{"id":13864,"date":"2026-07-30T06:48:38","date_gmt":"2026-07-30T06:48:38","guid":{"rendered":"https:\/\/hlh-js.com\/?p=13864"},"modified":"2026-07-30T06:48:38","modified_gmt":"2026-07-30T06:48:38","slug":"surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts","status":"publish","type":"post","link":"https:\/\/hlh-js.com\/zh\/resource\/blog\/surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts\/","title":{"rendered":"Surface Finish and Ra Values After Ceramic Bead Blasting SLS 3D Printed Parts"},"content":{"rendered":"<script type=\"application\/ld+json\">{\n    \"@context\": \"https:\\\/\\\/schema.org\",\n    \"@graph\": [\n        {\n            \"@type\": \"Article\",\n            \"headline\": \"Surface Finish and Ra Values After Ceramic Bead Blasting SLS 3D Printed Parts\",\n            \"description\": \"Comprehensive Ra and Rz data for ceramic bead blasting on SLS 3D printed parts \\u2014 covering as-built surface characteristics by build orientation, Ra by bead grade and size, surface uniformity improvement, targeting specific Ra values, and Ra consistency over ceramic vs glass media lifetime.\",\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\\\/surface-finish-and-ra-values-after-ceramic-bead-blasting-sls-3d-printed-parts\\\/\"\n            }\n        },\n        {\n            \"@type\": \"FAQPage\",\n            \"mainEntity\": [\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"What Ra is achievable on PA12 SLS parts with ceramic bead blasting?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"With ZS ceramic beads at 0.15\\u20130.25 mm and 60\\u201365 PSI, PA12 SLS parts typically achieve Ra 6\\u201311 \\u00b5m on horizontal surfaces and Ra 8\\u201314 \\u00b5m on angled side surfaces after a 6\\u201310 minute dry blast cycle. Stepping down to ZS 0.10\\u20130.15 mm at 50\\u201358 PSI achieves Ra 4\\u20138 \\u00b5m on horizontal and Ra 6\\u201310 \\u00b5m on side surfaces. The finest achievable Ra on SLS PA12 with dry ceramic bead blasting is approximately Ra 3\\u20135 \\u00b5m using ZrO\\u2082 beads at 0.05\\u20130.10 mm at 45\\u201352 PSI \\u2014 below this, wet blasting is needed to go further.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Why does surface roughness vary between horizontal and vertical faces on the same SLS part?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"This orientation-dependent variation is the staircase effect of layer-by-layer SLS sintering. Horizontal faces (perpendicular to the build direction) are the cross-section of each sintered layer and tend to be smoother \\u2014 Ra 12\\u201318 \\u00b5m as-built for PA12. Side and angled faces expose the stacked layer edges, creating visible stair-step texture at the layer thickness pitch (typically 100\\u2013120 \\u00b5m for PA12), resulting in Ra 20\\u201328 \\u00b5m as-built. Ceramic bead blasting reduces both values and \\u2014 importantly \\u2014 substantially reduces the Ra difference between orientations, from 8\\u201312 \\u00b5m as-built to 2\\u20135 \\u00b5m post-blast.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"How should I measure Ra on SLS parts after ceramic bead blasting?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Use a contact profilometer (stylus profilometer) with a 2 \\u00b5m radius stylus tip. Set the cutoff wavelength \\u03bbc to 0.8 mm, appropriate for the Ra range of 2\\u201312 \\u00b5m typical for blasted SLS surfaces, and evaluate over a length of at least 4 \\u00d7 \\u03bbc = 3.2 mm. Measure on a flat reference surface of defined build orientation \\u2014 a dedicated test coupon sintered with each production build is the standard approach, rather than measuring directly on complex-geometry production parts. Record Ra as the mean of at least 3 measurement runs; report with the surface orientation and process parameters.