{"id":6084,"date":"2026-05-25T18:26:36","date_gmt":"2026-05-26T02:26:36","guid":{"rendered":"https:\/\/haifengmachine.com\/?p=6084"},"modified":"2026-05-25T23:07:45","modified_gmt":"2026-05-26T07:07:45","slug":"pu-casting-machine-mechanics-pumps-pressure","status":"publish","type":"post","link":"https:\/\/haifengmachine.com\/ko\/pu-casting-machine-mechanics-pumps-pressure\/","title":{"rendered":"PU Casting Machine Mechanics: Mastering Metering Pumps &amp; Hydraulic Pressure [Part 4: Mechanics &amp; Fluid Dynamics]"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"6084\" class=\"elementor elementor-6084\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a647234 e-flex e-con-boxed e-con e-parent\" data-id=\"a647234\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-8da0086 elementor-toc--minimized-on-tablet elementor-widget elementor-widget-table-of-contents\" data-id=\"8da0086\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;exclude_headings_by_selector&quot;:[],&quot;marker_view&quot;:&quot;bullets&quot;,&quot;icon&quot;:{&quot;value&quot;:&quot;fas fa-dot-circle&quot;,&quot;library&quot;:&quot;fa-solid&quot;,&quot;rendered_tag&quot;:&quot;&lt;svg class=\\&quot;e-font-icon-svg e-fas-dot-circle\\&quot; viewBox=\\&quot;0 0 512 512\\&quot; xmlns=\\&quot;http:\\\/\\\/www.w3.org\\\/2000\\\/svg\\&quot;&gt;&lt;path d=\\&quot;M256 8C119.033 8 8 119.033 8 256s111.033 248 248 248 248-111.033 248-248S392.967 8 256 8zm80 248c0 44.112-35.888 80-80 80s-80-35.888-80-80 35.888-80 80-80 80 35.888 80 80z\\&quot;&gt;&lt;\\\/path&gt;&lt;\\\/svg&gt;&quot;},&quot;no_headings_message&quot;:&quot;No headings were found on this page.&quot;,&quot;headings_by_tags&quot;:[&quot;h2&quot;,&quot;h3&quot;,&quot;h4&quot;,&quot;h5&quot;,&quot;h6&quot;],&quot;minimize_box&quot;:&quot;yes&quot;,&quot;minimized_on&quot;:&quot;tablet&quot;,&quot;hierarchical_view&quot;:&quot;yes&quot;,&quot;min_height&quot;:{&quot;unit&quot;:&quot;px&quot;,&quot;size&quot;:&quot;&quot;,&quot;sizes&quot;:[]},&quot;min_height_tablet&quot;:{&quot;unit&quot;:&quot;px&quot;,&quot;size&quot;:&quot;&quot;,&quot;sizes&quot;:[]},&quot;min_height_mobile&quot;:{&quot;unit&quot;:&quot;px&quot;,&quot;size&quot;:&quot;&quot;,&quot;sizes&quot;:[]}}\" data-widget_type=\"table-of-contents.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-toc__header\">\n\t\t\t<h4 class=\"elementor-toc__header-title\">\n\t\t\t\tTable of Contents\t\t\t<\/h4>\n\t\t\t\t\t\t\t<div class=\"elementor-toc__toggle-button elementor-toc__toggle-button--expand\" role=\"button\" tabindex=\"0\" aria-controls=\"elementor-toc__8da0086\" aria-expanded=\"true\" aria-label=\"Open table of contents\"><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-down\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M207.029 381.476L12.686 187.132c-9.373-9.373-9.373-24.569 0-33.941l22.667-22.667c9.357-9.357 24.522-9.375 33.901-.04L224 284.505l154.745-154.021c9.379-9.335 24.544-9.317 33.901.04l22.667 22.667c9.373 9.373 9.373 24.569 0 33.941L240.971 381.476c-9.373 9.372-24.569 9.372-33.942 0z\"><\/path><\/svg><\/div>\n\t\t\t\t<div class=\"elementor-toc__toggle-button elementor-toc__toggle-button--collapse\" role=\"button\" tabindex=\"0\" aria-controls=\"elementor-toc__8da0086\" aria-expanded=\"true\" aria-label=\"Close table of contents\"><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-up\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M240.971 130.524l194.343 194.343c9.373 9.373 9.373 24.569 0 33.941l-22.667 22.667c-9.357 9.357-24.522 9.375-33.901.04L224 227.495 69.255 381.516c-9.379 9.335-24.544 9.317-33.901-.04l-22.667-22.667c-9.373-9.373-9.373-24.569 0-33.941L207.03 130.525c9.372-9.373 24.568-9.373 33.941-.001z\"><\/path><\/svg><\/div>\n\t\t\t\t\t<\/div>\n\t\t<div id=\"elementor-toc__8da0086\" class=\"elementor-toc__body\">\n\t\t\t<div class=\"elementor-toc__spinner-container\">\n\t\t\t\t<svg class=\"elementor-toc__spinner eicon-animation-spin e-font-icon-svg e-eicon-loading\" aria-hidden=\"true\" viewBox=\"0 0 1000 1000\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M500 975V858C696 858 858 696 858 500S696 142 500 142 142 304 142 500H25C25 237 238 25 500 25S975 237 975 500 763 975 500 975Z\"><\/path><\/svg>\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-484fe95 e-flex e-con-boxed e-con e-parent\" data-id=\"484fe95\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-21fcad3 elementor-widget elementor-widget-text-editor\" data-id=\"21fcad3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>In polyurethane casting, perfect chemical formulations will still produce defective shoe soles if your machine&#8217;s hydraulic heart (the pumps) and circulatory system (the pipelines) suffer from pressure differentials. This guide delves into the extreme fluid dynamics of PU casting machines. Haifeng&#8217;s Chief Engineer exposes the myths of metering pump precision, explains how our ceramic seals solve the fatal &#8220;air ingress (cavitation)&#8221; problem, and details how our PID closed-loop systems with mass flow meters guarantee 1\/1000th dispensing accuracy. Learn how to conquer &#8220;Back Pressure,&#8221; eliminate &#8220;Lead\/Lag (Spit Difference),&#8221; and achieve absolute hydraulic control on your shop floor.