask a toolmaker what wears out and the answer is usually the cavity surface. Ask a production engineer which tool failed last and the answer is usually the gate, the ejector pins or a crack at a corner. The two answers are both right and they describe different populations.<\/p>\n<p>Across a population of injection tools, about 34 percent of failures start at the gate. Twenty-six percent are cracks, usually at a thin core, a sharp corner or a weld repair. Eighteen percent are corrosion. Thirteen percent are erosion, which is wear from the melt itself on a filled compound. Nine percent are deformation, which is a tool that was overpacked or run too hot.<\/p>\n<p>The cavity surface wear that everyone worries about is part of the 13 percent erosion figure, and it is the slowest of the five. A cavity that is polished and run on an unfilled resin wears so slowly that the tool is usually replaced for another reason first.<\/p>\n<p>That changes the maintenance plan. A tool that is inspected at the gate every 50,000 shots and at the cavity every 200,000 will catch most of the failures before they produce scrap. A tool that is inspected visually at the cavity will not.<\/p>\n<h2 id=\"gate\">The gate wears because it is the smallest feature<\/h2>\n<p>The gate is the smallest cross-section in the flow path, so the melt velocity through it is the highest. On a 0.8 mm gate feeding a part in 0.6 seconds, the shear rate at the gate wall is an order of magnitude above the shear rate anywhere else in the tool. Wear scales with shear rate and with the cube of velocity, which is why the gate goes first.<\/p>\n<p>The wear is not a loss of material in the obvious sense. The gate edge rounds, the land shortens, and the effective gate area grows. A gate that starts at 0.80 mm measures 0.877 mm after 250,000 shots, and a 0.05 mm growth is already at the print limit.<\/p>\n<p>The consequence is not a visible defect. A larger gate freezes later, so the part packs for longer and gets heavier. The gate mark gets bigger and the cycle gets longer. The part is still in specification until the weight crosses the upper limit, and by then the tool has been drifting for 100,000 shots.<\/p>\n<p>That is why the gate dimension belongs on the control plan, not just on the drawing. Measuring the gate every 25,000 shots and plotting it against the shot count turns an invisible drift into a scheduled re-cut, and a re-cut gate is a two hour job while a gate that has grown 0.15 mm is a weld and a re-machine.<\/p>\n<figure>\n<img decoding=\"async\" src=\"https:\/\/uplastech.com\/wp-content\/uploads\/2026\/10\/mold-tool-life-chart.jpg\" alt=\"Bar chart of tool failure causes with gate wear at 34 percent, cracking 26, corrosion 18, erosion 13 and deformation 9, and gate width growing 0.077 mm over 250,000 shots against a 0.05 mm print limit\" width=\"1536\" height=\"909\"><figcaption>Left: where tool failures start, gate wear at 34 percent and cracking at 26. Right: gate width drift against shot count, 0.077 mm at 250,000 shots, past the 0.05 mm print limit at about 215,000.<\/figcaption><\/figure>\n<h2 id=\"cracks\">Cracks start where the drawing is thinnest<\/h2>\n<p>A crack is a stress concentration that found a fatigue load. The three places it happens are a thin core pin, a sharp internal corner and a weld repair. All three are places where the stress is higher than the section around them, and all three are visible on the drawing before the tool is cut.<\/p>\n<p>A thin core pin in a high-hardness insert is the classic. The pin bends every cycle under the melt pressure, and at 58 HRC a grinding mark is a crack initiation site. The tool then fails at 20,000 shots having been bought to last 300,000, and the fix is a lower hardness or a bigger core.<\/p>\n<p>A sharp internal corner is the second. A 0.5 mm radius at the bottom of a deep rib is a stress concentration of about 3, and a 2 mm radius is about 1.5. Doubling the radius halves the stress and it costs nothing at the design stage.<\/p>\n<p>A weld repair is the third, and it is the one that is nobody's fault. A tool that has been welded has a heat-affected zone with a different hardness and residual stress, and it will crack there rather than at the original damage. A welded repair on a hard cavity should be followed by a stress relief and a re-temper, and it usually is not.<\/p>\n<h2 id=\"corrosion\">Corrosion is a resin problem, not a plant problem<\/h2>\n<p>Eighteen percent of failures are corrosion, and the assumption is that they come from a humid plant. They usually come from the resin. PVC releases hydrogen chloride at processing temperature, and that combines with moisture to make hydrochloric acid, which attacks any steel that is not stainless.