{"id":835570,"date":"2026-09-14T11:18:02","date_gmt":"2026-09-14T11:18:02","guid":{"rendered":"https:\/\/www.abnewswire.com\/pressreleases\/?p=835570"},"modified":"2026-09-14T11:18:02","modified_gmt":"2026-09-14T11:18:02","slug":"investment-casting-tolerances-under-iso-8062-define-key-ct-grade-requirements","status":"publish","type":"post","link":"https:\/\/www.abnewswire.com\/pressreleases\/investment-casting-tolerances-under-iso-8062-define-key-ct-grade-requirements_835570.html","title":{"rendered":"Investment Casting Tolerances Under ISO 8062 Define Key CT Grade Requirements"},"content":{"rendered":"<p style=\"text-align: justify;\"><strong>Taiyuan, Shanxi<\/strong><strong>, China &#8211; September 1<\/strong><strong>4<\/strong><strong>, 2026 &#8211;&nbsp;<\/strong><a rel=\"nofollow\" title=\"Investment Casting\" href=\"https:\/\/www.simis-manufacturer.com\/custom-customized-investment-casting-factory-supplier\/\">Investment Casting<\/a> (lost-wax casting) can achieve dimensional tolerances of&nbsp;<strong>CT5 to CT7 per ISO 8062-3<\/strong>, depending on the shell process used &mdash; silica sol process delivers CT5&ndash;CT7, while water glass process delivers CT9&ndash;CT11. For a 50 mm dimension, this translates to approximately &plusmn;0.25 mm to &plusmn;0.50 mm. Surface finish ranges from Ra 6.3 &mu;m to Ra 12.5 &mu;m, and minimum wall thickness can be as thin as 1.5 mm. Understanding these tolerance grades is critical for engineers and procurement teams when specifying castings and evaluating supplier capabilities.<\/p>\n<p style=\"text-align: justify;\">What Is ISO 8062?<\/p>\n<p style=\"text-align: justify;\">ISO 8062 is the international standard that defines <strong>dimensional and geometrical tolerances for castings<\/strong>. The current version, <strong>ISO 8062-3:2019<\/strong>, specifies general dimensional tolerances, geometrical tolerances, and machining allowance grades for castings produced by all casting processes and all cast metals and alloys.<\/p>\n<p style=\"text-align: justify;\">The standard defines <strong>16 tolerance grades<\/strong>, designated <strong>CT1 through CT16<\/strong>, where CT1 is the tightest (most precise) and CT16 is the loosest (least precise). Each grade specifies a total tolerance band for a given nominal dimension range.<\/p>\n<p style=\"text-align: justify;\">Key points about ISO 8062:<\/p>\n<ul style=\"text-align: justify;\">\n<li>&middot; The CT value represents the <strong>total tolerance band<\/strong> (not a &plusmn; value). If your drawing specifies a bilateral &plusmn; tolerance, divide the CT value by 2. For example, CT6 at 50 mm = 0.64 mm total = &plusmn;0.32 mm.<\/li>\n<li>&middot; The standard applies to <strong>as-cast dimensions<\/strong> before any secondary machining.<\/li>\n<li>&middot; Different casting processes naturally fall into different CT grade ranges &mdash; no single process can achieve all 16 grades.<\/li>\n<li>&middot; The equivalent Chinese national standard is <strong>GB\/T 6414<\/strong>, and the German standard is <strong>VDG P690<\/strong> (where grade D2 roughly corresponds to CT5).<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Understanding CT Grades<\/p>\n<p style=\"text-align: justify;\">The CT grade system works on a simple principle: <strong>lower number = tighter tolerance = higher precision = higher cost<\/strong>.