{"product_id":"loose-ball-bearings-chrome-steel-grade-100","title":"Loose Ball Bearings chrome steel Grade 100 5.46mm 5.5mm 6mm 6.9mm 7mm 7.92mm 8mm","description":"\u003cdiv class=\"hdiy-desc\"\u003e\n\u003cdiv class=\"hdiy-overview\"\u003e\n\u003ch2\u003eChrome Steel Loose Ball Bearings Grade 100 — Precision Rolling Elements for Demanding Applications\u003c\/h2\u003e\n\u003cp\u003eWhen a worn bearing seat, a custom rebuild, or a tight-tolerance assembly demands an exact replacement diameter, finding the right loose ball bearing quickly matters. These chrome steel Grade 100 loose ball bearings are stocked across a wide diameter range — from 5.46 mm (0.215 in) to 8.1 mm (0.319 in) — so engineers, machinists, and serious DIYers can match the spec without compromise.\u003c\/p\u003e\n\u003cp\u003eEach ball is manufactured from through-hardened chrome steel (equivalent to AISI 52100 \/ GCr15) and finished to ABEC Grade 100 roundness and surface tolerances. Diameters span 5.46 mm through 8.1 mm (approximately 0.215 in – 0.319 in), with increments as fine as 0.01 mm to cover both metric and inch-derived sizes such as 6.35 mm (1\/4 in) and 7.938 mm (5\/16 in). Each order ships in a pack of 100 balls.\u003c\/p\u003e\n\u003cp\u003eTypical use cases include replacement rolling elements in deep-groove ball bearings, linear slide assemblies, and precision instrument pivots; load-distribution media in ball screws and recirculating ball guides; and custom bearing builds for robotics, RC drivetrains, and small-engine governor assemblies where off-the-shelf bearing sizes are unavailable.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-compat\"\u003e\n\u003cspan class=\"hdiy-compat-icon\"\u003e⚙️\u003c\/span\u003e \u003cstrong\u003eCompatibility note:\u003c\/strong\u003e Select the diameter that matches your bearing race groove or housing bore. Verify the required ball diameter with a micrometer before ordering — a 0.01 mm mismatch can affect preload and service life.\u003c\/div\u003e\n\u003cdiv class=\"hdiy-features\"\u003e\n\u003ch2\u003e✅ Key Features of These Chrome Steel Loose Ball Bearings\u003c\/h2\u003e\n\u003cul class=\"hdiy-list\"\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔩\u003c\/span\u003e\u003cstrong\u003eThrough-hardened chrome steel construction\u003c\/strong\u003e — AISI 52100-equivalent alloy delivers a surface hardness of typically 60–66 HRC, resisting deformation under cyclic compressive loads in bearing races.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📏\u003c\/span\u003e\u003cstrong\u003eGrade 100 dimensional accuracy\u003c\/strong\u003e — Roundness deviation ≤ 2.5 µm and diameter tolerance within ±1.25 µm per ISO 3290 Grade 100, ensuring consistent fit across all 41 available diameter options.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📐\u003c\/span\u003e\u003cstrong\u003eFine-increment diameter selection\u003c\/strong\u003e — Available in steps as small as 0.01 mm (5.46 mm to 8.1 mm), covering both standard metric sizes and inch-derived equivalents (6.35 mm = 1\/4 in, 7.938 mm = 5\/16 in).\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🔄\u003c\/span\u003e\u003cstrong\u003eLow surface roughness for smooth rolling\u003c\/strong\u003e — Surface finish Ra ≤ 0.025 µm (typical) minimises friction and noise in high-speed or lightly loaded applications such as instrument bearings and spindle assemblies.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e📦\u003c\/span\u003e\u003cstrong\u003eSold in packs of 100\u003c\/strong\u003e — Sufficient quantity for full bearing replacements, batch rebuilds, or stocking a workshop supply without over-ordering.\u003c\/li\u003e\n\u003cli\u003e\n\u003cspan class=\"hdiy-icon\"\u003e🛠️\u003c\/span\u003e\u003cstrong\u003eBroad application compatibility\u003c\/strong\u003e — Suitable for deep-groove ball bearings, angular contact bearings, ball screws, linear guides, and custom precision assemblies across industrial, automotive, and hobbyist contexts.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-table-wrap\"\u003e\n\u003ch2\u003e📐 Technical Specifications — Chrome Steel Loose Ball Bearings\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eMaterial\u003c\/th\u003e\n\u003ctd\u003eChrome steel (AISI 52100 \/ GCr15 equivalent)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eGrade\u003c\/th\u003e\n\u003ctd\u003eGrade 100 (ISO 3290)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eDiameter Range\u003c\/th\u003e\n\u003ctd\u003e5.46 mm – 8.1 mm (approx. 0.215 in – 0.319 in)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eDiameter Increments\u003c\/th\u003e\n\u003ctd\u003eAs fine as 0.01 mm; see variant options for all sizes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSurface Hardness\u003c\/th\u003e\n\u003ctd\u003eTypically 60–66 HRC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eRoundness Deviation\u003c\/th\u003e\n\u003ctd\u003e≤ 2.5 µm (Grade 100 per ISO 3290)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eSurface Finish (Ra)\u003c\/th\u003e\n\u003ctd\u003e≤ 0.025 µm (typical)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFinish \/ Coating\u003c\/th\u003e\n\u003ctd\u003eBright (uncoated), lightly oiled for corrosion protection during storage\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eQuantity per Pack\u003c\/th\u003e\n\u003ctd\u003e100 pieces\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eRecommended Lubrication\u003c\/th\u003e\n\u003ctd\u003eSee variant options \/ Contact us to confirm for specific applications\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOperating Temperature\u003c\/th\u003e\n\u003ctd\u003eSee variant options\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-faq\"\u003e\n\u003ch2\u003e❓ Frequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I determine which diameter I need?