Mechanical Magnetic Sensor Design Considerations
At Sensor Solutions, we provide several reasons to select us for your next project. Learn about our Mechanical Magnetic Sensor Design Considerations & Applications here!
- Mounting Style: Threaded Barrel vs. Flange
- Housing Size & shape
- Housing Material
- Stainless Steel housings
- Anodized Aluminum housings
- Plastic housings
- Connection Type & Cable Protection
- Free End Wires
- Jacketed Cables
- Shielded Cables
- Ribbon Cables
- Integral Connectors
- Pigtail Connections
- Sensor Target Details
- Custom Labeling & Packaging
- Examples of Magnetic Sensor Applications with Custom Mechanical Requirements
- Regulatory Requirements & Certifications Needed
- Examples of Magnetic Sensor Applications with Custom Regulatory Requirements
Mounting Style: Threaded Barrel vs. Flange
Hall Effect Sensors are typically provided with either a threaded barrel and lock nuts or have a flange with one or more holes for mounting. Sensor Solutions can provide custom sensors using any of our hundreds of existing stainless steel, aluminum, and plastic options, or we can design a new housing specific to your application.
The following should be considered when determining which type is best for a new application.
- Threaded barrel housings can be either threaded into a port or mounted to a simple bracket using lock nuts.
- Threaded barrel housings allow for easy adjustment of sensor orientation and gap to the target during installation.
- Special requirements exist for threaded barrel housings that are sealing into pressurized applications.
- Flange mount housings offer the quickest installation for guaranteed orientation and setting of gap.
- Flange mount housings can be provided with o-rings for sealing the sensor into pressurized applications.
- Flange mount housings allow the option to have the electronics parallel to the target to minimize the distance between the target and the back of the sensor.
Housing Size & Shape
Whether the concern is a minimum length, a maximum length, an existing bore diameter, or necessary features for holding the sensor when mounting there may be multiple aspects of the shape and size of the housing to be considered when designing a custom sensor. Consider the following if a custom housing design is required.
- The functional range of the sensor may determine a minimum length for a sensor to be both mounted and in range of the gear, magnet, or another target. Flange mount housings allow for a fixed installation gap guaranteeing the same gap between the sensor face and mounting location.
- In some applications, the space where the sensor can be mounted to detect the target may be limited by other components of the assembly. Determining a maximum length should always consider the type of connection and how it will exit the housing to ensure the sensor will fit when installed and that cabling is not bent beyond the minimum bend radius.
- In other applications, a sensor may be mounted into a port or other existing feature that defines either a sensor barrel diameter or specific thread pitch. Be sure when specifying thread requirements to identify the complete thread details (diameter, pitch, and class) to ensure sensors are built to properly mate into existing threads.
- In applications where the sensor is sealing into a pressurized motor or another assembly with a smooth barrel and an o-ring, the housing diameter, bore diameter, o-ring groove dimensions, pressure, and temperature range are all factors in determining the correct o-ring requirements.
Sensor Solutions provides a wide variety of sensors in housings made of stainless steel, aluminum, and plastic. We also have applications where sensor housings have been made of titanium and zinc. Other materials can be considered for applications as long they will not affect the magnetic fields being detected.
Stainless Steel housings are used in many applications where the sensor housing needs to be robust against harsh environmental conditions. Typically they are composed of 303 Grade Stainless, but 304 Stainless is also available. We have these housings machined to our specifications in any volume and we can typically have new custom stainless steel housings made to order in approximately 3-4 weeks.
Anodized Aluminum housings are a more cost-effective, lighter weight alternative to stainless steel. At moderate to high volumes they can also be more cost-effective than molded plastics once tooling costs are factored in. Typically we provide aluminum housings with a black anodization, but other colors are also available.