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-13c6f51 elementor-widget elementor-widget-image\" data-id=\"13c6f51\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"800\" height=\"501\" src=\"https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1-1024x641.jpg\" class=\"attachment-large size-large wp-image-6046\" alt=\"Polyurethane shoes soles haifeng\" srcset=\"https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1-1024x641.jpg 1024w, https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1-300x188.jpg 300w, https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1-768x481.jpg 768w, https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1-18x12.jpg 18w, https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/05\/Polyurethane-shoes-soles-haifeng-1.jpg 1280w\" sizes=\"(max-width: 800px) 100vw, 800px\" title=\"\">\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-90683dd elementor-widget elementor-widget-heading\" data-id=\"90683dd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">1.Introduction: Stop Treating the Casting Machine Like a Simple Blender<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b4be6cf elementor-widget elementor-widget-text-editor\" data-id=\"b4be6cf\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>In our previous installments, we mastered chemical formulations, conquered mold release agents, and established rigid Cup Test standards. But here is the brutal truth: <strong>none of that matters if your machine cannot deliver those liquids with absolute mechanical precision.<\/strong><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-df75ada elementor-widget elementor-widget-heading\" data-id=\"df75ada\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The \"Kitchen Blender\" Myth:<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b9f7de4 elementor-widget elementor-widget-text-editor\" data-id=\"b9f7de4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Many factory owners make a fatal conceptual error. They treat a PU casting machine like a simple kitchen blender\u2014pour Component A and Component B into the tanks, turn on the pump, and expect perfect shoes.<\/p>\n<p>In reality, a polyurethane casting line is not a mixer. It is a <strong>highly complex, ultra-precise hydraulic system<\/strong>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-bc7a467 elementor-widget elementor-widget-heading\" data-id=\"bc7a467\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Physics of Failure: <\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-10ae29a elementor-widget elementor-widget-text-editor\" data-id=\"10ae29a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Even if your A\/B chemical ratio is flawless on a spreadsheet, the laws of fluid dynamics will destroy your yield on the shop floor if pressure isn&#8217;t controlled:<\/p>\n<ul>\n<li><strong>The Pressure Differential:<\/strong> If there is a massive pressure gap between the Polyol (A) pipeline and the Isocyanate (B) pipeline, the high-pressure liquid will violently overpower the low-pressure liquid inside the mixing head.<\/li>\n<li><strong>The Consequence:<\/strong> A catastrophic deviation in your chemical ratio right at the nozzle, leading to uncured, ruined soles.<\/li>\n<\/ul>\n<p>In this installment, we break down the hardcore fluid dynamics of PU casting. We will show you exactly how Haifeng eliminates these hydraulic variables and engineers absolute precision into the mechanical heart of the machine.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c82f7e5 elementor-widget elementor-widget-heading\" data-id=\"c82f7e5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">2. The Heart of the Machine: Metering Pumps &amp; The \"Air Ingress\" Trap<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4524d7a elementor-widget elementor-widget-text-editor\" data-id=\"4524d7a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p data-path-to-node=\"21\">The metering pump is the mechanical heart that dictates how much A and B material flows into the mixing chamber.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-75767b1 elementor-widget elementor-widget-heading\" data-id=\"75767b1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Precision Myth:\u00a0<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b31c8bd elementor-widget elementor-widget-text-editor\" data-id=\"b31c8bd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A common misconception among factory owners is that &#8220;as long as I buy the most expensive, highest-precision gear pump, my A\/B ratio will be flawless.