In a mandatory filing with the SEC, PTC says it will increase its line of credit to $300 million, and might go to $450 million if bankers agree.

PTC has expanded its line of revolving credit, signaling a continued willingness to acquire other companies. The company reported the news by filing a mandatory notice with the US Securities and Exchange Commission.

The company’s old credit line was $230 million; today’s news brings it up to $300 million, and the company said it might go as high as $450 million if lenders approve.

Right now borrowing is cheap, relatively speaking. Many business executives prefer to fund acquisitions through cheap debt than with their more precious cash on hand. Early in the last decade, for example, Bentley Systems was close to going public, then switched strategies by acquiring a large line of revolving credit to fund a series of strategic acquisitions.

PTC has about $219 million in cash and equivalents, not nearly as much as key rivals Autodesk ($1.08 billion) and Dassault Systemes ($1 billion). So PTC needs the boost a line of credit offers, to be competitive. “As with the prior credit facility, PTC expects to use the new credit facility for general corporate purposes of PTC and its subsidiaries, including acquisitions of other businesses, and may also use it for working capital,” PTC said in the filing.

PTC’s most recent acquisition was Relex Software, a specialist in regulatory compliance and reliability tracking for manufacturing, in June 2009. Terms of that deal were not disclosed.

The revolving credit line is with a syndicate of 10 banks, with JPMorgan Chase Bank, N.A. as the administrative agent.