Cluster Management Excellence

WinAssistant

WinAssistant is a simple and clear tool for every injection moulder. Simple and uncomplicated, you can calculate with a few inputs important parameters for the initial setting of an injection moulding machine.

The following parameters can be calculated:

– Determination of a basic parameter setting for the initial setting of an injection moulding machine

– Calculation of the theoretical cooling time

– Determination of the cycle time

– Determination of the dryer volume

– Determination of the screw utilization and the residence time

 

Note: All information and calculation values are for guidance only and are non-binding values. In individual cases, you may deviate significantly from the actual conditions.

 

Further technical advice can be found in our online shop

 

1. Specific material and moulded part conditions

Material grade
Geometry

There are 5 geometries available that can be selected to calculate the theoretical cooling time:

  • Plate – Selection, if the cooling time for a common moulded part is to be calculated.
  • Cylinder long - Selection, if the cooling time for a cold runner system (eg bar gate) is to be calculated (length of sprue bar >> diameter).
  • Cylinder short - Selection, if the cooling time for dome-like moulded part area is to be calculated (length of the dome = diameter.)
  • Cube – Selection, if the cooling time for cube-like moulded part area is to be calculated.
  • Sphere – Selection, if you the cooling time for spheroidal shaped moulded part area is to be calculated.
Maximum moulded part wall-thickness mm

To calculate the theoretical cooling time, the cooling-time determining moulded part wall thickness (usually the maximum moulded part wall thickness) must be entered.

Maximum flow length
(Moulded part + cold runner sprue)
mm

For the initial setting of the injection time, an injection time of 1 sec per 100 mm flow path length is used as an orientation value. For this the maximum flow path length, which flows the melt in the mould, are entered as a value.

Shot weight
(Moulded part + weight of cold runner)
 g  
Shot volume cm³

2. Parameter Default Setting [Initial Setting]

2.1. Temperatures
Melt temperature
Mould wall temperature
Nozzle temperature
Barrel temperature T1
Barrel temperature T2
Barrel temperature T3
Barrel temperature T4
Flange temperature
2.2. Times
Calculated theoretical cooling time s

This means the cooling time, which depends theoretically on the parameters of moulded part wall thickness, mould wall and melt temperature, and material, in order to cool a moulded part down to a necessary average demoulding temperature. The cooling time is composed of the holding pressure time and residual cooling time.

Other cooling time than calculated? s

Here, an alternative value (eg actual known cooling time) can be entered instead of the calculated theoretical cooling time.

Holding pressure s

For an initial adjustment of the post-pressure time, 75% of the calculated theoretical cooling time can be taken as the orientation value. For exact determination of the max. effective holding time, the sealing point must be determined by weight determination.

Residual cooling time s

For an initial setting of the remaining cooling time, 25% of the calculated theoretical cooling time can be taken as the orientation value.

Injection time s
2.3. Plasticating condition
Peripheral screw speed
Peripheral screw speed
Specific holding pressure
Shot volume cm³
Supplement volume cm³
Metering volume cm³
Decompression volume cm³

3. Cycle time

1 Mould closing s
2 Aggregate unit forward s
3 Injection time s
4 Holding pressure time s
5 Residual cooling time s
6 Metering delay s
7 Metering time s
8 Aggregate unit back s
9 Mould opening s
10 Demoulding s
Calc. cycle time s

4. Determination of dryer volume

Compliance with the drying or residence time is an essential factor to achieve the required residual moisture content and also to avoid negative effects on the processing process and the quality of the moulded part. Too long residence times in the dryer can damage the material. Therefore, during production preparation, it is also recommended to calculate the necessary dryer volume with the following calculation.

Cycle time s
Drying temperature
Drying time
Material throughput  kg/h
Dryer volume  l

5. Determination of screw utilization and residence time

Plasticating unit Unit 1 Unit 2
Screw diameter mm mm
Maximum volume of metering stroke cm³  cm³

If the channel volume of a screw is not known, the approximate calculation of the channel volume can be replaced by the maximum metering volume of the screw with an average of 60% are used.

Input value here: Maximum metering volume.

Total screw channel volume cm³ cm³

The channel volume of a screw can be requested from the injection molding machine manufacturer. This means the total volume of the screw channels. This information is required for the calculation of the residence time.

Hot runner volume cm³ cm³
Metering volume cm³ cm³

Ist das Gangvolumen nicht bekannt, kann ersatzweise für die näherungsweise Berechnung des Gangvolumens auch das max. Dosiervolumen der Schnecke mit durchschnittlich 60% herangezogen werden.

Eingabewert hier: max. Dosiervolumen.

Metering stroke mm mm
Screw utilization D D

The bigger metering strokes of sD> 4D takes the effective screw length significantly during the plasticating process. This can lead to a decrease in the melt homogeneity (mechanical + thermal) during dosing. In multi-cavity moulds with long flow paths can also result uneven filling behaviour under certain circumstances. When metering strokes is sD <1D promote a risk that exceeds the allowable residence time of the material. Furthermore, it may lead to non-reproducible closing behaviour of the non-return-valve of the screw.

The blue bar in the screw diagram indicates the corresponding screw utilization.

Material residence time in cylinder s
min
s
min
Material residence time in hot runner s
min
s
min
Total residence time s
min
s
min

The term residence time refers to the time period between the times at which the material granulates is drawn into the Plasticating unit and the moment when it reaches the cavity. When using hot runner systems, the residence time of the melt in the hot runner must be added to the overall residence time. The admissibility of the residence time is specifically material dependent and should be asked by the raw material manufacturer on demand. In general it can be said that for many thermoplastic polymer materials the allowable residence time is within the range of 5 - 8 minutes as long as the thermal loads on the melt are in the recommended working range.

Unacceptable long residence times lead to thermal degradation of the material, and as a result burn marks can occur or the mechanical properties of material can be reduced.

6. Force

Injection pressure

For the approximate calculation of the closing force FS for the initial setting, first of all, an approximate average injection pressure pi of 500 bar can be expected.

Projected area cm²

The projected area is the proportion of the cavity area which, in conjunction with the internal mould pressure, generates a force which acts counter to the closing force.

Force to
Institute compact