Meeting emerging challenges in manufacturing with lightweight robotics — Part 2

The trend toward adaptive, low-volume, high-mix manufacturing presents a challenge to manufacturers, as current technologies in automation — based on the principle of high volume and minimal change — cannot readily adapt to meet the rapidly changing needs of the market. Lightweight robots can help alleviate these challenges.

As discussed in Part 1 of this article, today’s global marketplace has changed and continues to change the dynamics of manufacturing. For those manufacturers who have moved facilities abroad to leverage lower labour costs, the realisation is rapidly dawning that maintaining high-quality products using manual production methods is not a sustainable, long-term strategy. In addition, the trend towards mass customisation, with lower volumes and a higher product mix, creates the challenge of producing small lot sizes efficiently and meeting high-quality standards expected in today’s market.

Advances in mechanics and controls are now enabling the practical and economical application of lightweight robotics for manufacturing on an increasingly broad scale.

How lightweight robotics addresses the challenges

In Part 1 of this article, the main challenges for the flexible application of robotics were listed as part presentation, machine access, process rates, layout issues and cost. Point by point, the following is how lightweight robotics is fitting into the manufacturing process by addressing these challenges:

• Part presentation: While conventional vibratory solutions may work for some applications, they don’t work for others. In those cases, fixed trays or conveyors can be used as a staging area for the robot. The integration of vision-based solutions with robotic systems is proving to be the most flexible, lowest cost solution. Parts can be loosely positioned onto a tray, belt conveyor or vibratory belt where the vision system will determine the part location and orientation. The vision system then transfers the information to the robot, allowing it to pick up the part. The vision system eliminates the need for part location details or precision transfer devices, reducing the cost of processing a new part.
• Machine access: With the large variation of robot configurations available, many alternative system layouts are possible. An overhead robot can be a good solution for tending multiple machine tools. With proper guarding, it can allow manual access to each machine without shutting down the robot system. Many types of robot mounts, bases and positioners can also be designed to allow temporary repositioning of the robot for machine access. Collaborative lightweight robots enable the operator and robot to work side by side without the need for guarding or disabling the robot.
• Process rates: Piece rate is only one measure of an automation system. A more important measure of capability is net throughput. Robotic machine loading systems have proven to have a much higher percentage of uptime than comparable manual processes. This additional uptime creates more available hours of operation per shift than the manual process, so a robot system with a slower piece rate can still have a much higher net throughput.

Furthermore, robots continue to improve in terms of speed, reach and payload capabilities. Today’s robot may be more than 20% faster than a comparable model from five years ago.

• Space and layout considerations: As with the challenge of machine access, many space and system layout issues can be addressed with the variety of available robot configurations. One promising development is that recent changes to robotics industry safety standards allow safety-rated soft limits. Robots can now dynamically define operating space and restricted space based on the status of safety interlock signals. This allows tremendous flexibility in both system layout and access. In addition, robotic solutions are designed to be more compact and lighter for easy portability and reduced footprint.
• Cost: When justifying robotic automation, a range of factors must be considered — not just labour. A thorough return on investment evaluation must take into account all associated costs and savings, as well as changes in throughput. It can also be difficult to justify robotic automation because of the tendency to think ‘one to one’ — one robot for one machine or one robot to replace one operator. Instead, manufacturers should look at multiple processes in a production area. In many cases, what appears to be a situation of one operator per one machine can turn into one operator per three or four machines when the larger manufacturing picture is considered.

Additional benefits of employing lightweight robotics

The implementation of lightweight robotics offers many additional, tangible benefits for manufacturers:

• Improved process control: A properly designed automated process ensures that things happen when and how they are supposed to. For both regulated and non-regulated industries, this is essential to ensuring quality and meeting customer expectations. Hard benefits include reduced scrap, higher throughput and better responsiveness to volatile demand.
• Improved machine utilisation: A machine that is not running generates no income for the manufacturer. Typical machine usage for a manual machining process is 65%. For a comparable automated process, this number is greater than 90%. Better machine tool usage results in a faster return on investment for the machine tool while simultaneously improving production capacity.
• Better use of labour: The most flexible and valuable resource in any company is its people. Good use of that resource is not necessarily for machine tending, but for machine set-up and other operations that may not be suitable to automation.
• Greater agility: Today’s global marketplace is distinguished by accelerating change and volatile, hard-to-predict demand. Leveraging robotic technology improves a manufacturer’s ability to respond quickly and efficiently to these conditions, helping achieve the leaner, more agile operations essential to sustainable success.
• Improved leverage to cope with macroeconomic trends: Certain developments are beyond an organisation’s control, such as economic recessions and recoveries as well as changing workforce demographics. This has implications for hiring practices, as does the growing shortage of skilled labour. Automation provides a hedge to allow increased production without precipitously adding to the labour force before the recovery is at a stage that warrants that, or before the workers you really desire are available.

