{"title":"4\" Flap Discs for Angle Grinders","description":"\u003cp\u003eThis collection brings together our 4 inch flap discs for angle grinders that take a 4 inch disc. Use them to grind welds, blend and finish metal, stainless steel and wood, with grits from 40 to 120 and a choice of 5\/8 inch or 7\/8 inch arbor. Buy a single grit in a 10 pack, or an assorted pack to step from coarse to fine.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003e4 inch (100 mm) diameter with a 5\/8 inch (16 mm) or 7\/8 inch (22 mm) arbor.\u003c\/li\u003e\n\u003cli\u003eCalcined aluminum oxide discs in 40, 60, 80 or 120 grit, sold in 10 packs.\u003c\/li\u003e\n\u003cli\u003eZirconia and ceramic blend assorted pack of 20: six each of 40, 60 and 80 grit, plus two 120 grit.\u003c\/li\u003e\n\u003cli\u003eHalf curved edge zirconia and ceramic discs for fillet welds, corners and contours, 7\/8 inch arbor, 5 pack in 40 and 60 grit.\u003c\/li\u003e\n\u003cli\u003eConical Type 29 profile on the 120 grit calcined alumina disc.\u003c\/li\u003e\n\u003cli\u003eAll are listed for metal. The calcined alumina and half curved edge discs also list stainless steel, the calcined alumina discs list wood, and the assorted pack lists wood, concrete and stone.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\u003ch3\u003eWhat arbor does a 4 inch grinder flap disc need?\u003c\/h3\u003e\u003cp\u003eThe discs on this page come with a 5\/8 inch (16 mm) or 7\/8 inch (22 mm) arbor, and the right one is whichever your grinder's spindle and flange take. The calcined alumina and assorted discs are 5\/8 inch. The half curved edge fillet weld disc is 7\/8 inch. Check the maximum RPM marked on the disc and never exceed it.\u003c\/p\u003e\u003ch3\u003eWhich grit 4 in flap disc should I start with?\u003c\/h3\u003e\u003cp\u003eStart with 40 grit for heavy stock removal and weld grinding, move to 60 or 80 for blending, and finish with 120 to smooth the surface. The 20-disc assorted pack holds all four grits, so one box covers the whole sequence on a typical job.\u003c\/p\u003e\u003ch3\u003eZirconia and ceramic or calcined alumina: which 4 inch flap disc should I buy?\u003c\/h3\u003e\u003cp\u003eChoose zirconia and ceramic for weld work and rust removal: the half curved edge discs are listed for fillet welds on metal and stainless steel, and the assorted pack for grinding, deburring and rust removal. Choose calcined alumina for general grinding, blending, sanding and finishing on metal, stainless steel and wood. If you work on stainless, keep separate discs for stainless and carbon steel so you do not carry steel particles onto the stainless.\u003c\/p\u003e\u003ch3\u003eWhat is a half curved edge flap disc used for?\u003c\/h3\u003e\u003cp\u003eIts curved edge reaches into fillet welds, inside corners and contours that a flat-faced disc struggles to follow. The one in this collection is 4 inch with a 7\/8 inch arbor, in a zirconia and ceramic blend, and comes as a 5 pack with 40 and 60 grit.\u003c\/p\u003e\u003cp\u003eBrowse all sizes in \u003ca href=\"\/collections\/flap-disc\"\u003eFlap Discs\u003c\/a\u003e. To pick a grain, grit and profile, read \u003ca href=\"\/blogs\/news\/how-to-choose-a-flap-disc\"\u003ehow to choose a flap disc\u003c\/a\u003e and \u003ca href=\"\/blogs\/news\/type-27-vs-type-29-flap-disc\"\u003eType 27 vs Type 29 flap discs\u003c\/a\u003e.\u003c\/p\u003e","products":[{"product_id":"10pack-4-x-5-8-calcined-alumina-high-density-flap-disc-120-sanding-disc-grinding-wheel-for-angle-grinder-metal-stainless-steel-woodworking-4-inch-10pack-grit-120","title":"4\" x 5\/8\" 120 Grit Calcined Alumina Flap Discs for Metal \u0026 Stainless Steel","description":"\u003cp class=\"wa-rating-line\"\u003e\u003cstrong\u003eCustomer rating:\u003c\/strong\u003e 4.9 out of 5 from 14 customer ratings on our online marketplace store (November 2026).