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One Tube is Not Like Another

Compamed exhibitor Novoplast Schlauchtechnik, headquartered in Germany, has supplied the following article about medical tubing manufacturing.

Many business contacts start with questions regarding the price of a certain tube. Even if the inner and outer diameter are known, in the majority of cases it is not possible to make a reliable statement.

Basically it is easy to produce tubes in different dimensions. The basic ingredients are selected raw materials, the right auxiliary materials, good tools and a lot of experience. But to offer customised solutions it is indispensable to evaluate further particulars in advance, such as:

These questions have to be answered for serial products as well as for prototypes. A proper consulting is the basis for an effective product implementation.

Further processing

In most applications the tube is only one element of a complex system or device. On the basis of the available information the adaption of the tube in material, dimension and further parameters is made. Only in very rare cases all the facts are previously completely known.

If for example the customer wants to achieve smaller tube dimensions by complex procedures like stretching or pulling, properties like tensile strength and reproducibility are the most important parameters because in this case traditional material constants are not sufficient for the processing by extrusion and pulling. The more specific the requirements are, the higher are the influences on the processing parameters.

In one project we could reproducibly manufacture the tube with the requested properties by the height of the melt temperature, the consistence of the melt and the specified cooling rate. It would have been impossible to produce this tube with all desired features only by implementing and controlling the usual established product parameters like the defined dimensions including the corresponding tolerances or the surface structure.     

Always one step ahead—Further developments

Of course there is also progress in the production of tubes. The replacement of PTFE, FEP, plasticiser-free PVC alternatives and silicon by commercial thermoplastics are just a few examples.

The departments Development and Pre-series are extensively concerned with new developments of materials and possibilities of modification. In close cooperation with our customers we work out proposals and checked for suitability from all points of view.

Sliding friction coefficients similar to the one of PTFE are even feasible with modified standard thermoplastics considering the friction partners. Meanwhile also very soft materials can be manufactured economically into tubes as alternative to silicone. Furthermore these materials partly possess even better mechanical properties and with regard to the further processing they allow new possibilities like printing and gluing of the tube. 

Injection moulding versus extrusion

In the past injection moulding was often the first choice in the manufacture of high lot sizes of thick-walled, short, rotationally symmetric components. Today we are able to produce precisely fitting parts by extrusion without high investment costs which are in some cases unavoidable in injection moulding. Besides the advantage of low tool costs it is also possible to make changes in the dimensions and material during the product life cycle. There is significant potential for protective tubes of all kinds. It is possible to realise contoured inner and outer surfaces with reasonable tool costs.

Test procedures

All productions lines at Novoplast Schlauchtechnik are provided with modern equipment for the measuring of the relevant product dimensions. Furthermore we can perform optical inspections, strength and chemical resistance tests. These kind of tests become important (very often also in combination) especially in case of the development of new products or further developments. For the rapid transfer from the development to the series status we can support our customers by these actions and assist them for an enduring success of their products.

Conclusion

At the Novoplast Schlauchtechnik we do not only focus on asking for the parameters of the requested tube but also on research and consulting and on extensive tests up to the molecular level. Developing tubes there is much more to consider than it seems. First-class tubes for specific applications are rarely to find in the well-known catalogues. They are rather the result of the cooperation between customer and manufacturer and common development steps.

Authors:

Lars Graichen                                                            Andreas Hankel

Project Engineer Medical Technology                        Business Unit Manager

Novoplast Schlauchtechnik GmbH

In den Langen Stücken 6

38820 Halberstadt

Germany

Tel.:    +49 (0) 3941 68 69 0

Fax:    +49 (0) 3941 68 69 40

E-Mail: info@schlauchtechnik.de

Internet: www.schlauchtechnik.de

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