&#8221; This is false. While a high-precision pump ensures steady displacement, it cannot guarantee ratio accuracy if the upstream and downstream fluid pressures are fluctuating wildly. Furthermore, assuming that the physical rotational speed ratio of the A and B pump motors exactly equals the chemical output ratio is a rookie mistake. Fluid viscosity and internal pump slip alter the real-world output.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fd4f0ba elementor-widget elementor-widget-heading\" data-id=\"fd4f0ba\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Fatal \"Air Ingress\" Trap:<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-11bdda4 elementor-widget elementor-widget-text-editor\" data-id=\"11bdda4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>In workshop jargon, &#8220;air ingress&#8221; or cavitation is a catastrophic failure. This occurs when the pump body&#8217;s mechanical seals (shaft seals) wear down, allowing ambient air to be sucked directly into the high-pressure raw material pipelines. This injected air ruins the chemical reaction and destroys the pump&#8217;s gears.<\/p>\n<ul>\n<li><strong>The Old Reality:<\/strong>\u00a0Traditional pumps relied on packing seals or basic O-rings. The abrasive nature of PU chemicals meant these pumps often suffered seal failure and required replacement every 15 to 30 days.<\/li>\n<li><strong>Haifeng&#8217;s Ceramic Innovation:<\/strong>\u00a0To solve this, Haifeng developed proprietary\u00a0<strong>Ceramic Seals<\/strong>. Ceramic offers extreme hardness and resistance to chemical abrasion. By upgrading to these seals, we have successfully extended the lifespan of our metering pumps to an astonishing\u00a0<strong>180 to 270 days<\/strong>\u00a0of continuous operation (depending on specific chemical abrasiveness), drastically slashing your maintenance downtime.<\/li>\n<li style=\"list-style-type: none;\">\n<ul>\n<li style=\"list-style-type: none;\">\u00a0<\/li>\n<\/ul>\n<\/li>\n<\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2d72a9b elementor-widget elementor-widget-heading\" data-id=\"2d72a9b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">3.The Invisible Yield Killer: Circulation Pressure Differentials<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-40cee9f elementor-widget elementor-widget-heading\" data-id=\"40cee9f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">3.1 Why is circulation pressure the most critical indicator on a PU casting machine?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cb11d1e elementor-widget elementor-widget-text-editor\" data-id=\"cb11d1e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Because stable pressure is the absolute prerequisite for an accurate chemical ratio.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-62414b4 elementor-widget elementor-widget-heading\" data-id=\"62414b4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Danger of Imbalance:<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1a54bda elementor-widget elementor-widget-text-editor\" data-id=\"1a54bda\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>If the circulation pressure of the A-material line is 2.0 MPa and the B-material line drops to 0.5 MPa, what happens when both valves open into the mixing chamber? The high-pressure A-material will &#8220;bully&#8221; its way in, choking off the B-material. Your carefully calculated 1:1 ratio instantly becomes 1:0.5.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b66db13 elementor-widget elementor-widget-heading\" data-id=\"b66db13\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Overcoming the Pressure Control Dilemma:<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7163ace elementor-widget elementor-widget-text-editor\" data-id=\"7163ace\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Historically, automating pressure control was considered too expensive and technologically difficult for standard footwear equipment. Operators had to manually twist back-pressure valves and stare at analogue gauges.<\/p>\n<ul>\n<li><strong>Haifeng&#8217;s 2026 PID Closed-Loop System:<\/strong>\u00a0We have completely dismantled this limitation. Haifeng machines are equipped with advanced\u00a0<strong>Mass Flow Meters<\/strong>\u00a0acting as the feedback unit for a\u00a0<strong>PID Closed-Loop System<\/strong>. The machine&#8217;s PLC constantly monitors the exact mass of liquid flowing through the pipes. If a pressure drop alters the flow, the PID algorithm instantly adjusts the frequency inverters controlling the servo motors. This real-time compensation ensures that our dynamic dispensing accuracy remains within an unparalleled\u00a0<strong>1\/1000th (0.1%) deviation<\/strong>, regardless of external pressure fluctuations.