\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eHIGH QUALITY - Calcined alumina grain, durable and wear-resistant, with good grinding efficiency and long disc life.\u003c\/li\u003e\n\u003cli\u003eDURABLE - Heavy-duty calcined alumina, a heat-treated form of aluminum oxide for general-purpose grinding and blending on steel. Bevel Type 29 (T29) has a slightly upward surface, suitable for edge and weld blending, contours, and radius grinding.\u003c\/li\u003e\n\u003cli\u003eMULTIPURPOSE - Designed for grinding, blending, sanding and finishing on a wide range of materials such as metal, stainless steel, and wood.\u003c\/li\u003e\n\u003cli\u003eSIZE - 4\" x 5\/8\" Grit 120.\u003c\/li\u003e\n\u003cli\u003ePACKAGE - 10 pcs.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eQ: What is a flap disc used for?\u003c\/strong\u003e\u003cbr\u003eA: It grinds and finishes in one step — weld blending, deburring, rust and paint removal, and surface finishing on metal and wood.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the difference between Type 27 and Type 29 flap discs?\u003c\/strong\u003e\u003cbr\u003eA: Type 27 is flat for surface and edge work on flat areas; Type 29 is conical for more aggressive stock removal and better contact on edges and contours.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What grinder do these fit?\u003c\/strong\u003e\u003cbr\u003eA: Standard angle grinders matching the arbor size listed in the title and specifications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Which grit should I choose?\u003c\/strong\u003e\u003cbr\u003eA: Use a coarse grit (36–40) for heavy stock removal, medium (60–80) for general grinding, and fine (120+) for blending and finishing.\u003c\/p\u003e\u003ch2\u003eWhy choose Whitby Abrasives\u003c\/h2\u003e\u003cp\u003eWhitby Abrasives Inc. is a Canadian supplier of professional grinding, cutting, sanding, and finishing abrasives. We focus on consistent quality, fair pricing, and fast shipping across Canada so fabricators, welders, woodworkers, contractors, and DIYers get abrasives that perform job after job. Have a question about sizing or the right grit for your project? Our team is happy to help.\u003c\/p\u003e","brand":"Whitby Abrasives","offers":[{"title":"10 PC","offer_id":47870707892445,"sku":"F4-11","price":17.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0821\/2693\/0141\/files\/c47ea81e.jpg?v=1777666780"},{"product_id":"wa-5pcs-4-x7-8-half-curved-edge-fillet-weld-zirconia-ceramic-flap-discs","title":"4\" x 7\/8\" Half Curved Edge Fillet Weld Zirconia \u0026 Ceramic Flap Discs","description":"\u003cp\u003eWhitby Abrasives 4\" half-curved-edge fillet weld flap discs combine zirconia and ceramic grain for fast, cool cutting on fillet welds, corners, and contoured surfaces. The shaped face improves contact in hard-to-reach areas, and the durable grain grinds and finishes in one step on metal and stainless steel. Available in 40 and 60 grit.\u003c\/p\u003e\u003ch2\u003eKey features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eHalf-curved edge for fillet welds, corners, and contours\u003c\/li\u003e\n\u003cli\u003eZirconia and ceramic grain for fast, cool cutting\u003c\/li\u003e\n\u003cli\u003eGrinds and finishes in one step\u003c\/li\u003e\n\u003cli\u003eAvailable in 40 and 60 grit\u003c\/li\u003e\n\u003cli\u003eFits angle grinders with a 7\/8\" arbor\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the curved edge for?