{"id":13856,"date":"2026-07-30T06:48:28","date_gmt":"2026-07-30T06:48:28","guid":{"rendered":"https:\/\/hlh-js.com\/?p=13856"},"modified":"2026-07-30T06:48:28","modified_gmt":"2026-07-30T06:48:28","slug":"blast-pressure-and-cycle-time-for-ceramic-bead-sls-depowdering-optimization-guide","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/fr\/resource\/blog\/blast-pressure-and-cycle-time-for-ceramic-bead-sls-depowdering-optimization-guide\/","title":{"rendered":"Blast Pressure and Cycle Time for Ceramic Bead SLS Depowdering: Optimization Guide"},"content":{"rendered":"<script type=\"application\/ld+json\">{\n    \"@context\": \"https:\\\/\\\/schema.org\",\n    \"@graph\": [\n        {\n            \"@type\": \"Article\",\n            \"headline\": \"Blast Pressure and Cycle Time for Ceramic Bead SLS Depowdering: Optimization Guide\",\n            \"description\": \"Complete optimization guide for blast pressure and cycle time in ceramic bead SLS powder removal \\u2014 covering suction vs pressure-feed systems, pressure selection by material and wall thickness, nozzle setup, bead embedment prevention, and first-article process qualification.\",\n            \"datePublished\": \"2026-07-27\",\n            \"dateModified\": \"2026-07-27\",\n            \"author\": {\n                \"@type\": \"Organization\",\n                \"name\": \"Jiangsu Henglihong Technology Co., Ltd.\",\n                \"url\": \"https:\\\/\\\/hlh-js.com\"\n            },\n            \"publisher\": {\n                \"@type\": \"Organization\",\n                \"name\": \"Jiangsu Henglihong Technology Co., Ltd.\",\n                \"url\": \"https:\\\/\\\/hlh-js.com\"\n            },\n            \"mainEntityOfPage\": {\n                \"@type\": \"WebPage\",\n                \"@id\": \"https:\\\/\\\/hlh-js.com\\\/resource\\\/blog\\\/blast-pressure-and-cycle-time-for-ceramic-bead-sls-depowdering-optimization-guide\\\/\"\n            }\n        },\n        {\n            \"@type\": \"FAQPage\",\n            \"mainEntity\": [\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"What is the difference between suction-feed and pressure-feed blast cabinets for SLS depowdering?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"In a suction-feed cabinet, compressed air creates a venturi that draws media from the reservoir; this produces lower bead velocity at the same inlet PSI compared to a pressure-feed system. In a pressure-feed system, compressed air pressurises the media pot directly, propelling beads at higher velocity. For equivalent cleaning at the same inlet pressure, pressure-feed delivers approximately 30\\u201350% more kinetic energy per impact. In practice: when converting a suction-feed protocol to pressure-feed, reduce the inlet pressure by 10\\u201315 PSI to achieve equivalent impact energy. For SLS nylon, suction-feed is the preferred starting configuration because its lower velocity provides a safer process window for thin-walled features.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"How do I determine the correct cycle time for a new PA12 SLS part design?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Run the first blast cycle on a qualification part in 2-minute increments. After each increment, remove the part, blow clean with compressed air, and inspect under directional light for: (1) completeness of powder removal on all surfaces; (2) visible breaking and removal of the semi-sintered skin; (3) any signs of over-blasting on thin features. The minimum cycle time at which inspection criteria pass is your baseline. Add 10% to this baseline for the production specification to account for normal media charge aging over time. Document this baseline and the media charge state at qualification so future performance can be trended against it.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"What causes bead embedment in SLS nylon parts and how do I prevent it?