Unleash Modular Production Power

Valves are automatically assembled in the production cells of this plant’s large modular assembly lines. All photos courtesy Festo

Manufacturers are calling and modular, multi-tasking, plant-floor problem solvers are delivering in a big way.

By Nuzha Yakoo, Festo

The development and application of modular production systems (MPS) responds directly to industry issues around shorter product lifecycles, mass customization, and the need for improved manufacturing agility. Interest in these systems is also rising due their compatibility with cloud computing, and the Industrial Internet of Things (IIoT).

WHAT, HOW, WHY?

Individual MPS modules are relatively modest in cost, as well as fast and easy to build. Each module typically performs a limited number of operations before a work piece is conveyed to the next module. Limited operations reduce complexity.

Modules can be quickly refurbished, reused, and redeployed in any number of configurations to produce an entirely different product or component. They allow plants to quickly and cost-effectively scale production up or down as demand fluctuates. Noteworthy for their small footprints and short lead time to production, these systems help reduce costs by lowering work in process (WIP) and energy consumption. Modules can be manufactured in small series and fully tested prior to delivery. Application software features reduced complexity, making it easy to reprogram for new products.

For a high mix of products where manual labor had once been the best solution, MPS offer higher output at less cost. For a complex mix of products within a product family, manufacturers typically opt for flexible automation, relying on robotics. To produce maximum output of low-mix products with long lifecycles, dedicated automation remains the solution of choice.

Electronics-manufacturing modules, such as these, can be refurbished, reused, and redeployed, in any number of configurations, to produce entirely different products.

CURRENT TRENDS

Four industry trends are leading companies to evaluate MPS-based manufacturing. The first involves increased product demand caused by a growing economy and re-shoring. There are major impediments to increasing staff to meet production growth, including rising wages, skills shortages, training costs, and global competition from lower-wage countries. Through automated processes, MPS can cost effectively address these labor issues. MPS are not labor free, though. Technicians trained in modular manufacturing must be hired. Universities and community colleges that offer associate and other degree programs in manufacturing now equip their labs with MPS training systems to fill this need.

A second trend is shorter product lifecycle demands that are faced by all manufacturers. Long-lead-time, high-cost production systems aren’t feasible when products quickly appear and disappear. MPS are designed for fast startup and shorter product lifecycles.

Personalization is a trend that marketers are leveraging to distinguish their products. With the application of smart conveyors and MPS, products can be uniquely routed to a series of modules that can turn out any number of personalized items.

E-commerce is, another important trend. E-commerce integrates customer orders with business systems, factory production, supply chains, and logistics, creating a fast-response network. The quick, versatile fabrication and connection to cloud computing associated with today’s modular manufacturing systems makes them suited for E-commerce.

MPS-MODULE TASKS

The modules in an MPS are typically built for these operations:

• pick and place

• soldering, bonding, sealing

• small-parts assembly, including screwdriving and electronic testing

• feeding and mounting small components

• alignment and orientation of parts for assembly

• press fitting, pressing, punching, beveling, riveting, clamping, bending, stamping, clinching, crimping, adjusting, and spring testing.

The new generation of small, light-weight, two-armed dexterous robots, small-footprint SCARA robots, and collaborative robots are used for more individualized delicate and complex tasks.

Modules typically rely on combinations of these technologies:

• simple controls and connections that make it easy to integrate modules

• vision for bar-code reading and component inspection

• radio-frequency-identification (RFID) capability for reading and writing each operation performed on a part

• integrated functional safety and diagnostics

• compact Cartesian handling systems and Cartesian robots

• a control platform that integrates pneumatics, servo pneumatics, electromechanical motion, and vision systems

• dedicated, flexible, or adaptive grippers

• I/O link devices for process, device, and event data

• Fieldbus communication modules supporting a broad range of protocols.

A key enabling technology (one that’s not always needed but helpful for customization) is the new generation of smart conveyors that can individually route products to various modules. Parts are typically routed along a smart conveyor on carriers, which are often referred to as “pucks.” Smart conveyors adapt spacing between pucks and can clamp and transfer a part, as well as insert, press, and lift parts using linked carriers. Multiple pucks can be moved relative to each other without colliding—and also moved in synchronization with fixed distances between each other. Pucks can be grouped, separated, and regrouped. Smart conveyors remove the notion that various steps in a production process must be carried out sequentially.    

