If you are the designer of the new production line of the filling machine. Frequent cleaning with detergents or bactericides often requires that materials and equipment meet these conditions while maintaining performance. You are an engineer at a car manufacturer. Sensors near the torch are disabled at the frequency that each machine is cleaned once a week. Your job is to find a way to keep it running. In both cases, managers require engineers to select the right components for the system in these harsh environments, resulting in minimal downtime and minimal maintenance. Harsh environments involving water, chemicals, extreme temperatures, pressure, radio frequency interference/electromagnetic interference, welding, fire, and explosion are a challenge for equipment used in these processes. By using sensors specifically designed for these applications, less downtime and less maintenance can be achieved. Mixing professional sensors in these applications often extends the time to replace and provide replacements. So how do you choose the right sensor?
Thoroughly clean the application
Wet industrial environments, which are common in the food and beverage industry, such as dairy, brewery, frozen food, packaging and filling applications, provide disadvantages for equipment operating in these applications. Frequent cleaning with water, foam, detergents/biocides often allows the equipment to meet hygienic regulations set by the Food and Drug Administration and other agencies.
In these environments, sensors are used to transport carts, bottling and canning lines, packaging and filling functions, and other machines. To withstand the harsh environment caused by these humidities, the sensor is designed to be water and steam resistant while maintaining all specifications. Sensors are designed with integrated design features to the sensor’s front cover, plug-in connector, and integrated durable packaging materials such as 316 stainless steel.
Different manufacturers use different methods to prevent the front cover from passing through the sensor, some manufacturers use plastic or LCP covers; others have modified the inside of the cover by inserting an O-ring. Manufacturers also package these sensors in different materials and modify the plug-in connectors to help prevent moisture intrusion. These methods ensure that the sensor is designed for thorough cleaning capabilities to withstand high pressure, corrosive cleaning agents and rapid temperature changes. Because these sensors work well in these environments, they are rated IP68 and IP69K (environmental protection rating). Sensors are also designed for flooding applications such as oil rigs, offshore drilling platforms, dikes, ships, and septic tanks. These sensors work properly with a certain depth of penetration in the medium of oil, water or sea water. Typically these sensors are encapsulated in polypropylene to resist ingress of liquids and to protect against shock, vibration, and corrosive chemicals.
Extreme temperature application
Extreme temperatures are often required for applications in stoves, freezers, bread ovens, vulcanization, semiconductors, glassworks and steel mills. Many sensors can accommodate a range of temperatures, but some are more suitable for very low or very high environments; some have a wider range so that they can withstand extreme temperatures.
Before choosing a sensor, it is important to consider the temperature at which the sensor is mounted because different materials adapt to the environment. Plastic, stainless steel, Teflon, chrome-copper and other materials are used to package these sensors. Manufacturers also use proprietary packaging materials to package enclosures, front covers, and plug-in connectors that are specifically designed to withstand extreme temperatures. Remember: some materials are more suitable for low temperatures – down to -40 ° C, while other sensors are more suitable for high temperatures – up to 160 ° C.
Battery operated mobile device
The use of load shedding sensors in mobile devices is another option for a variety of electronic and mechanical components that measure the position of machine components. Sensor reliability and low maintenance also make it desirable to replace mechanical switches. In heavy-duty and unloading applications, switching devices, such as relays, alternator switches, or batteries for load switching, can cause discharges of up to 600V for 5 seconds. When some devices are powered, mobile vehicles using 12 or 24V battery systems, such as military vehicles, cranes, and agricultural machinery, are susceptible to sparks caused by transient discharges. This annoying electrical feedback is caused by capacitive, inductive or RF energy discharge when the electrical equipment is turned on or off.
Conventional inductive sensors measure the position of machine components, such as fork-shaped grippers on forklifts or load-bearing outriggers of backhoes, however they are susceptible to discharge. These discharges can cause temporary failure or permanent damage to conventional proximity sensors. Electrical discharge on the power line does not work for load shedding sensors, so it was developed to reduce downtime, production delays, and overspending. Solid-state load shedding sensors can be used to withstand high overload switching energies, which are longer than relays and are easier to solve and replace. These sensors have built-in protection circuitry that increases their chances of success in very demanding applications.
The load shedding sensor is not only designed to withstand sparks, but also works in extremely noisy environments while still functioning as a traditional non-contact solid-state inductive sensor. The dry sound does not work for these sensors, they continue to work as if there is no interference here: you cannot simply use a standard inductive sensor or mechanical switch.
High RF interference / electromagnetic interference environment
In the factory floor, RF noise is caused by inverters, stepper motors, high-energy communication devices such as AM/FM radios, two-way radios, pagers, and some cellular phones. The energy/frequency emitted from these devices can cause the sensor to output erroneously regardless of the current target.
Radio frequency noise is an electronic circuit that is generated by the above device power on/off signal and coupled to nearby sensors by air. It can be suppressed by the filter on the board of the dry sound emitting device, or the sensor can be designed to withstand a certain level of dry sound. The 60947-5-2 standard of the International Electrotechnical Commission (IEC) is a frequency range of 3V/m [volts/meter] or more than 80 MHz to 1000 MHz on a proximity switch. In addition, the test was conducted to measure the ability of an electronic product to withstand radio frequency noise, consistent with IEC 61000-4-3, 1 V/m, 3 V/m, 10 V/m. Or remove the interference on the sensor, or keep very low interference – typically less than half an inch, each of which is very important. Sensors developed to withstand such noise have integrated dedicated internal circuitry, on-board filters, shielding, and in some cases, integrated Zener diodes that clamp the voltage to reduce the level of RF noise hazard. Sensor manufacturers continue to work to minimize the effects of noise. It is increasingly difficult to develop these sources, which are closer to the signal with more power in a larger range.