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Bead embedment occurs when ceramic beads become lodged in the surface of a PA12 or PA11 part rather than bouncing off cleanly. It is caused by three concurrent factors: blast pressure above the material's surface yield stress, bead particles that have become irregular or angular due to degradation, and reentrant surface features (sharp internal corners, blind holes) where beads can accumulate. Prevention: stay within the qualified pressure range, maintain the ceramic bead charge within its specified size distribution via regular sieve analysis, and reduce pressure on parts with acute internal angles. Inspect for embedment at 5-10\\u00d7 magnification on first-article qualification runs for complex geometry.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Should I adjust blast pressure as my ceramic bead charge ages?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Yes, modest pressure adjustment may be needed as the media charge ages. As ceramic beads wear through spherical attrition, average particle size decreases and the charge delivers slightly less kinetic energy per impact at the same inlet pressure. If your reference Ra begins drifting upward while pressure remains constant, you can increase pressure by 3\\u20135 PSI to compensate \\u2014 but this is a short-term measure. A sustained Ra drift upward despite pressure increases indicates the media charge is approaching end of life and needs a top-up or partial replacement. Do not rely on pressure increases alone to compensate for severely degraded media.\"\n                    }\n                }\n            ]\n        }\n    ]\n}<\/script>\n<style>\n.hlh-sls-c05{font-family:'Segoe UI',Arial,sans-serif;color:#2c3e50;line-height:1.82;max-width:860px;margin:0 auto;font-size:16px}\n.hlh-sls-c05 h1{font-size:2rem;color:#1a3456;font-weight:700;line-height:1.28;margin:0 0 .5rem}\n.hlh-sls-c05 h2{font-size:1.46rem;color:#1a3456;font-weight:700;margin:2.5rem 0 .72rem;padding-bottom:.4rem;border-bottom:3px solid #d86e18}\n.hlh-sls-c05 h3{font-size:1.14rem;color:#1a3456;font-weight:700;margin:1.75rem 0 .5rem}\n.hlh-sls-c05 h4{font-size:1rem;color:#d86e18;font-weight:700;margin:1.2rem 0 .35rem}\n.hlh-sls-c05 p{margin:0 0 1rem}.hlh-sls-c05 ul,.hlh-sls-c05 ol{margin:0 0 1rem 1.5rem;padding:0}.hlh-sls-c05 li{margin-bottom:.38rem}\n.hlh-sls-c05 a{color:#d86e18;text-decoration:none;border-bottom:1px solid rgba(216,110,24,.35)}.hlh-sls-c05 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.fq{background:#f0f4f8;padding:.9rem 1.2rem;font-weight:600;font-size:.94rem;color:#1a3456;cursor:pointer;display:flex;justify-content:space-between;align-items:center;border:none;width:100%;text-align:left;transition:background .18s}.hlh-sls-c05 .fq:hover{background:#e4edf6}\n.hlh-sls-c05 .fi-icon{font-size:1.2rem;color:#d86e18;flex-shrink:0;margin-left:.9rem;transition:transform .22s;font-weight:400}.hlh-sls-c05 .fq.open .fi-icon{transform:rotate(45deg)}\n.hlh-sls-c05 .fa{display:none;padding:.88rem 1.2rem 1rem;font-size:.92rem;background:#fff;color:#2c3e50;line-height:1.78;border-top:1px solid #e2eaf2}.hlh-sls-c05 .fa.open{display:block}.hlh-sls-c05 .fa p:last-child{margin-bottom:0}\n.hlh-sls-c05 .cta{background:linear-gradient(135deg,#1a3456 0%,#24466e 100%);border-radius:10px;padding:2rem 2.3rem;margin:2.8rem 0 1rem;text-align:center}\n.hlh-sls-c05 .cta h3{color:#fff;font-size:1.28rem;margin:0 0 .6rem}.hlh-sls-c05 .cta p{color:rgba(255,255,255,.84);font-size:.94rem;margin-bottom:1.3rem}\n.hlh-sls-c05 .btn{display:inline-block;background:#d86e18;color:#fff!important;font-weight:700;font-size:1rem;padding:.73rem 2.1rem;border-radius:4px;text-decoration:none!important;border:none!important;transition:background .2s}.hlh-sls-c05 .btn:hover{background:#b85a10}\n@media(max-width:640px){.hlh-sls-c05 h1{font-size:1.5rem}.hlh-sls-c05 h2{font-size:1.2rem}.hlh-sls-c05 .cta{padding:1.5rem 1.2rem}.hlh-sls-c05 .dive{flex-direction:column;gap:.4rem}}\n<\/style>\n<article