\"\n                    }\n                },\n                {\n                    \"@type\": \"Question\",\n                    \"name\": \"Does ceramic bead blasting Ra stay consistent over the media charge lifetime?\",\n                    \"acceptedAnswer\": {\n                        \"@type\": \"Answer\",\n                        \"text\": \"Ceramic bead media (ZS or ZrO\\u2082) maintains Ra output within approximately \\u00b11\\u20132 \\u00b5m of the qualification baseline through 80% of its service life. This gradual drift is due to progressive size reduction via spherical attrition \\u2014 smaller beads carry less energy per particle, producing slightly lower Ra while requiring marginally longer cycle times for equivalent cleaning. Glass beads degrade much faster and less predictably, with Ra drifting 3\\u20136 \\u00b5m over 300\\u2013500 cycles as beads shatter into angular fragments that produce inconsistent impact patterns. The Ra consistency of ceramic media is one of the primary reasons professional SLS operations have switched from glass to ceramic.\"\n                    }\n                }\n            ]\n        }\n    ]\n}<\/script>\n<style>\n.hlh-sls-c07{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-c07 h1{font-size:2rem;color:#1a3456;font-weight:700;line-height:1.28;margin:0 0 .5rem}\n.hlh-sls-c07 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-c07 h3{font-size:1.14rem;color:#1a3456;font-weight:700;margin:1.75rem 0 .5rem}\n.hlh-sls-c07 h4{font-size:1rem;color:#d86e18;font-weight:700;margin:1.2rem 0 .35rem}\n.hlh-sls-c07 p{margin:0 0 1rem}.hlh-sls-c07 ul,.hlh-sls-c07 ol{margin:0 0 1rem 1.5rem;padding:0}.hlh-sls-c07 li{margin-bottom:.38rem}\n.hlh-sls-c07 a{color:#d86e18;text-decoration:none;border-bottom:1px solid 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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-c07 .fq:hover{background:#e4edf6}\n.hlh-sls-c07 .fi-icon{font-size:1.2rem;color:#d86e18;flex-shrink:0;margin-left:.9rem;transition:transform .22s;font-weight:400}.hlh-sls-c07 .fq.open .fi-icon{transform:rotate(45deg)}\n.hlh-sls-c07 .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-c07 .fa.open{display:block}.hlh-sls-c07 .fa p:last-child{margin-bottom:0}\n.hlh-sls-c07 .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-c07 .cta h3{color:#fff;font-size:1.28rem;margin:0 0 .6rem}.hlh-sls-c07 .cta p{color:rgba(255,255,255,.84);font-size:.94rem;margin-bottom:1.3rem}\n.hlh-sls-c07 .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-c07 .btn:hover{background:#b85a10}\n@media(max-width:640px){.hlh-sls-c07 h1{font-size:1.5rem}.hlh-sls-c07 h2{font-size:1.2rem}.hlh-sls-c07 .cta{padding:1.5rem 1.2rem}.hlh-sls-c07 .dive{flex-direction:column;gap:.4rem}}\n<\/style>\n<article class=\"hlh-sls-c07\">\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>Surface Finish and Ra Values After Ceramic Bead Blasting SLS 3D Printed Parts<\/h1>\n<p class=\"meta\">By Jiangsu Henglihong Technology Co., Ltd. &nbsp;|&nbsp; Last updated: July 2026<\/p>\n<p class=\"lead\">Surface finish is the most directly measurable outcome of ceramic bead SLS depowdering, and Ra is the metric buyers and engineers specify most often. This article provides the complete data reference: as-built SLS surface characteristics by build orientation, Ra achieved after blasting across bead grades and sizes, the surface uniformity improvement that matters as much as absolute Ra, a guide to targeting specific Ra values, and Ra consistency over the ceramic bead media lifetime.