Bonding Medical Plastics
 

By: Mr. Barun Bharadwaj, Henkel Adhesives Technologies India Pvt. Ltd.

Medical Device Assembly: The current methods that are in practice today for different device manufacturing are as follows: Mechanical Solvent Welding Ultrasonic Welding

1) Mechanical Method: The benefits of mechanical methods are : easy to use immediate full strength minimal regulatory concerns removable However the limitations are: They offer stress concentration Tolerance specific Beacause of the large gap that is developed it requires additional seal Have to maintain large number of components’ inventory Also gives unaesthetic look to medical devices Difficult to automate 2) Solvent Welding This method is very popular and it is very low cost and simple to process   The limitations are: Cannot be used on thermosets , glass or metal Solvents can cause stress cracking Residual solvent in bond No Control on Fixture time Harmful for operators because of the fumes that are generated. Regulatory concerns The gap filling is another major concern overhere. The technique that medical device manufacturer will have to maintain is extreme tolerances to ensure that gaps are minimal because if the gap is more than the solvent cannot bond and seal and could lead to leaks.   3) Ultrasonic Welding   The ultrasonic method is quite similar to solvent welding method. It is very simple to use, fast process and has minimal or no regulatory concerns. However the limitations are: Cannot be used on thermosets, elastomers, glass or metal Thermoplastics must be compatible to be joined Poor Gap Filling High Capital & running Cost of Equipment

Medical Device Assembly: Demands The other demands for medical device assembly from medical device manufacturers are as follows: Medical device manufacturer has to be Innovative Customized They have to produce huge volumes of components and devices of high quality Decrease time frames Medical Device Adhesives The medical device adhesives improve product performances and increase overall product efficiency. It also allows the combination of different materials like : plastic/metal, plastic/plastic, plastic/rubber, glass/ metal. It also allows new possibilities in design and also with easier and more cost saving part design. It also gives aesthetic features like invisible connection, invisible bondline, aesthetic design, etc. The additional method to connect subcomponents is also possible through adhesives. The other methods are mechanical fixing (e.g. threads luerlock ), welding, ultrasonic, insert moulding Medical Device Adhesives : Benefits It gives even stress distribution; means the load is not concentrated at a single point/line , no substrate distortion It has ability to bond dissimilar material and nearly every material is or can be made bondable Combine a large range of materials It can fill large gaps and can provide sealing. Reduces number of components Improve product appearance Useable in automatic manufacturing processes and hence reduces manufacturing time. Unique Consideration For Medical Device Manufacturers There are many considerations that a medical device manufacturer will have to keep in mind before a device is put into manufacturing. And they are : 1) Regulatory Issues The most of the products manufactured by Henkel Adhesives Technologies India Pvt. Ltd. are qualified for ISO. 2) Sterilization All the medical devices have to undergo suitable sterilization process. The different sterilization proceses are Autoclaving, Gamma Irradiation, Ethylene Oxide, Electron Beam & Chemical Immersion. All of the adhesives offered by Henkel Adhesives Technologies India Pvt. Ltd. have been tested for these sterilization process and they withstand the conditions required.

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