\u003c\/strong\u003e\u003cbr\u003eA: The shaped face improves contact on fillet welds, corners, and contoured surfaces.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What grain are these?\u003c\/strong\u003e\u003cbr\u003eA: A zirconia and ceramic blend for fast, cool cutting and long life.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What grinder do these fit?\u003c\/strong\u003e\u003cbr\u003eA: Angle grinders that accept a 4\" disc with a 7\/8\" arbor.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Which grit should I choose?\u003c\/strong\u003e\u003cbr\u003eA: 40 grit for heavier stock removal, 60 grit for general grinding and blending.\u003c\/p\u003e\u003ch2\u003eWhy choose Whitby Abrasives\u003c\/h2\u003e\u003cp\u003eWhitby Abrasives Inc. is a Canadian supplier of professional grinding, cutting, sanding, and finishing abrasives. We focus on consistent quality, fair pricing, and fast shipping across Canada so fabricators, welders, woodworkers, contractors, and DIYers get abrasives that perform job after job. Have a question about sizing or the right grit for your project? Our team is happy to help.\u003c\/p\u003e","brand":"Whitby Abrasives","offers":[{"title":"40 Grit \/ 5 PC","offer_id":47870707925213,"sku":"F4-C4","price":15.99,"currency_code":"CAD","in_stock":true},{"title":"60 Grit \/ 5 PC","offer_id":47870707957981,"sku":"F4-C5","price":15.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0821\/2693\/0141\/files\/cd5e4eb3.jpg?v=1777666849"},{"product_id":"wa-grinder-20pack-4-x-5-8-flap-disc-40-60-80-120-grits-sanding-disc-zirconia-and-ceramic-mix-grain-grinding-wheel-for-angle-grinder-metal-grinding-woodworking-t27-purple-assorted-grits","title":"4\" x 5\/8\" Flap Disc, 40\/60\/80\/120 Grits Sanding Disc","description":"\u003cp class=\"wa-rating-line\"\u003e\u003cstrong\u003eCustomer rating:\u003c\/strong\u003e 4.6 out of 5 from 39 customer ratings on our online marketplace store (November 2026).\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eENHANCED ZIRCONIA - Improved zirconia and ceramic blend grain offers greater strength and durability than aluminum oxide for demanding, heavy-duty applications.\u003c\/li\u003e\n\u003cli\u003eMULTIPURPOSE - Suitable for metal and woodworking, concrete grinding, finishing, and stone smoothing — grinding, deburring, rust removal, and more.\u003c\/li\u003e\n\u003cli\u003eSIZE - 4\" Diameter, 5\/8\" Arbor.\u003c\/li\u003e\n\u003cli\u003eGRITS - 40# x6, 60# x6, 80# x6, 120# x2.\u003c\/li\u003e\n\u003cli\u003ePACKAGE - 20 pcs.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eQ: What is a flap disc used for?\u003c\/strong\u003e\u003cbr\u003eA: It grinds and finishes in one step — weld blending, deburring, rust and paint removal, and surface finishing on metal and wood.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the difference between Type 27 and Type 29 flap discs?\u003c\/strong\u003e\u003cbr\u003eA: Type 27 is flat for surface and edge work on flat areas; Type 29 is conical for more aggressive stock removal and better contact on edges and contours.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What grinder do these fit?\u003c\/strong\u003e\u003cbr\u003eA: Angle grinders that accept a 4\" disc with a 5\/8\" arbor.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Which grit should I choose?\u003c\/strong\u003e\u003cbr\u003eA: Use a coarse grit (36–40) for heavy stock removal, medium (60–80) for general grinding, and fine (120+) for blending and finishing.