In-mold resin pressure measuring system

Advantages of introduction

  • 1. Detection of defects in mold products

    Waveform with alarm monitoring frame set

    By setting a monitoring range on the measurement waveform (reference waveform) obtained during proper molding, the system can detect abnormalities and output an alarm signal when defects such as short shots cause the measurement waveform to deviate from the monitoring range.

    Examples of Measures Taken After Detecting Defective Products

    • To prevent continuous molding of defective products (stop the molding machine)
    • ・Automatic ejection of defective products (ejecting into the defective box in coordination with the take-out robot)

  • 2. Efficiency in setting molding conditions under different environments

    Matching the measured waveform to the reference waveform

    By saving the waveform during the molding of good products (reference waveform), it is possible to adjust to this reference waveform even when starting molding under different environments. This enables efficient production of molded products with consistent quality.

    Examples of Environmental Changes

    • ・ When mass production is transferred overseas
    • ・ When changing the molding machine or auxiliary equipment (such as manufacturer or capacity, etc.)
    • ・When the temperature changes

  • 3. Evaluation of Mold Quality

    Waveform with poor cavity balance

    By analyzing the elapsed time and pressure values until the resin reaches the pressure sensor, it is possible to evaluate the quality of the mold.

    Examples of Evaluation

    • ・ Evaluation of runner balance and gate balance
    • ・ Evaluation after runner and gate modification
    • ・ Evaluation of release resistance (evaluation of draft angle)

  • 4. Confirmation of the correlation between pressure waveform and molding defects

    Waveform when a defect occurs

    By analyzing and comparing the waveform during the molding of good products (reference waveform) with the waveforms of each type of molding defect that occurred, it is possible to confirm the correlation between them.

    Examples of defects detectable from pressure waveforms

    • ・ Waveform measurement value
      Increase → Flash, overpacking
      Decrease →Short shots, sink marks


    • ・ Protruded waveform
      Large → Large release resistance
      Small → Small release resistance

Features

It is possible to display the resin pressure inside the mold, measured by a pressure sensor, as a waveform in real time using dedicated measurement software. By saving the waveform during good product molding as a "reference waveform," it can be used for setting conditions when starting molding under different environments. In addition, by defining a monitoring range for the reference waveform, molding defects such as short shots or burrs can be automatically detected when the waveform deviates from this range, and an alarm signal can be output.

As a result, it is possible to prevent the continuous molding of defective products and to automatically eject defective products into a defect box in coordination with the take-out robot. Therefore, this system is highly effective for defect monitoring during mass production molding.

In addition, by connecting the pressure sensor to the injection molding monitoring system "MVS08," it is possible to simultaneously measure not only resin pressure but also resin temperature, mold temperature, and mold opening.

  • Differences in measured waveforms depending on sensor installation position

    Waveforms vary depending on sensor installation position

  • Setting monitoring ranges on the measured waveform

    Waveform with monitoring frame set

Measurement principle

The pressure sensor embedded in the mold receives the pressure of the resin flowing inside the cavity via the ejector pin, detects it with an internal strain gauge, and outputs it as an electrical signal. The output electrical signal is processed by a measuring amplifier, and the processed result is displayed as a pressure waveform by dedicated measurement software.

  • Inside the sensor under no load and under applied pressure

    Comparison of the inside of the sensor when no load is applied and when pressure is applied

  • The force exerted on the sensor by the resin

    Resin force sensor

Types of measurement amplifiers and sensors

  • Pressure measurement amplifier<br /> MPS08B

    Pressure measurement amplifier
    MPS08B

    • As a standalone amplifier, this product can conduct monitoring, alarm output, and recording of measurement data.
    • Measurement data can be saved in a USB memory stick.
    • Up to four amplifiers can be connected, allowing simultaneous measurement of up to 32 channels (8 channels per unit).
    • On the measurement software, it is possible to switch languages between Japanese, English, Korean, Simplified Chinese, and Traditional Chinese.
    • Equipped with RS485 interface, this product is compatible with MODBUS communication protocol.
  • In-line pressure measurement unit MPS01A

    In-line pressure measurement unit
    MPS01A

    • Low-cost type for inline (mass production molding) use
    • Easy-to-read digital display, even in busy mass production sites
    • Conforming to RS485 communication standard, this product is capable of remote monitoring.
  • Pressure sensor: ejector pin type SSE series

    Pressure sensor – ejector pin type
    SSE Series

    • Due to its ejector pin shape, this product can replace the existing ejector pin. (*2)
    • The pin section can be cut in accordance with the mold.
    • The overall length of the pin can be specified as desired.

    *1 Requires combination with pressure measurement amplifier MPS08B.
    *2 Anti-rotation processing such as flange cutting is not possible.

  • Pressure sensor: button type SSB series

    Pressure sensor: button type SSB series

    • Since measurement is performed by placing the sensor directly beneath the ejector pin, the ejector pin currently in use can be utilized as is.
    • This product can be applied to a “small-diameter pin,” “square pin,” “pin with irregular tip shape,” and “pin with cut collar,” which cannot be measured by the ejector pin type.
    • A wide variety of rated capacities are available, ranging from 50 N to 16 kN.
    • A lineup of heat-resistant models capable of withstanding mold temperatures up to 200°C is available.

    *1 Requires combination with pressure measurement amplifier MPS08B.

  • Pressure sensor Button type Wiring storage type<br /> SCB series

    Pressure sensor – button type for junction boxes with cable storage space
    SCB Series

    • Cables can be stored inside a wiring storage-type junction box, reducing the risk of cable disconnection.
    • A lineup of low-capacity types is available, featuring a width of 3.5 mm and pin diameters of φ0.3 to 1.0 mm, suitable for the low-pressure range of 5 to 10 N (for a rated capacity of 10 N).
    • We also offer heat-resistant products that are applicable to mold temperature of up to 200˚C.
    • *1 It is necessary to combine this product with pressure measurement amplifier MPS08B.
  • ・For information on direct pressure sensors, refer to “Injection molding monitoring system.”

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