New orders in the domestic machine tools industry dropped 51 percent in the first nine months of this year, providing dramatic evidence that the industry has stripped its gears on the recession.

Machine tools are used to cut and form metal, primarily in auto and steel production--the two industries hardest hit by the economic downturn.

U.S. automakers, struggling to reduce swollen 1982 inventories, have done major surgery on production schedules for the rest of the calendar year. And those cuts are reflected in the 54 percent drop in new orders for metal-cutting type machine tools.

Steelmakers had planned to spend $7 billion on plant revitalization this decade. That would have been a boon to the metal-forming end of of the machine tools business. But the steelmakers' plans went awry as they followed their counterparts in the auto industry -- over the cliff.

Here are the most recent numbers for machine tools provided by the McLean-based National Machine Tool Builders' Association (NMTBA):

New orders for all domestically produced machine tools were down 51 percent, to a total value of nearly $1.2 billion, for the first nine months of this year.

* Industry shipments for the period, valued at $2.9 billion, were off 22 percent.

* New orders for September totaled $86.8 million, a 54 percent decline from September, 1981.

* September shipments were up 6 percent from August levels to a total value of $273.5 million. But the figure was 38 percent below rates for September 1981.

* Shipments of metal-forming tools for the first three quarters, valued at $561.9 million, were off 25 percent from last year. Septembev shipments of $514.4 million were 33 percent below September, 1981.

* New orders for metal-cutting machine tools, valued at $842.9 million for the first nine months, were off 54 percent from last year's rates. Orders for September, valued at $52.4 million, were off 65 percent from the year-ago month.

* Year-to-date shipments for metal-cutting machine tools, valued at $2.4 billion, were 22 percent below the same period last year. For September, the figure was $222.1 million, 39 percent below September 1981.

* Year-to-date new orders for metal-forming machine tools, totaling $326.4 million, were 42 percent below 1981 levels. Metal-forming tools orders for September, amounting to $34.9 million, were 6 percent below September a year ago.