<\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>CT Grade Range<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Precision Level<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Typical Processes<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CT1&ndash;CT3<\/p>\n<\/td>\n<td>\n<p>Ultra-high precision<\/p>\n<\/td>\n<td>\n<p>Rarely achieved by casting; typically requires Cnc Machining<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CT4&ndash;CT6<\/p>\n<\/td>\n<td>\n<p>High precision<\/p>\n<\/td>\n<td>\n<p>Silica sol investment casting, high-pressure die casting<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CT7&ndash;CT9<\/p>\n<\/td>\n<td>\n<p>Medium precision<\/p>\n<\/td>\n<td>\n<p>Water glass investment casting, Shell Molding, permanent mold casting<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CT10&ndash;CT12<\/p>\n<\/td>\n<td>\n<p>Standard precision<\/p>\n<\/td>\n<td>\n<p>Machine sand casting, gravity die casting<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CT13&ndash;CT16<\/p>\n<\/td>\n<td>\n<p>Low precision<\/p>\n<\/td>\n<td>\n<p>Hand mold sand casting, large castings<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\">For investment casting specifically, the achievable grade depends primarily on the <strong>shell-making process<\/strong>:<\/p>\n<ul style=\"text-align: justify;\">\n<li>&middot; <strong>Silica sol process<\/strong>: CT5&ndash;CT7 &mdash; the most precise investment casting method, suitable for stainless steel, alloy steel, and high-temperature alloys requiring tight tolerances and excellent surface finish.<\/li>\n<li>&middot; <strong>Water glass process<\/strong>: CT9&ndash;CT11 &mdash; more cost-effective for carbon steel and lower-precision applications, with slightly rougher surface finish.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Full ISO 8062 Tolerance Table<\/p>\n<p style=\"text-align: justify;\">The following table shows the <strong>total dimensional tolerance band<\/strong> in millimeters for CT4 through CT12, covering the range most relevant to investment casting and precision sand casting.<\/p>\n<p style=\"text-align: justify;\"><strong>Important:<\/strong> All values are total tolerance bands. For &plusmn; (bilateral) tolerances, divide by 2.<\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>Nominal Dimension (mm) &gt; &le;<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT4<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT5<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT6<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT7<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT8<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT9<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT10<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT11<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>CT12<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>0 &ndash; 10<\/p>\n<\/td>\n<td>\n<p>0.26<\/p>\n<\/td>\n<td>\n<p>0.36<\/p>\n<\/td>\n<td>\n<p>0.52<\/p>\n<\/td>\n<td>\n<p>0.74<\/p>\n<\/td>\n<td>\n<p>1.0<\/p>\n<\/td>\n<td>\n<p>1.5<\/p>\n<\/td>\n<td>\n<p>2.0<\/p>\n<\/td>\n<td>\n<p>2.8<\/p>\n<\/td>\n<td>\n<p>4.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>10 &ndash; 16<\/p>\n<\/td>\n<td>\n<p>0.27<\/p>\n<\/td>\n<td>\n<p>0.38<\/p>\n<\/td>\n<td>\n<p>0.54<\/p>\n<\/td>\n<td>\n<p>0.78<\/p>\n<\/td>\n<td>\n<p>1.1<\/p>\n<\/td>\n<td>\n<p>1.6<\/p>\n<\/td>\n<td>\n<p>2.2<\/p>\n<\/td>\n<td>\n<p>3.0<\/p>\n<\/td>\n<td>\n<p>4.4<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>16 &ndash; 25<\/p>\n<\/td>\n<td>\n<p>0.28<\/p>\n<\/td>\n<td>\n<p>0.40<\/p>\n<\/td>\n<td>\n<p>0.56<\/p>\n<\/td>\n<td>\n<p>0.82<\/p>\n<\/td>\n<td>\n<p>1.2<\/p>\n<\/td>\n<td>\n<p>1.7<\/p>\n<\/td>\n<td>\n<p>2.4<\/p>\n<\/td>\n<td>\n<p>3.2<\/p>\n<\/td>\n<td>\n<p>4.8<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>25 &ndash; 