Functionality of the large diameter thread macro

The Fanuc control macro performs roughing and finishing of large diameter thread, internal or external. It uses roughing and finishing strategies that allow very high pitch threads to be produced with low cutting forces and good surface finishes. Macro suitable for large diameter thread where shaped tools cannot be used. In large threads and consequently with high pitches, the use of shaped tools can present major problems of vibration and tool breakage.

In the case of both the screw and the leadscrew, roughing and finishing can be carried out with standard tools of radius shape; groove tools of radius shape or with inserts of form R or better still, when angles permit, standard turning tools of form V (e.g. VNMG) or D (e.g. DNMG). It is also possible to use tools with a flat line such as grooving tools.

The macro allows you to freely set the inclination degrees of the two sides of the thread. It also allows you to set the corner radii on both external and internal edges. For example, it can be used to machine buttress with standard and non-standard angles, trapezoidal and metric threads.

By setting the angle of the two flanks to zero, it is possible to perform spidering on bushings or square threads.

In roughing, the macro will perform for each X step a series of cuts to open the thread groove, committing the tool radius equal to a maximum value set with a parameter. In finishing, the macro allows you to set the value of the maximum ridge along the profile so as to control the roughness on the whole profile, both on the sides and on the bottom and also on the radii.

For trapezoidal thread where the radii at the bottom are almost zero, it is possible to set flat, parting or special tools.

The threading macro makes it easy and reliable to machine large diameter threads, helping to manage dimensions and reducing effort. In addition, using standard tools significantly reduces production costs, as no special shaped tools are required, which in addition to high costs create enormous cutting efforts.

The macro can be executed on all lathes with Fanuc control from series zero to series 31. For details, please refer to the manual with particular attention to the paragraph “Warnings”.