<\/li>\n<\/ul>\n<p><em>(Note: We also implement extreme modularity. Recognizing that different chemical formulations have vastly different viscosities, Haifeng customizes the hardware\u2014selecting specific valve body sizes and pipeline diameters\u2014to perfectly match the fluid dynamics of your chosen raw materials.)<\/em><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4175f02 elementor-widget elementor-widget-heading\" data-id=\"4175f02\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">4.The Micro-Physical War in the Mixing Chamber: Back Pressure &amp; Negative Pressure<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-116dbe2 elementor-widget elementor-widget-text-editor\" data-id=\"116dbe2\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>The mixing chamber is where the magic happens, but it is also a battleground of intense fluid physics.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8de9689 elementor-widget elementor-widget-heading\" data-id=\"8de9689\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">4.1 Mixing Chamber \"Back Pressure\"<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0e36074 elementor-widget elementor-widget-text-editor\" data-id=\"0e36074\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>When the circulation pressure and injection pressure are set too high, massive &#8220;Back Pressure&#8221; builds up inside the mixing chamber. [Image of high pressure fluid dynamics causing back pressure in a mechanical mixing chamber] The injected liquid violently rebounds upwards, forcing chemical residue past the upper bearings and shaft seals. This causes the bearings to overheat, seize, and ultimately destroys the mixing head. Furthermore, excessive injection velocity can trap air inside the mold, causing the &#8220;blisters&#8221; we discussed in Part 3.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5d5b61f elementor-widget elementor-widget-heading\" data-id=\"5d5b61f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">4.2 Mixing Chamber \"Negative Pressure\"<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1dfa476 elementor-widget elementor-widget-text-editor\" data-id=\"1dfa476\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Conversely, if the circulation pressure is too low, the violent spinning of the mixer can create a vacuum effect (&#8220;Negative Pressure&#8221;) at the injection nozzle. If the upper seals are slightly worn, this vacuum will actively suck ambient air down into the mixing chamber, instantly filling your PU mixture with micro-bubbles before it even hits the mold.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a2dbe22 elementor-widget elementor-widget-heading\" data-id=\"a2dbe22\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">5. Eliminating \"Lead\/Lag\" (The Spit Difference Problem)<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-98070ba elementor-widget elementor-widget-text-editor\" data-id=\"98070ba\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>&#8220;Lead\/Lag&#8221; (commonly called &#8220;Spit Difference&#8221; on the shop floor) refers to the severe A\/B ratio fluctuation that occurs in the very first fraction of a second when the injection valves open.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f30c01d elementor-widget elementor-widget-heading\" data-id=\"f30c01d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Cause: <\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a8c8f25 elementor-widget elementor-widget-text-editor\" data-id=\"a8c8f25\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Because Component A and Component B have drastically different viscosities and pipeline pressures, when both valves trigger simultaneously, one liquid inevitably spits out slightly faster than the other. This creates a &#8220;head material&#8221; (\u5934\u6599) that is chemically unbalanced and will never cure properly, leading to defective shoe soles.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9940f07 elementor-widget elementor-widget-heading\" data-id=\"9940f07\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">The Haifeng Solution (Continuous vs. Intermittent Pouring):<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-95c7865 elementor-widget elementor-widget-text-editor\" data-id=\"95c7865\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<ul>\n<li><strong>In Continuous Pouring Lines:<\/strong>\u00a0Lead\/lag becomes negligible. As the valves remain open and the mechanical system reaches a state of dynamic equilibrium, the initial spit difference is instantly swallowed by the sheer volume of correct material.