Applications and emerging technologies

Laboratory automation

Driven by the need for higher throughput and higher quality as well as to enable technically challenging processes, many labs in drug discovery and in vitro diagnostics that were not previously adopters of laboratory automation are being drawn to the potential of simple, small-scale, benchtop automation enabled by lightweight robotics. During the past decade, many vendors emerged that specialise in delivering complex automated solutions for large research labs, in some cases using hundreds of small robots that can perform the same task, the same way every time, for millions of cycles.

However, for each of these core labs there are hundreds of others potentially interested in more efficient ways to carry out routine tasks at a smaller scale.

Most of these potential automation opportunities do not require high throughput or involve processing thousands of assays per day. Nor does the average lab have the budget or the space to accommodate ‘big automation’. For this group, lightweight robotics has been a revelation.

The types of benchtop automation most deployed to date are stand-alone automated pipettors or manually fed dispensers. In the future, we will see more automated workstations made up of multiple processing stations linked together by a plate mover/gripper.

Consumer electronics and small-scale assembly

Other industries are also experiencing a marked increase in the benchtop application of lightweight robotic systems. In the consumer electronics industry, tasks such as electronic printed circuit board (PCB) testing are ideal. A solution such as the Festo EXCM could be employed in a stacked configuration so that machine throughput could be significantly increased as seen in the PCB test station of Figure 1. The electrical values are verified using test probes as part of the product quality test process.

Figure 1: A lightweight gantry robot being used for PCB testing.

This solution can also be used in the tactile examination of touch displays and switches and to verify the presence of installed components on a PCB. With the continuing miniaturisation of products, positioning and aligning small screws prior to insertion can significantly affect productivity. Automation of such intricate tasks can result in a significant increase in throughput.

Other desktop automation tasks include dispensing in bonding, sealing and gasketing; coating applications for dispensing adhesives, sealants and lubricants; and filling electronic casings with resin. Such solutions can also easily integrate into machinery for hand-feeding components, transferring workpieces and positioning small parts. Additionally, they can be employed in contactless inspection systems to move a camera or laser probe consistently and smoothly over the material being checked.

Printed electronics

Today, semiautomatic or automatic screen printing machines are used for printing on mobile phone panels, membrane switches, LCD display boards, etc. Such automated solutions provide the improved repeatability and speed required for high-volume production of miniature products. Other examples of printed electronics applications that use automated screen printing mainly involve the production of printed circuit boards, where a mask is applied to direct a metal circuit path (copper, silver or other) on a bare board with attached components, or in applications that require thick layers of materials, such as batteries/PV technology, membranes/touch panels, sensors and glucose test strips.

While screen printing has dominated most of the printed electronics applications to date, advanced industrial inkjet printers are emerging as an alternative technology, mainly in terms of cost, feature-size resolution and digital architecture. Inkjet printing is a digital imaging technology that creates an image by jetting droplets of ink onto a substrate. Inkjet printers are the most commonly used type of consumer printer, along with laser printers. Inkjet printing is particularly good for depositing small amounts of materials that have specific electrical or structural functionalities onto well-defined locations on a substrate. The materials deposited can be soluble liquids, dispersions of small (nanosized) particles, melts or blends.

The main advantages of inkjet printing are the ability to change what is printed without making a new printing plate and the ability to print variable digital patterns. As a result, inkjet printing can achieve excellent resolution and uses a wide range of ink types (conductive, hot melted wax, solder, biomaterials). It is receptive to on-the-fly error correction, uses small amounts of materials that involve little waste, can build up layers and is a clean, non-contact technology. The disadvantages include fairly slow throughput, sensitivity to substrate variations, problems with ink spreading, limited printing speeds and printhead/solvent compatibility.

3D printing

Three-dimensional printed parts are now used for a multitude of applications, from medical devices (custom medical implants) to aircraft (weight reduction of parts, resulting in billions of dollars in fuel savings), toys and industrial manufacturing (metal 3D-printed injection moulds). Typically, a 3D printer starts with a few layers of disposable support material to provide a foundation. The extrusion head, which moves about an xy-plane, lays down a ribbon of material. After each layer is complete, the z-axis lowers slightly to make way for the next layer.