Manufacturing by the removal of material may be among the oldest of human endeavors.  As Brad Cleveland, CEO of Proto Labs likes to explain, the “Stone Age” takes its name from the process of chipping away unwanted rock to yield useful tools.  Today, the process of computerized subtractive manufacturing has wide applications in industry.

And in the Military.  Think about it.  Who has a more exacting need for quickly copied parts, produced under the most severe conditions, than a battlefield commander  in combat?  So our U.S. Army has created sophisticated subtractive manufacturing centers for military installations at Camp Arifjan, Kuwait; Camp Anaconda, Iraq; and Bagram AFB, Afghanistan.

The program developed as MPH, the Mobile Parts Hospital. The Army describes MPH as a “self-contained, self-sustaining, C-130 transportable, mobile mini-manufacturing system of systems that can efficiently fabricate standard and unique parts at or near the point of need.”

The program includes a Lathe Manufacturing Model (LMM)  based on a 5-axis Mazak Integrex  with all tooling and maintenance equipment stored on board. Set up takes less than 1 hour.
• Max machining diameter: 11.42 in.
• Max machining length: 28.62 in.
• The LMM can machine both ferrous and nonferrous metals, plastics and ceramics.

Another part of the MPH is the Agile Manufacturing Cell.

This is a fixed facility that includes multiple manufacturing capability, reverse engineering, and finishing. It increases manufacturing capability of the MPH program with equipment that can’t be deployed due to size, weight, or environmental concerns.  Capabilities include:
• Machining of larger items
• Finishing: heat treating, surface-coating, hard-turning, broaching, grinding
• Reverse engineering
• Precision investment casting

Data functions of MPH are handled through a  Windchill PDM database that contains part-manufacturing information for use in both the RMS units or the Agile Cell.
• Engineering Data
• 2-D Drawings and 3-D Models
• Manufacturing  Data
• CNC Code
• Operator Instructions
• Quality Acceptance Criteria

Though it’s not a subtractive process, the Army is also looking into Near Net Shape laser processing of various steels to support its MPH program.  Major design considerations they have established for the Near Net Shape program include:
• Machine must be compact enough to fit in 8x8x20-ft ISO container along with all support equipment.
• Must be able to process different types of metals with consistent properties.
• Must deliver necessary mechanical properties without post processing.
• Must build near-net-shape parts at a sufficient rate with maximum material capture.

As part of the MPH program, the Army is researching microwave heat-treating.
• Partner with Dana Corporation; Atmoplas technology.
• Small batch (1-5 parts) processing.
• 30-60 seconds time to heat, compared to 3-4 hours in an oven.
• Size of unit comparable to home microwave

So while subtractive manufacturing dates back to the stone age, today’s applications of this technology can deal with the urgent needs of combat support.  But there are many applications and vendors  more conveniently located for your consideration than Iraq or Afghanistan.  Check out the users and suppliers mentioned in this special supplement for more information.

MPF