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Non-Contact Inductive Couplers Provide Wiring Advantages, Added Flexibility and Cost Savings Over Industrial Multi-Pin Connectors

Today, engineers are adding more and more sensors to in-die sensing packages in stamping applications. They do so to gain more information and diagnostics from their dies as well as reduce downtime. However, the increased number of sensors also increases the number of electric connections required in the automation system. Previously, the most common technique to accommodate large numbers of sensor in these stamping applications was with large, multi-pin connectors. (Figure 1)

Figure 1: A large multi-pin connector has been traditionally used in the past to add more electronics to a die.

The multi-pin connector approach works in these applications but can create issues, causing unplanned downtime. These problems include:

1. Increased cost to the system, not only in the hardware itself, but in the wiring labor. Each pin of the connector must be individually wired based on the sensor configuration of each particular die. Depending on the sensor layout of the die, potentially each connector could need to be wired differently internally.
2. A shorter life span for the multi-pin connector due to the tough stamping environment. The oil and lubrication fluids constantly spraying on the die can deteriorate the connectors plastic housings. Figure 1 shows the housing starting to come apart. When the connector is unplugged, these devices are not rated for IP67 and dirt, oil, and/or other debris can build up inside the connector.
3. Cable damage during typical die change out. Occasionally, users forget to unplug the connectors before pulling the die out and they tear apart the device. If the connector is unplugged and left hanging off the die, it can be run over by a fork truck. Either way, new connectors are required to replace the damaged ones.
4. Bent or damaged pins. Being mechanical in nature, the pin and contact points will wear out over time by regular plugging and unplugging of these devices.
5. A lack of flexibility. If an additional sensor for the die is required, additional wiring is needed. The new sensor input needs to be wired to a free pin in the connector and a spare pin may not be available.

Figure 2: Above is a typical set up using these multi-pin connectors hard-wired to junction boxes.

Inductive couplers (non-contact) are another solution for in-die sensors connecting to an automation system. With inductive couplers, power and data are transferred across an air gap contact free. The system is made up of a base (transmitter) and remote (receiver) units. The base unit is typically mounted to the press itself and the remote unit to the die. As the die is set in place, the remote receives power from the base when aligned and exchanges data over a small air gap.

The remote and base units of an inductive coupler pair are fully encapsulated and typically rated IP67 (use like rated cabling). Because of this high ingress protection rating, the couplers are not affected by coolant, die lubricants, and/or debris in a typical stamping application. Being inherently non-contact, there is no mechanical wear and less unplanned downtime.

When selecting an inductive coupler, there are many considerations, including physical form factors (barrel or block styles) and functionality types (power only, input only, analog, configurable I/O, IO-Link, etc…). IO-Link inductive couplers offer the most flexibility as they allow 32 bytes of bi-direction data and power. With the large data size, there is a lot of room for future expansion of additional sensors.

Adding inductive couplers can be an easy way to save on unexpected downtime due to a bad connector.

fig 3 — Figure 3: A typical layout of an IO-Link system using inductive couplers in a stamping application.

You have options when it comes to connecting your sensors

When it comes to connecting I/O in factory automation settings, there are many options one can choose to build an efficient and cost-effective system. This is one area where you can reduce costs while also boosting productivity.

Single Ended Cables and Hardwired I/O

It is common in the industry for single ended cables to be run from sensors to a controller input card in a centralized control cabinet. And while this method works, it can be costly for a number of reasons, including:

Flying leads on single ended cables are time consuming to prepare and wire
Wiring mistakes are often made leading to more time troubleshooting
I/O Cards for PLCs are expensive
Long cable runs to a centralized location add up quickly especially when dealing with analog devices which require expensive shielded cables
Lack of scalability and diagnostics

Double Ended Cables and Networked I/O

Using double ended cables along with network I/O blocks allows for a cost-effective solution to distribute I/O and increase up time. There are numerous benefits that come along with this sort of architecture. Some of these benefits are:

Reduced cabling — since I/O is distributed, only network cables need to be run back to the control cabinet reducing cost and cabinet size, and sensor cables are shortened since I/O blocks are machine mounted
Quicker build time since standard wiring is less labor intensive
Diagnostics allows for quicker trouble shooting, leading to lower maintenance costs and reduced downtime

IO-Link

Using IO-Link delivers all of the strengths of networked I/O as well as additional benefits:

I/O Hubs allow for scalability
Smart devices can be incorporated into your system
Parameterization capability
Increased diagnostics from intelligent devices
Reduced costs and downtime
Increased productivity

Inductive Coupling for non-contact connection

Many people are using inductive coupling technology to provide a non-contact connection for their devices. This method allows you to pass both power and signal across an air gap making it ideal for replacing slip rings or multi-pin connectors in many applications. This provides some great options for industry to gain benefits in these areas such as:

Reduced wear since there is no physical connection
Faster change over
Reduced downtime due to the elimination of damaged connector pins

For more information on connectivity and I/O architecture solutions please visit www.balluff.com.

