Product standardization makes sense for companies that have many locations and utilize multiple suppliers of production equipment. Without setting standards for the components used on new capital equipment, companies incur higher purchasing, manufacturing, maintenance, and training costs.
Sensors and cables, in particular, need to be considered due to the following:
The large number of manufacturers of both sensors and cables
Product variations from each manufacturer
For example, inductive proximity sensors all perform the same basic function, but some are more appropriate to certain applications based on their specific features. Cables provide a similar scenario. Let’s look at some of the product features you need to consider.
Inductive Proximity Sensors
· Style – tubular or block style
· Size and length
· Electrical characteristics
· Shielded or unshielded
· Sensing Range
· Housing material
· Sensing Surface
· Connector size
· Number of pins & conductors
· Wire gage
· Jacket material
· Single or double ended
Without standards each equipment supplier may use their own preferred supplier, many times without considering the impact to the end customer. This can result in redundancy of sensor and cable spare parts inventory and potentially using items that are not best suited for the manufacturing environment. Over time this impacts operating efficiency and results in high inventory carrying costs.
Once the selection and purchasing of sensors and cables is standardized, the cost of inventory will coincide. Overhead costs, such as purchasing, stocking, picking and invoicing, will go down as well. There is less overhead in procuring standard parts and materials that are more readily available, and inventory will be reduced. And, more standardization with the right material selection means lower manufacturing down-time.
In addition, companies can then look at their current inventory of cable and sensor spare parts and reduce that footprint by eliminating redundancy while upgrading the performance of their equipment. Done the right way, standardization simplifies supply chain management, can extend the mean time to failure, and reduce the mean time to repair.
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
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
Increased diagnostics from intelligent devices
Reduced costs and downtime
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.
New automation products hit the market every day and each device requires the correct cable to operate. Even in standard cables sizes, there are a variety of connector types that correspond with different applications.
When choosing a cable, it is essential to choose the correct size, length, number of connectors, pinout, and codes for your application. This post will review cable codes, which signify different capabilities and uses for a cable. Cables that are coded differently will have different specifications and electrical features, corresponding to their intended uses. To distinguish between the different styles of cable, each connector has a different keyway, as shown in Figure 1. This is to prevent a cable from being used in an incorrect application.
There are a wide variety of cable codings used for different purposes. Below are the five most common M12 cable codes and their uses. They are as follows:
A-coded connectors are the most common style of connector. These are used for sensors, actuators, motors, and most other standard devices. A-coded connectors can vary in its number of pins, anywhere between two pins and 12 pins.
B-coded connectors are mostly used in network cables for fieldbus connections. Most notably, this includes systems that operate with Profibus. B-coded connectors typically have between three and five pins.
C-coded connectors are less common than the others. These connectors are primarily used with AC sensors and actuators. They also have a dual keyway for added security, ensuring that this connector will not be accidentally used in the place of another cable. C-coded connectors have between three and six pins.
D-coded connectors are typically used in network cables for Ethernet and ProfiNet systems. D-coded connectors transfer data up to 100 Mb. These connectors typically provide three to five pins.
X-coded connectors are a more recent advancement of the cables. They are growing in popularity due to their ability to transfer large amounts of data at high speeds. X-coded cables transfer data up to 1 Gb. These are ideal for high-speed data transfer in industrial applications. While the other coded cables typically vary in number of connectors, X-coded cables will always have eight pins.
Using high-durability cables in application environments with high temperatures, weld spatter, or washdown areas improves manufacturing machine up-time.
It is important to choose a cable that matches your specific application requirements.
When a food and beverage customer needs to wash down their equipment after a production shift, a standard cable is likely to become a point of failure. A washdown-specific cable with an IP68/IP69 rating is designed to withstand high-pressure cleaning. It’s special components, such as an internal O-ring and stainless-steel connection nut, keep water and cleaners from leaking.
Welding environments require application-specific cables to deal with elevated temperatures, tight bend radiuses and weld spatter. Cables with a full silicone jacket prevent the build-up of debris, which can cause shorts and failures over time.
High Temperature cables
Applications with high temperatures require sensors that can operate reliably in their environment. The same goes for the cables. High temperature cables include added features such as a high temperature jacket and insulation materials specifically designed to perform in these applications.
Selecting the correct cable for a specific application area is not difficult when you know the requirements the application environment demands and incorporate those demands into your choice. It’s no different than selecting the best sensor for the job. The phrase to remember is “application specificity.”
For more information on standard and high-durability cables, please visit www.balluff.com.
Every time I enter tier 1 and tier 2 suppliers, there seems to be a common theme of extreme sensor and cable abuse. It is not uncommon to see a box or bin of damaged sensors along with connection cables that have extreme burn-through due to extreme heat usually generated by weld spatter. This abuse is going to happen and is unavoidable in most cases. The only option to combat these hostile environments is to select the correct components, such as bunker blocks, protective mounts, and high temperature cable materials that can withstand hot welding applications.
