Lexicon
Stereolithography SL
Stereolithography is derived from Greek and means "three-dimensional drawing". The part is generated layer by layer on a support structure in a liquid polymer mixture by using a UV-laser.
The polymerization caused by the UV rays and the photo activators is duroplastic. The material cannot be re-melted by heat treatment.
A wide range of materials with various features is available (technical data sheet SL). The accuracy of the SL-models falls within tolerance group parameters, which are common in series production; we rate our models according to these parameters. This means that if a design engineer faces difficulties with the tolerance level of the SL-model, the problems will most likely occur in series production as well. In this case, a change in construction is advisable. In only a few hours, the construction design can be tested, checked and corrected.
There has been an increase in the use of MoldFreeps-SL parts for pre-series and small series production. Taking concrete load conditions, dimensional accuracy and material choice into consideration, small filigreed parts can be manufactured very quickly and inexpensively.
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Laser sintering LS
Laser sintering results from the combination of the manufacturing process "sintering" with the use of a laser as a heat source.
The part is produced layer by layer from small particles of plastic or metal powders by using an IR-laser. The laser selectively fuses powdered material by scanning cross-sections on the surface of a powdered bed. After each cross-section is scanned, the powder bed is lowered by one layer thickness and a new layer of
material is applied on top. Subsequently, the surface cools to 10° below the melting point and hardens. This process is repeated until all part geometries are generated. After a necessary cooling phase, which takes several hours, and is meant to reduce uncontrollable part shrinkage, the loose powder is removed.
VG Kunststofftechnik exclusively uses thermoplastic materials and their mixtures with a wide range of features (techical data sheet LS). We do not use metal powder for metal parts and components. The accuracy of the LS parts is diminished compared to the SL parts due to thermal processes. However, the LS parts´ high mechanical and thermal abilities to withstand stress are of great advantage.
In only a few hours, the construction design´s function can be tested and stressed under standard production conditions.
Vacuum-casting VG
Due to the quick and high quality capabilities of the SL models, vacuumcasting moulds can be manufactured in 1 to 2 days. The models are completed by experts and prepared for casting with silicon rubber in a vacuum chamber. After the silicon rubber mould has cured, the master, or any other dimensionally accurate model can be taken from the cured mould.
Small undercuts in the mould can easily be removed, thanks to the elastic silicone rubber. The yield of good cast parts from such a mould is rather limited. It depends on how elaborate the design of the part is, and on the resin used. A mould will normally yield between 15 to 25 pieces. When greater quantities are desired, several moulds should be used for reasons of efficiency and time. The vacuum casting of the parts required special equipment and cast resins. The qualities of the available duroplastic PUR-cast resins are being constantly improved - the simulation of the mechanical properties is continually advancing (technical data sheet resin, elastomer). The ability to withstand continuous stress under temperatures of up to 200°, and dimensional tolerances of +/- 0,05 mm, increases the application of vacuum-cast parts in small-series production. The application of the vacuum-casting process can save time and costs of up to 95% compared to the classical small-series production (injection moulding). The quick availability and correctability of these models and prototypes allow for simultaneous development, testing and calculation for industrial scale manufacturing. The early detection of design defects cuts future costs for tool consruction, tool manufacture, testing, production begin and service.
Vacuum casting is an efficient method for the production of prototypes and small-series parts with dimensional accuracy, flawless surfaces and direct dyeing.
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Metal investment casting MG
Metal investment casting -
the extremely fast manu-
facturing of prototypes
in die cast quality.
We quickly managed to apply
the Rapid prototyping synergies
to the manufacturing of cast
metal parts.
The production of lost models through the rapid prototyping technologies:
- 3D-Printing – 3DP
- Laser sintering – LS
- Stereolithography – SL and
- Vacuum casting – VG
The reduction of processing steps through the manufacturing of model and casting moulds has, especially in smaller batch sizes, led to significant time and cost savings. With the use of new model and mould making materials, elaborate, thin-walled and dimensionally accurate cast parts with excellent surface properties can be produced. Because the model production, the assembly of the tree and its embedding under vacuum in a ceramic slurry can all be done in one place, an increase in quality and a reduction in the processing time of cast parts can be achieved. The melting and casting procedures are process-controlled in a special investment casting plant. The metal is melted inductively in a vacuum and is sucked into the casting mould at the exact required temperature. For protection, additional coats are added until sufficient shell thickness has been reached. The exercising of increased pressure presses the molten metal into mould chambers as small as 0.3 mm, assuring die cast quality under reproducible processing conditions. The application of aluminium, zinc and bronze alloys are preferred. (technical data sheet MG)
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TOOLIT 3D-C aluminium moulds
Aluminium with its toughness, efficient cutting tools and technically mature machine and control technology have helped to get multiaxis milling for the Rapid-Tooling techniques widely accepted in the last few years. If the mould cavities can be structured in such a way that they are producible through milling techniques, this mould-making technology ought to be applied. The cavities can be produced quickly due to the one-step process and high dimensional and positional accuracy is achieved. The surface quality and impermeability of the mould is good as well. High edge strength, removability from the mould and good cooling conditions guarantee quality for pre- and small-series production of up to 10,000 pieces.
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TOOLIT SG injection moulding parts
Prototypes of thermoplastic resins and elastomers are produced with injection moulding tools and TOOLIT moulds. The applied thermoplastics and elastomers can be easily deformed in a certain temperature range. This process is reversible and can - unlike duroplastic materials - be repeated as often as desired through cooling and reheating until fused, as long as the material does not decompose by heat. These thermoplastic resins are build up of scarcely or non-ramified linear plastic chains, which are linked through weak physical bonds. A distinction is made between amorphous and semi-crystalline resins. Thermoplastic resins can be fused by effect of heat and pressure with or without additional materials. VG makes use of this through the two- or multicomponent injection moulding technique.