40<\/p>\n<\/td>\n<td>\n<p>0.30<\/p>\n<\/td>\n<td>\n<p>0.42<\/p>\n<\/td>\n<td>\n<p>0.60<\/p>\n<\/td>\n<td>\n<p>0.86<\/p>\n<\/td>\n<td>\n<p>1.3<\/p>\n<\/td>\n<td>\n<p>1.8<\/p>\n<\/td>\n<td>\n<p>2.6<\/p>\n<\/td>\n<td>\n<p>3.6<\/p>\n<\/td>\n<td>\n<p>5.2<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>40 &ndash; 63<\/p>\n<\/td>\n<td>\n<p>0.32<\/p>\n<\/td>\n<td>\n<p>0.46<\/p>\n<\/td>\n<td>\n<p>0.64<\/p>\n<\/td>\n<td>\n<p>0.92<\/p>\n<\/td>\n<td>\n<p>1.4<\/p>\n<\/td>\n<td>\n<p>2.0<\/p>\n<\/td>\n<td>\n<p>2.8<\/p>\n<\/td>\n<td>\n<p>4.0<\/p>\n<\/td>\n<td>\n<p>5.6<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>63 &ndash; 100<\/p>\n<\/td>\n<td>\n<p>0.36<\/p>\n<\/td>\n<td>\n<p>0.50<\/p>\n<\/td>\n<td>\n<p>0.70<\/p>\n<\/td>\n<td>\n<p>1.0<\/p>\n<\/td>\n<td>\n<p>1.6<\/p>\n<\/td>\n<td>\n<p>2.2<\/p>\n<\/td>\n<td>\n<p>3.2<\/p>\n<\/td>\n<td>\n<p>4.4<\/p>\n<\/td>\n<td>\n<p>6.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>100 &ndash; 160<\/p>\n<\/td>\n<td>\n<p>0.40<\/p>\n<\/td>\n<td>\n<p>0.56<\/p>\n<\/td>\n<td>\n<p>0.78<\/p>\n<\/td>\n<td>\n<p>1.1<\/p>\n<\/td>\n<td>\n<p>1.8<\/p>\n<\/td>\n<td>\n<p>2.5<\/p>\n<\/td>\n<td>\n<p>3.6<\/p>\n<\/td>\n<td>\n<p>5.0<\/p>\n<\/td>\n<td>\n<p>7.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>160 &ndash; 250<\/p>\n<\/td>\n<td>\n<p>0.50<\/p>\n<\/td>\n<td>\n<p>0.70<\/p>\n<\/td>\n<td>\n<p>1.0<\/p>\n<\/td>\n<td>\n<p>1.4<\/p>\n<\/td>\n<td>\n<p>2.0<\/p>\n<\/td>\n<td>\n<p>2.8<\/p>\n<\/td>\n<td>\n<p>4.0<\/p>\n<\/td>\n<td>\n<p>5.6<\/p>\n<\/td>\n<td>\n<p>8.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>250 &ndash; 400<\/p>\n<\/td>\n<td>\n<p>0.56<\/p>\n<\/td>\n<td>\n<p>0.78<\/p>\n<\/td>\n<td>\n<p>1.1<\/p>\n<\/td>\n<td>\n<p>1.6<\/p>\n<\/td>\n<td>\n<p>2.2<\/p>\n<\/td>\n<td>\n<p>3.2<\/p>\n<\/td>\n<td>\n<p>4.4<\/p>\n<\/td>\n<td>\n<p>6.4<\/p>\n<\/td>\n<td>\n<p>9.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>400 &ndash; 630<\/p>\n<\/td>\n<td>\n<p>0.64<\/p>\n<\/td>\n<td>\n<p>0.90<\/p>\n<\/td>\n<td>\n<p>1.2<\/p>\n<\/td>\n<td>\n<p>1.8<\/p>\n<\/td>\n<td>\n<p>2.5<\/p>\n<\/td>\n<td>\n<p>3.6<\/p>\n<\/td>\n<td>\n<p>5.0<\/p>\n<\/td>\n<td>\n<p>7.0<\/p>\n<\/td>\n<td>\n<p>10.0<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>630 &ndash; 1000<\/p>\n<\/td>\n<td>\n<p>0.72<\/p>\n<\/td>\n<td>\n<p>1.0<\/p>\n<\/td>\n<td>\n<p>1.4<\/p>\n<\/td>\n<td>\n<p>2.0<\/p>\n<\/td>\n<td>\n<p>2.8<\/p>\n<\/td>\n<td>\n<p>4.0<\/p>\n<\/td>\n<td>\n<p>5.6<\/p>\n<\/td>\n<td>\n<p>8.0<\/p>\n<\/td>\n<td>\n<p>11.0<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\"><strong>Example:<\/strong> A stainless steel investment casting with a nominal dimension of 80 mm produced by silica sol process at CT6 has a total tolerance of 0.70 mm, or &plusmn;0.35 mm.<\/p>\n<p style=\"text-align: justify;\">What Tolerances Can Investment Casting Achieve?<\/p>\n<p style=\"text-align: justify;\">Investment casting is one of the most precise near-net-shape casting processes available. Here is a breakdown of achievable tolerances by process variant:<\/p>\n<p style=\"text-align: justify;\"><strong>Silica Sol Investment Casting<\/strong><\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>Parameter<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Capability<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Dimensional tolerance<\/p>\n<\/td>\n<td>\n<p>CT4&ndash;CT6 (ISO 8062)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Tolerance at 50 mm<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.18 mm to &plusmn;0.32 mm<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Surface finish (Ra)<\/p>\n<\/td>\n<td>\n<p>1.6 &ndash; 6.3 &mu;m<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Minimum wall thickness<\/p>\n<\/td>\n<td>\n<p>0.5 &ndash; 1.5 mm<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Typical