LEXINGTON, Mass. (AP) _ Patriot missile maker Raytheon Co. plans to clean up - in the washing machine business.

The giant defense contractor said Friday it was acquiring UniMac Co. a privately-held maker of commercial front-loading washers based in Marianna, Fla. The company employs 530 people and expects 1994 sales of $70 million.

Terms of the deal were not disclosed.

''We are making acquisitions to help our commercial businesses grow. This fills in an important niche in our appliance business,'' Raytheon spokeswoman Elizabeth Allen said.

Raytheon's Appliance Group makes home and commercial laundry equipment, refrigerators, air conditioners and other products under brand names including Amana, Caloric, Speed Queen and Sunray.

Raytheon, which had $9.2 billion in sales last year, gained fame during the Persian Gulf War for the Patriot. The Defense Department decided not to build a new generation of the missile.

Facing declining orders, Raytheon has reduced its weapons and other defense businesses and scrambled to increase revenues from civilian production. The company will lay off more than 8 percent of its 60,000 employees by the end of 1995, Allen said.