In many cases I have seen standard sensors and cables installed in a weld cell with essentially zero protection of the sensor. This results in a very non-productive application that simply cannot meet production demands due to excessive downtime. At the root of this downtime you will typically find sensor and cable failure. These problems can only go on for so long before a culture change must happen throughout a manufacturing or production plant as there is too much overtime resulting in added cost and less efficiency. I call this the “pay me now or pay me later” analogy.
Below are some simple yet effective ways to improve sensor and cable life:
Whether it’s through preventative maintenance or during planned machine downtime, reducing downtime is a common goal for manufacturers. Difficult environments create challenges for not just machines, but also the components like sensors or cables. Below are three tips to help protect these components and reduce your downtime.
Cables don’t last forever. However, they are important for operations and keeping them functional is vital. An easy way to help reduce downtime and save money is by implementing a “sacrificial cable” in unforgiving environments. A sacrificial cable is any cable less than two meters in length and placed in situations where there is high turnover of cables. This sacrificial cable does not have to be a specialty cable with a custom jacket. It can be a simple 1 meter PVC cable that will get changed out often. The idea is to place a sacrificial cable in a problematic area and connect it to a longer length cable, or a home-run cable. The benefits of this method include: less downtime for maintenance when changing out failures, reduced expenses since shorter cables are less expensive, and there is less travel for the cable around a cell.
A second way to help reduce downtime is consider your application conditions up front. We discussed some of the application conditions to consider in a previous blog post, but how can we address these challenges? Not only is it important to choose the correct sensor for the environment, but remember, cables don’t last forever. Choosing the appropriate cable is also key to reducing downtime. Welding environments demand a cable that weld beads will not stick to and fuse the cable to the sensor. There are a variety of jacket types like silicone, silicone tube, or PTFE that prevent weld debris from accumulating on the cable. I’ve also seen applications where there is a lot of debris cutting through cables. In this case, a stainless steel braid cable would be a better solution than a traditional cable. Fitting the right protection to the right application is crucial..
A third tip to help reduce your machine downtime is to simply add protection to your existing components. Adding protection, whether it is a protective bracket or a silicone product, will help keep components running longer. This type of protection can be added before or after the cell is operational. One example of sensor protection is adding a ceramic cap to protect the face of a sensor. You can also protect the connection by adding tubing to the cable out version of the sensor to shield it from debris. Mounting sensors in a robust bracket helps protect the sensor from being hit, or having debris cover the sensor. There are different degrees of changes that help prolong operations.
Metalforming expert, Dave Bird, explains some of these solutions in the video below. To learn more you can also visit our website at www.balluff.us.
When working in harsh environments and in heavy duty applications like welding, it is important to take a multi-angle approach to designing the application. When you are working with existing sensor installations, it is important to consider all the reasons for the sensor’s failure before determining a winning solution. An important step in any application is to protect the connection between the controller and the sensor. In a welding environment, whether the sensor cable fails from weld slag buildup or from physical damage from contact with a part, the cable can be the key to a successful weld-sensing application.
That being said, the number of options available to protect the connection can be overwhelming and at times even confusing. For example, silicone cables vs silicone tube cables. Silicone cables have a jacket that is made out of silicone material over the conductors. This usually allows for a smaller diameter and more variety with the cordsets i.e. length and connector types. On the other hand, a silicone tube cable is a standard sensor cable with a silicone pulled over the cable then over-molded. The silicone tube is a second jacket and the air is a good insulator, prolonging the life of the sensor cable.
Another important consideration is how to even connect your sensor. One option is to install a sensor with a connector. This allows for a quick disconnect from the cable. In this case, it may be better to use a right angle connector, so the bend radius of the cable is not hanging loose. A second option is to install a sensor with cable out. This can have flying leads or a connector added to the end. At times, when there is not enough room to add a cordset, the cable out gives extra space.
In any continuous manufacturing process such as steel production, increased throughput is the path to higher profits through maximum utilization of fixed capital investments. In order to achieve increased throughput, more sophisticated control systems are being deployed. These systems enable ever-higher levels of automation but can present new challenges in terms of managing system reliability. Maintenance of profit margins depends on the line remaining in production with minimal unexpected downtime.
It is essential that control components, such as sensors, be selected in accordance with the rigorous demands of steel industry applications. Standard sensors intended for use in more benign manufacturing environments are often not suitable for the steel industry and may not deliver dependable service life.
When specifying sensors for steel production applications, some environmental conditions to consider include:
High temperatures exist in many areas of the steel-making process, such as the coke oven battery, blast furnace, electric arc furnace, oxygen converter, continuous casting line, and hot rolling line. Electronic components are stressed by elevated temperatures and can fail at much higher rates than they would at room temperature. Heat can affect sensors through conduction (direct transfer from the mounting), convection (circulating hot air), or radiation (line-of-sight infrared heating at a distance). The first strategy is to install sensors in ways that minimize exposure to these three thermal mechanisms. The second line of defense is to select sensors with extended temperature ratings. Many standard sensors can operate up to 185° F (85° C) but high temperature versions can operate to 212° F (100° C) or higher. Extreme temperature sensors can operate to 320° F (160° C) or even 356° F (180° C).
