With the use of automation growing in all areas, Giles Forster, HepcoMotion’s chairman, discusses how today’s linear motion guided gantry systems are

capable of accomplishing the same tasks as an industrial robot while offering even more benefits, particularly for large work envelopes

Gantry systems slide into first place I

n nearly every application – from processing, assembly and inspection to packaging – automation is growing in demand, with gantries and

6-axis industrial robots being used for applications such as palletising, sorting, and pick & place tasks. Linear motion guided gantry systems, however, are capable of

accomplishing the same tasks as an industrial robot while incurring less cost and offering greater flexibility. In fact where the task involves moving heavy and awkwardly shaped products over a large distance, a gantry system is undoubtedly the better solution. To meet application demands, HepcoMotion offers a range of gantries – from a light payload, high speed, to a heavy payload solution. Such systems are capable of lifting higher loads over a greater distance.

As an example, a 3m square gantry can position a payload of 400kg anywhere within that 3m envelope on both axes. A robot, however, has limited capacity in terms of moment load, with the payload reducing the further it extends from the central axis. For example, the payload will reduce by approximately 50% when the horizontal reach is extended to just 0.7m with a typical 6-axis robot. So, as the work envelope grows in size, the gantry’s cost advantage increases. An example of this can be found at bespoke material handlers,

Avanti Conveyors. HepcoMotion has been working with the company for over 18 years, supplying a range of HDS2 gantry solutions to lift pallets. Each gantry has a payload of 120kg, with the X-axis moving at a speed of 2m/s, and the Z-axis moving at 1.8m/s, and providing a 2m stroke. Ranging from 12 to 30m long, these systems are picking and placing in larger working areas. HepcoMotion is also using a rack driven HDS2 X-Z gantry system in its

own factory to provide a multi-station chemical finishing dipping plant. Based on an overall payload of 700kg with a nominal speed of 0.5m/s, this solution provides a long X-axis stroke of 14,000mm. This application is ideal for a gantry system as it needs to lift and load

4m slides into seven dipping tanks. Two heads are utilised to provide stability, manoeuvring the 4m lengths – a challenging shape and size that does not lend itself to a robot.

THINKING OF THE FUTURE A further benefit of a gantry system is that, if the work area needs to increase when the system is in use, the length can be extended – a benefit if there is a need to increase production or if the process or application changes over time. With a gantry system, increasing the

horizontal reach from 2m to 4m, for example, is a relatively straightforward process requiring only a single axis to be extended to increase the stroke length. All other elements of the gantry remain the same with only one beam affected. This happened at IAC Engineering, a large electrical integration and


automation company based in South Wales. One of IAC’s customers had requested additional vertical stroke after the system was in build. Hepco was able to provide a replacement for the Z-axis beam only, which extended the stroke as required. Although it is possible to buy robots that have extended axis to allow

A gantry system can be beneficial where the task involves moving heavy and awkwardly shaped products over a large distance

a longer reach, this affects the robot’s payload, so extending an axis isn’t always the best solution. Under most circumstances, the customer would need to go to the next size robot.

MEETING MAINTENANCE DEMANDS For maximum efficiency, any system installation must offer low ongoing maintenance costs, especially for high duty applications covering long distances with heavy loads. To help, Hepco’s V guide system has a wiping action that expels debris, making it perform particularly well in harsh industrial environments. The outer diameter of the bearing travels at a faster speed than the inner diameter – the difference in speed causes particles nearer the centre to move outwards to the periphery, and to be expelled. Due to the geometry of the slide and bearing interface, debris is expelled to the outer diameter of the bearing in a spiral motion, away from the running surface. For maintenance, all bearings used in Hepco’s HDS2 gantry carriages

are removable and can be dismounted from the carriage without the need to remove the carriage from the end of the axis. Under lubricated conditions, there is also no need to change the guide. Changing bearings and pinions is comparatively straightforward and can easily be done by the customer’s in-house maintenance team. As a robot is fully programmable, it can be challenging to integrate into an existing system. A gantry system, however, is more simple and cost effective to integrate. A 3-axis gantry system will often pair with the existing controller and can be completely integrated within existing machine functions.

As gantries are mounted overhead, or sometimes below the work envelope, they offer the added benefit of saving valuable

floor space. They also allow greater access to workstations, a benefit for manufacturers focussed on reducing downtime and maximising productivity.



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