Tire manufacturing requires precise pressure monitoring to prevent dangerous situations like overpressure and premature unlocking of the curing press. Model MW, a robust industrial pressure switch, comes in a SIL 2-approved version for greater safety and performance in tire curing.
Numerous industrial processes, including tire production, rely on high pressure and high temperature to transform raw materials into usable products. To ensure the safety of workers and machinery, tire manufacturers use safety switches during the vulcanization process.
Preventing Dangerous Overpressure during Vulcanization
A pressure switch helps create a safer work environment in tire manufacturing by preventing steam from being released during the curing process.
In a closed steam-heated press, the raw tire is filled with a bladder of hot water that push it against the inner part of the mold. Then, under the conditions of around 250 psi (24 bar) and 300–340°F (150–170°C), vulcanization occurs to give the tire its elasticity and final shape.
Without appropriate monitoring, the curing press runs the risk of overpressurizing without warning, which increases the risk of allowing extremely hot steam to escape and burn bystanders. A pressure switch makes sure the press never reaches a critical pressure level.
Two Ways a Pressure Switch Increases Safety in Tire Manufacturing
A pressure switch in a vulcanization press serves two safety functions:
- Prevent overpressureby automatically shutting down the process when a preset high-pressure point is reached.
- Prevent accidental opening of the pressby locking the internal mechanism until a preset low-pressure point is reached.
In high-throughput, automated tire production, this mechanism is in constant use. Only high-quality pressure switches with a long service life can withstand continuous loading of the pressure system. Ordinary switches at this critical point risk premature wear or failure that leads to costly safety hazards and unplanned shutdown of equipment.
A Pressure Switch Designed for the Highest Performance
Because applications such as tire curing require robust pressure instruments, WIKA has developed the model MW pressure switch. It features several important features for greater safety and reliability:
- As a mechanical pressure switch, it does not require a power supply for the switching operation, making it ideal for safety critical applications.
- The switch’s enclosure is NEMA 4X (IP66) rated and is made of 316L stainless steel to withstand the corrosive and demanding operating conditions of tire production.
- The switch uses a diaphragm measuring system, which is capable of low set pressures and high overpressure safety, making this design optimal for the curing press operation.
A SIL 2 rating in accordance with the IEC 61508 standard certifies model MW’s functional safety and operational safety. Thus, the expected service life is about 90,000 pressure cycles and switching operations. A risk assessment in accordance with EN ISO 13849-1 by an external certification resulted in model MW receiving the highest performance level of PLe, which means it has the lowest probability of failure.
All model MW instruments have microswitches that switch electrical loads up to 250V AC, 20 A directly. For certain applications, microswitch versions with argon filling provide an additional boost to safety and service life, as this inert gas reduces oxidation, protects against corrosion, and prevents sparking. For lower switching power ratings, such as in PLC applications, there is a variant with gold-plated contacts.
WIKA USA, a Partner for Tire Manufacturers
In addition to the model MW diaphragm pressure switch, WIKA also offers the heavy-duty S-20 pressure transmitter for curing presses, as well as other innovative instruments for monitoring processes in tire manufacturing plants. Contact WIKA USA for expert advice on pressure and temperature measurement solutions, including how to retrofit pressure switches into your existing equipment for greater safety and peace of mind.
Product mentioned in this blog:
• Model MW diaphragm pressure switch