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In injection molding machine, the hydraulic system is responsible for controlling the actuation of the molds as they clamp together and pull apart. The pressure sensor frequently provides feedback on the hydraulic pressure of the mold actuation, enabling the pumps to efficiently and repeatably maintain the motion.

Challenges:
1.Mold Downtime: Failure of a pressure sensor can lead to mold downtime, resulting in production delays and decreased product output.
2.Low-Quality Molded Parts: Without accurate pressure feedback, it becomes challenging to maintain consistent hydraulic pressure, leading to the production of low-quality injection molded parts.
3.Tool Life Reduction: Inadequate pressure control can exert excessive force on the molds, causing premature wear and reducing the lifespan of the injection molding tools.
Solutions:
1.Prevention of mold downtime by promptly identifying and addressing sensor failures.
2.Improvement of molded part quality through accurate feedback on hydraulic pressure, ensuring consistent and precise control.
3.Extension of tool life by maintaining optimal pressure levels, reducing wear and damage to the molds.

Case Study:
Sensor Innovations: Revolutionizing Injection Molding Performance at Western Tool & Mold Limited
Client: Western Tool & Mold Limited (WTM)
Industry: High-precision molds and injection-molded parts manufacturer
Location: Hong Kong, China

WTM faced challenges in maintaining high standards and efficiency in their injection molding operations. Traditional pressure monitoring methods were insufficient, leading to mold downtime, inconsistent product quality, and reduced output. To tackle these issues, WTM needed a solution that could offer precise control and monitoring of the injection molding process.

The Solution: YD39 Series Pressure Sensors
To address these challenges, WTM implemented the YD39 series pressure sensors from YUNYI. These sensors are designed to measure differential pressure in a wide range of applications and offer excellent performance characteristics due to their micro-machined silicon transducers and 316L stainless steel construction. The double diaphragm sensor technology used in the YD39 series surpasses standard products in terms of accuracy, reliability, and static operating pressure.
Key Features
Exceptional Linearity and Performance Over Temperature: The YD39 sensors provided a long and reliable service life with excellent long-term stability.
High Accuracy: The sensors offered 0.25% accuracy with static operating pressures up to 10 bar.
Digital Compensation: Features such as digital compensation, pressure ports, electrical terminations, and various pressure ranges ensured optimal performance.
Working Principle
The working principle of piezoelectric pressure sensors involves converting pressure into a measurable charge. These sensors are equipped with high-precision quartz crystals (typically made of SiO₂), which generate a charge when subjected to pressure or force. The charge is then amplified by a charge amplifier, providing precise information about the cavity pressure in the mold. The sensor can be installed in different positions within the mold depending on the specific application. For general monitoring and process optimization, the sensor is typically placed near the end of the fill or on the ejection side of the mold to sense the cavity pressure and display it on the unit. In cases where specialized products are being molded, two cavity pressure sensors can be placed inside each cavity to understand the plastic behavior within the mold.
Benefits of Using Cavity Pressure Sensors:
Mould Monitoring: Cavity pressure sensors allowed WTM to precisely monitor mold performance under demanding processing conditions, such as high injection pressure and varying cooling rates. Customized monitoring for individual cavities was also possible.
Balance of Fill: The sensors enabled WTM to test the cavity balance in molds, whether new or existing. By checking multiple fill speeds and observing how different shear rates affected the balance, improvements were made.
Quality of Parts: Continuous production with pressure sensors helped WTM identify process deviations early, leading to the rejection of defective parts and ensuring better quality control.
Process Data Transfer: The wide range of data provided by cavity pressure sensors enabled the optimization of the viscosity curve, reducing process losses and allowing easy replication of the process on different machines.
Implementation at Western Tool & Mold Limited
Using a single pressure sensor for monitoring a mold is ineffective due to the viscosity of the plastic being molded. The cavity that fills first experiences relatively higher pressure compared to cavities that fill later. As plastic flows along the path of least resistance, once the first cavity is filled, the pressure is distributed to the other cavities that have not yet filled. This becomes problematic when the mold is large and has multiple cavities. To ensure effective monitoring, WTM implemented at least two sensors—one placed on the cavity that fills the fastest and another on the cavity that fills the slowest. These sensors were typically placed near the end of fill or behind the ejector pins to capture accurate data for analysis.
Results
The implementation of YUNYI’s YD39 series pressure sensors brought significant improvements to WTM’s injection molding operations:
Enhanced Accuracy: The high accuracy of the YD39 sensors ensured precise data collection, critical for optimizing the molding processes.
Increased Efficiency: Reliable and accurate measurements allowed for better management and control, leading to increased efficiency and reduced operational costs.
Improved Reliability: The durable and reliable YD39 sensors performed consistently even under demanding conditions, ensuring continuous and uninterrupted operation.
Consistent Quality: Continuous monitoring and data analysis helped identify and reject defective parts early, ensuring consistent product quality.
Conclusion
By implementing YUNYI’s advanced YD39 series pressure sensors, Western Tool & Mold Limited significantly improved their injection molding performance. The precise and reliable data collection facilitated better management of their processes, contributing to higher efficiency, improved product quality, and substantial cost savings. This case demonstrates the value of modern sensor technology in revolutionizing injection molding performance.