PROCESSING | SMALL BATCH COMPOUNDING
IMAGE: FEDDEM
Above: Feddem´s FRE cleaning unit with dual brush configuration can speed product changes
The company’s FRE dual brush cleaning unit can also help to shorten cleaning times, Hojer claims. After the screws have been removed and barrel openings plugged, the cleaning unit can be inserted directly into the figure-eight-shaped barrel bore without reducing the temperature. After a few movements back and forth along the barrel borings, the company says the extruder can be recommissioned. The latest compounding and pelletising system
from Steer — the SPL 40 — is said to be dedicated to lean manufacturing production environments. “What makes the SPL 40 unique are its features, high efficiency and attractive investment cost,” the company claims. The system comprises a co-rotat- ing twin-screw extruder with feeder, strand die head, water trough, air knife, pelletiser and classifier. Steer says it is built with the emphasis on reliability and safety to cater for the particular needs that arise from unscheduled/unplanned orders for small quantities and the associated requirement for better control over work in progress (WIP) during grade changes. According to Steer, the SPL 40 is capable of developing and testing new formulations as well as for scale up for commercial production. It comes in a standard design that offers simplified operation with a universal screw configuration suitable for most polyolefin and styrenic compounds. The company says the focus of the machine develop- ment has been to ensure minimum set-up and change-over time and maximum ‘first-pass-yield’.
The kneader option One fundamental question that compounders carrying out short runs on a regular basis may ask ask themselves is: “Should I be using twin-screw extruders or kneaders?” Companies such as Buss and X-Compound — both manufacturers of kneader extruders — recommend the latter. Flexibility is an intrinsic characteristic of kneader
extruders, says Francois Loviat, Head of Process at Buss. “As an example, Buss managed in our test centre to run three very different products on a kneader without any modifications to the machine configuration. In this way, switching between two products could be done within a couple of hours. Those three products were a TPU, a polyolefin and a halogen-free flame retarded cable compound. The ability to run those products on an identical machine configuration was of significant value to our commercial partner, who awarded Buss with an industrial project.” The most challenging changeovers are from high viscosity materials to low-viscosity ones, and from black compounds to white. So, in general, it is advis- able to run different formulations in a sequence going from low viscosity to high viscosity and from white to dark. “When switching from a compound containing carbon black to a white product, the most efficient method is usually to run the kneader empty, open it and clean it mechanically,” says Buss Senior Process Engineer Andreas Niklaus. Moving from a high to low viscosity material may be achieved using some appropriate purging
BKG® Pelletizing Solutions for Masterbatch Technology Colors in Focus!
Consistent, uniform pellet quality for high-end applications.
Pellet sizes from 0.5 mm to 12 mm possible Fast color changes due to low cleaning effort Easy die plate changes possible
WWW.NORDSONPOLYMERPROCESSING.COM
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