Plastic housings are the lowest cost solution for high volume OEM applications. Sensor Solutions offers a handful of options in flange mount and threaded plastic housings that are made of glass filled nylons that are suitable for under the hood and vehicle undercarriage applications. Dependent on the specifics of the design a custom molded plastic housing may be cost-effective at volumes of around 5,000 pieces, but tooling can be $20,000-$40,000 dependent on the housing shape, size, and the number of mold cavities.
Other housing materials are available. We have designed custom titanium housings for use in specific applications where material interactions were a concern and we have also provided zinc casted housings to provide lower cost sensors for applications with volumes of less than 5,000 per year.
Connection Type & Cable Protection
Sensor Solutions offers a wide variety of connection types to meet the needs of different applications. For custom sensors, we can provide free end wires or cables, connection pigtails, and integrated connectors dependent on the needs of the application. We separate our connection types into the following categories.
- Free End Wires are the lowest material cost solution and are offered with PVC, XLPE, or Teflon Insulation. We can provide wires to any defined length and these connections allow easy wiring when output wires are run to a different location than the power and ground wires.
- Jacketed Cables are also available in a variety of insulation and jacket materials dependent on the needs of the application. They can be provided in any required length with custom jacket and insulation stripping available.
- Shielded Cables are also available in a variety of insulation and jacket materials dependent on the needs of the application and options are available for either foil shields, braided shields, or both. They can be provided in any required length with custom jacket and insulation stripping available.
- Ribbon Cables are available for our 3 wire sensors and are another low-cost solution. The insulation is bonded together for easily running the wires, but they can be separated as well.
- Integral Connectors are available allowing for quick connection/disconnection of sensors at the mounting location. Sensor Solutions offers M12 integral connectors as well as a variety of MS style integral connections for a wide variety of applications. Whether an integral connector can be used in an application is dependent on the form factor of the sensor housing.
- Pigtail Connections are offered with a wide variety of connector types including Deutsch, Amphenol, Amp, Paccard, and MS style connectors. They can be built to any length required and with the wire/cable types as appropriate for the application.
Additional protection over individual wires or cables can also be added to any sensor type. We can protect wires with corrugated tubing, fiberglass sleeving, rubber hoses, or flexible conduit integrated directly into the sensor. We can also add mounting clips or design features into the sensor housings to allow for EMT to be run over the cable all the way to the sensor
Sensor Target Details
In addition to custom features of the sensors themselves, in many application the target the sensor is detecting may also be custom to the application. Custom targets may include steel or magnetic features used in counting, speed measurement, and position detection applications. Sensor Solutions offers the following Application Note with detailed information on designing custom ferrous metal sensor targets: Selection and Design of Sensor Targets.
Custom Labeling & Packaging
Sensor Solutions catalog sensors are engraved with part number and date code information so that we can quickly identify the production lot of every sensor built. For custom applications, we can provide customer part numbers/names/logos on the sensor as an alternative to our own.
In addition to custom labeling on the sensors we can also kit sensors with accessories such as brackets, o-rings, and mounting hardware and apply customer-specific labeling on sensor bags and boxes. We can also provide barcode labels for easy scanning in and out of inventory.
Examples of Magnetic Sensor Applications with Custom Mechanical Requirements:
- An engine block has a port for a sensor to measure speed of a rotating gear within the sensor. However, the sensors offered with the engine are not compatible with the ECU to be used in the vehicle. Sensor Solutions designed a replacement sensor housing made of anodized aluminum that matches the form factor to mount in the engine, but eliminated features from the back of the sensor housing that reduced the overall costs.
- A company that used low-cost sensors with molded threaded housings was experiencing a high failure rate in their application due to the assembly not being robust. Vibration and mechanical stress on the housing would cause the OEM sensors to fail after installation. Sensor Solutions provided a replacement design with a more robust aluminum housing and full encapsulation around the reed switch to dampen the affects of vibration. The housing was also modified with additional thread length to improve installation, a longer cable to eliminate an electrical junction, and determined a more robust sensing element to eliminate periodic electrically induced failures the customer was experiencing.