Production data related to the product being transported on a puck can be stored in the embedded RFID tag. By employing a RFID read/write head at each task-specific module, the module will carry out the required task or the smart conveyor will move the puck past any module operation that is not required. Instead of having various production lines for product families, product families can now be produced on a single line. Quality inspection/check stations can be positioned along the line. Errors in production such as product weight are identified immediately and corrected to minimize or eliminate rejects. This reduces time and cost of reworking and eliminates or reduces material waste.

Modular production systems are also suitable for additive manufacturing. Prototypes and low-volume units printed on demand offer cost advantages because no tooling is required. This flexibility also supports personalization and shorter product lifecycles.

DESIGN CONSIDERATIONS

To be as effective as possible, products must start out with a design that is based on modular production. Design for assembly and/or manufacturing strategies minimizes the number of assembly processes and helps define the modular steps that are needed. After part manufacturing is detailed, existing modules can be refurbished and redeployed as needed or new ones ordered. Modules rely on drop-in subassemblies, such as multi-axis handling systems and Cartesian robots, for fast time to market and reduced cost.

CLOUD-BASED BENEFITS

Because modular production systems are built for connection to business systems, they can be extended to the cloud.

With cloud-based MPS, personnel from any location can easily read the current state of a module and detect and diagnose operational or product defects for prompt corrective action. Personnel can monitor production flow in real time to reduce work-in-process inventory. Cloud computing allows condition-based maintenance alerts to reduce downtime and increase throughput. Access to real-time, actionable data enables companies to make more intelligent and timely decisions. EP

Real-World Success: MPS At Harwin PLC

Rear view of the three modules of Harwin’s Gecko Screw-Loc assembly line: (right) pin insertion; (middle) pin press-fitting; (left), contact-pin bending. Each module was designed using standard components and bundled software.

British company turned to a modular production system for flexible, automated plug-connector assembly.

Just as printed circuit boards have successfully managed to pack an increasing amount of power into a smaller space, developers of plug connectors are working to accommodate more power and a higher contact density into smaller, lighter plug connectors. Responding to this trend, Harwin plc, of Portsmouth, UK (harwin.com), wanted to increase the number of pins in its screw-lock electrical plugs for the consumer electronics, automotive, aerospace, and motor-sports industries.

Problem/Solution

This servo press is used in the connector-pins press-fitting operation that’s part of the assembly process carried out by the three-station modular-production system shown in the adjacent photo.

Products in Harwin’s Gecko range of Screw-Loc connectors have a pin pitch of only 0.05 in. (1.25 mm) and are half the size and 75% lighter than competing micro-D connectors. At first, the Gecko connectors were assembled manually. That’s because the high number of pin configurations—from 4 to 50 pins per plug—and wide set of mounting options made automating the assembly a difficult proposition. As demand increased for these connectors, however, manual assembly became unsustainable in terms of cost and the limited number that could be produced by hand.

To meet the needs of a growing global demand, Harwin developed an automated assembly process based on a three-station modular configuration built around servo presses and compact Cartesian handling systems. (X/Y-axis-positioning is performed by these types of Cartesian handling systems at all three stations.) Each of the three modules has a dedicated panel incorporating control for electrics and pneumatics:

At Module One, connector housings are precisely positioned for pin placement by a compact Cartesian handling system. The kinematics of the system enable dynamic and precise movement and ensure the connectors are accurately placed under the press-fitting tools.

At Module Two, a servo press fits the pins into the plugs. The servo press closed-loop servo motor, motion controller, and force detection result in precise, powerful, yet gentle movement as pins are pressed into the correct positions. Evaluation functions by press-application software detect whether the fit is within specified tolerance.

At Module Three, a compact Cartesian handling system and a servo press are coordinated for bending contact pins to the required angle. The intuitive graphical user interface makes it easy to adapt the press profile to the different connector variants without the need for special programming skills. Valve terminals, controlled by the master controller, actuate the numerous electric and pneumatic grippers and actuators.

Payoff

According to Paul McGuinness, Harwin’s director of operations, implementation of the MPS is paying off for the company on several fronts. “The automated modular concept of the three-station solution,” he noted, “ensures low production costs and high reliability, precision, repetition accuracy, and flexibility.”

Nuzha Yakoo is a senior technologist with Festo, Islandia, NY. For more information on modular-production systems and other manufacturing solutions, visit festo.com.