September 2020

such flexibility in a systemwith mechanically linked carriages. The investment has to be worthwhile A linear drive system requires sophisticated control technology, making the purchase price relatively high. There are also costs associated with training personnel and optimising production flow, for example by executing the slowest processes twice. In many cases, these additional costs are quickly recovered through increased productivity, but not always. For example, in a recent application in a porcelain factory the slowest step in a production process for making cups was painting, which takes 30 seconds per cup. As a result, the throughput time for the entire process of finishing the cup is quite long. At first glance, the installation of a linear motor driven systemwith individually controllable movers seems sensible in order to reduce throughput time and increase productivity. However, the purchase of an additional robot for painting the cups in order to increase the quantity of cups going through the machine could be in the region of £40K, in addition to the cost of the linear drive system. Investment in a linear drive system is not worthwhile in this instance; the flexibility it offers is not necessary for changing batch sizes and the faster production rate would not sufficiently recoup the initial investment. Linked carriages mean a solid system Another argument in favour of systems with linked carriages is in operating environments with consistently elevated operating temperatures. The electronics in linear motor systems are naturally sensitive to heat. Cooling mechanisms can be installed, for example in the base plate, but must be planned during the design of the system. With the DTS, the drive can be positioned such that it is shielded from a heat source. Overall, the simpler structure and less complex electronics of linked carriage systems makes them generally less sensitive to dirt, moisture and extremes of temperature. Linked systems can be advantageous wherever there are environmental conditions like this. Fewer carriages The clearest reason for employing a linear motor driven systemwith individually controllable carriages is its ability to handle products of different dimensions. The ability to move carriages independently and ease of programming allows flexibility. In the case of systems with linked carriages, a new production cell may have to be designed and installed for a change in product type or size. The cost of carriages to transport workpieces can also be an argument in favour of flexible driven systems. In some cases, carriages are so expensive to purchase that the cost of initial investment is recovered in linear motor driven systems where fewer carriages can be used compared to systems where carriages are mechanically linked. In a recent application in France for a leading cosmetics manufacturer, the number of carriages in the production cell was reduced by 80% when a linear motor driven systemwas specified. The bigger picture is crucial A linked carriage system such as the DTS is reliable, fast and lowmaintenance. If flexibility is not a primary objective and a standardised work processes with varying throughput times is not needed, the DTS is well placed to meet needs. For smaller companies in particular, a complete package such as DTS allows a clear overview of the costs involved and there are no significant follow-up costs. On the other hand, there are fewer and fewer ‘standard’production processes in manufacturing. The need for flexibility plays a growing role in all industries. In these cases, a linear motor driven systemwith guidance fromGFX offers unbeatable advantages. Ultimately, the machine builder must look at systems costs and benefits as a whole. Both system types can be of advantage, depending on the application, the bigger picture must be taken into account. A balance between priorities and consequences must be struck whilst considering the long term requirements of the system. A system driven with a linear motor can be programmed with different motion profiles to suit product configurations. Hepco’s GFX – Guidance for Beckhoff XTS is suited to higher duty Beckhoff XTS applications. HepcoMotion offers design engineers a range of lowmaintenance, linear and rotary systems which are used across a wide variety of industries. sales@hepcomotion.com tel: +44 (0)1884 257000 www.hepcomotion.com