part weight<\/p>\n<\/td>\n<td>\n<p>10 g &ndash; 50 kg<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Best for<\/p>\n<\/td>\n<td>\n<p>Stainless steel, alloy steel, high-temperature alloys; parts requiring tight tolerances and excellent surface finish<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\"><strong>Water Glass Investment Casting<\/strong><\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>Parameter<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Capability<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Dimensional tolerance<\/p>\n<\/td>\n<td>\n<p>CT6&ndash;CT9 (ISO 8062)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Tolerance at 50 mm<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.32 mm to &plusmn;0.50 mm<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Surface finish (Ra)<\/p>\n<\/td>\n<td>\n<p>3.2 &ndash; 12.5 &mu;m<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Minimum wall thickness<\/p>\n<\/td>\n<td>\n<p>1.5 &ndash; 3.0 mm<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Typical part weight<\/p>\n<\/td>\n<td>\n<p>50 g &ndash; 100 kg<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Best for<\/p>\n<\/td>\n<td>\n<p>Carbon steel, low-alloy steel; cost-effective medium-precision parts<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\"><strong>Key Tolerance Characteristics of Investment Casting<\/strong><\/p>\n<p style=\"text-align: justify;\">1. <strong>Consistency<\/strong>: Investment casting offers excellent repeatability &mdash; once the wax pattern and shell process are stabilized, batch-to-batch dimensional variation is minimal.<\/p>\n<p style=\"text-align: justify;\">2. <strong>Complex geometry<\/strong>: Tolerances are maintained even on parts with undercuts, internal passages, and thin walls &mdash; features that would require extensive machining in other processes.<\/p>\n<p style=\"text-align: justify;\">3. <strong>Draft angles<\/strong>: Investment casting requires minimal or no draft angles (0.5&deg;&ndash;1&deg; typical), compared to 1&deg;&ndash;3&deg; for sand casting and die casting.<\/p>\n<p style=\"text-align: justify;\">4. <strong>Shrinkage allowance<\/strong>: Pattern dimensions are designed with a shrinkage allowance (typically 1.5%&ndash;2.5% for steel, 1.0%&ndash;1.5% for aluminum) to compensate for metal solidification shrinkage.<\/p>\n<p style=\"text-align: justify;\">Casting Process Tolerance Comparison<\/p>\n<p style=\"text-align: justify;\">Choosing the right casting process involves balancing tolerance requirements, surface finish, material compatibility, part complexity, and cost. The following table compares the typical tolerance capabilities of common casting processes:<\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>Process<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Typical CT Grade<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Tolerance at 50 mm (&plusmn;)<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Surface Finish (Ra)<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Min. Wall Thickness<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Material Range<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Investment Casting (Silica Sol)<\/strong><\/p>\n<\/td>\n<td>\n<p>CT5&ndash;CT7<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.18&ndash;0.32 mm<\/p>\n<\/td>\n<td>\n<p>1.6&ndash;6.3 &mu;m<\/p>\n<\/td>\n<td>\n<p>0.5&ndash;1.5 mm<\/p>\n<\/td>\n<td>\n<p>All metals (steel, stainless, alloy, aluminum, copper)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Investment Casting (Water Glass)<\/strong><\/p>\n<\/td>\n<td>\n<p>CT9&ndash;CT11<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.32&ndash;0.50 