PROCESS CONTROL | INLINE MEASUREMENT
Right: Sikora’s PurityScanner Advanced system is designed to provide 100% inline inspec- tion of pellets
benefit, the company is working to use this colour data in a feedback loop to automatically control the addition of colorant to the process to maintain a target product colour. Several factors present challenges to imple- menting true closed-loop control, the company says. Firstly, it says the extrusion equipment market is highly fragmented and there are many different vendors of extruders and feeders for dosing the pigments. Extruders may be single-, twin- or multi-screw and come in a wide range of output capacities while feeders may be gravimetric or volumetric and allow for multiple colorants to be dosed into the extruder for a specific recipe. The company says there are also a multiplicity of vendors of plant-control software packages to which the data and results will need to be commu- nicated. It says it has found that no two manufactur- ing sites handle process data in exactly the same way, so flexibility in the communications capabili- ties of software developed in a project will be vital. Equitech says it is currently developing algorithms
that utilise in-line, real-time ultraviolet-visible (UV-vis) spectroscopic data as feedback for closed-loop process control, together with an interface/control module that will manage the communications between the process and the in-line instrument. The control algorithms and interface/control module will also enable the utilisation of other types of in-line instrumentation and further expand the implementa- tion of real-time product control of extrusion operations. These could include near-infrared and Raman spectroscopy, as well as melt viscometry. The company offers two probe types for use in the plastics industry. The Large Area Surface Probe (LASP) is a non-contact probe used to measure colour of sheets, films and other solid surfaces. The Reflection Polymer Melt Probe (RPMP) is a contact probe intended to measure colour directly in the molten polymer at process conditions up to 5,000 psi and 500℃.
Pellet inspection
German inspection systems maker Sikora has developed its PurityScanner Advanced system for optical online inspection and sorting of plastic pellets. The company says raw material shortages and price increases mean that demands in terms of quality control of pellets are increasing. “Even the smallest, critical contamination are reliably detect- ed and sorted out by the system,“ says Ralf Kulen- kampff, Head of Sales – Plastics at the company. “Both the detection and the ejection behaviour of contaminated pellets are perfectly coordinated.” Sikora says that, due to the modular concept of
66 COMPOUNDING WORLD | November 2022
its systems, different camera types can be used depending on the material to be inspected. In addition to optical 25 micron high-resolution optical cameras, which detect black specks and discolouration, an X-ray camera can be installed to detect metallic contamination. Common systems in use in the market have up to two optical cameras. However, these reach their limits due to relatively low coverage once the contaminant is outside the cameras’ field of view. Integrating a third black and white camera can significantly increase the detection rate in such applications and is an option Kulenkampff claims is unique to the Purity Scanner Advanced design. Detected contamination is removed using a blow-out unit. Sikora has developed a hybrid blow out function to allow customers to optimise the by-catch to suit their own particular requirements. For example, it is possible to define in advance which contaminants are uncritical and select a smaller blow-out unit for these to reduce the by-catch. This could include small, light-coloured black specks that frequently occur in the material. On the other hand, a larger blow-out unit can be specified for critical contaminants, such as metal fragments, which can impair the functionality of the subsequent end-product. “The interaction of reliable detection and hybrid blow-out ensures the highest material quality,” says Kulenkampff. “At the same time, production processes are optimised, and the reduced by-catch contributes to cost-efficient and sustainable production.”
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.extruders.leistritz.com �
www.skz.de �
www.colvistec.de �
www.kraussmaffei.com �
www.ampacet.com/liad-smart �
www.equitechintl.com �
www.sikora.net
www.compoundingworld.com
IMAGE: SIKORA
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72
