Sensor housing plays an important role in shielding sensors from environmental issues such as moisture, dust, and extreme temperatures, which ensures their accuracy and durability. In today’s world filled with automation, precise monitoring, and smart devices, sensors can be found everywhere. They are used in car engines, airplanes, and medical tools.
According to MarketsandMarkets, the global occupancy sensor market is expected to reach $5.20 billion in 2030. Choosing the right housing is crucial for getting the best performance from sensors, as there are many materials and types to choose from. In this article, we will explain everything you need to know about sensor housing, including materials, IP ratings, CNC machining tips, and costs.
The Role of Sensor Housing in Device Performance
Environmental Protection
Sensors frequently face harsh conditions like moisture, dust, chemicals, and extreme temperatures. A properly designed housing protects the delicate parts of the sensor from these factors, helping to avoid malfunctions and increasing their durability.
Thermal Management
Materials like aluminum and stainless steel are good at dissipating heat, ensuring that sensors remain accurate in high-temperature conditions. If the housing is not designed properly, it can cause thermal distortion, leading to inaccurate readings.
Electromagnetic Shielding
In industrial or automotive settings, electromagnetic interference can disrupt how sensors work. Using enclosures made from specific materials can protect the sensor from this type of interference.
Integration and Mounting
A key aspect of sensor housings is their ability to allow for easy integration into various applications. Ideally, the design of the housing should make it simple to connect with other machines or electronic systems.
Threat Type and How Sensor Housing Protects Against It
| THREAT | HOW SENSOR HOUSING PROTECTS |
|---|---|
| Moisture and liquids | Using advanced gaskets, epoxy encapsulation, and reinforced mechanical interfaces protects sensors from water and vapor. |
| Dust and particulates | IP rating indicates the ingress protection of a product. An IP rating of IP67 represents a level 6 for dust protection. So, using a sensor with an IP seal of IP67/IP68 will protect your device from dust and other environmental contaminants. |
| Corrosion | Stainless steel is the perfect choice for sensor housing, especially in harsh environments. Aluminum is equally a good option, although not as corrosion-resistant as stainless steel. Also, plastics like PEEK and PTFE are suitable for chemically aggressive environments due to their high chemical resistance. |
| Mechanical impact | Rugged casings (reinforced polymer) are made with high-quality plastics, silicone, or rubber, and have reinforced corners to protect a device from impact. For sensors, it will help absorb shock and prevent cracking. |
| Electromagnetic interference | Conductive enclosures and coatings help prevent electromagnetic waves from entering or leaving the housing. |
Materials Used in Sensor Housing
According to ASTM standards, materials for enclosure must meet requirements like corrosion resistance and temperature tolerance.
1. Stainless Steel (304, 316L)
Stainless steel is used in many engineering applications as a specialized material because of its impressive strength even at high temperatures, resistance to corrosion, and ability to be shaped and molded easily. A stainless steel sensor housing provides a protective case for sensors, helping them remain reliable in various conditions. It is suitable for extreme environments.
2. Aluminum (6061, 7075)
Aluminum is also a perfect choice because it is lightweight with a high strength-to-weight ratio. It resists corrosion and has great electrical and thermal conductivity. However, it is more expensive than stainless steel and has a complex welding process.
3. Plastics (PEEK, PPS, PA66)
PPS, PEEK and PA66 are semicrystalline, high-performance thermoplastics. They are known for their remarkable resistance to harsh chemicals, along with strong mechanical properties and dimensional stability. They can withstand hydrolysis from steam, water, and seawater. PEEK, for instance, stays stiff even at temperatures as high as 338°F (170°C). These features make them a good choice for sensor housing.
For more understanding, read our guide on the major differences between stainless steel and aluminum.
Choosing Materials Based on Industry and Environment
Aerospace and Defense
Aluminum or titanium alloys will be perfect here. They are significantly lighter than steel and easily shaped and fabricated. Aluminum naturally has a protective oxide layer, making it highly resistant to corrosion and all other harsh conditions that aircraft are exposed to. Titanium is used for the high-temperature parts.
Chemical Plants and Oil and Gas
Stainless steel is the best choice for this industry. It is low maintenance due to its corrosion resistance, which saves costs. Especially for industries handling food or pharmaceutical items, stainless steel should be used because they are non-reactive and easy to clean, therefore ensuring a high-level of hygiene.
