This is a general overview for processing our products; injection moulding guides of specific products can be downloaded from the "Products" section


Injection moulding of PA66
Polyamide 66 is easy to mould material, which is not particularly sensitive to moulding conditions. A few general guidelines are given here.

Pre-drying
Polyamide is hygroscopic and moisture sensitive, so pre-drying is recommended as a matter of rule. Material that is not pre-dried to a moisture level below 0.1% will degrade, causing surface defects, parts that are out of dimension and brittle parts. It is recommended to dry material for 4 hours at 80 °C to 85 °C in a desiccant dryer with more than one desiccant element.
 
A few tips to ensure proper operation of the dryer:

• Ensure the thermocouple that regulates the temperature is placed immediately before the entry of the air into the dryer. There can be a significant temperature drop in the air-conveyance system!
  
• The temperature of the air going out of the dryer silo should not be more than 30 °C lower than the air entering the system. If this is the case, you have insufficient air capacity.
  
• From time to time, monitor the dew point of the dry air to ensure the desiccant elements are functioning properly.
  
•  Often, less air runs through the very bottom part of a dryer silo. Therefore, it is recommended that you take the material out of the bottom of the dryer and feed back into the top when you start up your process.
  

Moulding temperatures
For polyamide 66, the melt temperature must be kept below 300 °C. Any higher temperature will cause rapid degradation, which can be recognized by foaming of the material or splash marks on the surface of the part.
 
The following barrel settings are recommended:

Material               Zone 1 (hopper)  Zone 2           Zone 3           Zone 4 (Nozzle)
Unfilled grades       260-295 °C          270-295 °C   275-290 °C   275-295 °C
FR Grades             260-280 °C          260-280 °C   270-280 °C   275-285 °C
Reinforced Grades  270-290 °C          270-295 °C   270-295 °C   275-295 °C
HI Grades              260-275 °C          260-280 °C   270-280 °C    275-285 °C


Tool temperature
Mould temperature is always a compromise. On the one hand, tool temperature should be as a high as possible to give optimum crystallization and dimensional, optimal surface finish and optimal mechanical performance. On the other hand, lower tool temperature can significantly cut cycle time. For Polyamide 66, 80 °C should be maintained as a minimum, for reinforced grades values of 90 to 110 °C are preferred.

Pressure and speed
Injection pressure should generally be around 70 to 100 Mpa; this results in a minimum clamping force of the moulding machine in tonnes of 0.7 times the projected surface area in cm2.
 
Holding pressure is generally in the area of 90 Mpa.
 
For glassfibre reinforced compounds, the screw speed should be kept low, a rough indication is as follows:

Screw Diameter (mm)     Maximum rpm
             20                          150
             30                          100
             40                          70
             50                           60
             60                           50
             70                           40
             80                           35
           >80                           30

Back pressure should be kept to a practical minimum


Use of regrind
Reground sprues and runners can be used on most materials. It is not recommended to use regrind on FR grades. When regrind is used, observe these simple rules:
 

•   Use a constant ratio of regrind and virgin material. When a material has been processed once, its viscosity and fibre length have been decreased. Using varying rations of regrind can lead to variations in dimensions, mechanical performance and processing characteristics.
  
• Either feed the regrind straight back into the machine, or pre-dry the regrind before usage.
  
• Store regrind in a dry, clean place to avoid contamination and excess moisture.
  
• Ensure sharp cutting blades to keep dust generation to a minimum; cut glass fibre reinforced material when it is still hot.
  
• Clean the grinder regularly to avoid build up of dust.
  
•  Do not use splayed, discoloured or degraded parts and runners

 

For an injection moudling guide of a specific grade, look in the products section.


Injection moulding of PA6
Polyamide 6 is easy to mould material, with a very wide processing window. A few general guidelines are given here.

Pre-drying
Polyamide is hygroscopic and moisture sensitive, so pre-drying is recommended as a matter of rule. Material that is not pre-dried to a moisture level below 0.1% will degrade, causing surface defects, parts that are out of dimension and brittle parts. It is recommended to dry material for 4 hours at 80 °C to 85 °C in a desiccant dryer with more than one desiccant element.
 
A few tips to ensure proper operation of the dryer:

• Ensure the thermocouple that regulates the temperature is placed immediately before the entry of the air into the dryer. There can be a significant temperature drop in the air-conveyance system!
  
• The temperature of the air going out of the dryer silo should not be more than 30 °C lower than the air entering the system. If this is the case, you have insufficient air capacity.
  
• From time to time, monitor the dew point of the dry air to ensure the desiccant elements are functioning properly.
  
•  Often, less air runs through the very bottom part of a dryer silo. Therefore, it is recommended that you take the material out of the bottom of the dryer and feed back into the top when you start up your process.
  

< Moulding temperatures
Polyamide 6 can be processed between 225 and 310 °C, depending on the grade used.


