Precision engineered rheometry dies
process control, control equipment, Instrumentation
Aptifirst Ltd has supplied specially designed extrusion dies to a major polymer research and development organisation to allow precise measurements of the flow properties of polymeric melts to be made using a capillary extrusion rheometer. Both dies were made to very tight toelrances from tungsten carbide by electron discharge machining (EDM), and were designed to fit the customer's Kayeness capillary extrusion rheometer, although Aptifirst can also supply benchtop, floor-standing or special-purpose remote control rheometers, and accessories for them too. One of the dies had a conical profile, with a 3.00mm diameter entrance, 4.00mm diameter exit and was 10mm in length. Another had a 2mm parallel bore, machined to a tolerance of ±0.0035mm, with a length of 30mm.
Capillary rheology is a valuable tool in the study of processing characteristics of materials, not least because, being of itself an extrusion process, can act as a process mimic for extrusion, injection moulding and, recently, for a rapid manufacturing firect writing process. Samples may be taken of the extrudate and tested further, for example by various thermal analysis techniques, tensile testing, microscopy and others, to build a picture of how the act of processing effects the structure and properties of the extrudate.
Said Aptifirst's MD, Roy Carter, "We have a very great depth of knowledge of the science of rheology, and in the design and application of rheological testing instruments, especially capillary extrusion rheometers, and are very pleased that we could apply our skills to provide our customer with the especially designed dies for his research programme. We have made such extrusion dies in the past, indeed, we have supplied more complex designs such as dies with a hyperbolic profile, which have been used to study the extensional or tensile flow behaviours of materials including polymers, wood composites and oilfield drilling muds, and we are always happy to look at new projects. We provide also consultancy and training within the field of applied rheology."
Aptifirst supplies also accessories for capillary extrusion rheometry and on-line monitoring, including die swell and shear heating measurements and devices for measuring the pressure coefficient of viscosity, a parameter which can markedly affect the processing performance of some materials. Additionally, Aptifirst supplies a wide range of instrumentation including strain gauge and load cell amplifiers, load cells, sapphire window probes, GSM remote temperature monitoring instruments, dataloggers, process and temperature controllers, flammability tests, radio telemetry, and especially-designed bespoke machinery and software.
, Industrial Process Control
, materials testing
, monitoring equipment
, process control