Medical and Food Equipment
Materials need to comply with FDA/USP Class VI or ISO 10993 standards. PEEK, PTFE, and 316L stainless steel are suitable here because of biocompatibility and sterilization.
Consumer Electronics and IoT
PA66 (nylon) and stainless steel are the best options. They are lightweight, cost-effective, and suitable for indoor use.
Automotive and Transportation
Choose aluminum or coated steel for better heat management and to reduce vibrations in engine compartments or transmission systems.
Important Design Considerations for Sensor Housing
Sealing and IP Ratings
Proper sealing keeps moisture, dust, chemicals, and other harmful substances out of the housing so they can’t damage the sensor.
IP ratings are two-digit numbers associated with an electrical or mechanical enclosure, indicating the item’s resistance to dust, foreign objects, accidental contact, and water.
| IP RATING | WHAT IT PROTECTS AGAINST (SOLID: FIRST DIGIT) | WHAT IT PROTECTS AGAINST (LIQUID: SECOND DIGIT) |
|---|---|---|
| 0 | No protection | No protection |
| 1 | Protection against solid objects (greater than 50mm). | Protection against vertically falling water. |
| 2 | Protection against objects (greater than 12.5mm). | Protection against dripping water raised up to 15°C. |
| 3 | Protection against objects (greater than 2.5mm). | Protection from water sprayed vertically up to 60°C. |
| 4 | Protection against objects (greater 1mm). | Protection against water splashing from any direction. |
| 5 | Dust protection (limited ingress). | Protection against water jets from any direction. |
| 6 | Dust tight (no ingress). | Protection against water jets and heavy seas. |
| 7 | – | Protection against immersion in water. |
| 8 | – | Protection against continuous immersion in water. |
For a better understanding, read IP Ratings Explained.
Mounting and Integration
Mounting
You can mount sensor housings in different ways based on how you plan to use them and the surroundings. Some popular methods for mounting include using stud mounting, adhesive mounting, magnetic mounting, and probe tips.
Tolerance and Fit
There must be a clearance fit that allows for easy assembly and disassembly. There must be an interference fit that creates a connection between the sensor housing and the mating part. A poor fit can cause vibration, drift, or the sensor to be out of alignment.
Thermal Expansion and Material Compatibility
- The thermal expansion coefficient (CTE) should match the material of the sensor to prevent stress.
- Metal housings expand in a different way compared to plastic ones, so hybrid assemblies need adjustments.
- In high-temperature settings (over 150°C), it’s best to use materials such as PEEK, ceramics, or nickel alloys.
- Thermal interface materials (TIMs) can assist in spreading heat when necessary.
EMI/RFI Shielding
Electromagnetic radiation (EM) consists of waves of alternating electric and magnetic energy and the frequency of each wave. Electromagnetic interference can corrupt sensor readings.
- Metal housing, like aluminum and stainless steel, provides built-in protection against EMI.
- For plastic housing, use conductive gaskets or coatings.
- To ensure effective shielding, it is important to ground it correctly.
Regulatory Compliance and Safety
You have to ensure that sensor housings follow rules and safety guidelines. This is important for their proper function and to prevent any danger. This means paying attention to safety regulations in areas like electricity, chemicals, biology, and physical risks. Some of these regulations are:
- Medical: ISO 10993, FDA, USP Class VI.
- Automotive: ISO 16750, SAE J1455.
- Explosive Environments: ATEX, IECEx for sensor housings in oil, gas, and mining.
- Environmental: RoHS, REACH for chemical safety.
Pressure Equalization and Venting Systems in Sensor Housing
Why Does Pressure Build Up Effect Sensor Accuracy?
Changes in Barometric Pressure
Sensors that detect pressure, such as MEMS, barometers, and differential pressure sensors, may provide inaccurate readings if the pressures inside and outside are not equal.
Calibration Errors in Sensors
When pressure remains unbalanced for an extended period, it can cause small stresses on the materials of the sensor, leading to a shift in its calibration over time.
Formation of Condensation
When moist air enters a sealed case and cools, it can form water droplets on electronic components or optical lenses.
Damage to Seals
If the pressure inside becomes too high for the housing to manage, gaskets may crack or lose their shape, which can reduce their effectiveness in blocking dust and water.
