Molding Conditions

The standard molding conditions for SUMIKAEXCEL PES and SUMIPLOY are shown below.

Table 4-1-1 Standard Molding Conditions for SUMIKAEXCEL PES

Grade		3600G 4100G		4800G		3601GL20 / 3601GL30 4101GL20 / 4101GL30 ES5340
		Recommended	Range	Recommended	Range	Recommended	Range
Drying temperature (°C)		160-180		160-180		160-180
Drying time (hr)		5-24		5-24		5-24
Cylinder temperature (°C)	Rear	320	300-340	320	320-340	320	300-340
	Center	340	320-370	340	330-370	340	320-370
	Front	350	330-380	360	340-390	350	330-380
	Nozzle	350	330-380	360	340-390	350	330-380
Suitable resin temperature (°C)		350	350-360	360	350-370	350	350-360
Tool (Mold) temperature (°C)		140-180	120-180	140-180	120-180	140-180	120-180
Injection pressure (MPa)		100-200	100-200	100-200	100-200	100-200	100-200
Injection speed		Low speed	Low to medium speeds	Low speed	Low to medium speeds	Low speed	Low to medium speeds
Screw rotation (rpm)		50-100	50-100	50-100	50-100	50-100	50-100
Back pressure (MPa)		5-10	5-10	5-10	5-20	5-10	5-10
Holding pressure (MPa)		50-100	50-100	50-100	50-150	50-100	50-100

Table 4-1-2 Standard Molding Conditions for SUMIPLOY

Grade		GS5620 CS5220 / CS5530 / CS5600		E3010 FS2200		CK3400 / CK3420 CK4600
		Recommended	Range	Recommended	Range	Recommended	Range
Drying temperature (°C)		160	160-180	160	160-180	160	160-180
Drying time (hr)		8	5-24	8	5-24	5	5-24
Cylinder temperature (°C)	Rear	320	320-340	320	300-340	380	360-400
	Center	340	330-370	340	320-370	390	370-410
	Front	360	340-390	350	330-380	390	380-420
	Nozzle	360	340-390	350	330-380	400	380-420
Suitable resin temperature (°C)		360	340-390	350	350-360	400	380-420
Tool (Mold) temperature (°C)		140-180	120-180	140-180	120-180	180	120-180
Injection pressure (MPa)		100-200	100-200	100-200	100-200	100-200	100-200
Injection speed		Low speed	Low to medium speeds	Low speed	Low to medium speeds	Low speed	Low to medium speeds
Screw rotation (rpm)		50-100	50-100	50-100	50-100	50-100	50-100
Back pressure (MPa)		5-10	5-10	5-10	5-10	5-10	5-10
Holding pressure (MPa)		100-200	50-200	50-100	50-150	100-200	50-200

Pre-drying

As SUMIKAEXCEL PES is susceptible to water absorption, it must be dried thoroughly prior to usage. PES resin should be dried at temperatures ranging from 160 to 180°C for 5 to 24 hours, using a hot air circulation oven or a dehumidifying dryer. When drying using oven trays, PES resin should be spread on the trays to a thickness of 50mm or less. In particular, for molding large sized moldings, it is recommended that PES resin is dried at a temperature of 180°C.
In addition, the use of a dehumidifying dryer is recommended for non-reinforced grades and for large sized moldings. If a hopper dryer is used, it is important to ensure that it has both adequate resin capacity and large heat capacity. If pre-drying is sufficient, then silver streaking or flashing may appear on the surface of the molding. If this kind of phenomena occurs, then further drying of the resin is necessary.
As SUMIKAEXCEL PES is not susceptible to hydrolysis, it will not deteriorate during the drying process, if dried in accordance with the abovementioned conditions.

Figure 4-1-1 Drying Curve of 4100G

Resin Temperature

A resin temperature of 330 to 380°C is recommended. As SUMIKAEXCEL PES possesses high melt viscosity, the resin temperature tends to increase to a value higher than the cylinder temperature setting due to shear heat generation, and this may result in a temperature difference of more than 40°C. The resin temperature must be carefully monitored while molding operations are performed.

Figure 4-1-2 Flow length of PES (1mm)

Resin Residence Time

The length of time that it stays in the cylinder has a major impact on injection molding product quality. The residence time should be no longer than 10 minutes. The longer the residence time, the greater the possibility of thermal deterioration resulting in discoloration, black streaks, or black spots on molded parts.

Mold Temperature

The mold temperature should be set in a manner such that the surface temperature will be between 120 to 180°C. Also, ensure that the surface of the mold has a uniform temperature distribution.
If the mold temperature is excessively low, moldings may warp or crack (rupture) due to residual stresses. Residual stresses may also cause glass fibers to be visible on the surface of moldings for glass fiber grades. Moldings having low residual stresses can be obtained by using a high mold temperature. However, if the tool temperature is excessively high, deformation may occur during mold release.
With respect to the methods used for mold heating, both heaters and oil temperature control are recommended. However, for the following molds, oil temperature control should be implemented in order to ensure the most uniform mold temperature distribution: molds that have complex shapes; deep molds; and molds that have slide cores.
In particular, when molding large sized products and when using non-reinforced grades, additional precautions must be taken to ensure that proper mold temperatures are maintained.

