DAC102021

38 n MACHINE BUILDING October 2021 www.drivesncontrols.com Adding flexibility to material-handling operations S uccess in manufacturing is a moving target. Planners routinely face demands to cut cycle times, increase capacity, introduce new products more quickly, and use available floorspace efficiently. The methods used to move workpieces between the various production processes can significantly influence the extent to which these goals are achieved. Here are four techniques to consider when looking to improve the efficiency of production line processes. Scale production when factory floorspace is full Sometimes, rotary indexing tables are used to move workpieces from one machine to the next to perform a sequence of assembly processes. When designing and setting up an assembly sequence using these tables, engineers need to consider critical parameters such as resolution, repeatability, accuracy, and allowable backlash and hysteresis. If throughput needs to be increased, it may be possible simply to increase the rotational speed as the table moves between index positions. It can be a complex task if an extra machine needs to be added to a sequence, either around the perimeter of the table or in the centre. The equipment already in place must usually be moved to a new position. Scalability is limited, however, by the circumference of the table. Adding an extra machine may be physically impossible. When the limits of speed and table size have been reached, the only alternative may be to add an extra indexing table. This can require significant extra space, which may not be available. Findways to cut line cycle times When moving workpieces fromone process to another along a production line, belt-and-roller conveyors are often the transport of choice. These can also carry workpieces between automatedmachinery or hand- assembly stations. Typically, the conveyor speed is fixed and it moves in one direction. To cut cycle times and thus to raise throughput, the obvious course of action may simply be to increase the conveyor speed. But this is not always successful and can be counterproductive. When stopping moving workpieces – typically done using a device such as a microswitch or end-stop that brings the conveyor to an abrupt stop – the workpieces can become displaced and the carrier trays or pallets damaged. Stopping work to remedy these issues can affect productivity. Cut costs and space by sharing processes When working out how to automate the assembly of a new product, some processes – such as driving screws, applying adhesive or installing multi-part bezels – may need to be performed more than once on the same workpiece. To achieve this in a traditional unidirectional sequence, the same type of machine would need to be installed at several points along the assembly line. If, say, a workpiece could be returned to a screwdriving machine to install a second set of screws Yamaha’s LCMR200 linear conveyor modules are available in lengths from 200–1,000mm and can operate at slider speeds up to 2,500mm/s, for payloads up to 10kg. The maximum acceleration is 1.3g – equivalent to 0-100km/h in less than 2.2s. Matching controllers can centralise control of the sliders and other devices such as Scara and Cartesian robots and peripherals, allowing users to set up a complete automated assembly cell quickly and easily. A software tool simplifies programming using ladder graphics or text entry, and helps to visualise the cell and to optimise interactions between the robots and sliders. Linear conveyor modules can be integrated easily with industrial robots. Circulation systems at the line ends can enhance flexibility and optimise the layout. Traditional material-moving technologies for production lines, such as rotary indexing tables and roller conveyors, have attractions – but also limitations. Oumayma Grad fromYamaha’s Factory Automation business examines their capabilities and considers an alternative technology that offers potential benefits.