<\/p>\n<div class=\"stats\">\n  <div class=\"stat\"><span class=\"stat-n\">Ra 15\u201325 \u00b5m<\/span><span class=\"stat-l\">Typical as-built PA12 SLS surface (all orientations)<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">Ra 4\u201312 \u00b5m<\/span><span class=\"stat-l\">Achievable range with standard ceramic bead blasting<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">8\u201312 \u00b5m<\/span><span class=\"stat-l\">As-built Ra difference between horizontal and side faces<\/span><\/div>\n  <div class=\"stat\"><span class=\"stat-n\">2\u20135 \u00b5m<\/span><span class=\"stat-l\">Ra difference between orientations after ceramic bead blast<\/span><\/div>\n<\/div>\n<nav class=\"toc\"><p class=\"toc-h\">Table of Contents<\/p>\n<ol>\n<li><a href=\"#c07-params\">Surface Roughness Parameters: Ra, Rz, and Rq Explained<\/a><\/li>\n<li><a href=\"#c07-asbuilt\">As-Built SLS Surface Characteristics by Build Orientation<\/a><\/li>\n<li><a href=\"#c07-mechanism\">How Ceramic Bead Blasting Modifies SLS Surface Texture<\/a><\/li>\n<li><a href=\"#c07-data\">Comprehensive Ra Data Table by Bead Grade, Size, and Pressure<\/a><\/li>\n<li><a href=\"#c07-uniformity\">Surface Uniformity Improvement: Beyond Absolute Ra Numbers<\/a><\/li>\n<li><a href=\"#c07-target\">Targeting Specific Ra Values: Parameter Control Guide<\/a><\/li>\n<li><a href=\"#c07-consistency\">Ra Consistency Over Ceramic vs. Glass Media Lifetime<\/a><\/li>\n<li><a href=\"#c07-measure\">Ra Measurement Protocol for SLS Depowdering QC<\/a><\/li>\n<li><a href=\"#c07-faq\">Frequently Asked Questions<\/a><\/li>\n<\/ol><\/nav>\n\n<h2 id=\"c07-params\">1. Surface Roughness Parameters: Ra, Rz, and Rq Explained<\/h2>\n<p>Three surface roughness parameters appear most frequently in SLS production quality specifications. Understanding what each measures \u2014 and why Ra dominates SLS depowdering QC \u2014 prevents misinterpretation of measurement data.<\/p>\n<p><strong>Ra (arithmetic mean roughness)<\/strong> is the average absolute deviation of the surface profile from its mean line, measured over the evaluation length. It is the most widely used parameter for SLS depowdering QC because it is stable, repeatable, and directly correlated with visual and tactile surface quality. Ra is specified in the pillar page and throughout this series.<\/p>\n<p><strong>Rz (mean roughness depth)<\/strong> is the average of the five largest peak-to-valley heights within the evaluation length. Rz is more sensitive to isolated deep valleys or high peaks than Ra. For SLS surfaces with occasional sub-surface voids or particularly high sintering peaks, Rz provides a more conservative safety indicator for applications where extreme surface events matter \u2014 coating adhesion on sintered nylon parts, for example, is better predicted by Rz than Ra.<\/p>\n<p><strong>Rq (root mean square roughness)<\/strong> weights outliers more heavily than Ra. It is less commonly specified for SLS depowdering QC but appears in optical scattering models and some medical device specifications. For general SLS production, Ra is the primary specification parameter.<\/p>\n\n<h2 id=\"c07-asbuilt\">2. As-Built SLS Surface Characteristics by Build Orientation<\/h2>\n<p>The as-built surface of SLS nylon parts is not uniform \u2014 it varies systematically with build orientation due to the layer-by-layer sintering process. Understanding this starting point is necessary to interpret post-blast Ra data correctly.