One for all: a single tap solution for multiple applications

Related Vendors

DIPROFIL Diamantprodukter AB

Ramada Acos

Iscar Ltd

A single tap meets material and application restrictions

Iscar has introduced a new product line, called Onetap, which has an optimised cutting geometry for universal use in a wide range of materials. It is said to allow customers the opportunity to significantly reduce their tap stock usage and also achieve the highest efficiency in production.

The tap Iscar developed has a unique patented geometry that :

• Both reduces and distributes the cutting load, preventing overfeed tapping process.

• Assures the highest surface quality (even in the last part).

• Increases tool life up to two times (depending on cutting conditions and workpiece material).

The line will be available in two of the most common geometries: gun-point tap for through holes and spiral flute tap for blind holes.

Users are said to be able to use the same type for machining grey iron and stainless steel as well, while maintaining excellent tool life and precise thread standards.

In one field test, the testing focussed on carbon steel C45 and the thread type was M8X1.25. A standard tap reached a tool life of 152 parts. The Onetap achieved 245 parts, said to be significantly higher. With the same tap geometry tested on grey iron GG25, tool life was increased by 27% as well.

The next step was to check thread tolerance specifications, which is found to be suited for standard thread specifications.

Normal tap tolerance (medium class) is ISO 2 (6H), to create an average quality fit between screw and nut. Lower tolerance (close class) ISO 1 (4H;5H) creates a fine fit without a gap on the flanks between the screw and the nut. High tolerance, (free class) ISO 3 (7H;8H), generates a rough fit with a large gap (intended for the nuts which will have a coating layer).

Standard Iscar tap tolerances are classified as ISO 2 according to DIN 13, which is 6H for metric threads and 2B for unified threads, according to the table. (See Figure 2 in photo gallery.)

The next stage would be the holder since the tap must be mounted on the axis of the core hole. On non-synchronised machines (feed/speed) we recommend using tapping holders (Iscar GTI, GTIN collets). With non-synchronised machine spindles the feed rate should be, as a rule, programmed approximately 5-10% lower than the thread pitch.

In these cases a tapping chuck must be used. It will compensate the difference between the feed rate and the thread pitch. It is important that the tension spring in axial compensation is set to a minimum pressure in order to avoid tap loading. The compression spring should be tensioned so the tap starts to cut by compression of the spring up to one-half of the pitch. Torque requirements for forming taps are considerably higher than for cutting taps. When forming taps are used, chuck capacity must be decreased by 25%.

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