Injection molding simulation – the way to produce precise parts!
Posted by Grant Cameron on
Injection molding simulation – the way to produce precise parts!
An essential factor for efficiency is precision in component production!
In our everyday lives, we take the use of countless important items for granted – whether these be the housing of a high-quality smartphone, an acoustically optimized sound bar or the safety-relevant components of a car dashboard. Applying their know-how, product design engineers repeatedly develop innovations like these on their computers. And they naturally have to be brought to market in as profitable a manner as possible. But the route from the idea through to serial production can differ greatly in length. A key factor in efficiency is the precision with which the part is manufactured.
In our everyday lives, we take the use of countless important items for granted – whether these be the housing of a high-quality smartphone, an acoustically optimized sound bar or the safety-relevant components of a car dashboard. Applying their know-how, product design engineers repeatedly develop innovations like these on their computers. And they naturally have to be brought to market in as profitable a manner as possible. But the route from the idea through to serial production can differ greatly in length. A key factor in efficiency is the precision with which the part is manufactured.
Candles and plastic parts
Today, the majority of plastic parts are produced by injection molding. This means that the corresponding mold is first designed and built. Liquid plastic is then injected into the mold in order to produce the part. It sounds simple but there is plenty of scope for error!
For the users of mobile phones, sound bars and cars, this can be vividly illustrated as follows: molding your own candles is as easy as pie, or so the instructions in the box say. You simply have to pour liquid wax into two mold halves that are fitted together. We all know what the candle looks like afterwards. Sometimes it loses its shape when it cools down, sometimes bubbles and depressions are apparent on the surface and sometimes part of it is simply missing because the wax didn’t get that far. The result is not very pleasing, and the candle doesn’t burn very nicely either!
For the users of mobile phones, sound bars and cars, this can be vividly illustrated as follows: molding your own candles is as easy as pie, or so the instructions in the box say. You simply have to pour liquid wax into two mold halves that are fitted together. We all know what the candle looks like afterwards. Sometimes it loses its shape when it cools down, sometimes bubbles and depressions are apparent on the surface and sometimes part of it is simply missing because the wax didn’t get that far. The result is not very pleasing, and the candle doesn’t burn very nicely either!
Even the slightest defects are unacceptable
The injection molding process employed in plastics engineering poses comparable challenges for product and mold developers – albeit much more complex ones, with much more costly attendant circumstances. Numerous correction loops frequently have to be run through before a suitable injection mold has been constructed. These corrections not only take time but also cost money! Designing injection molds thus not only requires specialist knowledge of the flow behavior of the plastic but also calls for a great deal of experience. Even with a wealth of experience, however, it is impossible to fully satisfy the market’s constantly rising requirements on the dimensional accuracy of plastic parts. The increased demands on plastic parts today allow virtually no tolerance in terms of dimensional deviations, flatness and curves. Uncompromising precision is required here.
The simulation of injection molding processes speeds up the classic development chain and considerably reduces the costs. Working on the basis of mathematical models, the latest simulation programs also permit precise prediction of the feasibility, dimensional accuracy and low warpage of plastic parts. They pave the way for observing the industrial specifications for injection molding complex small and micro parts and also particularly large objects. In so doing, they take a large number of influences into account. The target of achieving the optimal product is within much easier reach with a prediction of the filling process. Modern tools are able to identify weld lines and entrapped air that constitute mechanical or optical weak points. The gating points can then be varied in such a way that weld lines are moved to uncritical locations or avoided altogether. The geometry, gate system or heating/cooling system can also be optimized. As the final touch, process parameters can be improved, permitting injection molded parts to be produced cost-efficiently in a high quality.
Tools capable of learning
Computer-aided simulations of the injection molding process with integrated artificial intelligence, or AI for short, calculate variations in the injection molding process in advance. Simulation programs like Varimos record all the calculations they have performed and combine these, using them to determine optimal process parameters or advantageous wall thicknesses. Not only does this shorten the development times from the injection mold right through to the serial part, it also ensures that the qualitative requirements placed on the new parts are precisely fulfilled.
The more complex, the more efficient
In the case of particularly complex parts, the use of simulation software is virtually unavoidable. It calculates potential problem points in advance, together with the shrinkage and warpage, allowing corrections to be made at an early stage. Simulating various process parameters, gate systems, heating/cooling systems and also the geometry of the mold permits the production of an optimum part. Precise calculations can also be performed of fiber-reinforced plastics and parts made of biopolymers.