<\/li>\n<li><strong>In Intermittent (Stop-and-Go) Pouring:<\/strong>\u00a0This is where precision matters. Haifeng utilizes\u00a0<strong>High-Frequency Solenoid Valves<\/strong>\u00a0to execute synchronized control. However, the absolute most reliable method is mechanical synchronization\u2014physically adjusting the mechanical linkages to force the A and B valves to crack open at the exact same millisecond.\u00a0<em>(Haifeng provides dedicated technical video tutorials to our clients, training their operators on how to perfectly calibrate this mechanical synchronization on the factory floor).<\/em><\/li>\n<\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-99979db elementor-widget elementor-widget-heading\" data-id=\"99979db\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">6. The Iron Rule: Why the PU Machine Must Never Stop<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cdfa231 elementor-widget elementor-widget-text-editor\" data-id=\"cdfa231\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A PU casting machine is designed for continuous, relentless circulation.<\/p>\n<p>Once the machine is powered on and raw materials are loaded into the tanks, the gear pumps must keep the A and B liquids constantly circulating through the pipelines and back to the tanks, even when you are not actively pouring into a mold. Why?<\/p>\n<ol>\n<li><strong>Thermal Stability:<\/strong>\u00a0Circulation ensures the chemical temperature remains absolutely uniform throughout the entire length of the piping system, avoiding cold spots that ruin viscosity.<\/li>\n<li><strong>Pressure Equilibrium:<\/strong>\u00a0Continuous movement maintains the dynamic hydraulic pressure we just discussed, ensuring the machine is primed and ready to dispense the perfect ratio the second the trigger is pulled.<\/li>\n<li><strong>Preventing Crystallization\/Sedimentation:<\/strong>\u00a0Particularly for Component B (MDI), stagnation in cold pipes can lead to localized crystallization, permanently choking the hydraulic system.<\/li>\n<\/ol>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6721e39 elementor-widget elementor-widget-heading\" data-id=\"6721e39\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Conclusion: Conquering the Fluid Dynamics of Footwear<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3016083 elementor-widget elementor-widget-text-editor\" data-id=\"3016083\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Mastering PU casting is not just about understanding chemistry; it is about dominating fluid dynamics.<\/p>\n<p>When you equip your factory with Haifeng machinery, you are no longer fighting blind battles against invisible pressure differentials and failing pump seals. By leveraging our proprietary ceramic seals (extending pump life to 270 days), implementing precise mechanical valve synchronization to eliminate lead\/lag, and utilizing our PID closed-loop mass flow systems to guarantee 1\/1000th dispensing accuracy, you transform chaotic fluid dynamics into predictable, high-yield manufacturing.<\/p>\n<p>This level of absolute hydraulic control is what separates ordinary shoe factories from the global industry elite.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e55cd54 elementor-widget-divider--view-line elementor-widget elementor-widget-divider\" data-id=\"e55cd54\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"divider.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-divider\">\n\t\t\t<span class=\"elementor-divider-separator\">\n\t\t\t\t\t\t<\/span>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c0794e4 elementor-widget elementor-widget-text-editor\" data-id=\"c0794e4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p><strong>[If you are tired of battling ratio drift and pump failures, and are ready to upgrade your factory with Haifeng&#8217;s PID closed-loop casting technology and ceramic-sealed metering pumps, contact our Engineering Team today for a comprehensive technical consultation.]<\/strong><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5602764 elementor-widget elementor-widget-heading\" data-id=\"5602764\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">The Ultimate EPC+M+O Guide to PU Shoe Sole Manufacturing:<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f869170 elementor-icon-list--layout-traditional elementor-list-item-link-full_width elementor-widget elementor-widget-icon-list\" data-id=\"f869170\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/haifengmachine.com\/pu-shoe-sole-formulation-raw-materials-guide\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\"> [Part 1: Materials &amp; Chemistry]<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/haifengmachine.com\/pu-shoe-sole-manufacturing-cup-test-foaming\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">[Part 2: Practical Processing]<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/haifengmachine.com\/pu-shoe-sole-defects-release-agents-troubleshooting\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\"> [Part 3: Workshop Chemicals]<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/haifengmachine.com\/pu-casting-machine-mechanics-pumps-pressure\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\"> [Part 4: Mechanics &amp; Fluid Dynamics]<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/haifengmachine.com\/pu-shoe-factory-layout-automation-turnkey-lines\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\"> [Part 5: Factory Layout]<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e1c91ab elementor-widget elementor-widget-heading\" data-id=\"e1c91ab\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">FAQ<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-668c1df elementor-widget elementor-widget-n-accordion\" data-id=\"668c1df\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;default_state&quot;:&quot;expanded&quot;,&quot;max_items_expended&quot;:&quot;one&quot;,&quot;n_accordion_animation_duration&quot;:{&quot;unit&quot;:&quot;ms&quot;,&quot;size&quot;:400,&quot;sizes&quot;:[]}}\" data-widget_type=\"nested-accordion.default\">\n\t\t\t\t\t\t\t<div class=\"e-n-accordion\" aria-label=\"Accordion. Open links with Enter or Space, close with Escape, and navigate with Arrow Keys\">\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1070\" class=\"e-n-accordion-item\" open>\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"1\" tabindex=\"0\" aria-expanded=\"true\" aria-controls=\"e-n-accordion-item-1070\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> What should I do if the pressure sensor suddenly fails or gives erratic readings? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1070\" class=\"elementor-element elementor-element-666d3f5 e-con-full e-flex e-con e-child\" data-id=\"666d3f5\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1070\" class=\"elementor-element elementor-element-3fa5bf3 e-flex e-con-boxed e-con e-child\" data-id=\"3fa5bf3\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-9250858 elementor-widget elementor-widget-text-editor\" data-id=\"9250858\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>This is a common issue on the Component B (Iso) line. Over time, or if exposed to cold drafts, MDI can freeze and crystallize directly onto the pressure sensor&#8217;s diaphragm, freezing the reading.\u00a0<em>Solution:<\/em>\u00a0Carefully remove the sensor head and place it in a heating oven set to\u00a0<strong>no higher than 50-70\u00b0C<\/strong>\u00a0for a few hours to gently melt the crystallized B-material.\u00a0<em>(Note: Never use 180-200\u00b0C open flames or high heat, as this will permanently destroy the MDI and the sensor).<\/em>\u00a0Replace sensors periodically as part of routine maintenance.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1071\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"2\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1071\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Why is my circulation pressure reading abnormally low?  <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1071\" class=\"elementor-element elementor-element-745eb0d e-con-full e-flex e-con e-child\" data-id=\"745eb0d\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1071\" class=\"elementor-element elementor-element-7efe4bb e-flex e-con-boxed e-con e-child\" data-id=\"7efe4bb\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-f721321 elementor-widget elementor-widget-text-editor\" data-id=\"f721321\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>A sudden drop in circulation pressure usually indicates a restriction\u00a0<em>upstream<\/em>\u00a0of the metering pump. Check the primary material filters inside the holding tanks for clogs, and ensure the pump&#8217;s inlet pipes are not obstructed or sucking air.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1072\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"3\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1072\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\">  Why is my circulation pressure reading abnormally high? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1072\" class=\"elementor-element elementor-element-cb93ca7 e-con-full e-flex e-con e-child\" data-id=\"cb93ca7\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1072\" class=\"elementor-element elementor-element-8d3d3b7 e-flex e-con-boxed e-con e-child\" data-id=\"8d3d3b7\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7fe6436 elementor-widget elementor-widget-text-editor\" data-id=\"7fe6436\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>High pressure indicates a blockage\u00a0<em>downstream<\/em>\u00a0of the pump, anywhere between the pump outlet and the tank return port. In older machines, Component B pipelines slowly constrict over time as MDI residue polymerizes and deposits on the inner walls. Most critically, inspect the injection valves at the mixing head for blockages.