About injection-molding

Drying conditions

  1. For general applications, use a hot-air dryer. Start with base point settings of 130-150°C temperature and 3-5 hours drying time.
  2. For applications where the product shape is more susceptible to blistering, metering instability or random shorts, the use of a dehumidifying dryer (preferably a vacuum dryer) is recommended to remove moisture content better than would be possible in the above item 1. Use the following drying conditions.
  • Drying temperature: 150°C
  • Drying time: 4-5 hours.
    (Exercise caution against using a low temperature. Drying at a low temperature will not sufficiently remove water content, regardless of the drying time.)

Molding conditions

Ⅰ. Molding temperature

The optimal resin temperature for a standard type is 315-340°C and for a heat-resistant type, 325-350°C. Keeping the material at high temperatures for extended periods of time can lead to deterioration in physical properties, discoloration or dissolution, so exercise caution. Meanwhile, due to the high flowability rate of SIVERAS™, depending on the nozzle tip shape and temperature, material could drip from the nozzle. If this problem occurs, try lowering the temperature setting by 10-20°C. See the table below for examples of molding temperature conditions for SIVERAS™.

Recommended molding temperature conditions for SIVERAS™

(Unit: °C)
Type Nozzle ※ C1 (Front zone) C2 (Middle) C3 (Rear)
LX70 series 300 ~340 330 ~350 310 ~350 270 ~350
L304 series 300 ~340 330 ~350 310 ~350 270 ~350
L204 series 300 ~320 320 ~340 300 ~330 270 ~330

*Raise the temperature setting by 10-20°C when using a long, narrow nozzle.

Ⅱ. Mold temperature

SIVERAS™ can be molded across a broad range of temperatures, from 30°C to 150°C. That said, the optimal temperature range is 90°C to 130°C, in light of product mechanical properties and weld strength, as well as dimensional change under exposure to the operating environment.

Ⅲ. Injection pressure and injection speed

Because SIVERAS™ has a low melt viscosity, it can be molded at pressures lower than what is possible with PBT or PPS resins. A good approach is to start low, then gradually increase pressure. Depending on the product shape and mold structure, a range of pressure from 20 MPa to 90 MPa can mold successfully.
Thanks to the higher flowability rate of SIVERAS™ compared to other LCP resins, it is possible to mold product shapes that present filling challenges at low injection speeds. Raising the injection speed could lead to jetting at the gates caused by the capturing of air, as well as blistering issues, so exercise caution.

Sprue and runner shapes

Because of the superb flowability of SIVERAS™, using conventional sprues could lead to jetting within the sprue and product defects caused by air captured within. Therefore, use the smallest sprue diameter possible.

  1. Use a narrow, long nozzle on the molding machine. The nozzle diameter should be small (φ1.0-2.0mm) and the sprue length should be short.
  2. Make the sprue taper small (1-2” on one side).
  3. Eliminate steps. Any steps in the sprue will create dead space and could lead to blistering issues.

The runner also needs to be narrow to handle the superior flowability of SIVERAS™.
Using narrower sprues and runners makes it possible to reduce the amount of resin used and shorten the time until resin begins flowing into the mold cavity. This allows more time to solidify the resin and broadens the range of options for molding conditions.

Advice on dealing with molding issues

Failure to use the appropriate molding conditions when injection-molding SIVERAS™ could lead to a variety of problems. The following figure discusses options to prevent these problems.

Issue Category
Mold temperature Cylinder temperature Injection Pressure Injection Speed Hold pressure Sack back Screw rotation speed
Drooling   Lower nozzle temperature
Blistering   Increase
Warpage (after molding) Lower
Unstable metering   Increase
hopper zone
Insufficient strength   Increase
Sticking to mold Increase

*These are examples of possible countermeasures and may not work in all situations.