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Ideal Ways To Use Index Rotary Tables Tables

By Aisha Jacaruso


Rotary Index Tables are high precision positioning tools used in special cases of milling and metalworking. Their basic function is to offer the machinist the ability to work based on fixed intervals around a horizontal or vertical axis.

By turning a lever connected to a worm-screw that is positioned under the rotary table, users can turn it clockwise or counter-clockwise in full turns. The worm-screw drives some axles that are fixed in intervals under the table, so the table is turned with great accuracy. The ratio between the worm-screw and the axles determines the maximum indexing resolution, and so the applications that each RIT is suitable for.

Unique Milling Techniques

Rotary index tables can be used for a number of specialized processing techniques and provide solutions in demanding occasions. The most noteworthy utilization of RITs is when combined with a chuck, tailstock and stepper electric motor to work as a light lathe alternative. This use though requires special care and the fast turning of the worm-screw by the motor can accelerate the wear of the table axles.

Another popular use is to process a bolt's head to perform spanner flats. As almost all bolt head designs feature pentagonal, hexagonal, or octagonal shaping, the use of rotary index tables is ideal. The only consideration in this case is the ratio of the worm-screw to the table, as it should allow the desired number of intervals.

Cutting & Drilling Uses

Rotary Index Tables are also regularly used for the cutting of straight lines at any angle, arcs and circular shapes. The arcs, being a demanding milling process, can be achieved by adding a compound table so that the center of the table's rotation can be displaced, thus resulting in a progressively off-centric machining.

It is often the case that a machinist is called to drill a large diameter hole that the driller can't handle due to its insufficient power. This is another case where indexing tables can help by helping the operator drill multiple smaller holes around the set center of the larger hole. This boring process results in a hole that is equally accurate in terms of dimension and inner finishing as an one-drill hole.

Maybe the most demanding cutting process that index tables can help with is the realization of helixes. These three dimensional shapes are especially demanding as they require movement along at least three axis which is almost never possible by lathes alone. RITs come as a supplementary solution to this process, moving the workpiece rotational (two axis) while the cutting tool moves along the third axis thus creating the helix.

Last, there is one simple purpose that rotary index tables fulfill with great success and that is the drilling of equidistant holes on a circular flange. The operator calculates the technical details based on the RIT ratio, holes number and distance of boring centers. The table is then properly configured and the holes are bored with speed and precision. If the holes diameter exceeds the drilling limitations, multiple smaller holes can be drilled using an additional compound table.




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