<\/p>\n<div class=\"tw\"><table><thead><tr><th>Surface Orientation<\/th><th>PA12 As-Built Ra<\/th><th>PA11 As-Built Ra<\/th><th>Origin of Texture<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Horizontal (top, perpendicular to build)<\/strong><\/td><td>12\u201318 \u00b5m<\/td><td>12\u201318 \u00b5m<\/td><td>Cross-section of sintered layer \u2014 smoothest as-built face<\/td><\/tr>\n<tr><td><strong>Side \/ angled (parallel to build direction)<\/strong><\/td><td>20\u201328 \u00b5m<\/td><td>19\u201326 \u00b5m<\/td><td>Staircase effect of stacked layer edges at layer thickness pitch<\/td><\/tr>\n<tr><td><strong>Downward-facing (in-bed bottom)<\/strong><\/td><td>16\u201323 \u00b5m<\/td><td>15\u201322 \u00b5m<\/td><td>Contact with powder bed during sintering; moderate texture<\/td><\/tr>\n<tr><td><strong>TPU (any orientation)<\/strong><\/td><td colspan=\"2\">14\u201325 \u00b5m (Shore A 85\u201395, all orientations)<\/td><td>Similar staircase effect; compliance adds variability<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>The anisotropy \u2014 the Ra difference between horizontal and side surfaces \u2014 is typically 8\u201312 \u00b5m on as-built PA12 SLS parts. This difference is clearly visible to the eye: horizontal top faces appear noticeably smoother than angled side walls. On assemblies where different face orientations are simultaneously visible in the finished product, this anisotropy is one of the most common appearance quality complaints from customers receiving unprocessed SLS output.<\/p>\n\n<h2 id=\"c07-mechanism\">3. How Ceramic Bead Blasting Modifies SLS Surface Texture<\/h2>\n<p>Ceramic bead blasting modifies SLS surface texture through two simultaneous mechanisms. First, the impact force breaks and dislodges the semi-sintered powder skin \u2014 removing the outermost heterogeneous layer and exposing the more uniform fully sintered nylon substrate. Second, the compressive peening action of spherical beads deforms micro-peaks on the surface (reducing peak height) and partially fills micro-valleys through plastic deformation of the surrounding material.<\/p>\n<p>The combined effect is a more uniform, lower-amplitude surface texture. Micro-peaks that were responsible for the highest Ra values on side faces are reduced; valleys are partially filled; and the overall profile becomes more sinusoidal and less jagged. Importantly, this smoothing effect is most pronounced on the rougher surfaces (angled side walls) \u2014 which reduces the Ra differential between orientations more than it reduces Ra on already-smoother horizontal faces. The result is not just lower Ra but substantially less anisotropy.<\/p>\n\n<h2 id=\"c07-data\">4. Comprehensive Ra Data Table by Bead Grade, Size, and Process<\/h2>\n<p>All values below are for dry blast, suction-feed cabinet, PA12 SLS (100 \u00b5m layer, standard build parameters). PA11 values are within \u00b11 \u00b5m of PA12 at equivalent conditions.<\/p>\n<div class=\"tw\"><table><thead><tr><th>Bead Grade \/ Size<\/th><th>Pressure<\/th><th>Cycle<\/th><th>Horizontal Ra<\/th><th>Side Ra<\/th><th>Bottom Ra<\/th><th>Ra Anisotropy<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>ZrO\u2082 0.05\u20130.10 mm<\/strong><\/td><td>48 PSI<\/td><td>14 min<\/td><td>3\u20135 \u00b5m<\/td><td>5\u20138 \u00b5m<\/td><td>4\u20136 \u00b5m<\/td><td>2\u20133 \u00b5m<\/td><\/tr>\n<tr><td><strong>ZS 0.05\u20130.10 mm<\/strong><\/td><td>45 PSI<\/td><td>16 min<\/td><td>3\u20136 \u00b5m<\/td><td>5\u20139 \u00b5m<\/td><td>4\u20137 \u00b5m<\/td><td>2\u20133 \u00b5m<\/td><\/tr>\n<tr><td><strong>ZrO\u2082 0.10\u20130.15 mm<\/strong><\/td><td>55 PSI<\/td><td>9 min<\/td><td>4\u20136 \u00b5m<\/td><td>5\u20139 \u00b5m<\/td><td>4\u20137 \u00b5m<\/td><td>1\u20133 \u00b5m<\/td><\/tr>\n<tr><td><strong>ZS 0.10\u20130.15 mm<\/strong><\/td><td>52 PSI<\/td><td>10 min<\/td><td>4\u20137 \u00b5m<\/td><td>6\u201310 \u00b5m<\/td><td>5\u20138 \u00b5m<\/td><td>2\u20133 \u00b5m<\/td><\/tr>\n<tr><td><strong>ZS 0.15\u20130.25 mm<\/strong><\/td><td>62 PSI<\/td><td>7 min<\/td><td>6\u201310 \u00b5m<\/td><td>8\u201313 \u00b5m<\/td><td>6\u201311 \u00b5m<\/td><td>2\u20134 \u00b5m<\/td><\/tr>\n<tr><td><strong>ZS 0.25\u20130.35 mm<\/strong><\/td><td>68 PSI<\/td><td>5 min<\/td><td>9\u201314 \u00b5m<\/td><td>11\u201317 \u00b5m<\/td><td>9\u201315 \u00b5m<\/td><td>2\u20134 \u00b5m<\/td><\/tr>\n<tr><td><strong>Glass 0.10\u20130.18 mm<\/strong><\/td><td>60 PSI<\/td><td>8 min<\/td><td>6\u201312 \u00b5m<\/td><td>9\u201316 \u00b5m<\/td><td>7\u201313 \u00b5m<\/td><td>3\u20135 \u00b5m<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>The glass bead row is included for direct comparison. Note the wider Ra ranges for glass beads, reflecting the higher variability in Ra output that results from glass bead degradation even within a single run as bead sphericity decreases.<\/p>\n\n<h2 id=\"c07-uniformity\">5. Surface Uniformity Improvement: Beyond Absolute Ra Numbers<\/h2>\n<p>The most commercially significant outcome of ceramic bead blasting on SLS parts is often not the absolute Ra value achieved but the <strong>reduction in Ra anisotropy<\/strong> \u2014 the Ra difference between horizontal and side faces. This difference, which ranges from 8\u201312 \u00b5m as-built, drops to 2\u20134 \u00b5m after ceramic bead blasting across all bead sizes in the table above.<\/p>\n<p>Why this matters commercially: buyers of SLS parts evaluate appearance quality visually. A part where the top face looks smoother than the side walls is visually obviously &#8220;not finished.&#8221; Even if both faces pass a Ra specification individually, a part where horizontal Ra = 8 \u00b5m and side Ra = 20 \u00b5m will look two-toned and unrefined. After ceramic bead blasting, a part where horizontal Ra = 7 \u00b5m and side Ra = 10 \u00b5m looks visually uniform \u2014 the 3 \u00b5m difference is imperceptible to the eye and touch, even though the absolute Ra values are not identical.<\/p>\n<p>This is why ceramic bead blasting is described as providing a &#8220;uniform matte finish&#8221; on SLS parts rather than a specific Ra value \u2014 the uniformity is often the commercial deliverable, and it is achieved reliably across bead size and pressure settings in the production range.<\/p>\n\n<h2 id=\"c07-target\">6. Targeting Specific Ra Values: Parameter Control Guide<\/h2>\n<div class=\"tw\"><table><thead><tr><th>Ra Target<\/th><th>Recommended Bead<\/th><th>Pressure<\/th><th>Cycle Time<\/th><th>Application<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Ra 3\u20135 \u00b5m<\/strong><\/td><td>ZrO\u2082 0.05\u20130.10 mm<\/td><td>45\u201352 PSI<\/td><td>12\u201318 min<\/td><td>Premium appearance, fine-finish specifications<\/td><\/tr>\n<tr><td><strong>Ra 4\u20137 \u00b5m<\/strong><\/td><td>ZS 0.10\u20130.15 mm<\/td><td>48\u201356 PSI<\/td><td>8\u201314 min<\/td><td>Appearance parts, pre-dye for light colours<\/td><\/tr>\n<tr><td><strong>Ra 6\u201310 \u00b5m<\/strong><\/td><td>ZS 0.15\u20130.25 mm<\/td><td>58\u201368 PSI<\/td><td>5\u201310 min<\/td><td>Standard production, pre-dye for standard\/dark colours<\/td><\/tr>\n<tr><td><strong>Ra 8\u201314 \u00b5m<\/strong><\/td><td>ZS 0.20\u20130.35 mm<\/td><td>62\u201372 PSI<\/td><td>4\u20137 min<\/td><td>Functional parts where appearance is secondary; coarser dyeing<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>Ra is a probabilistic output \u2014 it falls within a range rather than hitting a single value, because it depends on local part geometry, blast angle, and coverage uniformity. Specify Ra ranges in production documentation rather than single target values. A specification of &#8220;Ra 5\u20139 \u00b5m&#8221; is achievable and inspectable; &#8220;Ra exactly 7 \u00b5m&#8221; is not.