\u003c\/p\u003e\u003ch2\u003eWhy choose Whitby Abrasives\u003c\/h2\u003e\u003cp\u003eWhitby Abrasives Inc. is a Canadian supplier of professional grinding, cutting, sanding, and finishing abrasives. We focus on consistent quality, fair pricing, and fast shipping across Canada so fabricators, welders, woodworkers, contractors, and DIYers get abrasives that perform job after job. Have a question about sizing or the right grit for your project? Our team is happy to help.\u003c\/p\u003e","brand":"Whitby Abrasives","offers":[{"title":"20 PC","offer_id":47870708580573,"sku":"FZC000458111","price":21.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0821\/2693\/0141\/files\/b07f80bb.jpg?v=1777666829"},{"product_id":"10pack-4-x-5-8-calcined-alumina-grit-40-60-80-high-density-flap-discs-for-metal-stainless-steel-wood","title":"4\" x 5\/8\" Calcined Alumina Flap Discs, 40, 60 or 80 Grit","description":"\u003cp class=\"wa-rating-line\"\u003e\u003cstrong\u003eCustomer rating:\u003c\/strong\u003e 4.5 out of 5 from 45 customer ratings on our online marketplace store (November 2026).\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eHIGH QUALITY - Calcined alumina grain, durable and wear-resistant, with good grinding efficiency and long disc life.\u003c\/li\u003e\n\u003cli\u003eDURABLE - Heavy-duty calcined alumina, a heat-treated form of aluminum oxide for general-purpose grinding and blending on steel.\u003c\/li\u003e\n\u003cli\u003eMULTIPURPOSE - Designed for grinding, blending, sanding and finishing on a wide range of materials such as metal, stainless steel, and wood.\u003c\/li\u003e\n\u003cli\u003eSIZE - 4\" Diameter, 5\/8\" Arbor (100mmx16mm). Choose 40, 60 or 80 grit.\u003c\/li\u003e\n\u003cli\u003ePACKAGE - 10 PACK.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\u003cp\u003e\u003cstrong\u003eQ: What is a flap disc used for?\u003c\/strong\u003e\u003cbr\u003eA: It grinds and finishes in one step — weld blending, deburring, rust and paint removal, and surface finishing on metal and wood.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What is the difference between Type 27 and Type 29 flap discs?\u003c\/strong\u003e\u003cbr\u003eA: Type 27 is flat for surface and edge work on flat areas; Type 29 is conical for more aggressive stock removal and better contact on edges and contours.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: What grinder do these fit?\u003c\/strong\u003e\u003cbr\u003eA: Standard angle grinders matching the arbor size listed in the title and specifications.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eQ: Which grit should I choose?\u003c\/strong\u003e\u003cbr\u003eA: Use a coarse grit (36–40) for heavy stock removal, medium (60–80) for general grinding, and fine (120+) for blending and finishing.\u003c\/p\u003e\u003ch2\u003eWhy choose Whitby Abrasives\u003c\/h2\u003e\u003cp\u003eWhitby Abrasives Inc. is a Canadian supplier of professional grinding, cutting, sanding, and finishing abrasives. We focus on consistent quality, fair pricing, and fast shipping across Canada so fabricators, welders, woodworkers, contractors, and DIYers get abrasives that perform job after job. Have a question about sizing or the right grit for your project? Our team is happy to help.\u003c\/p\u003e","brand":"Whitby Abrasives","offers":[{"title":"80 Grit \/ 10 PC","offer_id":47964400287965,"sku":"HW-3XWB-UI3V","price":17.99,"currency_code":"CAD","in_stock":true},{"title":"40 Grit \/ 10 PC","offer_id":47964400320733,"sku":"P7-O9BW-0XBS","price":18.99,"currency_code":"CAD","in_stock":true},{"title":"60 Grit \/ 10 PC","offer_id":47964400353501,"sku":"QE-RHGW-U4RP","price":19.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0821\/2693\/0141\/files\/e06b7dd0.jpg?v=1777666741"}],"url":"https:\/\/whitbyabrasives.ca\/collections\/flap-discs-4-inch.oembed","provider":"Whitby Abrasives Inc.","version":"1.0","type":"link"}