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1073\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"4\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1073\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> How do I minimize the A\/B circulation pressure differential? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1073\" class=\"elementor-element elementor-element-ef1b472 e-flex e-con-boxed e-con e-child\" data-id=\"ef1b472\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-ac565ce elementor-widget elementor-widget-text-editor\" data-id=\"ac565ce\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Circulation pressure is dictated by pipeline diameter and length. To balance the system, Haifeng machines are equipped with adjustable &#8220;Back-Pressure Valves&#8221; located near the injection head or on the tank return lines. Carefully adjusting these valves allows operators to artificially balance the resistance on both the A and B lines.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t\t<details id=\"e-n-accordion-item-1074\" class=\"e-n-accordion-item\" >\n\t\t\t\t<summary class=\"e-n-accordion-item-title\" data-accordion-index=\"5\" tabindex=\"-1\" aria-expanded=\"false\" aria-controls=\"e-n-accordion-item-1074\" >\n\t\t\t\t\t<span class='e-n-accordion-item-title-header'><div class=\"e-n-accordion-item-title-text\"> Is it true that I can just match the pump motor RPM ratio to my desired chemical ratio? <\/div><\/span>\n\t\t\t\t\t\t\t<span class='e-n-accordion-item-title-icon'>\n\t\t\t<span class='e-opened' ><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-minus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h384c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t\t<span class='e-closed'><svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-plus\" viewBox=\"0 0 448 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M416 208H272V64c0-17.67-14.33-32-32-32h-32c-17.67 0-32 14.33-32 32v144H32c-17.67 0-32 14.33-32 32v32c0 17.67 14.33 32 32 32h144v144c0 17.67 14.33 32 32 32h32c17.67 0 32-14.33 32-32V304h144c17.67 0 32-14.33 32-32v-32c0-17.67-14.33-32-32-32z\"><\/path><\/svg><\/span>\n\t\t<\/span>\n\n\t\t\t\t\t\t<\/summary>\n\t\t\t\t<div role=\"region\" aria-labelledby=\"e-n-accordion-item-1074\" class=\"elementor-element elementor-element-a7fdeb4 e-flex e-con-boxed e-con e-child\" data-id=\"a7fdeb4\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-f553992 elementor-widget elementor-widget-text-editor\" data-id=\"f553992\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Absolutely not. For example, if your formula requires a 1:1.2 ratio of A to B, simply setting the motor speeds to 1:1.2 will fail. You must account for the vastly different viscosities and flow characteristics of the two liquids. This is why Haifeng utilizes mass flow meters\u2014we measure the actual mass of the liquid being delivered, not just how fast the motor is spinning.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/details>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4709772 elementor-widget elementor-widget-html\" data-id=\"4709772\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<script type=\"application\/ld+json\">\r\n{\r\n  \"@context\": \"https:\/\/schema.org\",\r\n  \"@type\": \"FAQPage\",\r\n  \"mainEntity\": [\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"What should I do if the pressure sensor suddenly fails or gives erratic readings?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"This is a common issue on the Component B (Iso) line. Over time, MDI can freeze and crystallize directly onto the pressure sensor's diaphragm, freezing the reading. Carefully remove the sensor head and place it in a heating oven set to no higher than 50-70\u00b0C for a few hours to gently melt the crystallized B-material. Never use open flames.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Why is my circulation pressure reading abnormally low?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"A sudden drop in circulation pressure usually indicates a restriction upstream of the metering pump. Check the primary material filters inside the holding tanks for clogs, and ensure the pump's inlet pipes are not obstructed or sucking air.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Why is my circulation pressure reading abnormally high?