Injection Pressure and Holding Pressure

In general, the injection molding of SUMIKAEXCEL PES requires high injection pressure of 100 to 200MPa. Over 150MPa of injection pressure is required for the molding of thin-walled products, for the molding with glass fiber reinforced grades, and for the molding of products with large flow length.
It is recommended that the holding pressure is set to 1/2 to 1/3 of the injection peak pressure, and it should be set as low as possible at the level that does not cause sink marks. The lower the holding pressures, the less residual stress there will be on the molded products.
The higher the peak pressure and holding pressure, the more difficult it is to release from the mold. Therefore, adjust the V-P switching position so that the peak pressure does not increase too much.

Injection speed

In general, SUMIKAEXCEL PES should be molded at low to medium injection speeds. However, the optimum injection speed will vary depending on the shape of the products.
As SUMIKAEXCEL PES has high melt viscosity, an excessively high injection speed will result in burning and silver streaking, due to the heat generated by shear and adiabatic air compression. However, high injection speeds are required for the molding of both thin-walled products (1mmt or less) and products with large flow length. In general, lower injection speeds result in products that have less residual stress.

Screw Rotation Speed and Back Pressure

It is recommended that screw rotation speed is between 50 to 100rpm in order to prevent increases in resin temperature due to shear heat generation.
The appropriate back pressure allows for consistent melting of resin. The recommended back pressure is 5 to 10MPa. When molding PES grades that have high molecular weights, ensure that a greater back pressure is applied. However, if back pressure is too high, problems such as resin overheating and overloading may occur.

Temporary Suspension of Molding

Whenever the molding process is suspended for a short period of time, set the cylinder temperature to 250 to 260°C, in order to prevent thermal deterioration of the resin. If the resin temperature decreases to less than 250°C, the screw surfaces and internal walls of the cylinder may be damaged and foreign objects may be caused after the molding process has resumed. When the molding process is to be suspended for a long period of time, reduce the cylinder temperature only after the inside of the cylinder has been purged with purging materials.

Purging Method

Recommended purging materials are as follows : polyethylene that has a high molecular weight of approximately MFR 0.05 ; polycarbonate ; or more preferably, the same materials containing glass fiber.

• As SUMIKAEXCEL PES requires high processing temperatures, smoke, gas emission, and resin blown-off may occur during the purging process.
• Ensure that none of the purging material is left within the cylinder.

Table 4-1-3 Recommended Purging Procedure (When Switching to SUMIKAEXCEL PES)

Item		Recommended Conditions/Procedures
Setup	Back pressure	High (Ensure that the screw retracts slowly.)
	Screw rotation speed	Set the same rotation speed as for when molding the prior resin.
Purging	1. Prior resin discharge	Discharge as much of the prior resin from the hopper and cylinder as possible.
	2. Purging material input	Input purging material while maintaining the prior resin molding temperature, and perform sufficient purging. When using a glass fiber reinforced purging material replace it with a non-reinforced purging material before replacing it with PES so that no glass fibers remain.
	3. Temperature change	Change to the PES molding temperature while continuing to input purging material.
	4. Purging material discharge and PES input	Discharge the purging material thoroughly after reaching the moldingtemperature of PES, and then input the PES.
	5. Molding	After purging with PES, it is possible to perform molding once the cylinder temperature becomes stable.

Checking of Residual Stress

SUMIKAEXCEL PES molded products may suffer from defects such as cracking or breakage during mold release, due to the effects of residual stress.
The following method can be used to check the residual stress of SUMIKAEXCEL PES molded products. This method can also be used for determining optimum molding conditions.

• Test method

1. Allow the molded products to cool to room temperature
2. Immerse the molded products in xylene for 90 seconds
3. Clean it them in cold water
4. Check the molded products carefully for cracks.
5. If there are no cracks, perform the same test in toluene. Thereafter, perform the test in the same manner, changing the solvent to ethyl acetate, then methyl ethyl ketone, in that order.
6. The kind of solvent that caused the cracks can be used to estimate the magnitude of the residual stress in the molded product. (see "Table 4-1-4")

Table 4-1-4 Residual Stress Checking Method for SUMIKAEXCEL PES (4100G)

Solvent	Residual strain	Residual stress
Cracks occurred in xylene	1.3-1.5% or more	30-40MPa or more
Cracks occurred in toluene	1.0% or more	27MPa or more
Cracks occurred in ethyl acetate	0.50% or more	14MPa or more
Cracks occurred in methyl ethyl ketone	0.35% or more	10MPa or more