Non-contact proximity switches are used in stamping and die applications in industrial metal forming, for example, in automotive mold applications. These sensors are used to measure quantities including position (too much feed and too little feed), part demolding, hole positioning and inlaying. The sensor verifies the process and reduces the possibility of damage to the mold.
The sensor is mounted directly on the mold to determine the position and placement of the part. In these applications, some sensors are independent during the die and bending stages. The sensors in the mold are also used for double impact, positioning and part demoulding. The environment used by the robot is also to use the proximity switch to move large parts between other equipment, to weld the parts together or to keep the parts in place. In these applications, one sensor measures the movement of the piston by a sensor placed near the arm cylinder, and the jaw or pliers opens at the corresponding angle of the cylinder. This method can be configured to allow the pliers to open to the exact position corresponding to the part. The drawback of this method is that the pliers cannot determine if the actual part is in the pliers or if the part is moved to the proper position. Another measurement used by manufacturers in clamp applications is to detect the position of the part and/or whether the part is in the jaws. This method is to place a sensor in the slot of the jaws. By doing so, the sensor can detect if the part is actually in the jaws, if the jaws are in the correct position, or if the part is moved to the proper position.
In the automotive industry, welding is used to fuse parts of the body, and sensors are used to detect the placement of automotive metal parts to ensure proper placement of parts prior to welding. An automatic (robot) welding arm moves to the correct position, welding multiple points around the vehicle. This causes the sensor to experience varying degrees of exposure as it approaches the welding spark. The sensor fails when it involves a rate that depends on the amount of welding, and where it is located according to the welding command (speed, angle, distance of the welding spark).
The sensor is affected by the conditions generated by the welding, and the strong electromagnetic field causes the standard proximity switch to not trigger or track. Welding sparks or Mars accumulate on the sensor or melt the encapsulating material to form a “pitting”. These places are easily affected by welding sparks or Mars. Some manufacturers solve this problem by making a front cover using a different material, such as Teflon. Some manufacturers use different material packages, such as Teflon or copper. Some manufacturers use special materials that are specifically resistant to soldering for the package and front cover. When the package is not completely sealed to prevent slag/sparks and is not completely resistant to electromagnetic field interference, ensure that the front cover (measurement surface) has resistance to measurement of the weld zone, slag, and spark. This is because the measuring surface of the sensor is often exposed directly to the welding spark, and the slag and Mars will adhere to the surface of the sensor, rather than sliding to the side with less accumulation. Sensors that work in a soldering environment also integrate technology into their designs, allowing the sensor to withstand stronger electromagnetic fields. One type of sensor that uses separate independent transmit and receive coils on the PCB and removes the core is not subject to magnetic field interference at all, which often occurs in electrical welding, cranes, and electric furnaces. The absence of a core also allows a type of sensor to operate at a higher switching frequency. It is common for users to handle sensor failures by simply replacing sensors in this environment. Some users repair the sensor by using a tool (screwdriver) to shovel the slag. Sensors repaired in this way can work for a while, but with less arc burn, the fault will occur again until it is abandoned. Repairing the sensor in this way is not recommended and can result in sensor failure when the surface is damaged. Users do not need to accept this dilemma, the study found that high-end sensors can withstand up to 20,000-30000 welding sparks. When selecting a sensor for the welding environment, remember that there are also man-made damage or mechanical damage depending on where the sensor is placed. In this case, the user needs a more protective package than Teflon or copper. The manufacturer’s protective cover mounts these sensors to prevent both sides and front from being affected. Some manufacturers integrate the mounting panel into the sensor before packaging the sensor, making the sensor a piece that actually seals against physical damage from both sides and damage from the front (when using a special anti-welding front cover or coating).
The welding environment also creates some problems for the cable. Much like the sensor, the cable is damaged by the welding slag. The connector to the sensor is also melted by the welding slag. Protective sleeves can be used in cables and other applications that are resistant to high temperatures and melting. Welding slag builds up on the protective casing rather than accumulating on the cable casing, keeping the connectors and cables intact. This sleeve is made of woven glass wool for use in high temperature environments, although it works well in low temperature environments.
Cables with PVC jackets are best suited for long-term exposure to thoroughly cleaned chemicals, such as sodium chloride, sulfuric acid, and sulfuric acid, which can cause cables made from other materials (such as PUR) to become brittle. These chemicals do not work for PVC, and the 316 stainless steel coupling nut is well suited to these environments. There is also a cable designed for another method, which is directly buried in the underground and cable tray wiring through cable trough wiring. The aluminum sheath and PVC cable housing prevent chemicals, cutting, wear, etc., and can also be connected to the shield to the nut. When used in hazardous or safe situations, the use of Kaifa ITC cables can provide important benefits because no further mechanical protection is required. This self-contained metal cable is self-grounding and is considered open wiring, making it ideal for hazardous locations where NEC allows. Integrated components that are resistant to the environmental conditions in which they are installed are the relevant steps to ensure continuous operation. In the long run, take the time to investigate which sensors and corresponding components are best suited for special environmental conditions, saving time and money, and making troubleshooting and maintenance simple.