class=\"hlh-sls-c05\">\n<div class=\"back\">&#8592; Part of: <a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-beads-sls-powder-removal-complete-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads for SLS Powder Removal \u2014 Complete Guide<\/a><\/div>\n<h1>Blast Pressure and Cycle Time for Ceramic Bead SLS Depowdering: Optimization Guide<\/h1>\n<p class=\"meta\">By Jiangsu Henglihong Technology Co., Ltd. &nbsp;|&nbsp; Last updated: July 2026<\/p>\n<p class=\"lead\">Once bead size is selected, blast pressure and cycle time are the two primary controls that determine how effectively ceramic beads depowder your SLS parts \u2014 and whether the result is clean and dimensionally sound or over-blasted and out of specification. This guide covers the physics behind pressure selection, the critical differences between suction-feed and pressure-feed systems, pressure tables by material and geometry, nozzle setup, bead embedment prevention, and the first-article process qualification approach that underpins a stable production protocol.<\/p>\n<div class=\"stats\">\n  <div class=\"stat\"><span class=\"stat-n\">10\u201315 PSI<\/span><span class=\"stat-l\">Pressure reduction needed when switching from suction-feed to pressure-feed<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">50\u201375 mm\u00b2\/s<\/span><span class=\"stat-l\">Typical nozzle coverage rate per second at production standoff<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">2-min<\/span><span class=\"stat-l\">Recommended first-article blast increment for new geometry<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">10%<\/span><span class=\"stat-l\">Buffer to add over first-article cycle time for production spec<\/span><\/div>\n<\/div>\n<nav class=\"toc\"><p class=\"toc-h\">Table of Contents<\/p>\n<ol>\n<li><a href=\"#c05-physics\">The Physics of Blast Pressure in Ceramic Bead SLS Depowdering<\/a><\/li>\n<li><a href=\"#c05-systems\">Suction-Feed vs. Pressure-Feed: Same Pressure, Different Velocity<\/a><\/li>\n<li><a href=\"#c05-table\">Blast Pressure Reference Table by SLS Material and Geometry<\/a><\/li>\n<li><a href=\"#c05-nozzle\">Nozzle Diameter and Standoff Distance<\/a><\/li>\n<li><a href=\"#c05-cycletime\">Cycle Time Determination Methodology<\/a><\/li>\n<li><a href=\"#c05-embedment\">Bead Embedment: Recognition, Causes, and Prevention<\/a><\/li>\n<li><a href=\"#c05-qualify\">Process Qualification and Parameter Documentation<\/a><\/li>\n<li><a href=\"#c05-faq\">Questions fr\u00e9quemment pos\u00e9es<\/a><\/li>\n<\/ol><\/nav>\n\n<h2 id=\"c05-physics\">1. The Physics of Blast Pressure in Ceramic Bead SLS Depowdering<\/h2>\n<p>Blast pressure controls bead velocity, and velocity \u2014 squared \u2014 controls kinetic energy. The relationship is: KE = \u00bdmv\u00b2. At the same blast pressure, a denser bead (ZrO\u2082 at 5.5 g\/cm\u00b3) delivers more kinetic energy than a lighter bead (glass at 2.5 g\/cm\u00b3) because its mass (m) is greater for an equal-size particle. This is why ceramic beads depowder more effectively than glass beads at equivalent pressure settings, and why ceramic bead protocols use lower pressures than steel shot for comparable cleaning tasks.<\/p>\n<p>For SLS nylon depowdering, the pressure window is defined by two constraints: the lower bound is the minimum pressure at which the ceramic bead has sufficient kinetic energy to break the semi-sintered powder bond on the part surface; the upper bound is the pressure above which the nylon substrate begins to erode, thin walls deform, or bead embedment occurs. For PA12, this window is approximately 40\u201375 PSI depending on geometry; for flexible TPU it narrows to 28\u201345 PSI.<\/p>\n<p>Blast pressure at the nozzle is not the same as inlet regulator pressure. Pressure drops through the blast hose, fittings, and nozzle. The pressure difference between regulator and nozzle exit depends on hose length, hose diameter, fittings, and media flow rate. For consistent results, calibrate nozzle pressure with a direct gauge reading at the nozzle inlet rather than relying on the regulator display alone.