Press Shops Boost Productivity with Non-Contact Connections

In press shops or stamping plants, downtime can easily cost thousands of dollars in productivity. This is especially true in the progressive stamping process where the cost of downtime is a lot higher as the entire automated stamping line is brought to a halt.

BIC presse detail 231013

Many strides have been made in modern stamping plants over the years to improve productivity and reduce the downtime. This has been led by implementing lean philosophies and adding error proofing systems to the processes. In-die-sensing is a great example, where a few inductive or photo-eye sensors are added to the die or mold to ensure parts are seated well and that the right die is in the right place and in the right press. In-die sensing almost eliminated common mistakes that caused die or mold damages or press damages by stamping on multiple parts or wrong parts.

In almost all of these cases, when the die or mold is replaced, the operator must connect the on-board sensors, typically with a multi-pin Harting connector or something similar to have the quick-connect ability. Unfortunately, often when the die or mold is pulled out of the press, operators forget to disconnect the connector. The shear force exerted by the movement of removing the die rips off the connector housing. This leads to an unplanned downtime and could take roughly 3-5 hours to get back to running the system.

Another challenge with the multi-conductor connectors is that over time, due to repeated changeouts, the pins in the connectors may break causing intermittent false trips or wrong die identification. This can lead to serious damages to the system.

Both challenges can be solved with the use of a non-contact coupling solution. The non-contact coupling, also known as an inductive coupling solution, is where one side of the connectors called “Base” and the other side called “Remote” exchange power and signals across an air-gap. The technology has been around for a long time and has been applied in the industrial automation space for more than a decade, primarily in tool changing applications or indexing tables as a replacement for slip-rings. For more information on inductive coupling here are a few blogs (1) Inductive Coupling – Simple Concept for Complex Automation Part 1, (2) Inductive Coupling – Simple Concept for Complex Automation Part 2

For press automation, the “Base” side can be affixed to the press and the “Remote” side can be mounted on a die or mold, in such a way that when the die is placed properly, the two sides of the coupler can be in the close proximity to each other (within 2-5mm). This solution can power the sensors in the die and can help transfer up to 12 signals. Or, with IO-Link based inductive coupling, more flexibility and smarts can be added to the die. We will discuss IO-Link based inductive coupling for press automation in an upcoming blog.

Some advantages of inductive coupling over the connectorized solution:

Since there are no pins or mechanical parts, inductive coupling is a practically maintenance-free solution
Additional LEDs on the couplers to indicate in-zone and power status help with quick troubleshooting, compared to figuring out which pins are bad or what is wrong with the sensors.
Inductive couplers are typically IP67 rated, so water ingress, dust, oil, or any other environmental factor does not affect the function of the couplers
Alignment of the couplers does not have to be perfect if the base and remote are in close proximity. If the press area experiences drastic changes in humidity or temperature, that would not affect the couplers.
There are multiple form factors to fit the need of the application.

In short, press automation can gain a productivity boost, by simply changing out the connectors to non-contact ones.

Benefits of Non-contact Linear Position Sensing Technology

Linear position sensors that provide continuous, typically analog, feedback are used extensively in a variety of applications in many different industries and markets. Linear position sensors employ various technologies, but at the most basic level the technologies can be classified as being either non-contact or contact based.

For the purpose of this article, when we talk about contact based technology, the example we’re using is resistive linear potentiometers. And for non-contact technology, we’re talking about magnetostrictive sensors.

In industrial linear position sensing applications, both ultimately do the same job; provide variable analog signals that represent the linear position of a machine or a process. The difference is how the signal is derived.

Resistive linear potentiometers employ a resistive element upon which a spring-loaded contact rides:

The output of the sensor represents the position of the slider along the resistive element and typically ranges from 0-10Vdc or -10 to +10Vdc. Out of the box, performance and accuracy is pretty good. But after repeated cycles, wear can start to place that affects the connection between the resistive element and the contact. The end result is signal anomalies and worsening performance over time, as can be seen in the image below.

Other external factors, such as dirt and/or moisture only serve to accelerate this declining performance.

Non-contact technology, such as is incorporated into magnetostrictive linear position sensors, isn’t vulnerable to mechanical wear and subsequent performance degradation.

Unlike, resistive sensors, magnetostrictive sensors operate on the principle of magnetism. Interacting magnetic fields define the output value, which changes as a moving magnet travels along a sensing element, called a waveguide. There is no mechanical contact, so there is no mechanical wear. The result is greatly enhanced life expectancy and consistently excellent performance

Cost Considerations

Generally, resistive linear position sensor cost a bit less than magnetostrictive sensors. However, that doesn’t tell the whole story. True cost of ownership has to be considered. For a more complete discussion about cost of ownership, take a few minutes to review the Sensortech article The True Cost of Low Cost.