Membrane Vent and Breather Valves
If outdoor housings do not have a vent system to balance pressure, they can be affected by quick changes in temperature, air pressure, or altitude. These pressure differences can put a lot of stress on the seals until they break.
- A membrane vent keeps the sensor safe from pollutants like water, salt, and other harmful liquids to make sure it works accurately. Materials used for this include PTFE, PU film, or nonwoven materials.
- A breather valve actually has two vent valves: a pressure valve, which opens to let vapor out, and a vacuum valve, which opens to let air in. Install vents at the highest spot in a vertical position so warm air can get out.
Techniques for Sensor Housing Manufacturing
CNC MACHINING
CNC machining describes how machines used in manufacturing are run by computers. CNC is used in manufacturing sensor housings due to its high precision and accuracy, repeatability, and flexibility. It costs about $10-$60 per unit.
The cons are:
- It has a higher unit cost.
- There’s a longer production time for large runs.
DIE CASTING
Die casting is used in the electronics industry because it can make complex, detailed, and precise metal parts in large quantities. Aluminum die casting is a common choice for sensor housings because of its weight and corrosion resistance. It costs about $2-$10 per unit.
The pros are:
- It is best suited for high-volume production.
- It has a smooth surface finish, reducing the need for extensive machining.
- The low cost per part in large volumes makes die casting a cost-effective choice for mass-produced sensors.
The cons are:
- It is less flexible for design changes.
- It is only limited to non-ferrous metals like aluminum, zinc, and magnesium alloys. For more details, read our guide on ferrous and non-ferrous materials.
- It is not ideal for small-scale production or prototyping.
INJECTION MOLDING
Injection molding is a very efficient way to make sensor housings, particularly for gadgets like smartwatches and thermal cameras. This process includes dropping hot liquid plastic into a mold to form the shape you want. It costs about $0.30-$5 per unit.
The pros are:
- It has a high production speed.
- There’s design flexibility, which means that you can have sensor housings with different features and geometry.
- It supports a wide range of materials, including thermoplastics.
The cons are:
- The cost of designing and creating the mold tool is high.
- Some designs can be challenging to produce.
- There’s a likelihood of issues like sink marks, warping, and knit lines.
Read our comprehensive guide on mastering silicone injection molding.
Maintenance and Cleaning Guidelines for Sensor Housings
Cleaning Agents Based on Material
| TYPE OF MATERIAL | CLEANING AGENTS (RECOMMENDED) | CLEANING AGENTS (AVOID) |
|---|---|---|
| Stainless steel (304/316) | Isopropyl alcohol, mild detergents. | Bleach, solvents with chloride. |
| Aluminum alloys | Warm soapy water, vinegar, and a microfiber cloth. | Alkaline, abrasive scrubs. |
| Plastics | Non-alcoholic wipes, water-based cleaners. | Alcohol-based cleaners. |
| Anodized finishes | Water and mild soap. | Acidic or caustic soap. |
Conclusion
Picking the right sensor housing is more than just a technical choice. It is an important decision that impacts how long your system lasts, how reliable it is, and how accurate it can be. Whether you’re using sensors in harsh industrial settings or in medical devices, the housing needs to be the right material in strength, sealing, venting, and compliance with global standards.
At RichConn, it is our job to create custom CNC machining and produce high-precision sensor housings designed specifically for your industry and environmental requirements without compromising quality. Contact us today to upgrade your sensor housing solutions.
FAQs
How Often Should Sensor Housing Seals or Gaskets Be Replaced?
There’s no specific time, as it depends largely on the material, quality, operating conditions, engine type, and manufacturer’s recommendations. However, you’re to replace it when there’s a visible leak or signs of wear.
Are Plastic Sensor Housings Reliable in Industrial Settings?
Plastic sensor housings can perform effectively in certain industrial settings, but this relies on the type of material chosen. Plastics such as PEEK, PTFE, and reinforced polycarbonate are ideal for industrial use because they are chemical resistant, have strong mechanical properties, and provide good insulation.
What do IP67 or IP68 mean for sensor housing?
Both IP67 and IP68 provide strong defense against dust and water. Your choice should be based on what you need:
- Select IP67 if your device needs dependable protection from dust and some exposure to water.
- Pick IP68 for tougher situations where the device might be submerged in water for a long time.
