{"product_id":"hertel-e4040020-square-end-mill-5-16-in-4-flute-cobalt","title":"Hertel E4040020 Square End Mill 5\/16 in 4 Flute Cobalt","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe HERTEL E4040020 is a cobalt square end mill designed for precision material removal in ferrous and high-temperature alloy applications. Built from M42 cobalt high-speed steel, it handles higher heat generation than standard M2 HSS tooling, making it well suited for stainless steels, alloy steels, and work-hardening materials. The cutter measures 0.3125 inches in diameter with a 1.375-inch length of cut and a 0.375-inch shank diameter. A titanium nitride (TiN) surface treatment increases surface hardness and reduces friction at the cutting edge. The four-flute, single-end geometry is centercutting, allowing plunge entry as well as conventional peripheral and slot milling operations.\u003c\/p\u003e\n\u003cp\u003eThis end mill is used in manual mills, CNC machining centers, and knee mills across job shops, maintenance facilities, and production environments. Its 3.125-inch overall length is a standard reach suitable for the majority of general-purpose milling work. The TiN coating and M42 substrate combination makes it a practical choice for shops that cut a mix of mild steel, 304 and 316 stainless, and medium-alloy materials where uncoated HSS tooling wears prematurely. Machinists, tool-and-die makers, and maintenance technicians working with manual or CNC equipment install and replace this style of tooling.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003eM42 cobalt HSS substrate provides higher red-hardness than standard M2 for improved performance in tough alloys\u003c\/li\u003e\n  \u003cli\u003eTiN finish reduces friction and improves wear resistance at the cutting edge\u003c\/li\u003e\n  \u003cli\u003eCentercutting design allows direct plunge cuts without a pre-drilled pilot hole\u003c\/li\u003e\n  \u003cli\u003eFour-flute configuration balances chip clearance with surface finish quality\u003c\/li\u003e\n  \u003cli\u003e3\/8-inch shank fits standard R8, ER, and Weldon-style collet and end mill holders\u003c\/li\u003e\n  \u003cli\u003eSingle-end geometry for standard milling, slotting, and profiling operations\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned as a standard-shank replacement cobalt end mill for use in any manual or CNC milling machine equipped with a 3\/8-inch collet, end mill holder, or Weldon-style chuck.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eEnd mills of this type are installed and changed by machinists and tool-and-die professionals. Always de-energize and lock out the spindle before changing cutting tools. Confirm the tool holder bore and collet size match the 0.375-inch shank before tightening. Inspect the shank and holder for chips or burrs that would cause runout before securing the tool.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMill Diameter\u003c\/strong\u003e: 5\/16 inch (0.3125 inches)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNumber of Flutes\u003c\/strong\u003e: 4\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEnd Mill Material\u003c\/strong\u003e: Cobalt (M42 HSS)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSurface Treatment\u003c\/strong\u003e: TiN (Titanium Nitride)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLength of Cut\u003c\/strong\u003e: 1-3\/8 inches (1.375 inches)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eShank Diameter\u003c\/strong\u003e: 3\/8 inch (0.375 inches)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall Length\u003c\/strong\u003e: 3-1\/8 inches (3.125 inches)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCentercutting\u003c\/strong\u003e: Yes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVariable Helix\u003c\/strong\u003e: No\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVariable Index\u003c\/strong\u003e: No\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChipbreaker\u003c\/strong\u003e: No\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEnd Type\u003c\/strong\u003e: Single End\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.01 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStandard Information\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: HERTEL\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: E4040020\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"HERTEL","offers":[{"title":"Default Title","offer_id":51730444910898,"sku":"E4040020","price":40.47,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/4e02f501c93bbbf7de1b3ea062abd5c8.jpg?v=1788717586","url":"https:\/\/voomisupply.com\/products\/hertel-e4040020-square-end-mill-5-16-in-4-flute-cobalt","provider":"Voomi Supply","version":"1.0","type":"link"}