When looking at the ongoing development of products and manufacturing methods, no one can deny that additive production methods of metallic components will be a part of the future. Even though today this method is only applicable on rather small components in an economical way (nevertheless the capability of additive production covers parts up to one ton of net weight), there is a potential of technical opportunities given, which will require a total new sight on engineering, design and application knowledge.
Additive production denotes all production methods, in which the part to be produced is built up layer by layer out of a raw material, available as a powder or as a wire. Today the selective laser melting (SLM) is the main method on high-precision parts. Here metal powder is applied in typical 20-100 µm layers and then completely molten by means of a laser beam selective at those areas which shall become the component. With the solidification of those areas to a compact metal structure with the physical properties of the original material, and after removing the remaining, not molten metal powder at the end of the production process, the final component is built up.
One of the main features of all additive production methods is, that almost each inside contour or cavity can be produced without problems; and this by directly using given CAD-data. With this, there are no additional costs for patterns or special tools - the additive production method is the ideal method for batch size “1”.
Today, under the precondition of relatively high specific costs of additive produced components, the economic and commercial application is restricted to such parts, which
- cannot be (or only with high complexity) produced by conventional machining methods.
- are of such size and weight, that the cost of additive production is in a reasonable relation to the market price of the complete product (e.g. a control valve).
- are components, where the additive production method offers a detectable customers benefit. This might be a short delivery time (for example in case of urgently required spare parts), but also technical advantages either given by the absolute functional design or achieved by the individual adaptability to any specific process case or condition.
Based on these parameters, a systems engineering for the design of multistage throttling cartridges used in ARCA ECOTROL® control valves was developed, which generates ready to use CAD-data directly out of the control valves sizing. These throttling cartridges can be conducted either with given (constant) number of single throttling stages, but also with a variable number of stages (as a function of the valve opening).
The design with variable number of throttling stages is suitable for applications, where there is a significant dependency between flow and differential pressure. This means at low flow (small valve opening) there is a high differential pressure across the control valve (with susceptibility for cavitation) whereas at full valve opening the pressure drop is quite small, requiring a rather high flow coefficient.
Whatever your application looks like - additive manufacturing - and ARCA – realize almost everything!