Technical plastic parts: From the material to the processing to the component design
Highly stressed plastic parts can be found in a wide variety of applications. From medical technology to the energy industry to the automotive industry. In surgery in the form of breast spreaders and in the field of diagnostics in the form of endoscopic handles; in wind turbines in ball bearing cages and in cars in brake boosters or exhaust gas recirculation valves. As different as the demands may be – they all have an extremely high requirement profile in common. Characterized by high temperatures, mechanical/dynamic loads, the highest demands on strength, impact strength and/or rigidity. How do plastic parts ensure this? How technical plastics or high-performance plastics help to keep people healthy or technical systems running day and night or enable them to perform at their best? You can find the answers here.
Which materials are suitable for technical plastic parts and plastic processing?
Clearly: Every plastic has its physical/chemical limits (you can also get a good overview of the subject with our guide "Tribologically modified plastics. Basics and connections presented in an easy-to-understand manner.")
The KO criteria include temperature stress or chemical resistance (a polyamide in sulfuric acid simply does not work because it simply dissolves). If we look at the temperature spectrum, the following is noticeable - viewed from "below" - or the following technical plastics play a role for the plastics processing industry and component developers:
- POM, polyethylene, ABS, PC/ABS are used in plastics technology up to 100 degrees Celsius.
- Technical plastics such as polypropylene, polyketone, polyamide or polyester play an important role in the 100 to 120/125 degree range.
- Polyamide 66, PBT and PET “still” work in the 120 to 150 degree range.
- PA46, PPA, PPS, PEEK, PES, PEI are used from a long-term load of 150 degrees Celsius – ie already in the high-temperature range for plastic parts.
Let's further step down the range above 150 degrees Celsius:
- From 150 to 180 degrees PA46, PPA or Polyethersulfone will work,
- above that then PPS to 220 degrees long term and 240 degrees Celsius short term, and then come up
- PEEK or TPI are used.
Then “only” marginal increases follow: PEK, PEKK with melting points increased by a further 10, 20 or 30 degrees or continuous service temperatures increased by 15 degrees on the basis of restructured molecular chains and the resulting higher glass transition points.
With long-term exposure to 280 degrees Celsius, technical plastics or planned plastic parts are at the end of the road when it comes to plastics processing. Everything that goes beyond that is clearly associated with risks or a time limit.
From surgery to the energy industry: Plastic parts can be used in many different ways
Are you wondering when to choose which processing technology? Here is a brief overview of the characteristics of the three most important processes:
- Extrusion is a very widespread method in the plastics processing industry. In view of the high level of efficiency, the shaping process has gained great importance in the series production of engineering plastics.
- In plastics processing, injection molding is preferred when around 1,000 plastic parts – or significantly more; going into the millions – are to be manufactured per year. From then on, the high investment in an injection molding machine and the tool begins to pay for itself. Injection molding is also particularly suitable for complex technical plastic parts that are produced by machine.
- 3D printing shows its strengths in the construction of prototypes, for example, when tactile plastic parts are required. LEHVOSS focuses on technical components in small and medium quantities and functional prototypes. This is made possible by materials optimized for the process based on a wide range of engineering plastics. When a construction is to leave the paper or screen stage and you need something you can touch, something that you can rotate and view from all sides. In addition, there is the spare parts sector – here 3D printing can also be used very efficiently in the plastics processing industry. Another strength of 3D printing is its sustainability. Like our other materials, LEHVOSS 3D printing materials are fully recyclable and can be fully used for the next print.
Plastic processing is an art in itself
But what should be considered when designing the component? Here are the most important aspects:
- First of all, the requirement profile must be precisely defined. LEHVOSS, for example, uses a specially developed specification for this. In this, all process-critical parameters are queried in advance. It's all about the requirements in the application, e.g. temperature stress, contact with chemicals, UV stress, strength.
- Then the material selection begins: Which material can work? Is the design already tailored to a material? Can the material be optimally processed in the envisaged manufacturing process?
- This is followed by the determination of characteristic values for any planned simulations - from the filling simulation to the FEM calculation to the tool design.
- Then it's on to the manufacturing process: Injection molding? extrusion? 3D printing? compression molding? How many cavities in the mold makes sense? Is it possible to build 16 cavities into the mold or will that cause huge problems? Can the material actually be processed in the hot runner?
Would you like to find out more about the material development at LEHVOSS? For further information, please contact one of our plastics experts.
Conclusion: When processing plastics for technical components, it's all about the little things
In the plastics processing industry, numerous pieces of the jigsaw puzzle have to be put together so that they fit together exactly so that a high-strength plastic part comes out of a technical plastic or plastic granules at the end of the processing process - or even millions of them are produced by machine. Material - construction - tool - manufacturing process - processing parameters: all of them are small pieces of the jigsaw puzzle that need to be put together so that the result is stronger than the sum of its individual parts.
We at LEHVOSS can do that. As a material developer who, as part of our application-related advice, not only knows all the little pieces of the jigsaw puzzle, but above everything all the – supposed – stumbling blocks and knows how to successfully clear them out of the way – in the interest of everyone involved.