mm<\/p>\n<\/td>\n<td>\n<p>3.2&ndash;12.5 &mu;m<\/p>\n<\/td>\n<td>\n<p>1.5&ndash;3.0 mm<\/p>\n<\/td>\n<td>\n<p>Carbon steel, low-alloy steel<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>High-Pressure Die Casting<\/strong><\/p>\n<\/td>\n<td>\n<p>CT4&ndash;CT6<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.10&ndash;0.25 mm<\/p>\n<\/td>\n<td>\n<p>0.8&ndash;3.2 &mu;m<\/p>\n<\/td>\n<td>\n<p>0.5&ndash;0.75 mm<\/p>\n<\/td>\n<td>\n<p>Non-ferrous only (aluminum, zinc, magnesium)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><a rel=\"nofollow\" href=\"https:\/\/www.simis-manufacturer.com\/shell-mold-casting\/\">Shell Molding<\/a><\/p>\n<\/td>\n<td>\n<p>CT7&ndash;CT9<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.40&ndash;0.60 mm<\/p>\n<\/td>\n<td>\n<p>3.2&ndash;12.5 &mu;m<\/p>\n<\/td>\n<td>\n<p>2.0&ndash;3.0 mm<\/p>\n<\/td>\n<td>\n<p>Ferrous and non-ferrous<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Permanent Mold Casting<\/strong><\/p>\n<\/td>\n<td>\n<p>CT6&ndash;CT9<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.30&ndash;0.50 mm<\/p>\n<\/td>\n<td>\n<p>1.6&ndash;6.3 &mu;m<\/p>\n<\/td>\n<td>\n<p>2.0&ndash;3.0 mm<\/p>\n<\/td>\n<td>\n<p>Aluminum, zinc, magnesium, cast iron<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Machine Sand Casting<\/strong><\/p>\n<\/td>\n<td>\n<p>CT10&ndash;CT13<\/p>\n<\/td>\n<td>\n<p>&plusmn;0.75&ndash;1.50 mm<\/p>\n<\/td>\n<td>\n<p>12.5&ndash;50 &mu;m<\/p>\n<\/td>\n<td>\n<p>3.0&ndash;6.0 mm<\/p>\n<\/td>\n<td>\n<p>All metals<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p><strong>Hand Mold Sand Casting<\/strong><\/p>\n<\/td>\n<td>\n<p>CT12&ndash;CT16<\/p>\n<\/td>\n<td>\n<p>&plusmn;1.50&ndash;3.00 mm<\/p>\n<\/td>\n<td>\n<p>25&ndash;100 &mu;m<\/p>\n<\/td>\n<td>\n<p>5.0&ndash;10 mm<\/p>\n<\/td>\n<td>\n<p>All metals, especially large parts<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\"><strong>Key takeaway:<\/strong> If your part requires steel or stainless steel with tolerances tighter than CT8, <strong>investment casting (silica sol process)<\/strong> is the only viable casting process &mdash; die casting cannot handle ferrous metals, and sand casting cannot achieve CT8 or tighter.<\/p>\n<p style=\"text-align: justify;\">Factors That Affect Casting Tolerances<\/p>\n<p style=\"text-align: justify;\">Several factors influence the actual tolerances achievable on a specific investment casting:<\/p>\n<p style=\"text-align: justify;\"><strong>1. Part Geometry<\/strong><\/p>\n<ul style=\"text-align: justify;\">\n<li>&middot; <strong>Size<\/strong>: Larger parts have wider absolute tolerances (the CT grade is a percentage of dimension, so absolute tolerance increases with size).<\/li>\n<li>&middot; <strong>Wall thickness<\/strong>: Very thin walls (<\/li>\n<li>&middot; <strong>Complexity<\/strong>: Parts with deep pockets, undercuts, or internal cores may have slightly wider tolerances in those features.<\/li>\n<li>&middot; <strong>Section thickness variation<\/strong>: Abrupt changes in section thickness cause differential shrinkage and potential distortion.<\/li>\n<li>&middot; <strong>Shrinkage rate<\/strong>: Different alloys have different solidification shrinkage rates (steel ~2%, aluminum ~1.5%, copper ~1.6%). Higher shrinkage = more potential for dimensional variation.<\/li>\n<li>&middot; <strong>Melting point<\/strong>: Higher melting point alloys (stainless steel, high-temperature alloys) require hotter pouring, which increases shell thermal expansion and can slightly widen tolerances.<\/li>\n<li>&middot; <strong>Alloy composition<\/strong>: Elements that affect fluidity and solidification behavior can influence dimensional consistency.