<\/p>\n<p>The other corrosive resins are the ones with acidic additives: a flame retardant, an acid-based stabiliser, a blowing agent that decomposes to an acid. A tool that runs these resins in a non-stainless steel will pit within months, and a pit on a cavity surface is a mark on every part.<\/p>\n<p>The corrosion also hides. A cavity that is pitting looks dull rather than rough, and the operator polishes it, which removes the evidence and exposes fresh steel to the same attack. The cycle repeats until the cavity is out of tolerance.<\/p>\n<p>The fix is either a stainless insert or a coating. A PVD coating on a P20 cavity gives corrosion resistance better than most stainless, and its weakness is a sharp edge where the coating chips. On a cavity with sharp edges, the stainless insert is the better answer.<\/p>\n<h2 id=\"drift\">Reading the drift before it becomes scrap<\/h2>\n<p>A tool does not fail suddenly, except when it cracks. It drifts, and the drift shows up in the part before it shows up in the tool. The four numbers that catch it are part weight, a critical dimension, the gate mark size and the cycle time.<\/p>\n<p>Part weight is the earliest indicator, because it responds to the gate and to the cavity at the same time. A weight that has drifted 1.5 percent over 100,000 shots is a tool that needs a look, even if the part is still in specification. A weight that steps by 0.5 percent between two shots is a tool that has just changed.<\/p>\n<p>A critical dimension is the second. A dimension that was 12.00 plus or minus 0.05 and is now 12.03 has not failed, but it has used 60 percent of its tolerance. Plotting it against the shot count gives a slope, and the slope predicts the failure date.<\/p>\n<p>The gate mark is the third, and it is the one that is easiest to measure and most often ignored. A gate mark that was 1.2 mm across and is now 1.5 mm is a gate that has grown 25 percent, and the weight and the dimension are following it.<\/p>\n<table>\n<thead>\n<tr>\n<th>Indicator<\/th>\n<th>What it catches<\/th>\n<th>How often to check<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Part weight<\/td>\n<td>Gate growth, cavity wear<\/td>\n<td>Every shift<\/td>\n<\/tr>\n<tr>\n<td>Critical dimension<\/td>\n<td>Cavity and core wear<\/td>\n<td>Weekly<\/td>\n<\/tr>\n<tr>\n<td>Gate mark size<\/td>\n<td>Gate wear<\/td>\n<td>Every 25,000 shots<\/td>\n<\/tr>\n<tr>\n<td>\u30b5\u30a4\u30af\u30eb\u30bf\u30a4\u30e0<\/td>\n<td>Gate freeze, cooling<\/td>\n<td>\u9023\u7d9a<\/td>\n<\/tr>\n<tr>\n<td>Flash<\/td>\n<td>Parting line wear, clamp<\/td>\n<td>Every shift<\/td>\n<\/tr>\n<tr>\n<td>Crack inspection<\/td>\n<td>Thin cores, corners<\/td>\n<td>Every 50,000 shots<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 1 \u2014 The indicators that catch a drifting tool<\/p>\n<h2 id=\"maintenance\">What maintenance actually buys<\/h2>\n<p>A planned maintenance interval of 50,000 shots on a general purpose tool costs a day of toolroom time and a day of production, twice a year on a 200,000 shot tool. It buys a gate that is re-cut before it is out of tolerance, a parting line that is stoned before it flashes and a crack that is found before it propagates.<\/p>\n<p>The alternative is unplanned. A gate that has grown to the point of flashing costs a weld, a re-machine and a re-polish, which is a week, and it happens on the day the customer is waiting. The cost of the unplanned event is five to ten times the planned one.<\/p>\n<p>The maintenance itself is simple: clean the vents, stone the parting line, measure and re-cut the gate if needed, inspect the thin sections for cracks with a dye penetrant, and check the water circuits for scale. It is not a rebuild and it does not need a specialist.<\/p>\n<p>What it does need is a record. A tool with a maintenance history that says the gate was re-cut at 120,000 and 210,000 shots is a tool whose next failure can be predicted. A tool with no history is a tool that is inspected from scratch every time, which means it is inspected less often.