<\/p>\n\n<h2 id=\"c07-consistency\">7. Ra Consistency Over Ceramic vs. Glass Media Lifetime<\/h2>\n<p>Ra output consistency over the service life of the blast media charge is one of the most important \u2014 and most often overlooked \u2014 factors in selecting between ceramic and glass beads for SLS depowdering.<\/p>\n<div class=\"tw\"><table><thead><tr><th>\u5a92\u4f53\u7c7b\u578b<\/th><th>Service Life (cycles)<\/th><th>Ra Drift Over Lifetime<\/th><th>Consistency Characteristic<\/th><\/tr><\/thead>\n<tbody>\n<tr><td><strong>Ceramic ZS<\/strong><\/td><td>1,500\u20132,500<\/td><td>\u00b11\u20132 \u00b5m from qualification baseline<\/td><td>Gradual, predictable drift; stable for 80% of service life<\/td><\/tr>\n<tr><td><strong>Ceramic ZrO\u2082<\/strong><\/td><td>2,500\u20134,000<\/td><td>\u00b10.5\u20131.5 \u00b5m from baseline<\/td><td>Most stable Ra output of all media types<\/td><\/tr>\n<tr><td><strong>\u73bb\u7483\u73e0<\/strong><\/td><td>400\u2013800<\/td><td>3\u20136 \u00b5m upward drift over 300\u2013600 cycles<\/td><td>Ra degrades as beads shatter and shift to angular population<\/td><\/tr>\n<\/tbody><\/table><\/div>\n<p>The practical consequence for SLS production: with glass beads, Ra monitoring becomes a daily task because drift can be rapid. Parts qualified at Ra 8 \u00b5m on a fresh glass bead charge may reach Ra 13 \u00b5m by the time the charge is halfway through its service life \u2014 a drift that may push parts out of Ra specification without any change in blast parameters. With ceramic ZS or ZrO\u2082 beads, Ra monitoring can be done weekly or monthly with far less risk of undetected out-of-specification production.<\/p>\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-beads-vs-glass-beads-for-sls-3d-printing-depowdering-performance-and-cost\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads vs. Glass Beads for SLS Depowdering: Performance and Cost<\/a>\n<p>Full comparison of Ra consistency, recycling cycles, failure mode, and cost-per-part between ceramic and glass bead media.<\/p>\n<\/div><\/div>\n\n<h2 id=\"c07-measure\">8. Ra Measurement Protocol for SLS Depowdering QC<\/h2>\n<p>Consistent Ra measurement requires a standardised protocol so results are comparable across shifts, operators, and batches. The following protocol applies to contact profilometry (stylus instrument) on PA12\/PA11 SLS reference coupons:<\/p>\n<div class=\"box box-a\">\n<h4>Standard Ra measurement protocol for SLS depowdering QC<\/h4>\n<ul>\n<li><strong>Instrument:<\/strong> contact profilometer (stylus tip radius 2 \u00b5m)<\/li>\n<li><strong>Cutoff wavelength (\u03bbc):<\/strong> 0.8 mm (appropriate for Ra 2\u201312 \u00b5m per ISO 4288)<\/li>\n<li><strong>Evaluation length:<\/strong> 4 mm (5 \u00d7 \u03bbc = 4.0 mm is the standard evaluation length for \u03bbc 0.8 mm)<\/li>\n<li><strong>Surface:<\/strong> flat reference coupon, horizontal build orientation (top face), sintered in each production build<\/li>\n<li><strong>Measurement location:<\/strong> central zone of the flat reference face, avoiding edges (\u22653 mm from any edge)<\/li>\n<li><strong>Number of runs:<\/strong> minimum 3; report as mean \u00b1 standard deviation<\/li>\n<li><strong>Frequency:<\/strong> once per production batch (once per build) at minimum<\/li>\n<li><strong>Record:<\/strong> coupon ID, build date, bead grade, bead size, pressure, cycle time, media charge age, Ra mean \u00b1 SD<\/li>\n<\/ul>\n<\/div>\n<p>Do not measure Ra directly on production parts for routine QC \u2014 the profilometer stylus can leave a detectable scratch on clean blasted nylon surfaces, and complex part geometry prevents standardised measurement positioning. The reference coupon approach is reproducible, non-destructive to production parts, and creates a documented trend record that supports both process control and customer quality evidence requirements.