The vital role of switches in making Industry 4.0 a reality

14th November 2017
Joe Bush

The Internet of Things (IoT) has been anointed as the harbinger of Industry 4.0, a state in which factory automation devices are integrated within information technology (IT) platforms such as manufacturing execution systems (MES), enterprise resource planning (ERP) and business intelligence (BI) systems to create significant efficiency and productivity gains.

True to any good technology buried within the hype cycle, industry pundits are buzzing with potential over smart factories but aren’t discussing a key variable that will help usher in this new age of manufacturing - hardware and, more importantly, switches. Mike Bolduc, Global Marketing Manager, C&K explains.

Tiny ‘configuration’ switches are only a small part of an end device but are typically the product component users interact with most. This makes switches critical for not only communicating an image of overall product quality, but also to have a direct contribution to a product’s overall performance.

Infrastructure is a vital component to Industry 4.0 initiatives, too. High volume assembly for many products, such as iPhones, is performed on automatic assembly equipment that uses motorised belts or indexing tables that move the product from station to station, each one adding and modifying various components of a product until it’s fully assembled. This wouldn’t be possible without the basic components of these systems, which include communication devices, controllers, sensors and actuators.

Communication devices used for factory automation typically fall into two broad categories; fieldbus products, which connect equipment such as sensors and controllers at the shop floor level; and edge devices, which connect the factory floor to the industrial Ethernet, cloud servers, and the various IT systems.

Fieldbus networks (similar to the local area networks that connect desktop computers) link sensors, actuators and controllers on automated equipment. Fieldbus networks are known under many names, including DeviceNet, HART and Profibus as well as the newer Ethernet-based platforms such as EtherCat and Profinet. These local hardware systems allow data transfer between the sensor/actuator level and the control level and include devices such as input/output (I/O) bus modules, media and protocol converters, couplers and repeaters. These products are generally tailored to the particular protocols used (i.e. DeviceNet).

Fieldbus networks typically link to wireless and cellular networks through gateways and routers, commonly called ‘edge devices’. Edge devices can be embedded or standalone components that interface with wired or wireless components. The Cloud-based data generated is used to manage scheduling and other priorities among globally dispersed factories, and vendors have emerged to manage these device networks and systems, advertising themselves under the category Platform-as-a-Service (PaaS).

Communication devices use a variety of slide switches as well as standard and rotary coded DIP switches for configuration and addressing.

Control Systems
The control system takes input from various sensors and, based on the control logic or program, sends signals to the actuators to carry out a variety of operations. Machine control can be carried out with a Programmable Logic Controller (PLC), a Programmable Automation Controller (PAC), or a Windows-based industrial computer. Additional components can include Variable Speed Drives (VSDs), servo motor controllers and power supplies.

Almost all control system components utilise some type of electromechanical switch for setup, addressing or configuration. PLCs, for example, generally use either a slide or toggle switch to change from run to program mode at setup or when changes are made. General purpose VSDs often use slide switches for current and voltage selection as well as standard and rotary DIP switches for configuration or to set network addresses. Embedded and industrial computers can use tact, pushbutton or key switches for setup and operation.

The various tact, DIP, slide and toggle switches used on control devices need to perform reliably for many years under harsh conditions. Attributes such as small form factors, resistance to corrosion and low power consumptions are critical for proper performance.

Sensors are a critical part of any Industry 4.0 initiative. Before anything happens on the equipment, all the components and fixtures must be in the correct locations. In addition, for safety reasons, machines must be aware of people that may be in dangerous areas. These functions are carried out by a number of different devices including basic snap switches, capacitive and inductive proximity sensors, and photoelectric or light sensors.

For the safety circuit, there are dedicated relays that monitor the inputs from emergency stop buttons and light curtains. Vacuum grippers, commonly used to grab and place small components, also require the use of pressure switches to assure the components have been placed correctly. The sensors and switches used for these functions generally need to have small form factors and be able to withstand harsh manufacturing environments.

These devices also need to be configured for sensitivity, delays and limits when the machine is put in service or when changes are made. Tact and DIP switches are typically used for these functions. These ‘configuration’ switches need to have small footprints, be able to withstand exposure to oils, grease and other chemicals, perform reliably for many cycles and have low power consumption. Miniature tact switches used on proximity and pressure sensors must also have appropriate haptics to make it easy for technicians to setup and configure the device.

Once sensors determine that everything is safely in the correct location, components are placed into fixtures and various operations, including cutting, stamping, riveting and welding. Actuators typically come in linear or rotary configurations, driven by electric motors or pneumatics. These actuators use a number of devices for control and protection.

With electric motors, overload relays and circuit breakers are also routinely used. These devices typically require switches for setup and configuration. Tact and DIP switches (both standard and coded rotary) can be used in these applications to set output current levels and time delays while rotary switches can be used to manually turn devices on or off. Miniature snap-type switches are often used inside circuit breakers to determine trip conditions and send signals to a controller.

Relative to pneumatic actuators, valve terminals and valve controllers are used to power and control several actuators. These devices commonly use standard and rotary DIP switches for addressing and configuration. Similar to the switches used for factory automation sensors, these products need to be robust and able to perform in harsh environments. Miniature footprints, sealing against corrosive fluids and low power consumption are also key requirements for the switches used on these devices.

The factory 4.0 gold rush has already begun for many manufacturing equipment companies. When creating any product, customer loyalty is often borne out of a customer’s experience with a product. Switches have the rare ability to contribute to a product’s form and function and should never be an afterthought for smart product designers.

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