<\/p>\n<table>\n<thead>\n<tr>\n<th>Task<\/th>\n<th>Interval<\/th>\n<th>Time<\/th>\n<th>What it prevents<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Clean vents<\/td>\n<td>Every 25,000 shots<\/td>\n<td>1 hour<\/td>\n<td>Burns, short shots<\/td>\n<\/tr>\n<tr>\n<td>Stone parting line<\/td>\n<td>Every 50,000 shots<\/td>\n<td>2 hours<\/td>\n<td>Flash<\/td>\n<\/tr>\n<tr>\n<td>Measure and re-cut gate<\/td>\n<td>Every 50,000 shots<\/td>\n<td>2 to 4 hours<\/td>\n<td>Weight drift<\/td>\n<\/tr>\n<tr>\n<td>Dye penetrant on thin cores<\/td>\n<td>Every 50,000 shots<\/td>\n<td>2 hours<\/td>\n<td>Cracking<\/td>\n<\/tr>\n<tr>\n<td>Water circuit descale<\/td>\n<td>Every 100,000 shots<\/td>\n<td>3 hours<\/td>\n<td>Hot spots, warpage<\/td>\n<\/tr>\n<tr>\n<td>Full strip and inspect<\/td>\n<td>Every 250,000 shots<\/td>\n<td>2 days<\/td>\n<td>Everything above<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p class=\"tablecap\">Table 2 \u2014 A maintenance schedule that fits a general purpose tool<\/p>\n<div class=\"myth\">Myth: the cavity surface is what wears out. A third of tool failures start at the gate and another quarter are cracks at thin sections, while cavity erosion is 13 percent and the slowest of the five. A tool that is polished and inspected at the cavity is being looked after in the place it is least likely to fail.<\/div>\n<div class=\"faq\">\n<h3>What wears out first on an injection mould?<\/h3>\n<p>The gate. It is the smallest cross-section, so the melt velocity and shear rate there are the highest. About 34 percent of tool failures start at the gate.<\/p>\n<h3>How fast does a gate wear?<\/h3>\n<p>On a typical unfilled resin a 0.80 mm gate reaches 0.877 mm after 250,000 shots, which is past a 0.05 mm print limit at about 215,000 shots.<\/p>\n<h3>What does gate wear do to the part?<\/h3>\n<p>It freezes later, so the part packs longer and gets heavier, the gate mark grows and the cycle time rises. The part stays in specification until the weight crosses the upper limit.<\/p>\n<h3>Why do tools crack at thin cores?<\/h3>\n<p>Because a thin core bends every cycle and a hard steel has no toughness left to absorb it. At 58 HRC a grinding mark is a crack initiation site.<\/p>\n<h3>Is corrosion a plant humidity problem?<\/h3>\n<p>Usually not. It comes from the resin: PVC releases hydrogen chloride, and acidic additives do the same. The fix is a stainless insert or a coating, not a dehumidifier.<\/p>\n<h3>How often should a tool be maintained?<\/h3>\n<p>Every 50,000 shots on a general purpose tool: clean the vents, stone the parting line, measure the gate, dye-penetrant the thin sections. Planned maintenance costs a tenth of the unplanned failure.<\/p>\n<\/div>\n<div class=\"cta\">\n<p class=\"cta-h\">A tool that is drifting, or one that just cracked?<\/p>\n<p>Send the shot count, the part weight trend and the gate dimension. We will tell you whether it needs a re-cut, a repair or a replacement.<\/p>\n<p><a class=\"btn\" href=\"https:\/\/uplastech.com\/ja\/injection-molding\/\">Ask about mould maintenance<\/a>\n<\/div>\n<div class=\"rel\">\n<h4>Continue reading<\/h4>\n<ul>\n<li><a href=\"https:\/\/uplastech.com\/ja\/mold-steel-selection\/\">Mould Steel Selection: Hardness, Polishability and Cavity Life<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ja\/mold-venting-depth\/\">Mould Venting: Depth, Position and the 0.02 mm That Prevents a Burn<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ja\/mold-cooling-channel-design\/\">Mold Cooling Channel Design: Diameter, Pitch and Turbulence<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ja\/flash-injection-molding\/\">Flash in Injection Molding: Clamp, Vent and the Parting Line<\/a><\/li>\n<li><a href=\"https:\/\/uplastech.com\/ja\/injection-molding\/\">Injection Molding: From Tool to Production<\/a><\/li>\n<\/ul>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>A third of tool failures happen at the gate, not on the cavity. And the gate grows 0.077 mm over 250,000 shots, which is past the 0.05 mm print limit long before the cavity looks worn.<\/p>","protected":false},"author":1,"featured_media":8283,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[35],"tags":[],"class_list":["post-8285","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\/ja\/wp-json\/wp\/v2\/posts\/8285","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/comments?post=8285"}],"version-history":[{"count":0,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/posts\/8285\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/media\/8283"}],"wp:attachment":[{"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/media?parent=8285"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/categories?post=8285"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/uplastech.com\/ja\/wp-json\/wp\/v2\/tags?post=8285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}