After 100 years, Banbury mixer still integral to industry

TOPEKA, Kan.—The Banbury mixer turns 100 this October, and a century later it remains a vital part of the rubber industry.

Some of the reasons why it still is in wide use is the versatility of the machine, along with the improvements made to it over the years, according to Frank Borzenski, who retired at the beginning of 2015 as manager/director of product development and laboratories for HF Mixing Group.

He gave a presentation on the history and development of the Banbury Mixer during the recent International Mixing Seminar, held April 26-27 by HF Mixing in Topeka. A week before that at the spring meeting of the ACS Rubber Division in San Antonio, Texas, Borzenski received the Fernley H. Banbury Award for contributions in development of production equipment, control systems and instrumentation.

Fernley H. Banbury received his original patent on Oct. 2, 1916, and Borzenski spent much of his 45-year career working with the iconic tangential mixer. He was hired by Farrel Corp. in June 1969 and worked mostly at the firm's Ansonia, Conn., base, lasting through several ownership changes that brought Farrel and the Banbury mixer into the HF Group fold in early 2009.

And through all the changes to the design of the Banbury, Borzenski said the mixer remains a leader in the field and has been supported fully by all of the post-Farrel owners.

“The Banbury will mix a broad range of compounds,” he said during an interview at the mixing seminar in Topeka. “As the market changes, the standard machine has been able to mix these materials without a lot of change to the basic design.”

Despite a number of evolutionary improvements of the machine, the basic concept of feeding rubbers of all different forms, shapes and types—along with the corresponding chemicals and fillers—the Banbury still is able to mix and produce an acceptable product that works in many applications, he said.

For example, there are Banbury machines that mix floor tiles, rubber compounds, thermoplastic elastomers and even some in the pharmaceutical industry, mixing very high-temperature fluoropolymers. “It's the same machine, just different speeds and different operating parameters, but it works,” Borzenski said.

One of the big upgrades to Banbury mixers has been the rotor design, he said. “That's the key to the machine, how it actually mixes the rubber,” the retired HF Mixing official said. “The improvement of the mechanical strength of the mixers, to be able to have more horsepower, was important. The original machines had very little horsepower, and the newer machines literally quadruple the connected horsepower.”

Another key development was the advent of finite element analysis, which he said helps optimize heat transfer, temperature uniformity and mechanical strength.

Even today, though, work continues to boost performance and meet customer expectations. Borzenski said he remembers when HF Group took over the Farrel business, Andreas Limper—a member of the HF Mixing Group management board—gathered process and mechanical engineers from Germany and the U.S. to review the mixer's design. They looked for improvements and introduced a new model, the BM series.

“Since then, they are still looking at improving the machines, from rotor designs to dust-ups to improve its functionality and broaden its use in the rubber and plastics industry,” Borzenski said.

Within the area of tangential mixers, he doesn't believe any other machines rival the Banbury, and he also thinks it's not intended to be in competition with intermeshing mixing technology.

“There are areas of applications where the Banbury is very good, and it can out-produce the Intermix, and there are areas where the Intermix can out-produce the Banbury,” he said. “There's still a place for both in the industry.”

Even during the years that Farrel's ownership changed hands several times—going through private, corporate and public ownership—the firm remained strong, Borzenski said.

“We had such a strong installed machine base,” he said. “Every new owner that took charge of the company recognized the benefit of the machinery that we had and its extensive use in the industry.”

Even when the firm was negotiating with HF Group on the acquisition, Farrel was continuing to develop new rotor technology for the Intermix-brand intermeshing technology—a brand dating back to Francis Shaw in the 1930s—that it had bought earlier in an asset sale.

“That's one of the things when we were taken over by HF, I said the machines are changing,” Borzenski said. “People have an affinity; some people like Banbury and some like Intermix. Let's have both of these machines in the lab like we had at Farrel where a customer can come in, run both machines and do a comparison.”

And that's a practice he said remains in place at HF's technical center in Germany. Borzenski is certain that HF Group is the right company to carry on the legacy of the Banbury mixer.

“They are more focused on R&D and committed to the rubber industry than any company that I've ever seen,” he said. “And they're very, very technically competent.”

After the acquisition, Borzenski had recently patented a “keel” bottom weight technology, and HF officials were very interested in the development. “The thing that was interesting is they weren't prejudiced,” he said. “They said, "Let's look at this technology, and if it's good, let's use it.' “

For Borzenski, receiving the ACS Rubber Division's Fernley H. Banbury Award was a fitting honor to spotlight his career. “Basically, anybody—especially myself—has to have passion to be able to identify with the product and feel good about what you do in terms of supporting the rubber and plastics industries.”

A frequent presenter at Rubber Division and other industry conferences, he said he especially enjoyed working with people on commissioning machines in various places around the world.

“I found out that no matter where you are, people are just like us,” he said. “They want to be able to make a living, they want to support their family, and they really want to do a good job. No matter where I've went—any country, any language—that was basically something that was very satisfying for me.”

Borzenski said one regret in his career is that he never met Banbury, who died in 1963 at the age of 81, six years before Borzenski joined Farrel. “I did work for people who had,” Borzenski said. “They would relate stories to me about him and how he conducted his development.”

In his remarks at the Rubber Division ceremony where he accepted the award, Borzenski said he thought the inventor “would have been proud to see the current design of the Banbury mixer because it followed through on what his approach was to the development of the machine: continual improvement.”