<\/p>\n\n<h2 id=\"c05-systems\">2. Suction-Feed vs. Pressure-Feed: Same Pressure, Different Velocity<\/h2>\n<p>The two most common blast cabinet configurations for SLS depowdering \u2014 suction-feed (siphon) and pressure-feed (direct pressure pot) \u2014 deliver different bead velocities at the same inlet pressure. This matters significantly for SLS nylon, where the process window between effective cleaning and surface damage can be narrow.<\/p>\n<div class=\"tw\"><table><thead><tr><th>Factor<\/th><th>Suction-Feed<\/th><th>Pressure-Feed<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Bead velocity at 60 PSI inlet<\/strong><\/td><td>Moderate (~40\u201355 m\/s)<\/td><td>Higher (~65\u201385 m\/s)<\/td><\/tr>\n<tr><td><strong>Equivalent cleaning pressure<\/strong><\/td><td>60 PSI baseline<\/td><td>~47\u201350 PSI for same impact energy<\/td><\/tr>\n<tr><td><strong>Throughput<\/strong><\/td><td>Mod\u00e9r\u00e9<\/td><td>Haut<\/td><\/tr>\n<tr><td><strong>Process window for SLS nylon<\/strong><\/td><td>Wider \u2014 more forgiving<\/td><td>Narrower \u2014 requires tighter control<\/td><\/tr>\n<tr><td><strong>Best for<\/strong><\/td><td>New protocol development, complex geometry, flexible SLS<\/td><td>High-volume rigid PA12 production<\/td><\/tr>\n<tr><td><strong>Equipment cost<\/strong><\/td><td>Lower<\/td><td>Higher<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p><strong>Practical conversion rule:<\/strong> when converting a suction-feed protocol to pressure-feed at equivalent impact energy, reduce the inlet pressure by 10\u201315 PSI. A suction-feed protocol at 65 PSI for PA12 standard geometry translates to approximately 50\u201355 PSI on a pressure-feed system. Always verify by first-article inspection after converting \u2014 do not assume the conversion is exact without measurement.<\/p>\n\n<h2 id=\"c05-table\">3. Blast Pressure Reference Table by SLS Material and Geometry<\/h2>\n<p>All values are for suction-feed cabinets with ZS ceramic beads in the 0.15\u20130.25 mm size range. For pressure-feed systems, reduce by 10\u201315 PSI. For finer beads (0.10\u20130.15 mm), the lower end of each range applies.<\/p>\n<div class=\"tw\"><table><thead><tr><th>SLS Material<\/th><th>Part Type<\/th><th>Min Feature<\/th><th>Suction-Feed Pressure<\/th><th>Cycle Time<\/th><th>Key Watch Point<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>PA12<\/strong><\/td><td>Large simple geometry<\/td><td>Wall \u2265 3 mm<\/td><td>65\u201378 PSI<\/td><td>4\u20137 min<\/td><td>Even coverage on flat faces<\/td><\/tr>\n<tr><td><strong>PA12<\/strong><\/td><td>Standard production<\/td><td>Wall 2\u20133 mm<\/td><td>58\u201372 PSI<\/td><td>5\u201310 min<\/td><td>Open surfaces + channel exits<\/td><\/tr>\n<tr><td><strong>PA12<\/strong><\/td><td>Complex geometry<\/td><td>Wall 1.5\u20132.5 mm<\/td><td>48\u201362 PSI<\/td><td>7\u201314 min<\/td><td>Inspect fine features mid-cycle<\/td><\/tr>\n<tr><td><strong>PA12<\/strong><\/td><td>Fine channels &lt; 1 mm<\/td><td>Body \u2265 1.5 mm<\/td><td>40\u201355 PSI<\/td><td>12\u201320 min<\/td><td>Channel exit powder check<\/td><\/tr>\n<tr><td><strong>PA12<\/strong><\/td><td>Thin walls<\/td><td>Wall 0.8\u20131.5 mm<\/td><td>38\u201350 PSI<\/td><td>8\u201316 min<\/td><td>Inspect thin walls for stress marks<\/td><\/tr>\n<tr><td><strong>PA11<\/strong><\/td><td>Standard<\/td><td>Wall \u2265 2 mm<\/td><td>55\u201370 PSI<\/td><td>5\u201310 min<\/td><td>Fixture flexible features before blast<\/td><\/tr>\n<tr><td><strong>PA11<\/strong><\/td><td>Flexible assembly<\/td><td>Flex sections<\/td><td>45\u201358 PSI<\/td><td>7\u201313 min<\/td><td>Inspect fixtured sections mid-cycle<\/td><\/tr>\n<tr><td><strong>TPU A85\u201395<\/strong><\/td><td>Standard body<\/td><td>Wall \u2265 2 mm<\/td><td>35\u201345 PSI<\/td><td>3\u20135 min\/cycle<\/td><td>Inspect after every