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eMeasure the existing balls with a calibrated micrometer or ball gauge. Alternatively, check the bearing manufacturer's datasheet — the ball diameter is listed as a component dimension. If replacing worn balls, measure the race groove width and cross-reference with standard ball sizing charts. A 0.01 mm error in diameter selection will alter bearing preload and can shorten service life.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between Grade 100 and other ball grades?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eISO 3290 grades define the maximum allowable roundness deviation and lot diameter variation. Grade 100 allows a roundness deviation of ≤ 2.5 µm and is suitable for standard industrial bearings, ball screws, and general precision assemblies. Grades 10 and 25 offer tighter tolerances for ultra-precision spindles and instrument bearings, while Grade 200 and above are used in lower-precision or high-load bulk applications.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre these balls corrosion-resistant?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eChrome steel (AISI 52100) is not inherently stainless. The balls are lightly oiled at the factory to prevent surface oxidation during storage and transit. For wet, humid, or chemically exposed environments, apply a compatible bearing grease or oil after installation, or consider stainless steel Grade 100 balls (AISI 440C) for your application. Contact us if you need guidance on material selection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use these balls to replace the rolling elements in an existing bearing?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eYes — loose ball replacement is a common maintenance procedure for open-style or separable bearings. Disassemble the bearing, clean the races thoroughly, install the new balls with the correct diameter and quantity, and re-lubricate before reassembly. Ensure the replacement balls match the original diameter exactly; even a 0.01 mm oversize ball can cause excessive preload and premature race wear.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat applications are these balls suitable for?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eThese chrome steel Grade 100 balls are used in deep-groove and angular contact ball bearings, recirculating ball screws, linear ball guides, precision instrument pivots, RC vehicle drivetrains, small-engine governor assemblies, and custom bearing builds. They are not recommended for food-contact, medical implant, or highly corrosive chemical environments without additional protective measures.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhy are there so many diameter options in such small increments?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eBearing balls are manufactured to exact diameters because even a 0.01 mm difference changes the fit class within a bearing race. Fine increments allow you to select an oversize replacement ball to compensate for a worn race groove, or to achieve a specific preload in a custom assembly. Inch-derived sizes such as 6.35 mm (1\/4 in) and 7.938 mm (5\/16 in) are also included to cover legacy imperial-dimensioned bearings.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat lubrication should I use with these balls?\u003c\/summary\u003e\n\u003cdiv class=\"hdiy-faq-body\"\u003e\n\u003cp\u003eFor most bearing applications, a lithium-based NLGI Grade 2 grease is appropriate. For high-speed spindles or instrument bearings, a low-viscosity oil (ISO VG 10–32) reduces drag. For ball screw applications, use a dedicated ball screw grease. Always clean the factory protective oil from the balls before applying your chosen lubricant to avoid compatibility issues.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"hdiy-cta\"\u003e🛒 Select your Diameter and Quantity above, then add to cart.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"HomeDIYer","offers":[{"title":"6.9mm \/ 100","offer_id":52410266976530,"sku":"GLFBLFF2024GANGZHU4838x100","price":17.97,"currency_code":"USD","in_stock":true},{"title":"6.95mm \/ 100","offer_id":52410267009298,"sku":"GLFBLFF2024GANGZHU4839x100","price":18.16,"currency_code":"USD","in_stock":true},{"title":"6.98mm \/ 100","offer_id":52410267042066,"sku":"GLFBLFF2024GANGZHU4840x100","price":18.31,"currency_code":"USD","in_stock":true},{"title":"7mm \/ 100","offer_id":52410267074834,"sku":"GLFBLFF2024GANGZHU4841x100","price":18.31,"currency_code":"USD","in_stock":true},{"title":"7.01mm \/ 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