<\/p>\n\n<h2 id=\"c07-faq\">Frequently Asked Questions<\/h2>\n<div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">What Ra is achievable on PA12 SLS parts with ceramic bead blasting? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>With ZS beads at 0.15\u20130.25 mm and 60\u201365 PSI, PA12 SLS parts typically achieve Ra 6\u201310 \u00b5m on horizontal surfaces and Ra 8\u201313 \u00b5m on side surfaces. Stepping down to 0.10\u20130.15 mm at 50\u201358 PSI achieves Ra 4\u20137 \u00b5m horizontal and Ra 6\u201310 \u00b5m side. The finest Ra achievable with dry ceramic bead blasting is approximately Ra 3\u20135 \u00b5m using ZrO\u2082 beads at 0.05\u20130.10 mm \u2014 below this, wet ceramic bead blasting is needed, which can achieve Ra 3\u20135 \u00b5m at equivalent bead sizes due to the water-cushioned impact reducing peak surface stress.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">Why does surface roughness vary between horizontal and vertical faces on the same SLS part? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>This orientation-dependent variation is the staircase effect of layer-by-layer SLS sintering. Horizontal faces are the cross-section of each sintered layer and tend to be smoother \u2014 Ra 12\u201318 \u00b5m as-built for PA12. Side and angled faces expose the stacked layer edges at the layer pitch (typically 100\u2013120 \u00b5m for PA12), creating visible stair-step texture at Ra 20\u201328 \u00b5m as-built. Ceramic bead blasting reduces both values significantly, and \u2014 crucially \u2014 reduces the Ra difference between orientations from 8\u201312 \u00b5m as-built to 2\u20134 \u00b5m post-blast, producing the visually uniform matte surface that professional SLS output requires.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">How should I measure Ra on SLS parts after ceramic bead blasting? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Use a contact profilometer with a 2 \u00b5m radius stylus tip, cutoff wavelength \u03bbc = 0.8 mm, and evaluation length of 4 mm. Measure on a flat reference coupon sintered with each production build \u2014 on the horizontal top face at a defined central location, avoiding edges. Record the mean of at least 3 measurement runs. Do not measure directly on production parts for routine QC; the profilometer stylus leaves a detectable mark on clean blasted nylon and complex geometry prevents standardised positioning. The reference coupon approach is reproducible and non-destructive to production parts.<\/p><\/div><\/div>\n<div class=\"fi\"><button class=\"fq\" aria-expanded=\"false\">Does Ra stay consistent over the ceramic bead media charge lifetime? <span class=\"fi-icon\">+<\/span><\/button>\n<div class=\"fa\"><p>Yes \u2014 ceramic bead media (ZS or ZrO\u2082) maintains Ra output within approximately \u00b11\u20132 \u00b5m of the qualification baseline through 80% of its service life. Gradual drift is due to progressive bead size reduction through spherical attrition; smaller beads produce marginally lower Ra and require slightly longer cycles. Glass beads degrade much faster and less predictably, with Ra drifting 3\u20136 \u00b5m upward over 300\u2013500 cycles as beads shatter into angular fragments. The Ra consistency of ceramic media is one of the primary commercial reasons professional SLS operations have replaced glass beads with ceramic \u2014 it enables less frequent Ra measurement and reduces the risk of undetected out-of-specification production.