RAPID SERVICES CX - Numerical Simulation - Details

Course of a rheological simulation project

The course of a simulation project can be described as follows:

Establishing of contact by the customer, meeting with customer if necessary;
Transfer of CAD data;
Check of data quality;
Calculation of project and drawing up of an offer;
Placing of an order by the customer;
Transfer of all necessary data for simulation (mould concept including the sprue and location of gates, cooling system, designation of material, process parameters);
Preparation of geometry data and establishing of the grid;
Release of grid data;
Start of simulation;
Transfer of first results to the customer;
Optimization loops are carried out if necessary;
The results are summarised in a report, (separate report with multi-component parts);
Transfer of end-results to the customer;
Presentation of results at the customer when appreciated;
Termination of project.

The time required for a rheological simulation including simulation of shrinkage and warpage lies at 3 to 4 weeks starting with the placing of the order, depending on the number and complexity of the component parts as well as the number of necessary optimization loops. Usually first results are available after 1 week.

RAPID SERVICES CX - Mechanical simulation

With the use of the FINITE ELEMENT METHOD parts can be analyzed with regard to their strength and strain behaviour. The scope of these analyses range from 2D modells with triangular elements to multi-node 3D volume models.

Preconditions for the calculations are:

flawless CAD data,

geometrical load situation,

Situation of support and fixation (boundary conditions),

Type of load (static, dynamic),

Material data (Elastic modulus, thermal expansion coefficient).

Example for results of a mechanical simulation

The figure shows the equivalent stresses acc. to Mises for the part REAR WING STABILIZER.

The left figure shows the FE network for the component part SCHEINWERFERABDECKUNG. This part is been manufactured with the CLEAN SHOT PROCESS which is a horizontal turning process. During the production process in 2-components injection moulding occurs a deformation (warpage) of the component part because of shrinkage differences between the two components. The calculated deformations are shown in the right figure in the unit mm.

RAPID SERVICES CX - Rheological simulation

In the rheological simulation the injection moulding process is simulated by the means of finite element analyses. A 2½ dimensional modell is used, the thickness of the part is assigned as a parametric value. The grid consists solely of triangular elements. Using newer methods of simulations it is also possible to calculate at the surface of the part, which makes it possible to model more complex geometries with even shorter grid building times.

Calculations can be done for nearly all thermoplastic materials, as long as there is data for it included in the databases of the software packages. Anisotropic behaviour due to fibre reinforcement of the materials with regard to shrinkage and warpage is considerated. Besides regular injection moulding processes also multi component solutions as well as injection compression moulding processes and reaction injection moulding processes (RIM) can be calculated.

Phases of the calculation:

Filling phase:
Flow pattern, location of weld lines, level of bulk-temperature and pressure in the part, trace of clamp force until changeover to holding pressure (end of filling), Thickness of solidified layer, inclusions of air, shear stresses at the cavity wall;
Cooling phase
Efficiency of cooling, temperature of cavity wall, difference in temperature between the cavity surfaces;
Holding pressure phase
pressure- and temperature-conditions over the whole cycle, course of clamp force, volumetric shrinkage, sink marks;
Shrinkage and warpage
deformation of part, deformation in x-, y- and z direction;
Fiberorientation.

Example for results of a rheological simulation

The represented animation shows the filling of a component part (FRONT COVER, WINDOW ASSEMBLY – BOEING 717). The material used is PEI at a bulk temperature of + 390 °C.

The production of the component part HECKABLAGEWANNE should be possible with a 32 MN injection moulding machine. The obtained results with the first feed system lead to a clamping force of 50 MN (shown in the upper figures).

An improvement of the feed system and the insertion of flow promoters leads to a reduction of the pressure requirement. The result is a lower clamping force of 29 MN (shown in the figures below).