<\/li>\n<li>&middot; <strong>Wax pattern quality<\/strong>: Injection temperature, pressure, and cooling time affect pattern dimensional accuracy and stability.<\/li>\n<li>&middot; <strong>Shell building<\/strong>: Number of shell layers, slurry viscosity, and drying conditions influence shell strength and dimensional stability.<\/li>\n<li>&middot; <strong>Pouring temperature<\/strong>: Higher pouring temperatures increase metal shrinkage and shell thermal expansion.<\/li>\n<li>&middot; <strong>Shell preheat temperature<\/strong>: Preheating the shell before pouring affects metal flow and solidification rate.<\/li>\n<li>&middot; <strong>Cooling rate<\/strong>: Controlled cooling reduces residual stress and distortion.<\/li>\n<li>&middot; <strong>Cutting and grinding<\/strong>: Removing gates and risers can introduce local distortion if not done carefully.<\/li>\n<li>&middot; <a rel=\"nofollow\" href=\"https:\/\/www.simis-manufacturer.com\/heat-treatment\/\">Heat treatment<\/a>: Quenching and normalizing can cause dimensional changes, especially for parts with non-uniform section thickness.<\/li>\n<li>&middot; <strong>Shot blasting \/ sandblasting<\/strong>: Surface cleaning can remove a small amount of material (typically 0.02&ndash;0.05 mm), affecting critical dimensions.<\/li>\n<li>&middot; <a rel=\"nofollow\" href=\"https:\/\/www.simis-manufacturer.com\/cnc-machining\/\">CNC machining<\/a>: Secondary machining can achieve tolerances down to IT5&ndash;IT7 (&plusmn;0.01&ndash;0.05 mm) for critical features.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><strong>2. Material<\/strong><strong>3. Process Parameters<\/strong><strong>4. Post-Casting Operations<\/strong><\/p>\n<p style=\"text-align: justify;\">How to Achieve Tighter Casting Tolerances<\/p>\n<p style=\"text-align: justify;\">If your application requires tolerances at the tighter end of the investment casting range (CT4&ndash;CT5), consider these strategies:<\/p>\n<p style=\"text-align: justify;\"><strong>1. Design for Manufacturability (DFM)<\/strong><\/p>\n<ul style=\"text-align: justify;\">\n<li>&middot; <strong>Avoid abrupt section changes<\/strong>: Use gradual transitions (fillets, tapers) to minimize differential shrinkage.<\/li>\n<li>&middot; <strong>Specify critical dimensions<\/strong>: Clearly identify which dimensions are critical and which can use general tolerances &mdash; trying to hold every dimension to CT4 increases cost unnecessarily.<\/li>\n<li>&middot; <strong>Allow for machining stock<\/strong>: For features requiring tolerances tighter than casting can achieve, design with machining allowance (typically 0.5&ndash;1.5 mm per surface) and specify CNC machining for those features.<\/li>\n<li>&middot; <strong>Avoid thin, long features<\/strong>: Long thin sections are prone to warpage during cooling.<\/li>\n<li>&middot; <strong>Use silica sol process<\/strong>: If currently using water glass, switching to silica sol can improve tolerances by 1&ndash;2 CT grades and significantly improve surface finish.<\/li>\n<li>&middot; <strong>Stabilize wax injection<\/strong>: Use precision wax injection machines with controlled temperature, pressure, and cycle time. Use dimensionally stable wax blends.<\/li>\n<li>&middot; <strong>Control shell drying<\/strong>: Ensure consistent drying time and humidity for each shell layer &mdash; rushed drying causes shell deformation.<\/li>\n<li>&middot; <strong>Use casting simulation software<\/strong>: Tools like MAGMA, ProCAST, or AnyCasting can predict shrinkage, porosity, and distortion before tooling is cut, allowing design optimization.