cycle<\/td><\/tr>\n<tr><td><strong>TPU A75\u201385<\/strong><\/td><td>Any<\/td><td>Wall \u2265 1.2 mm<\/td><td>28\u201336 PSI<\/td><td>2\u20133 min\/cycle<\/td><td>Deformation check after each cycle<\/td><\/tr>\n<\/tbody><\/table><\/div>\n\n<h2 id=\"c05-nozzle\">4. Nozzle Diameter and Standoff Distance<\/h2>\n<h3>Nozzle diameter<\/h3>\n<p>Nozzle diameter controls the coverage rate \u2014 the area of part surface blasted per unit time \u2014 and the blast plume concentration. Larger diameter nozzles blast more area per second but produce a dispersed plume with lower peak intensity; smaller diameter nozzles produce a concentrated, high-intensity blast over a smaller footprint.<\/p>\n<ul>\n<li><strong>6\u20138 mm nozzle:<\/strong> fine geometry, complex assemblies, lattice structures, channels \u2014 high precision, slower area coverage<\/li>\n<li><strong>10\u201312 mm nozzle:<\/strong> standard PA12 production \u2014 balanced throughput and coverage uniformity<\/li>\n<li><strong>14\u201316 mm nozzle:<\/strong> large flat surfaces, high-volume simple-geometry parts \u2014 fastest throughput, higher average Ra<\/li>\n<\/ul>\n<h3>Standoff distance<\/h3>\n<p>Standoff distance \u2014 the distance from the nozzle exit to the part surface \u2014 is an underappreciated process variable. As standoff increases, the blast plume expands and per-unit-area impact intensity decreases. As standoff decreases, impact intensity increases but coverage area per pass reduces and localised over-blasting risk increases on exposed edges.<\/p>\n<div class=\"tw\"><table><thead><tr><th>Standoff Distance<\/th><th>Impact Intensity (relative)<\/th><th>Coverage Area per Pass<\/th><th>Application<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>40\u201360 mm<\/td><td>High (1.8\u20132.5\u00d7)<\/td><td>Small, concentrated<\/td><td>Targeted channel cleaning; stubborn recesses<\/td><\/tr>\n<tr><td>70\u2013100 mm<\/td><td>Standard (1\u00d7)<\/td><td>Mod\u00e9r\u00e9<\/td><td>Standard PA12 production; most SLS depowdering<\/td><\/tr>\n<tr><td>110\u2013150 mm<\/td><td>Reduced (0.55\u20130.75\u00d7)<\/td><td>Broad<\/td><td>Thin-wall PA12; flexible TPU; large flat surfaces<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>For most SLS depowdering, 75\u2013110 mm standoff is the practical working range. Use shorter standoff (<70 mm) only for targeted spot cleaning of specific powder-filled recesses, not as the general cabinet setting.<\/p>\n\n<h2 id=\"c05-cycletime\">5. Cycle Time Determination Methodology<\/h2>\n<p>Cycle time for a given part geometry and blast protocol cannot be reliably predicted from first principles without empirical validation. The correct approach is the incremental first-article method:<\/p>\n<ol>\n<li><strong>Set up:<\/strong> confirm bead grade, size, pressure, and nozzle per protocol specification<\/li>\n<li><strong>Run Increment 1:<\/strong> blast for 2 minutes, remove part, blow clean with compressed air<\/li>\n<li><strong>Inspect:<\/strong> assess powder removal completeness on all surfaces and channel exits; note any areas still showing semi-sintered skin; check thin features for any signs of stress<\/li>\n<li><strong>Continue or stop:<\/strong> if complete \u2014 record 2 minutes as baseline; if incomplete \u2014 run Increment 2 and re-inspect; repeat until criteria pass<\/li>\n<li><strong>Add buffer:<\/strong> production cycle time = baseline \u00d7 1.10 (10% buffer for media charge aging)<\/li>\n<li><strong>Document:<\/strong> record bead grade, size, media charge age (cycles since last replacement), pressure, nozzle, standoff, cycle time, and Ra measurement on reference coupon<\/li>\n<\/ol>\n<p>The 10% buffer accommodates the gradual decline in media kinetic energy as beads wear through their service life. Without this buffer, a protocol qualified on a fresh media charge may begin failing mid-service-life as the average bead diameter shrinks and kinetic energy per particle decreases.