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Molding Conditions

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LAPEROS(R) LCP Grade Composition This page's PDF(619KB)

7. Molding Conditions

7.1 Cylinder temperature

General nozzle and cylinder temperatures are shown in Table 7-1 and they are recommended as standard conditions. Temperatures be changed within a range of 10°C to 20°C depending on molding conditions. In order to prevent stringiness and drooling, nozzle temperature can be lowered 10°C to 20°C. However, it is advised to pay attention to the following remarks.

When lowering the cylinder temperature

Degradation of mechanical properties due to cold slug or insufficient plasticization.

When raising the cylinder temperature

There is no major problem as LAPEROS® LCP will rarely turn into gel or generate corrosive gas in the cylinder due to normal or extended retention time. However, it is recommended to lower cylinder temperature when interrupting molding for a long time, and purge several shots of material in the cylinder when restarting.

 

If unstable metering occurs, setting as shown below is recommended for cylinder temperature distribution.

(Example) In case of E130i:

(NH) 350°C - 350°C - 350°C - 350°C (Flat)

(NH) 350°C - 350°C - 360°C - 370°C (Raise temperature at rear section)

 

Table 7-1 Recommended Cylinder Temperature Setting of Each Grade

Grade Nozzle Front section Center section Rear section Water
cooling
section
A grade 290°C - 320°C 290°C - 320°C 280°C - 300°C 270°C - 310°C 80°C
B grade 290°C - 320°C 290°C - 320°C 280°C - 300°C 270°C - 310°C
C grade 330°C - 350°C 330°C - 350°C 320°C - 340°C 310°C - 350°C
D grade 310°C - 330°C 310°C - 330°C 300°C - 330°C 300°C - 340°C
Ei grade 340°C - 365°C 340°C - 365°C 340°C - 360°C 330°C - 370°C
GA/HA grade 350°C - 370°C 360°C - 380°C 330°C - 350°C 315°C - 335°C
S grade 355°C - 370°C 355°C - 370°C 350°C - 380°C 350°C - 390°C
T grade 370°C - 380°C 370°C - 380°C 370°C - 390°C 360°C - 400°C

 

7.2 Mold Temperature

It is generally recommended to set mold temperature in a range of 50°C to 120°C when molding LAPEROS. Mold temperature of 50°C rarely causes problems normally. However, if there is any problem in appearance such as surface roughness or gloss, a higher mold temperature is recommended.

 

7.3 Plasticization

Generally, screw rotational speed is approximately 100 rpm. Higher screw rotational speed is allowable for reduction of cycle time or metering stability. It is recommended to set back pressure at approximately 0 MPa to 2 MPa to prevent drooling and fiber breakage.

 

7.4 Injection Pressure and Injection Speed

Each LAPEROS grade has very low melt viscosity and, therefore, can be molded at much lower pressure than those applied for other thermoplastic polymers. In most cases, a resin pressure of 15 MPa to 45 MPa can be adopted for molding. Furthermore, as LAPEROS has fast solidifying speed, fast injection speed may produce better results in most cases.

 

7.5 Starting and Stopping the Molding Machine and Changing the Molding Material

(1) Stopping the Molding Machine

After purging of LAPEROS remaining in the cylinder at the molding temperature of LAPEROS, the cylinder should be purged with a resin which is the same molding temperature as LAPEROS and has good thermal stability. (Commercially available glass-fiber reinforced polycarbonate, high-density polyethylene or acrylic type purging materials are recommended.) If LAPEROS is to be subsequently molded, the cylinder can be purged with LAPEROS.

 

(2) Starting the Molding Machine

In starting up a machine containing another resin that is stable within the LAPEROS molding temperature range, cylinder temperature can be raised to this level and purging can be done with LAPEROS. However, LAPEROS has a very low melt viscosity, which makes purging of the remaining resin in the cylinder difficult, so extremely thorough purging is required. It is efficient to purge cylinders with glass-fiber reinforced polycarbonate first, and then purge with LAPEROS.

 

When the resin remaining in the cylinder has a different molding temperature range, the following steps should be carried out:

  • Set the cylinder temperature at the molding temperature of the remaining resin.
  • Purge the cylinder with a resin that has good thermal stability and can be used in the molding temperature ranges of both LAPEROS and the remaining resin (for example, glass-fiber reinforced polycarbonate, high-density polyethylene, or polycarbonate as the case may be).
  • After that, set the cylinder temperature at the LAPEROS molding level and purge the cylinder again according to the instructions for a resin stable in the LAPEROS molding temperature range.

 

In general, when LAPEROS is the resin remaining in the cylinder, it is possible to raise the cylinder temperature to the LAPEROS molding level and to purge with LAPEROS. However, as the molding temperature ranges of LAPEROS differ depending on the grade, it is necessary to confirm the molding temperature ranges of the remaining LAPEROS grade and the replacement LAPEROS grade prior to purging. When the molding temperature range of the remaining LAPEROS grade is different from that of replacement LAPEROS grade, the purging should be done according to the instructions when the case that the resin remaining in the cylinder has a different molding temperature range.

 

(3) Changing the molding material

When the resin has the same molding temperature range as LAPEROS, the cylinder can be purged at the molding temperature, following the same procedures used in starting and stopping the molding machine.

When the resin cannot be replaced under the same molding condition, it is recommended to purge the cylinder with a resin that can be used at the molding temperatures of both LAPEROS and the replacement, and has good thermal stability (e.g. glass-fiber reinforced polycarbonate or high-density polyethylene). Then, set the cylinder temperature at the replacement resin molding level.

Especially when the resin remaining in the cylinder has a higher viscosity than that of LAPEROS, it is quite difficult to replace it with LAPEROS. Very thorough purging is required.

 

(4) Other

If LAPEROS remains in the cylinder for a long time, degradation and contamination may occur. In such a case, extremely thorough purging is required.

When it is difficult to purge dark colored materials such as black coloring materials, purging should be done with glass-fiber (GF) reinforced polycarbonate, then with polyethylene. Repeat purging with GF reinforced polycarbonate and polyethylene alternately is recommended. It is more effective if the new purging material is fed into the cylinder after completely purging the previous material.

Note: Make sure to read purging material SDS prior to use.

 


Contents Introduction Pre-drying Use of Regrinds Selection of Molding Machine
 Mold Designing Molding Properties Molding Conditions Safety Precautions