- In a sea floor exploration application, a speed sensor is exposed is exposed to high external pressures and 303 Stainless steel would potentially have long term corrosion issues. Sensor Solutions performed pressure testing to verify the sensor will function properly on the ocean floor and builds the sensors using Passivated 304 Stainless Steel housings and vacuum de-aired encapsulants to ensure the sensors will continue to function properly throughout the ROVs exploration of the ocean floor.
- A heavy equipment manufacturer designed their own magnetic sensors for measuring the speed and direction of a rotating shaft on their equipment. They contacted Sensor Solutions when the contractor indicated they would be closing their facility and no longer be able to produce the sensors. Sensor Solutions took over production of the sensors and was able to provide the customer sensors at a lower cost than the prior source. Our companies then worked together to determine additional improvements to the design and manufacturing processes to further decrease the unit costs while making the sensors more durable and easier to install. In this applications, sensors are provided mounted in custom brackets and individually kitted with barcode labels and Sensor Solutions also provides custom mating cable sets with the customer part number marked along the entire cable run for quick identification.
- Sensor Solutions was approached by an Energy company that had tried multiple solutions for monitoring when a hatch on top of oil storage containers was open or closed. Sensor Solutions determined a solution where a sensor was mounted into the latch and a custom target to replace the pin. Then another customer indicated they would prefer the sensor on the latch pin and the target moved to another location. Sensor Solutions now offers both patented solutions that are compatible with a variety of wireless transmitters that are more reliable and a fraction of the cost of alternative options on the market. Learn more about our Thief Hatch Detection Systems here.
Regulatory Requirements & Certifications Needed
Dependent on the industry and application, there may be specific regulations placed on sensors requiring proof of compliance to standards or even external certifications and lab testing. When an application has these types of requirements such as "Explosion Proof", "RoHS Compliant", or meeting specific UL, CSA, or other standards please be sure to provide this information at the start of the project. This way the requirements can be considered in the mechanical and electrical design and testing of the sensors as well as for determining the costs of production sensors.
For RoHS compliance, we currently offer some, but not all of our products as compliant. Dependent on the sensor type and electrical options we may need to have compliant versions of the circuitry and connection assemblies created. The associated costs can be paid as an upfront tooling cost or amortized into the first production run.
For CE compliance with the Low Voltage Directive and some other options Sensor Solutions can often perform the necessary testing and documentation internally. For other CE, UL, CSA, and other standards external testing and certification may be required. Over the years Sensor Solutions has had many products certified to meet requirements specific to an application. We work with several highly qualified test labs and send a Design Engineer to be there during testing to oversee the process and minimize potential issues or questions that can delay or increase the costs of testing.
Examples of Magnetic Sensor Applications with Custom Regulatory Requirements:
- A Murphy Bed manufacturer requested a sensor and magnet for opening and closing a relay to allow/prevent power to LED lights built into the headboard dependent on if the bed was open or folded up into the wall. The customer did extensive testing and purchased multiple production lots before asking if the sensors met specific NIST regulatory requirements for electrical components in furniture. Fortunately, in this case, the sensors themselves were compliant and labeling requirements were able to be satisfied by adding labels to the cables.
- An agricultural equipment manufacturer has detailed specific testing requirements for their sensors that are based on a variety of Regulatory requirements the sensors must meet. During the design phase of the application Sensor Solutions determined which tests could be done in our facility and which would require external lab certification, saving the customer thousands of dollars in testing costs.
- Sensor Solutions was approached by an Energy company that had tried multiple solutions for monitoring when a hatch on top of oil storage containers was open or closed. As the sensors are directly attached to tanks containing explosive liquids and gasses electronics in the area are required to be either certified to be intrinsically safe, or meet the requirements to qualify as a simple apparatus that can neither store nor generate the electricity required to cause a spark, Sensor Solutions designed the sensor for the application to meet the Simple Apparatus requirements which eliminates the need for expensive certifications, resulting in a lower cost solution. Learn more about our Thief Hatch Detection Systems here.