<\/p>\n\n<h2 id=\"c05-embedment\">6. Bead Embedment: Recognition, Causes, and Prevention<\/h2>\n<p>Bead embedment \u2014 ceramic particles lodged in the surface of a nylon SLS part \u2014 is one of the most consequential process failures in SLS depowdering. Embedded beads create surface contamination that interferes with dyeing (producing pinholes or uncoloured spots), coating adhesion (local delamination), and dimensional measurement (raised surface spots that appear as dimensional non-conformances).<\/p>\n<h4>Causes<\/h4>\n<ul>\n<li><strong>Excess blast pressure:<\/strong> energy above the material&#8217;s surface yield stress drives beads into the surface during impact rather than allowing clean rebound<\/li>\n<li><strong>Degraded, angular media:<\/strong> beads that have broken down from spherical to angular have a higher tendency to embed due to their irregular impact geometry<\/li>\n<li><strong>Reentrant features:<\/strong> acute internal corners, blind holes, and undercuts create accumulation zones where beads can pack and progressively embed under continued blast impact<\/li>\n<li><strong>High-velocity pressure-feed at same PSI as suction-feed protocol:<\/strong> over-energy delivery leading to embedment on parts that were clean at suction-feed settings<\/li>\n<\/ul>\n<h4>Detection<\/h4>\n<p>Inspect suspected embedment areas at 5\u201310\u00d7 magnification under oblique light. Embedded ceramic beads appear as white or cream-coloured spherical inclusions sitting above or flush with the nylon surface. Under UV light (365 nm), ZrO\u2082 beads may show weak fluorescence that distinguishes them from the nylon background.<\/p>\n<h4>Prevention<\/h4>\n<ul>\n<li>Stay within the qualified pressure range; never increase pressure beyond specification without a formal re-qualification<\/li>\n<li>Monitor media condition by sieve analysis; maintain the size distribution within the specified range to preserve spherical morphology<\/li>\n<li>Reduce pressure on parts with acute internal angles or blind features<\/li>\n<li>Limit cycle time: once the semi-sintered skin is removed, additional blast time does not clean further \u2014 it only risks embedment and dimensional removal<\/li>\n<\/ul>\n\n<div class=\"dive\"><div class=\"dive-i\">&#128196;<\/div><div>\n<span class=\"dive-l\">Related Reference<\/span>\n<a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-size-selection-for-sls-powder-removal-matching-mesh-to-part-geometry\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Bead Size Selection: Matching Mesh to Part Geometry<\/a>\n<p>Bead size must be specified before pressure \u2014 this article provides the complete size selection matrix for all SLS materials and geometry types.<\/p>\n<\/div><\/div>\n\n<h2 id=\"c05-qualify\">7. Process Qualification and Parameter Documentation<\/h2>\n<p>A qualified blast protocol is a documented set of parameters \u2014 bead grade, bead size, pressure, nozzle, standoff, cycle time, and media charge state \u2014 that consistently delivers the specified surface quality (Ra, powder-free status) within the dimensional tolerance of the part. Qualification is performed once per part design and then maintained as the frozen production specification.<\/p>\n<div class=\"box box-a\">\n<h4>Minimum qualification record content<\/h4>\n<ul>\n<li>Part number and revision<\/li>\n<li>Ceramic bead grade (ZS \/ ZrO\u2082 \/ alumina-silicate) and size range (mm)<\/li>\n<li>Blast cabinet type (suction-feed \/ pressure-feed)<\/li>\n<li>Inlet pressure at qualification (PSI), measured at nozzle inlet<\/li>\n<li>Nozzle diameter (mm) and standoff distance (mm)<\/li>\n<li>Cycle time (minutes)<\/li>\n<li>Media charge state at qualification (cycles since last replacement or top-up)<\/li>\n<li>Ra result on reference coupon (\u00b5m, surface orientation specified)<\/li>\n<li>Pre-blast and post-blast dimension on at least one OD and one ID reference feature<\/li>\n<li>Visual inspection result: powder-free Y\/N, embedment absent Y\/N<\/li>\n<\/ul>\n<\/div>\n<p>For SLS parts used in regulated applications (medical devices, aerospace), the blast process qualification should be maintained as a special process validation record (e.g., per NADCAP, AS9100, ISO 13485). Jiangsu Henglihong Technology Co., Ltd. can supply Certificate of Conformance and material data sheets for ceramic bead media to support customer process validation dossiers.