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"High pressure indicates a blockage downstream of the pump, anywhere between the pump outlet and the tank return port. In older machines, Component B pipelines slowly constrict over time as MDI residue polymerizes and deposits on the inner walls. Most critically, inspect the injection valves at the mixing head for blockages.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"How do I minimize the A\/B circulation pressure differential?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"Circulation pressure is dictated by pipeline diameter and length. To balance the system, Haifeng machines are equipped with adjustable 'Back-Pressure Valves' located near the injection head or on the tank return lines. Carefully adjusting these valves allows operators to artificially balance the resistance on both the A and B lines.\"\r\n      }\r\n    },\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"Is it true that I can just match the pump motor RPM ratio to my desired chemical ratio?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"Absolutely not. For example, if your formula requires a 1:1.2 ratio of A to B, simply setting the motor speeds to 1:1.2 will fail. You must account for the vastly different viscosities and flow characteristics of the two liquids. This is why Haifeng utilizes mass flow meters to measure the actual mass delivered, not just motor speed.\"\r\n      }\r\n    }\r\n  ]\r\n}\r\n<\/script>\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-e74f193 e-flex e-con-boxed e-con e-parent\" data-id=\"e74f193\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-fee5b2e elementor-widget elementor-widget-author-box\" data-id=\"fee5b2e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"author-box.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-author-box\">\n\t\t\t\t\t\t\t<a href=\"https:\/\/www.linkedin.com\/in\/jiacheng-dai-haifeng-automation\/%20EEAT\u80cc\u4e66\" class=\"elementor-author-box__avatar\" target=\"_blank\" rel=\"noopener\">\n\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/haifengmachine.com\/wp-content\/uploads\/2026\/04\/6f52b74a24f1daff3840682463cc195c-300x300.png\" alt=\"Picture of Jiacheng Dai\" loading=\"lazy\" title=\"\">\n\t\t\t\t<\/a>\n\t\t\t\n\t\t\t<div class=\"elementor-author-box__text\">\n\t\t\t\t\t\t\t\t\t<a href=\"https:\/\/www.linkedin.com\/in\/jiacheng-dai-haifeng-automation\/%20EEAT\u80cc\u4e66\" target=\"_blank\" rel=\"noopener\">\n\t\t\t\t\t\t<span class=\"elementor-author-box__name\">\n\t\t\t\t\t\t\tJiacheng Dai\t\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t<div class=\"elementor-author-box__bio\">\n\t\t\t\t\t\t<p>Vice President, Sales & Marketing of Zhejiang Haifeng Automation Equipment Co., Ltd<br \/>\n- Member of the Polyurethane Equipment Professional Committee, China Polyurethane Industry Association<br \/>\n- Member of the Expert Committee on Footwear and Apparel Equipment, China Leather Association<br \/>\n- Executive Vice President, Wenzhou Footwear Machinery Chamber of Commerce, China<\/p>\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>In polyurethane casting, perfect chemical formulations will still produce defective shoe soles if your machine&#8217;s hydraulic heart (the pumps) and circulatory system (the pipelines) suffer from pressure differentials. This guide delves into the extreme fluid dynamics of PU casting machines. Haifeng&#8217;s Chief Engineer exposes the myths of metering pump precision, explains how our ceramic seals solve the fatal &#8220;air ingress (cavitation)&#8221; problem, and details how our PID closed-loop systems with mass flow meters guarantee 1\/1000th dispensing accuracy. Learn how to conquer &#8220;Back Pressure,&#8221; eliminate &#8220;Lead\/Lag (Spit Difference),&#8221; and achieve absolute hydraulic control on your shop floor.<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[1],"tags":[],"table_tags":[],"class_list":["post-6084","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"acf":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/posts\/6084","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/comments?post=6084"}],"version-history":[{"count":13,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/posts\/6084\/revisions"}],"predecessor-version":[{"id":6194,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/posts\/6084\/revisions\/6194"}],"wp:attachment":[{"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/media?parent=6084"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/categories?post=6084"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/tags?post=6084"},{"taxonomy":"table_tags","embeddable":true,"href":"https:\/\/haifengmachine.com\/ko\/wp-json\/wp\/v2\/table_tags?post=6084"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}