The following topics support the use of Kistler mold cavity pressure sensors:

• CAD Data for Mold Design
• Indirect Sensors: Ejector Pins
• Indirect Sensors: Calculation of Pressure Sensitivity
• Indirect Sensors: Maximum Permissible Pressure
• Direct Sensors: Installation with Spacer Sleeve and Grub
  Screw
• Securing of Extension Cables

CAD Data for Mold Design

The CAD data of the different types of sensor ensures sensor holes and the connector recesses to be used as model files. The data is available in the common model formats:

• ACIS
• IGES
• STEP
• Parasolid

Download CAD Data

Indirect Sensors: Ejector Pin Design Information

Provided a few mold and ejector design guidelines are followed, indirect measurement also delivers exact results with a high degree of accuracy. Eight basic principles should be followed:

1. The pin may only be positioned close to the cavity.
2. The guided length l1 should not exceed twice the pin diameter d1.
3. Behind the guide the pin must be free over the entire length l3.
4. The length l2 of the bore with the small diameter d1 should be as short
   as possible (see diagram).
5. A pin diameter d2 as large as possible should be chosen, while ensuring the pin remains free!
6. If the force is measured behind the ejector, the ejector must be designed to be particularly rigid.
7. The sensor must not be preloaded. The recommended gap between pin and sensor is 0,03 … 0,05 mm.
8. To minimize friction the pin should be provided with a diamond-like coating over the length of the guide.

Indirect Sensors: Calculation of Pressure Sensitivity

The effective pressure sensitivity is determined by the size of the front of the ejector located in the cavity wall. The formula uses the surface area of the pin to convert the acting force into pressure (bar).

S_P = A x S_F x 0,1

S_P = Pressure sensitivity [pC/bar]
A   = Area of ejector pin d1, d.h. A = (d1/2)2 x π [mm2]
S_F = Force sensitivity [pC/N], as per identification plate

The following table shows this with reference to the sensor Type 9211B...:

Indirect Sensors: Maximum Permissible Pressure

Indirect sensors measure the cavity pressure as a value derived from the force transferred by the ejector. The ejector pin diameter therefore has to be taken into account when choosing a sensor. Data sheets and instruction manuals indicate the permissible pairings and the corresponding maximum pressures. As a rule of thumb a small ejector pin diameters should be used for high injection pressures.

The following table shows the maximum allowable pressures for sensor Type 9211B...:

Direct Sensors: Installation with Spacer Sleeve and Grub Screw

When installing a direct sensor in a mold without a supporting platen, or installing it laterally, a grub screw can be used to secure the spacer sleeve. The usual installation clearance of 0,01 to 0,03 mm applies. The diameter of the screw must be sufficient to avoid distorting the sleeve and the sensor. The following guide values therefore apply:

For ø4 spacer sleeve (Type 6464A1): 
grub screw at least M5

For ø7 spacer sleeve (Type 6459):
grub screw at least M10

Installation of Extension Cables

Even though well shielded, freely suspended cables can affect measurement signals. Secure cables on the mold or the ejector plate with or clips or clamps. Ensure sufficient slack for strain relief.