<\/p>\n\n<h2 id=\"c05-faq\">Questions fr\u00e9quemment pos\u00e9es<\/h2>\n<div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">What is the difference between suction-feed and pressure-feed blast cabinets for SLS depowdering? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>In a suction-feed cabinet, compressed air creates a venturi that draws media from the reservoir at lower bead velocity for the same inlet PSI. In a pressure-feed system, the media pot is pressurised directly, propelling beads at higher velocity. For equivalent cleaning at the same inlet pressure, pressure-feed delivers approximately 30\u201350% more kinetic energy per impact. When converting a suction-feed protocol to pressure-feed, reduce inlet pressure by 10\u201315 PSI to match impact energy. For SLS nylon, suction-feed is the preferred starting configuration because its lower velocity provides a safer process window for thin-walled features and complex geometry.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">How do I determine the correct cycle time for a new PA12 SLS part design? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Run the first blast cycle on a qualification part in 2-minute increments. After each increment, remove the part, blow clean, and inspect under directional light for completeness of powder removal on all surfaces and any signs of over-blasting on thin features. The minimum cycle time at which all inspection criteria pass is your baseline. Add 10% to this baseline for the production specification to accommodate normal media charge aging. Document all parameters (pressure, bead grade, size, nozzle, cycle time, media charge state) and the Ra result on a reference coupon at qualification. This becomes the frozen production specification.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">What causes bead embedment in SLS nylon parts and how do I prevent it? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Bead embedment occurs when ceramic beads become lodged in the nylon surface rather than bouncing off cleanly. It is caused by: blast pressure above the material surface yield stress; beads that have become irregular or angular due to degradation (maintain sieve-analysis monitoring); and reentrant features such as acute internal corners where beads can accumulate and pack. Prevent by staying within qualified pressure limits, maintaining the media charge within its specified size distribution, reducing pressure on parts with acute internal geometry, and avoiding extended blast cycles beyond the point of complete powder removal.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">Should I adjust blast pressure as my ceramic bead charge ages? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Modest pressure adjustment (3\u20135 PSI increase) can compensate for the gradual decline in per-impact energy as beads wear and average particle size decreases. However, sustained Ra drift upward despite pressure increases is a sign the media charge is approaching end of life and needs top-up or partial replacement \u2014 do not continue raising pressure as a long-term substitute for media management. The better approach is to include a 10% cycle time buffer at qualification (rather than pressure increase) and use sieve analysis monitoring to replace media before significant performance degradation occurs.<\/p><\/div><\/div>\n<\/div>\n\n<h2>Related Articles in This Series<\/h2>\n<p>Return to the <a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-beads-sls-powder-removal-complete-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads for SLS Powder Removal \u2014 Complete Guide<\/a> for the full overview.