The Dormer MTT-X E044 cobalt steel spiral flute tap has a round shank with a square end, gold oxide finish, an axial coolant-through channel, and a modified bottoming chamfer, and is used to create metric right-hand threads in a number of materials, with best performance in alloy steel. The 15-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 internal coolant channel of this tap has an axial outlet at the tip of the tool that directs lubricant flow ahead of the tool; this feature is also most suited for bottoming holes. Gold oxide is a low-temperature heat treatment that reduces grinding stress within the tool. The modified bottoming chamfer on this tool 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). Cobalt steel is used for tough machining applications because it resists abrasion and high cutting temperatures and has higher feed rates compared to 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 E044 series, taps with nominal diameters of 8 mm to 12 mm have three flutes and those with nominal diameters of 16 mm and 20 mm have four flutes. All taps have modified bottoming chamfers. This tap conforms to ISO 529 standards and can create threads to a depth two 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.