Tech equipment maker Brooks Automation is shutting down its Petaluma facility, a closure that affects about 85 workers.

The Lakeville Highway plant produces sophisticated equipment that allows cryogenic processes at extremely low temperatures for semiconductor manufacturers and life science companies. But nearly all the semiconductor makers today are based in Asia and it has become too costly to install, modify and service such complex products so far from where they are made, a local manufacturing group leader said Thursday.

“It’s just a market-driven need to be where your customers are,” said Dick Herman, president of 101 MFG, a Petaluma-based alliance of manufacturing executives.

The plant’s closure came to light because of a unique job fair that took place there Wednesday — an effort by job development groups to connect the Brooks workers with local manufacturers. Both the sponsors and some of the 19 companies that took part called the effort a success and praised Brooks for hosting the event.

Even so, Brooks officials remained silent about the timing of layoffs, which are expected to begin about Oct. 1, according to a July 1 letter the company sent the city of Petaluma.

A Brooks manager in Petaluma referred questions to company headquarters in Chelmsford, Mass. A spokeswoman there declined comment.

The Petaluma plant is one of seven Brooks manufacturing facilities in the United States, Mexico, South Korea and England, according to filings with the Securities and Exchange Commission. For fiscal year 2013, Brooks reported 1,471 employees and $450.9 million in revenues.

The Petaluma plant’s workers have known of the coming closure for about two years, Herman said. It is a sign of their dedication that they have continued to “meet the challenge” and produce great equipment, he said.

Following federal labor law, Brooks in July sent the city a letter about the coming closure, said Ingrid Alverde, the city’s economic development manager.

Alverde then collaborated with the Sonoma County BEST job development program and the county’s Job Link program to produce the job fair, which drew such companies as JDSU and Keysight Technologies. Brooks brought in a consultant to help workers prepare résumés and cover letters.

“Our goal is to keep the jobs local,” Alverde said. The Brooks workers represent “valuable talent that we don’t want to lose.”

Julie Vasquez, human resources manager at Small Precision Tools in Petaluma, said the job fair proved valuable for manufacturers that regularly look for skilled workers.

“We would love to do this again,” Vasquez said. “I hope this catches on.”

Brandon Jewell, BEST’s associate director of business development, said the sponsors plan to produce more specialized job fairs.

“We’ve created a recipe that we can use over and over again,” he said.