Cavity Pressure Monitoring

Cavity Eye system consists on the one hand out of pressure sensors installed in the injection molding tool. The second part of the system includes hardware and software that evaluates information from the injection molding machine and the internal pressure curves of each cavity in the tool.

Molding Technology

There are two common methods for sensor installation. In case of direct method, the flush  mound sensors are installed by tight fit directly to the mould cavity. In the industry this method is known as the more punctual one, but the sensor’s precision changes with every maintenance and installation. Because of the tight fit the sensors are continuously under preload, and this has also a negative effect on accuracy. By the indirect method, the sensors are placed in the ejector plate. With the movement of ejector plate the sensors are moving as well, which can cause damage of the sensor and loss of accuracy over time.

 

In Cavity Eye we believe in using the indirect method, but we install the sensors into the clamping plate instead of the ejector plate. Behind the ejector pin a transfer pin is connected by loose fit, which transfers the force from the cavity pressure to the sensor head like a domino system. It is important to find the optimal length for the transfer pin to avoid preloading the sensors. Because of the easy fit the sensors there is a cushion around it, so friction has no effect on the measurement accuracy. The sensors can be installed into the clamping plate from two directions: front or rear. We usually use the rear-installed design, because the manufacturing process is simpler this way.

Pressure sensors

Pressure sensors

The Cavity Eye newly developed more precise, durable, water and shock resistant sensors are available. The company offers sensors in different diameters (15 and 26 mm), which have a maximum load range of 1 to 40 kN.

 

The pressure sensors operate on an electro-resistive principle, which is one of the oldest and most stable measuring methods. Cavity Eye uses only indirect sensors. From our experiences, the indirect measurement is much more precise, than the direct measurement. Using indirect measurement results in no need for sensor maintenance during the whole lifetime of the mold. Thanks to the sensor geometry we designed, the sensor installation is as easy as it gets! The final form of the sensors was achieved with years of hard work and development, so you get the most reliable source of information about your mold.

 

The brand name of the new type sensor is RC, which refers to Ring Cell because the sensors have a rubber ring around the diameter of the sensor which is aiming to help the following:

• Simplify the mold modification process

• Eliminate the fitting problems caused by the radius of the bottom of the sensor pocket

• More precise positioning of the sensors inside the pocket

• Enables smaller manufacturing precision and larger tolerances

 

Every sensor type has an item number, for example RC-15-1— where RC refers to the type of the sensor, 15 refers to the diameter of the sensor in mm and the last number refers to the maximum load: 1 kN. The possible two characters at the end of the code refers to the operating temperature of the sensor. Every sensors has a high-temperature range variation (HT) which is capable of measuring up to 200°C.

 

Please note that we are not distributing the PC type sensors. The PC type sensors here are only for information purposes. The following table helps you in choosing the right sensor for your mold.

Technical data

Type of sensor

Maximum load [kN]

Maximum mould temperature [°C]

Diameter [mm]

Height [mm]

Max. ejector pin Diameter / Area [mm] / [mm2]

RC15-1

1

150

15

8

3 / 7

RC15-1-HT

1

200

15

8

3 / 7

RC15-5

5

150

15

8

6 / 28

RC15-5-HT

5

200

15

8

6 / 28

RC26-20

20

150

26

12

12 / 113

RC26-20-HT

20

200

26

12

12 / 113

RC26-40

40

150

26

12

20 / 314

RC26-40-HT

40

200

26

12

20 / 314

 

Mold Plug with Memory

Mold Plug with Memory

The Cavity Eye Mold Plug with Memory (MPM) socket was developed for the Injection Molds equipped with Cavity Eye pressure sensors. The wiring of the sensors takes place in this device, and it is also the counterpart of the Cavity Eye Smart Measuring Plug (SMP). This socket is equipped with a special, integrated memory, and responsible for storing the data of the molds and the Cavity Eye sensors. The memory can also contain the production data of the mold, for example: reference curves, tolerances, pin diameters, cavity IDs, etc.

 

There are two types of Mold Plugs you can choose from, depending on how much sensor signal is required to handle. MPM8-B type can be used up to 8 sensors. Over 8 sensors and up to 16 sensors 2 MPM8-B device can be applied. In case of higher sensor number, the MPM32-A device can be used. It can handle 32 sensors at the same time. In case of using more, than 32 sensors but maximum 64 sensors, 2 MPM32-A device is the right choice. The production starting and restarting procedure is getting quicker and easier with the memory in the MPM. You only have to upload memory content once, and the mold can be transferred to any injection machine afterwards, because the information is moving with the mold.

 

The following table helps You in choosing the right MPM socket.

Technical data

Type of socket

Max. number of sensors

Operating temperature [°C]

Dimensions [mm]

MPM8-B

8

0 – +80

96×93×45

MPM32-A

32

0 – +80

127×140×57