CHICAGO—HP Inc., the largest maker of personal computers, unveiled its Metal Jet printer at the IMTS show here on Monday. Early customers include the engineering firm GKN Plc, which expects to print millions of production-grade Metal Jet parts for customers as early as next year.

Since its split from Hewlett Packard Enterprise Co., HP has redoubled efforts to expand beyond its core PC and paper printer businesses. 3D printing is a big part of this plan. The new steel-printing machine could open up new opportunities in the automotive, industrial and medical-equipment fields. Metal parts manufacturer Parmatech Corp. has also signed on as a partner.

HP said in a statement that Metal Jet can produce a lot more parts at "significantly" lower cost than existing machines.

Stephen Nigro, president of 3D printing at HP, says that it will be at least five to 10 years before the unit generates a material share of HP’s sales, which topped $50 billion last year. The reason for the caution is that the printer will be reserved for specialty parts on certain models, and not for the highest-selling vehicles.

Volkswagen will start out with cosmetic pieces, having partner GKN use the printers to make customized car key rings and nameplates that drivers can put on their trunk lid or door. For its next generation of cars, Volkswagen plans to use printed mirror mounts and gearshift knobs, and continues to evaluate other use-cases for HP’s machines.

“The sweet spot of 3D printing technologies is not in giant numbers in vehicles like the Golf,” says Sven Crull, Volkswagen’s head of design for new manufacturing technologies. “There’s a better use case in more specialty parts for vehicles with volume of 50,000 to half a million.”