Positioning Equipment (ll) - Rotary Index Table

The next positioning equipment is Rotary Index Table.

What is Rotary Index Table?
Rotary Index Table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis. Some rotary tables allow the use of index plates for indexing operations, and some can also be fitted with dividing plates that enable regular work positioning at divisions for which indexing plates are not available.

Examples of how it can be used:

Machine spanner flats on a bolt

Drill equidistant holes on a circular flange

Cut a round piece with a protruding tang

Cut complex curves (with proper setup)

Rotary tables are made with a solid base, which has provision for clamping onto another table or fixture. The actual table is a precision-machined disc to which the work piece is clamped (T slots are generally provided for this purpose). This disc can rotate freely, for indexing, or under the control of a worm (handwheel), with the worm wheel portion being made part of the actual table.

Rotary indexing tables have either fixed or adjustable indexing angles. During each revolution, the table stops for a specified period of time so that an operation can be performed at each station. The bearings that support rotary indexing tables determine both the load capacity and accuracy.

Criteria in selecting rotary index table:

Selecting rotary indexing tables requires an analysis of specifications and features. Specifications include maximum indexing increment, work table diameter, maximum axial load, and maximum radial load.

Rotary indexing tables are powered by pneumatic and electric motors, hydraulic drives, and manual actuation.

• Pneumatic rotary indexing tables are suitable for small and medium loads. They are powered by one of more pneumatic cylinders, each of which represents an index. During the return stroke, a pawl locks the table in place. With some devices, the pawl can be adjusted to change the number of indexes.



• Electrically-powered tables are generally faster than pneumatic devices and can handle heavier loads.



• Tables that are powered by hydraulic drives use a pressurized fluid that transfers rotational kinetic energy.



• Manually-actuated rotary indexing tables often include a hand crank or are loosened, turned, and adjusted by hand.
  

Rotary Index Table Safety

Like wise, the safety of rotary index table is also as important as any other equipment.

• In a rotary index table, the parts are loaded well away from the point of operation.
• The operator’s hands are kept a safe distance from the riveting area.
• The rate of production depends on the time required to load the parts.
• Normal cycle time is the time required to load component parts plus approximately 5 second for indexing.
• Riveting is done during the loading process.
• Preventative maintenance are also established and maintained to reduce downtime for repairs and replacement of parts. It is important to take note that when doing preventive maintenance, make sure that the electrical power and air supply to the machine are OFF! :
  
  Cleaning :
  Prior to operation, or on a daily basis, perform the following procedure:
  1. Using a clean, dry cloth, wipe the machine to remove accumulated dust or other contamination.
  2. Using a solvent or similar cleaning fluid, remove accumulated oil or grease from areas not requiring lubrication.
  3. Using an approved–type air hose, blow out any chips or metal particles that may be in the working area.
  
  Inspection :
  1. Inspect the entire machine for evidence of loose or broken parts. Repair or replace as necessary.
  2. Inspect all moving parts for excessive wear. Replace worn parts if required.
  3. Inspect all air lines and connections for excessive leakage. Repair or replace as required.
  4. Inspect all electrical wiring for loose connections or cracked or worn insulation. Repair or replace if required.
  
  Lubrication :
  The Rotary Index Table is equipped with grease fitting under the machine base. Access to the fitting is gained by removing the top of the plastic guard, then using a grease gun with a hose and fitting.
  Lubricate the machine with Mobil HP Lithium 12 grease (or equivalent) every 20,000 rotations. Use the same grease to lubricate the drive screw on any optional moving insertion heads.
  
  Moisture and Scrap Removal :
  Periodically check the moisture separators at the air supply inlet area of the machine, and drain if necessary.
  

Also check the scrap containers. During normal operation of the machine, the scrap from the terminal strip is placed in the container on the side of the machine, and scrap from the housing (wire and nib) is placed in the container located at the back of the machine.

Ways to remove scrap from container: To remove the scrap from the container, carefully unscrew the container; remove the cylindrical screen from the inside of the container, and dispose of the scrap in an appropriate manner. Replace the cylindrical screen in the container and replace the container before resuming production.