<\/li>\n<li>&middot; <strong>Use precision tooling<\/strong>: CNC-machined aluminum or steel wax injection dies with tight tolerances (&plusmn;0.02 mm) ensure pattern accuracy.<\/li>\n<li>&middot; <strong>Implement first-article inspection<\/strong>: Perform full dimensional inspection (CMM) on the first production samples and adjust tooling dimensions accordingly.<\/li>\n<li>&middot; <strong>Use statistical process control (SPC)<\/strong>: Monitor key dimensions over production runs to detect process drift early.<\/li>\n<li>&middot; <strong>Consider 3D-printed wax patterns<\/strong>: For low-volume or prototype parts, 3D-printed wax patterns (SLA\/DLP) can achieve pattern tolerances of &plusmn;0.05 mm, eliminating tooling-related variation.<\/li>\n<li>&middot; For critical features requiring tolerances tighter than CT4 (&plusmn;0.1 mm or better), <strong>CNC machining is the standard solution<\/strong>. Investment casting provides a near-net-shape blank, and machining achieves the final precision.<\/li>\n<li>&middot; Typical machining tolerances: IT5&ndash;IT7 per ISO 286 (&plusmn;0.01&ndash;0.05 mm for small dimensions).<\/li>\n<li>&middot; Combining investment casting with CNC machining often yields the lowest total cost for precision steel parts &mdash; better than machining from solid billet, and more precise than casting alone.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><strong>2. Process Optimization<\/strong><\/p>\n<p style=\"text-align: justify;\"><strong>3. Tooling and Quality Control<\/strong><strong>4. Secondary Machining<\/strong><\/p>\n<p style=\"text-align: justify;\">SIMIS Investment Casting Tolerance Capabilities<\/p>\n<p style=\"text-align: justify;\">At <strong>Taiyuan Simis Investment Casting Co., Ltd.<\/strong>, we operate both silica sol and water glass investment casting lines, with 6 foundries and 2 dedicated CNC machining workshops. Our tolerance capabilities include:<\/p>\n<table>\n<tbody>\n<tr>\n<td>\n<p><strong>Capability<\/strong><\/p>\n<\/td>\n<td>\n<p><strong>Specification<\/strong><\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Silica sol investment casting<\/p>\n<\/td>\n<td>\n<p>CT5&ndash;CT7 per ISO 8062<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Water glass investment casting<\/p>\n<\/td>\n<td>\n<p>CT9&ndash;CT11 per ISO 8062<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Surface finish (silica sol)<\/p>\n<\/td>\n<td>\n<p>Ra 3.2 &ndash; 6.3 &mu;m<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Surface finish (water glass)<\/p>\n<\/td>\n<td>\n<p>Ra 6.3 &ndash; 12.5 &mu;m<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Minimum wall thickness<\/p>\n<\/td>\n<td>\n<p>3.0 mm (silica sol); 5.0 mm (water glass)<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>CNC machining tolerance<\/p>\n<\/td>\n<td>\n<p>IT5&ndash;IT7 (&plusmn;0.01 &ndash; 0.05 mm) for critical features<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Part weight range<\/p>\n<\/td>\n<td>\n<p>10 g &ndash; 100 kg<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Materials<\/p>\n<\/td>\n<td>\n<p>Carbon steel (WCB, WCC), alloy steel (4140, 4340), stainless steel (304, 316\/L, CF8M), duplex stainless, heat-resistant alloys, aluminum (A356.2, ADC12), copper alloys, cast iron, Ni-Resist<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Standards<\/p>\n<\/td>\n<td>\n<p>ASTM, AISI, DIN, JIS, GB, ISO 8062<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Quality certification<\/p>\n<\/td>\n<td>\n<p>ISO 9001:2015<\/p>\n<\/td>\n<\/tr>\n<tr>\n<td>\n<p>Inspection equipment<\/p>\n<\/td>\n<td>\n<p>CMM (coordinate measuring machine), optical projector, spectral analyzer, tensile tester, hardness tester, X-ray, UT, dye penetrant<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: justify;\">We provide <strong>DFM (Design for Manufacturability) review<\/strong> for every new project &mdash; our engineering team will analyze your drawings, recommend the optimal casting process, identify features requiring CNC machining, and provide a tolerance feasibility assessment before production begins.