TOPEKA, Kan.—The HF Mixing Group has launched Banbury Mixer BM700N, a new internal batch mixer with tangential rotors designed to offer customers greater efficiencies in rubber mixing.
Ian Wilson, business unit director of tangential mixers, outlined the machine's enhancements compared to the mixer it is replacing, the F620, in a presentation at the firm's International Mixing Seminar Sept. 23-24 in Topeka, Kan. The firm said the new mixer officially was released to the market in September.
He said the BM700N is produced at its facility in Rochdale, England, the location of the Tangential Business Unit of the HF Mixing Group.
Wilson said it was necessary to implement improvements to the F620 following in line from HF's successful implementation of the F270 and F370 Banbury replacements BM305N and BM440N. Wilson said the firm has sold more than 60 of the new N-series Banbury Mixers to date.
The BM700N will be equipped with super cooling rotors developed specifically for the new mixer. He said the spiral cooling ability will lead to 50 percent higher cooling efficiencies compared to the F620 for lower temperatures at the compound's discharge.
The length to diameter ratio is improved compared to the F620. According to Wilson, the F620 has about a 2:1 L/D ratio, which he said is very poor compared to other tangential mixers. The BM700N will have 1.5:1.
“You will have better homogenization as a result of the improved L/D ratio, and this results in much shorter mixing times, thus higher productivities can be realized,” Wilson said. “Also, the compact rotor geometry and better cooling provides better energy efficiency.”
The GK650N and F620 have two oil injector drillings in each drilled side and one in the throat restrictor. He said HF decided to remove the throat restrictors because they offer no value and only add cost to the design of the mixer. In eliminating the covers, the firm increased the number of vile injector ports to three per side.
The BM700N's rotor end plates will have a milled groove with welded closure plates, which Wilson said will provide an increased surface area for heat transfer medium.
“The end frames have no throat restriction, just a very simple hardened throat plate,” he said. “The end frames will be split for easy maintenance. Often there are lifting capacity restraints in the mill room. So access to the rotor can be improved.”
The machine's door top will seal the mixing chamber tightly as it is driven under the rotor end plates. Wilson said this prevents the typical wear found on tangential mixers' doors.
The drop door is bigger compared to the F620, more than 630 millimeters, which Wilson said leads to a shorter batch discharge and less material hang up. The faster discharge should result in shorter mixing times, and the dwell times can be reduced from batch-to-batch, saving 1.5 seconds between each batch.