Non-contact Power & Data Exchange For Assembly Automation

Assembly automation has evolved multi-fold since Ford’s first linear assembly plant. Assembly automation is of course commonly found in Automotive or heavy industries but it has found its way in small parts assembly, consumer goods and other industries that are embracing automation full on.

Typically, in assembly automation, pallets of sub-assemblies travel along the conveyor maze making stops at various stations to get further components and assemblies put on or some kind of operation is being performed on them.

Several times, inspection, measurement or other process specifics demand sensors and actuators to be on-board these pallets. A very common challenge people face in this environment is to provide power and communicate with this traveling assembly. Pin based automatic couplers and/ or manual intervention is common solution. As explained in my previous blog “Inductive Coupling for Robotic End Effectors” the pin based coupling has downfall of being susceptible to environmental elements and mechanical wear. Thus, offering a solution that requires some regular maintenance and related downtime. Manual intervention for inspection or measurement is of course time consuming and laborious activity.

Non-contact inductive coupling offers great benefits in this scenario. Typically, the base (transmitter) is mounted along the conveyor and the remote (receiver) is mounted on the moving pallets. As the pallet moves along the assembly line, the remote, when in-zone of the base, receives power and exchanges data over small air-gap with the base unit. There are three major benefits of this approach

Because of magnetic induction phenomenon, these non-contact couplers are immune to dust, humidity, oil or vibrations, unlike the pin based couplers.
Misalignment tolerance: Inductive couplers do not need to be in exact axial or angular alignment. They can tolerate angular or axial offsets. The amount of offset they can tolerate depends on the particulars but typically 10-20° angular offset is acceptable. So over-time when the conveyor system develops some slag, the inductive couplers won’t fail you that easily.
Scalability: Inductive couplers come in various form factors and functionality that includes Power-only, input only, analog, configurable channels of inputs and outputs, and with IO-Link bi-directional communication. IO-Link inductive couplers offer the greatest benefits as they allow exchanging up to 32bytes of data bi-directionally- so in future if the I/O needs grow for your pallets, it can be easily handled.

You can always learn more about inductive couplers on Balluff’s website at www.balluff.us. You can also learn more in our Basics overview.

Inductive coupling – simple concept for complex automation

Inductive coupling is not new to automation. The concept in various forms has been around for over few decades. It was not actively used, and my guess is that more than form factor or functionality of couplers, it has to do with automation technology relying on mechanical and hard wired components. With growing complexity and ever evolving technology, the inductive coupling has also evolved. Nowadays, you can charge your smart phones or tablets using the charging pad that uses the very same technology.

power&dataexchange — Figure 1: Inductive coupling for power and data exchange

In industrial automation space, inductive sensors are very popular and commonly used for detecting proximity of metal objects such as food cans, or machine parts. Inductive coupling uses magnetic induction to transfer power and data over an air gap. Yes, it is a kind of very short range wireless technology that also enables power transfer.

In this series of blogs on inductive coupling, we can explore various use cases of inductive coupling in complex automation. Today, let’s see how inductive coupling compares with traditional slip-ring mechanism.

Slip-rings, also known as rotary connectors, are typically used in areas of the machine where one part rotates and other part of the machine remains stationary. For example, an indexing table or turn table where stations on the indexing table need power and I/O but the table rotates through full 360°, hence standard cable solutions are ineffective. A slip ring could be installed at the base of the table.

ReplacingSlipRing — Figure 3: Inductive coupling replacing the slip-ring

Since, slip rings are electromechanical devices, in the long term they are subject to wearing out. Unfortunately, the signs of wear are not evident unless one day there is no power to the table. An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base coupler could be mounted at the base of the table and the remote coupler could be mounted on the rotating part of the table. Slip rings are susceptible to noise and vibration because they are electromechanical devices, whereas inductive couplers are not because there is no contact between the base and the remote. In fact, the turn table shown above uses an inductive coupler.

Inductive coupler, typically have IP67 rating for the housing are not affected by dirt or water, are immune to vibrations, and most important they are contact free so no maintenance is required unless you hammer one out. Learn more about Balluff inductive couplers: www.balluff.us.

Hit Me With Your Best Shot: Sensors Must Withstand Punishing Applications

In today’s competitive manufacturing environment, the name of the game is increased throughput. Unprecedented global competition means that industrial manufacturing machinery must be able to run better (faster, longer, hotter, etc.) and more reliably than ever before.

Continue reading “Hit Me With Your Best Shot: Sensors Must Withstand Punishing Applications”