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Benchtop robots are capable of assembling modestly sized products and offer a cost-effective production tool for SMEs in manufacturing, says Peter Swanson, managing director at Intertronics.

Small robots with footprints approximately A4 in size and working areas of 200 x 200mm have all the functionality of large machines.

Bigger versions cover 800 x 600mm with a Z-axis of 200mm.

They are robust, fit for shop-floor use and maintenance is relatively simple, often with internal computers and self-diagnostic protocols.

Typically, programming is via a simple teach pendant with prompted inputs and programmes are stored internally or kept on a computer.

Software may be generic, allowing programmer control of functionality, or function specific, for a task such as dispensing.

Customised software is more user friendly, with selectable point-to-point or continuous path motion.

While two-axis machines are available, three-axis are the most popular, with full interpolation of lines, arcs and circles through all three axes.

A fourth, rotational axis is used for more complex, non-planar jobs.

Positional repeatability is typically 0.01mm and movement speeds can reach one m/sec.

Inputs and outputs allow interfacing with external devices, such as pick-and-place pneumatics.

Sophisticated camera-based position-correction systems are now available.

There are three major types of robot recognised in the benchtop format.

First, the semi-automatic, cartesian robot, with which the work is placed on a moving plate on the bed of the machine, which provides x-axis movement.

Overhead, a beam mounted traveller gives the y- and z-axis movement.

Second is the SCARA robot, which stands for Selectively-Compliant-Articulated-Robot-Arm, or sometimes Selective-Compliant-Assembly-Robot-Arm.

With joints much like a human arm, with shoulder, elbow and wrist axes, it performs pick and place, palletising or dispensing functions.

Third, with a Gantry robot, an overhead beam moves back and forth over the work on a fixed base.

A Z-axis component slides on the gantry.

All types are suitable for semi-automatic batch operation, where the work is manually loaded and unloaded.

The SCARA and Gantry types will also work with automatic feed by, for example, being placed next to or over a conveyor.

They can find application in dispensing, soldering, brazing, welding, pick and place, screwdriving, engraving, cutting and testing/calibration.

Dispensing Adhesives, sealants, encapsulants, potting compounds, coatings, inks, paints, greases, oils, solder pastes and so on may be accurately metered onto workpieces, dispensed from barrels or cartridges mounted on the machine z-axis, or remotely located and fed through a robot-mounted dispensing valve.

Beads, coatings or micro-dots are common.

Metering and mixing equipment can be interfaced to dispense two-part systems.

One popular application is the dispensing of form-in-place (FIP) gaskets onto a component, which then cures into a soft, sealing gasket.

The bead must be the same diameter over its entire length, and so the dispense needle travel-speed must match the FIP gasket flow rate, even around corners in three dimensions.

A robot can be programmed to do this, whereas a human would find it impossible.

Typically a camera is sequentially positioned over a number of small parts.

The image is then examined by computer, to detect a pass or fail.

Reject parts may be identified, marked or removed while on the robot.

Probes can be accurately positioned to measure electrical or thermal characteristics.

The engineers at Intertronics have noted the general qualities of benchtop robots falling into certain advantageous categories.

First, the robots are more consistent and accurate as they do not get distracted or interrupted, enhancing product integrity.

Second, reject rates tend to go down.

Third, robots can work continuously and can be much faster than humans.

Fourth, there can be significant savings in material usage.

Expensive materials are dispensed accurately and multi-part material mixing may require purging or nozzle changes unless dispensed continuously.

Automotive, telecom and medical applications are popular, often in tier-two or three sub-assembly manufacturers, also for optoelectronics, fibre-optics, medical devices and simple tasks such as dome coating of small labels and badges.

Consequently, with technology costs now lower than ever in real terms, it is clear that benchtop robots achieve a high level of functionality, are readily available, simple to implement and surprisingly inexpensive, with prices starting at about GBP4,000.

At this level, cost justification by higher throughput and yields, fewer rejects, better quality or reduced labour content is relatively straightforward.

Payback times can be as little as a few weeks, which is vital to companies that would like to see domestic manufacturing stay in the UK and lead the economic recovery.

Intertronics

INTERTRONICS supplies a comprehensive range of bonding and protective materials – together with the associated consumables and equipment – to customers in high technology, high performance assembly industries – including electronics, medical device, plastics, optical, automotive, energy, defence and aerospace.

INTERTRONICS supplies a comprehensive range of bonding and protective materials – together with the associated consumables and equipment – to customers in high technology, high performance assembly industries – including electronics, medical device, plastics, optical, automotive, energy, defence and aerospace. The company supplies over 3,000 regular customers, including multinational manufacturing giants, production facilities, specialist design and development businesses, universities, training organisations and government establishments.

adhere is INTERTRONICS’ brand which encompasses its bonding, coating, sealing, encapsulating, potting, masking and gasketing materials, together with the most appropriate equipment and accessories for dispensing and curing them.

Because adhere brings together this proven range of integrated products from selected and trusted partners, INTERTRONICS’ customers have the confidence that everything will work together efficiently and cost-effectively, underpinned by the company’s experience and expert advice.

This advice is an essential element of the programme, and it ensures that customers benefit from the optimal material and process choice for the manufacture, assembly or repair of their products … safeguarding and enhancing performance and integrity and in turn, profitability and reputation.

Also key to customer success and satisfaction are the provision of process implementation and training, ongoing expert technical support and the assurance of highly competent supply chain management.

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