<\/p>\n<p style=\"text-align: justify;\">For parts requiring tolerances beyond casting capability, our <strong>in-house CNC machining centers<\/strong> deliver precision finishing with full traceability &mdash; eliminating the need for a separate machining subcontractor and ensuring consistent quality from raw casting to finished part.<\/p>\n<p style=\"text-align: justify;\"><strong>Contact our engineering team<\/strong> today with your drawings for a free tolerance feasibility review and quotation.<\/p>\n<p style=\"text-align: justify;\"><strong>About Us<\/strong><\/p>\n<p style=\"text-align: justify;\">Taiyuan Simis Investment Casting Co., Ltd., is a professional foundry that integrates development and production. The company specializes in producing various investment castings, sand castings, die castings, forgings, sheet metal fabrications, and precision machined parts.<\/p>\n<p><span style='font-size:18px !important;'>Media Contact<\/span><br \/><strong>Company Name:<\/strong> <a href=\"https:\/\/www.abnewswire.com\/companyname\/simis-manufacturer.com_153025.html\" rel=\"nofollow\">Taiyuan Simis Investment Casting Co., Ltd.<\/a><br \/><strong>Contact Person:<\/strong> Media Relations<br \/><strong>Email:<\/strong> <a href=\"https:\/\/www.abnewswire.com\/email_contact_us.php?pr=investment-casting-tolerances-under-iso-8062-define-key-ct-grade-requirements\" rel=\"nofollow\">Send Email<\/a><br \/><strong>Country:<\/strong> China<br \/><strong>Website:<\/strong> <a href=\"https:\/\/www.simis-manufacturer.com\/\" target=\"_blank\" rel=\"nofollow\">https:\/\/www.simis-manufacturer.com\/<\/a><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.abnewswire.com\/press_stat.php?pr=investment-casting-tolerances-under-iso-8062-define-key-ct-grade-requirements\" alt=\"\" width=\"1px\" height=\"1px\" \/><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Taiyuan, Shanxi, China &#8211; September 14, 2026 &#8211;&nbsp;Investment Casting (lost-wax casting) can achieve dimensional tolerances of&nbsp;CT5 to CT7 per ISO 8062-3, depending on the shell process used &mdash; silica sol process delivers CT5&ndash;CT7, while water glass process delivers CT9&ndash;CT11. For &hellip; <a href=\"https:\/\/www.abnewswire.com\/pressreleases\/investment-casting-tolerances-under-iso-8062-define-key-ct-grade-requirements_835570.html\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[401,410,403,404,416],"tags":[],"class_list":["post-835570","post","type-post","status-publish","format-standard","hentry","category-Business","category-Manufacturing-Industry","category-UK","category-US","category-World"],"_links":{"self":[{"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/posts\/835570","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/comments?post=835570"}],"version-history":[{"count":0,"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/posts\/835570\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/media?parent=835570"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/categories?post=835570"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.abnewswire.com\/pressreleases\/wp-json\/wp\/v2\/tags?post=835570"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}