<\/p>\n<div class=\"rel-g\">\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-size-selection-for-sls-powder-removal-matching-mesh-to-part-geometry\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Bead Size Selection Guide<\/a><p>Bead size must be set before pressure \u2014 the complete selection matrix for all SLS materials.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts\/\" target=\"_blank\" rel=\"noopener noreferrer\">Surface Finish Ra Values After Blasting<\/a><p>Full Ra dataset \u2014 how pressure interacts with bead size to control surface roughness.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/dimensional-accuracy-and-tolerances-after-ceramic-bead-blasting-sls-nylon-parts\/\" target=\"_blank\" rel=\"noopener noreferrer\">Dimensional Accuracy and Tolerances<\/a><p>How pressure and cycle time control material removal from SLS parts.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-blasting-pa12-nylon-sls-parts-depowdering-and-surface-prep\/\" target=\"_blank\" rel=\"noopener noreferrer\">PA12 SLS Depowdering Protocol<\/a><p>Applying pressure and cycle time parameters to the most common SLS material.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-blasting-tpu-flexible-sls-parts-gentle-depowdering-without-deformation\/\" target=\"_blank\" rel=\"noopener noreferrer\">TPU Flexible SLS Depowdering<\/a><p>Low-pressure protocol for flexible SLS \u2014 the most demanding pressure calibration challenge.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-bead-recycling-and-lifespan-management-in-sls-depowdering-operations\/\" target=\"_blank\" rel=\"noopener noreferrer\">Bead Recycling and Lifespan Management<\/a><p>How media aging affects blast pressure performance and when to top up the charge.<\/p><\/div>\n<\/div>\n<div class=\"cta\"><h3>Need Help Setting the Right Blast Pressure for Your SLS Operation?<\/h3>\n<p>Jiangsu Henglihong Technology Co., Ltd. supplies ceramic blasting beads with full technical documentation \u2014 including recommended pressure ranges by bead grade and size. Tell us your SLS material, part geometry, and blast cabinet type, and we will recommend starting parameters and supply samples for first-article qualification.<\/p>\n<a href=\"https:\/\/hlh-js.com\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"btn\">Request Technical Support<\/a><\/div>\n<\/article>\n<script>(function(){var b=document.querySelectorAll('.hlh-sls-c05 .fq');b.forEach(function(btn){btn.addEventListener('click',function(){var a=this.nextElementSibling,o=a.classList.contains('open');document.querySelectorAll('.hlh-sls-c05 .fa').forEach(function(x){x.classList.remove('open')});document.querySelectorAll('.hlh-sls-c05 .fq').forEach(function(x){x.classList.remove('open');x.setAttribute('aria-expanded','false')});if(!o){a.classList.add('open');btn.classList.add('open');btn.setAttribute('aria-expanded','true')}})})})();<\/script>","protected":false},"excerpt":{"rendered":"<p>&#8592; Part of: Ceramic Beads for SLS Powder Removal \u2014  [&#8230;]<\/p>","protected":false},"author":1,"featured_media":13858,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,175,138],"tags":[],"class_list":["post-13856","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13856","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/comments?post=13856"}],"version-history":[{"count":2,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13856\/revisions"}],"predecessor-version":[{"id":13859,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/posts\/13856\/revisions\/13859"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/media\/13858"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/media?parent=13856"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/categories?post=13856"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/fr\/wp-json\/wp\/v2\/tags?post=13856"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}