Don’t forget to consider the temperature rating of any quick-disconnect cables that will be used with the sensors. Many standard cable materials will melt or break down quickly at higher temperatures. Fiberglass-jacketed cables, for example, are rated to 752° F (400° C).
Shock and Vibration
Steel making involves large forces and heavy loads that generate substantial amounts of shock under normal and/or abnormal conditions. Vibration is also ever-present from motors, rollers, and moving materials. As with heat, look for sensors with enhanced specifications for shock and vibration. For sensors with fixed mountings, look for shock ratings of at least 30 G. For sensors mounted to equipment that is moving (for example, position sensors on hydraulic cylinders), consider sensors with shock ratings of 100 to 150 G. For vibration, the statement of specifications can vary. For example, it may be stated as a frequency and amplitude, such as 55 Hz @ 1 mm or as acceleration over a frequency range, such as 20 G from 10…2000 Hz.
Don’t forget that the quick-disconnect connector can sometimes be a vulnerability under severe shock. Combat broken connectors with so-called “pigtail” or “inline” connectors that have a flexible cable coming out of the sensor that goes to a quick-disconnect a few inches or feet away.
The best way to protect sensors from mechanical impact is to install them in protective mounting brackets (a.k.a. “bunker blocks”) or to provide heavy-duty covers over them. When direct contact with the sensor cannot be avoided, choose sensors specifically designed to handle impact.
Another strategy is to use remote sensor actuation to detect objects without making physical contact with the sensor itself.
Corrosion and Liquid Ingress
In areas with water spray and steam, such as the scale cracker on a hot strip line, corrosion and liquid ingress can lead to sensor failure. Look for stainless steel construction (aluminum can corrode) and enhanced ingress protection ratings such as IP68 or IP69K.
When All Else Fails…Rapid Replacement
If and when a sensor failure inevitably occurs, choose products and accessories that can minimize the downtime by speeding up the time required for replacement.
Strategies include quick-change sensor mounts, rapid-replacement sensor modules, and redundant sensor outputs.
In the case of redundant sensor outputs, if the primary output fails, the system can continue to operate from the secondary or even tertiary output.
In industrial automation we put our products through a lot. Extreme temperatures, harsh environments, and the demands of high performance can put a strain on the components of any machine. This led me to wonder, if our products could talk, what would they say?
Cordset: Cables have certain limpness which makes installing the cordset in automation easier to fit in tight spaces. Most cable installers prefer to have the least amount of slack in cable to prevent the cable being snagged or pulled during operations. Cables need to have a bend radius to prevent kinking of the conductors and a continuous flow of power. The bend radius is “the smallest radius of curvature into which a material can be bent without damage” (McGraw-Hill Dictionary of Architecture and Construction). Typically in a fixed (stationary) application, an unshielded sensor cable has a minimum bending radius of 8 times the outer diameter of the cable.
Power Supply: Everyone wants a friend. When a load is too much for one power supply, adding another power supply helps increase the voltage or current output. “The simplest method to create higher current is to connect the power supplies in parallel and leave only one supply in constant voltage mode. Some power supplies are equipped with analog control signals that allow auto-parallel or auto-tracking, a more elegant way to control multiple power supplies. Auto-parallel supplies can be controlled with a single master supply; a second advantage is that all of the master power supplies features can be used.” (Keysight Technologies) By stringing together power supplies, it allows more voltage or current but also keeps operations up and running.
There are many different types of cable jackets and each jacket works well in a specific application. The three main sensor cable jackets are PVC (Polyvinyl Chloride), PUR (polyurethane) and TPE (thermoplastic elastomer). Each jacket type has different benefits like washdown, abrasion resistant or high flexing applications. Finding the correct jacket type for your application can extend the life of the cable.
PVC is a general purpose cable and is widely available. It is a common cable, and typically has the best price point. PVC has a high moisture resistance, which makes it a good choice for wash-down applications.
PUR is found mostly in Asia and Europe. This cable jacket type has good resistance against abrasion, oil and ozone. PUR is known for being Halogen free, not containing: chlorine, iodine, fluorine, bromine or astatine. This jacket type does have limited temperature range compared to the other jacket types, -40…80⁰C.
TPE is flexible, recyclable and has excellent cold temperature characteristics, -50…125⁰C. This cable is resistant against aging in the sunlight, UV and ozone. TPE has a high-flex rating, typically 10 million.
The table below details the resistance to different conditions. Note that these relative ratings are based on average performance. Special selective compounding of the jacket can improve performance.
Choosing the right jacket type can help reduce failures in the field, reducing downtime and costs. Please visit www.balluff.us to see Balluff’s offering of sensor cables in PVC, PUR and TPE.