The Dormer MTT-X E008/MTT-X E018 powdered-metal steel spiral flute tap has a round shank with a square end, black oxide finish, and a modified bottoming chamfer, and is used to create metric right-hand threads in a number of materials, with best performance in steel. It is available in two different thread specification standards: Metric Coarse (M) or Metric Fine (MF). The 48-degree spiral flutes of this tap pull chips back from the tip of the tool, up and out of the hole to prevent clogging, making it suitable for blind or bottoming holes (with only one opening). The tap’s black oxide finish improves lubricity, resists corrosion, and will not chip or flake. Black oxide also helps to prevent buildup and welding of material on the tap’s cutting edge when working with iron and steel. The modified bottoming chamfer has additional length to reduce chip load, add tool life in difficult-to-machine materials, and permit higher tapping speeds.
Right-hand threads are designed to tighten when a head or nut is rotated clockwise (the most common threading direction). Powdered-metal steel offers performance that approaches that of solid carbide tools but with the toughness and shock-resistance of high-speed steel. The round shank with square end helps to minimize rotation in the tool holder. This tool can be used in machines, such as drill presses or lathes, or with hand tools such as tap wrenches.
In the Dormer MTT-X E008/MTT-X E018 series, all taps have three flutes and modified bottoming chamfers. This tap conforms to ANSI standards and can create threads to a depth two-and-a-half times its diameter. It is suitable for the 6H tolerance class: 6H is used for a normal length of thread engagement and medium tolerance quality.
Taps produce internal threads in previously formed holes and can be used in machines (such as drill presses) or with hand tools. Common types of taps include hand taps, spiral point taps, spiral flute taps, thread forming taps, and pipe taps. Hand taps (straight-flute taps) collect chips in the straight flutes of the tool; spiral point taps push chips through holes ahead of the tool; and spiral flute taps pull chips back from the tip of the tool, up and out the hole. Thread forming taps, also known as cold forming taps, press rather than cut to create threads in a drilled hole, and no chips are created. Pipe taps create threads in pipes and pipe fittings. Each thread type designates a thread profile and each type is identified with an abbreviation. In the U.S. and Canada, the Unified Thread Standard is the dominant thread type, including UNC (Unified Coarse), UNF (Unified Fine), and NPT (National Pipe Taper) threads, among others.
Precision Dormer manufactures cutting tools under the following brands: Precision Twist, Dormer, and Union Butterfield. The company has locations around the world, and provides tools adhering to ANSI, NAS, and DIN standards.