The application of rotary index tables for part transfer through sequential processes is a highly effective automation method that can delivery advantages in speed, cost and reliability in many applications. This article looks at some ways of implementing rotary part transfer to unlock these advantages within larger automation projects.
Historically, rotary transfer was used extensively to connect dedicated processing steps arranged radially at a series of operation station. High speed rotary indexing tables were developed that combined fast rotation indexes between stations, precise positioning accuracy, high rigidity and reliable operation in 24h production.
Subsequently, the increased scope of automation and integration throughout a production facility have favoured the development of linear transportation methods either directly carrying components on conveyor systems or using palletised components. Such large-scale automation allows entire facilities to be implemented with flexible programmable transportation of parts from raw stock through to final quality controlled and packaging of the product.
However, some specific advantages of rotary indexing make this technique a simpler and more efficient transfer method for many applications. The logic of circular movement implies naturally returning to the starting point, and this principle delivers inherent efficiency in the simultaneous movement of multiple components around a system from the first to the last processing steps without the need for complicated positioning stops, gating or a pallet return. The simplest implementation of this principle is the 180 degree loading indexer, where one fast, simple movement both loads and unloads parts between a loading and a working station with an efficiency that is unmatched by any other mechanism.
Processes requiring multiple operations to be automated are accommodated similarly with a precise table index motion of nominally 30, 45, 60 or 90 degrees while retaining the mechanical simplicity of a single mechanism transferring all parts to the next position simultaneously. The simplicity of the rotary index system delivers inherent advantages of reduced cost, high positioning accuracy, higher speed and excellent reliability. In addition, the kinematics of a cam index cycle naturally achieves smooth sinusoidal acceleration and deceleration compared to alternative pneumatic or hydraulic systems.
The identification of suitable characteristics in a group of processes allows implementation of rotary transfer cells within a larger automation project to deliver advantages in the cost and efficiency of the whole system. Different aspects of a process or set of processes may make them particularly suitable. This may be related to a set of core processing steps for all products, where increased production efficiency is achievable by implementing a dedicated processing cell. Another scenario is where a long processing time is able to be offset by the efficiency of a loading indexer or is able to be divided between multiple processing steps at different stations. Specialised tooling may be required to hold parts at a certain stage of production, and is able to be efficiently mounted on a rotary index table. Similarly, high accuracy processes may be grouped together using a precision rotary index transfer mechanism for these operations, if high precision is not needed for other processes.
The availability of flexible rotary index systems using a CNC driven table has added new possibilities for rotary indexing, where multiple parts may be flexibly processed in different sequences or using different stations, and stop positions become fully programmable.
In summary, the implementation of rotary indexing cells within larger automated systems should be considered as a means of improving process efficiency and reducing system cost. Large gains are made possible by implementing specific processing requirements for groups of operations, such as high positioning accuracy or special fixture tooling; of raising the efficiency of long cycle operations; and of achieving the highest processing efficiency of core sets of operations with automatic part return to the starting position.
Fibrotor precision cam-driven rotary index tables and programmable rotary index tables are offered to meet all rotary indexing and rotary positioning requirements for automated production in diverse applications ranging from micro components to heavy engineering.