The following barrel settings are recommended:

Material               Zone 1 (hopper)  Zone 2           Zone 3           Zone 4 (Nozzle)
Unfilled grades       220-260 °C          225-270 °C   225-270 °C   225-275 °C
FR Grades             225-260 °C          230-260 °C   235-265 °C   235-265 °C
Reinforced Grades  240-280 °C          240-290 °C   240-290 °C   240-295 °C
HI Grades              220-265 °C          225-260 °C   225-265 °C   230-275 °C


Tool temperature
Mould temperature is always a compromise. On the one hand, tool temperature should be as a high as possible to give optimum crystallization and dimensional, optimal surface finish and optimal mechanical performance. On the other hand, lower tool temperature can significantly cut cycle time. For Polyamide 6, 80 °C should be maintained as a minimum, for reinforced grades values of 90 to 110 °C are preferred.

Pressure and speed
Injection pressure should generally be around 70 to 100 Mpa; this results in a minimum clamping force of the moulding machine in tonnes of 0.7 times the projected surface area in cm2.
 
Holding pressure is generally in the area of 90 Mpa.
 
For glassfibre reinforced compounds, the screw speed should be kept low, a rough indication is as follows:

Screw Diameter (mm)     Maximum rpm
             20                          150
             30                          100
             40                          70
             50                           60
             60                           50
             70                           40
             80                           35
           >80                           30

Back pressure should be kept to a practical minimum


Use of regrind
Reground sprues and runners can be used on most materials. It is not recommended to use regrind on FR grades. When regrind is used, observe these simple rules:
 

•   Use a constant ratio of regrind and virgin material. When a material has been processed once, its viscosity and fibre length have been decreased. Using varying rations of regrind can lead to variations in dimensions, mechanical performance and processing characteristics.
  
• Either feed the regrind straight back into the machine, or pre-dry the regrind before usage.
  
• Store regrind in a dry, clean place to avoid contamination and excess moisture.
  
• Ensure sharp cutting blades to keep dust generation to a minimum; cut glass fibre reinforced material when it is still hot.
  
• Clean the grinder regularly to avoid build up of dust.
  
•  Do not use splayed, discoloured or degraded parts and runners

 

For an injection moudling guide of a specific grade, look in the products section.


Injection moulding of PBT
One of the most important aspects of processing PBT correctly, is to ensure the material is pre-dried to a moisture level below 0.05%. 

Pre-drying
PBT is very moisture sensitive, so pre-drying is recommended as a matter of rule. Material that is not pre-dried to a moisture level below 0.05% will degrade, causing mechanical failure due brittle parts. It is recommended to dry material for 4 hours at 120 °C to 130 °C in a desiccant dryer with more than one desiccant element.
 
A few tips to ensure proper operation of the dryer:

• Ensure the thermocouple that regulates the temperature is placed immediately before the entry of the air into the dryer. There can be a significant temperature drop in the air-conveyance system!
  
• The temperature of the air going out of the dryer silo should not be more than 30 °C lower than the air entering the system. If this is the case, you have insufficient air capacity.
  
• From time to time, monitor the dew point of the dry air to ensure the desiccant elements are functioning properly.
  
•  Often, less air runs through the very bottom part of a dryer silo. Therefore, it is recommended that you take the material out of the bottom of the dryer and feed back into the top when you start up your process.
  

Moulding temperatures
For PBT, the melt temperature must be kept below 280 °C. Any higher temperature will cause rapid degradation, resulting in brittle parts.
 
The following barrel settings are recommended:

Material               Zone 1 (hopper)  Zone 2           Zone 3           Zone 4 (Nozzle)
Unfilled grades       240-260 °C          240-265 °C   240-270 °C   250-270 °C
FR Grades             240-260 °C          240-260 °C   240-265 °C   240-270 °C
Reinforced Grades  250-270 °C          250-270 °C   250-275 °C   260-280 °C


Tool temperature
Mould temperature is always a compromise. On the one hand, tool temperature should be as a high as possible to give optimum crystallization and dimensional, optimal surface finish and optimal mechanical performance. On the other hand, lower tool temperature can significantly cut cycle time. For Polyamide 66, 80 °C should be maintained as a minimum, for reinforced grades values of 90 to 110 °C are preferred.

Pressure and speed
Injection pressure should generally be around 70 to 100 Mpa; this results in a minimum clamping force of the moulding machine in tonnes of 0.7 times the projected surface area in cm2.
 
Holding pressure is generally in the area of 90 Mpa.
 
For glassfibre reinforced compounds, the screw speed should be kept low, a rough indication is as follows:

Screw Diameter (mm)     Maximum rpm
             20                          150
             30                          100
             40                          70
             50                           60
             60                           50
             70                           40
             80                           35
           >80                           30

Back pressure should be kept to a practical minimum


Use of regrind
Reground sprues and runners can be used on most materials. It is not recommended to use regrind on FR grades. When regrind is used, observe these simple rules:
 

•   Use a constant ratio of regrind and virgin material. When a material has been processed once, its viscosity and fibre length have been decreased. Using varying rations of regrind can lead to variations in dimensions, mechanical performance and processing characteristics.
  
• Either feed the regrind straight back into the machine, or pre-dry the regrind before usage.
  
• Store regrind in a dry, clean place to avoid contamination and excess moisture.
  
• Ensure sharp cutting blades to keep dust generation to a minimum; cut glass fibre reinforced material when it is still hot.
  
• Clean the grinder regularly to avoid build up of dust.
  
•  Do not use splayed, discoloured or degraded parts and runners

 

For an injection moudling guide of a specific grade, look in the products section.