<\/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>The primary variable controlling Ra \u2014 complete size-to-Ra selection matrix.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/blast-pressure-and-cycle-time-for-ceramic-bead-sls-depowdering-optimization-guide\/\" target=\"_blank\" rel=\"noopener noreferrer\">Blast Pressure and Cycle Time Optimization<\/a><p>How pressure adjustments shift Ra within the range set by bead size.<\/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>The companion quality metric to Ra \u2014 how blasting affects SLS part dimensions.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/wet-vs-dry-ceramic-bead-blasting-for-sls-nylon-powder-removal-process-comparison\/\" target=\"_blank\" rel=\"noopener noreferrer\">Wet vs. Dry Ceramic Bead Blasting<\/a><p>How wet blasting achieves 1\u20133 \u00b5m lower Ra than dry at the same bead size.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/ceramic-beads-vs-glass-beads-for-sls-3d-printing-depowdering-performance-and-cost\/\" target=\"_blank\" rel=\"noopener noreferrer\">Ceramic Beads vs. Glass Beads<\/a><p>Why ceramic&#8217;s Ra consistency over media life is a key commercial differentiator.<\/p><\/div>\n<div class=\"rel-c\"><a href=\"https:\/\/hlh-js.com\/resource\/blog\/color-consistency-and-dye-preparation-for-sls-parts-after-ceramic-bead-blasting\/\" target=\"_blank\" rel=\"noopener noreferrer\">Color Consistency and Dye Preparation<\/a><p>How Ra level controls dye uptake depth and colour saturation in PA12\/PA11 SLS.<\/p><\/div>\n<\/div>\n<div class=\"cta\"><h3>Specify Ceramic Beads for Your SLS Surface Finish Target<\/h3>\n<p>Jiangsu Henglihong Technology Co., Ltd. supplies ZS and ZrO\u2082 ceramic blasting beads in ISO-classified sizes from 0.05 mm to 0.60 mm with full PSD documentation. Tell us your Ra specification and SLS material \u2014 we will identify the right bead grade and size and supply samples for first-article Ra qualification.<\/p>\n<a href=\"https:\/\/hlh-js.com\/contact\/\" target=\"_blank\" rel=\"noopener noreferrer\" class=\"btn\">Request Samples &amp; Ra Data<\/a><\/div>\n<\/article>\n<script>(function(){var b=document.querySelectorAll('.hlh-sls-c07 .fq');b.forEach(function(btn){btn.addEventListener('click',function(){var a=this.nextElementSibling,o=a.classList.contains('open');document.querySelectorAll('.hlh-sls-c07 .fa').forEach(function(x){x.classList.remove('open')});document.querySelectorAll('.hlh-sls-c07 .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":13866,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[62,175,138],"tags":[],"class_list":["post-13864","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-industry","category-resource"],"_links":{"self":[{"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/posts\/13864","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/comments?post=13864"}],"version-history":[{"count":2,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/posts\/13864\/revisions"}],"predecessor-version":[{"id":13867,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/posts\/13864\/revisions\/13867"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/media\/13866"}],"wp:attachment":[{"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/media?parent=13864"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/categories?post=13864"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/hlh-js.com\/zh\/wp-json\/wp\/v2\/tags?post=13864"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}