January 31, 2011 Leave a comment
In this second article from Parker Hannifin, Nigel Steel, from the electromechanical and drives division looks at the latest automation technology and at how the newest modular systems can help users reduce operating costs and improve productivity.
Robotics systems have been widely used for a range of duties in the automotive and electronics manufacturing sectors for many years, where production volumes enable the relatively high cost of automation to be more easily absorbed. Until recently, however, the uptake of robotics equipment in other sectors of industry, has been somewhat restricted due to relatively high capital costs and system complexity. This is especially true in applications such as pallet handling, case erection and component pick-and-place, for products ranging from building materials and DIY goods to food and medical cartons.
With current market pressures placing an increasing need for companies to be extremely flexible, able to respond quickly to short term changes in market conditions or urgent customer orders, a growing number are realising the benefits that can be offered from the use of a wide variety of automation equipment. Perhaps as importantly, the use of the latest generation of automation technology is enabling the costs of production and materials handling to be driven down, helping end users to protect operating margins and stay ahead in today’s increasingly challenging global marketplace.
Despite this fact, there are still some sectors of industry, particularly where volumes are smaller or where short run product variants are being manufactured or handled, that are being slower to automate many of their production processes, but which could nevertheless realise real technical and commercial benefits.
The main issues that have stalled the wider uptake of automated palletising and gantry systems in such applications have generally been the high capital costs and the length of time that has typically been required for system design, build, testing and installation. It is not unusual for this process to take many months as well as often involving repeated on-site adjustments before a system runs effectively. Moreover, many of these custom built systems are suitable for one purpose only and can be difficult and expensive to reconfigure quickly. Collectively, these issues make it particularly difficult for companies to meet rapidly changing business needs.
In response to these problems and to make automation a far more viable option in a much wider range of applications, a number of leading manufacturers have developed innovative new systems that are supplied either pre-assembled or as kits, enabling them to be constructed and commissioned quickly and easily on-site. These systems are easy to configure, install and test, and can usually be reconfigured quickly and simply by maintenance or engineering staff, making them particularly suitable for use in small to medium volume applications where product changeover frequently requires adjustments to handling mechanisms. Additionally, further technological advances now mean that such systems are available at relatively low capital cost and are typically inexpensive to operate and maintain; indeed, it is not unusual for such systems to be making a return on investment within weeks of initial installation.
An integral element and key to the success of this new generation of automated gantry and palletising systems is the use of the latest modular drive and automation parts, in particular, high performance linear motion systems, digital servo drives and easy to program controllers. Generally, these devices are supplied either as basic assemblies or sub-systems, for instance a simple X-Y line gantry unit with linear actuator, gearbox and motor, ready to fit into an existing support structure. They could also require an integrated system capable of complex multi-axis motion, delivered complete with all cabling, switches and sensors for a new build installation.
Line- and space-gantries, along with palletising systems, generally rely on linear actuators to control the movement and positioning of work-pieces such as tools, gripper’s or suction pads, and the products or packs being handled. In essence, there are a variety of basic types of linear actuators suitable for use in automation systems. Each type features a slide mechanism that is driven either indirectly from a separate motor via a belt or screw mechanism and appropriate gearing or directly by means of a linear motor that is integrated into the body of the actuator.
Depending on the application, each of these drive methods offers a number of advantages. For example, belt drives are generally simple, low cost devices that can operate at high speeds with rapid acceleration, but are limited in terms of accuracy and overall performance. Screw drives, on the other hand, offer excellent rigidity with a reasonable degree of precision and resolution. By comparison, systems that incorporate linear motors offer exceptional levels of precision, deliver very high speeds and acceleration, require virtually no maintenance and provide a long operating life.
Some of the latest, most sophisticated systems incorporate high-performance actuators that use timing belts or rack-and-pinion drive units to provide high speeds of 5m/sec, precision and repeatability to within ±0.05mm, with the ability to handle heavy loads of up to 1,600kg. Additionally, these devices can offer extended travel for particularly large gantry systems, with a standard actuator running up to 6m and longer runs being possible by mating two or more units together.
Alternatively, linear motors provide an ideal solution for systems where there is a specific need for extremely rapid acceleration with precise positional accuracy and repeatability. This is because linear motors are capable of operating at speeds of up to 10m/sec with rates of acceleration of 50m/s², and repeatability of just ±0.1μ. By comparison with many other traditional devices, linear motors do not suffer from backlash and can be supplied with integrated encoders to enable the position of the items being handled to be accurately determined.
Another key element of the latest gantry and palletising systems is a reliable control system. The use of standard or modular devices, such as Parker’s Compax3 family of digital servo drives and controllers, are essential for reducing the cost, complexity and lead times of the latest automation systems. In particular, the ability to interface these control devices directly with standard PCs and Windows operating systems, as well as the use of easy to learn and use programming techniques, in turn, allows gantry and palletising systems to be commissioned and set-up rapidly and simply on-site. Furthermore, production and maintenance engineers can subsequently reconfigure such systems and operating programs to suit any future needs, enabling companies to remain flexible and adaptable to rapidly changing conditions.
Collectively, the recent technological developments in automation systems have enabled leading suppliers to introduce innovative gantry and palletising systems that are faster, smaller, more cost effective and, in general, perform far better than ever before.
This, along with the introduction of packaged or integrated solutions, is enabling both OEMs and end users alike to benefit from quicker specification, installation and set-up, reduced maintenance requirements, longer product life and enhanced system performance. Perhaps most importantly, the new generation of handling systems offer a number of important benefits that enable companies to retain a competitive edge, which is vital at a time when industry is coming under increasing pressure to boost productivity and meet ever shorter lead times, while simultaneously cutting operating costs.
Parker Hannifin is the world’s leading diversified manufacturer of motion and control technologies and systems, providing precision-engineered solutions for a wide variety of mobile, industrial and aerospace markets.