Bridge Mills Offer Large-Load Handling in Smaller Footprint

Available from Absolute Machine Tools, the Johnford DMC series bridge mill is built from a one-piece Meehanite cast iron bridge/column assembly that takes up less floor space than comparable C-frame VMCs.

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Available from Absolute Machine Tools, the Johnford DMC series bridge mill is built from a one-piece Meehanite cast iron bridge/column assembly that takes up less floor space than comparable C-frame VMCs. It is available in both moving-table and sliding-column versions, and features a long base casting that completely supports the table over the full 51" of Y-axis travel, enabling machining of very large loads.

The Y and Z axes hold fixed loads at all times, while the X axis carries the only dynamic load, allowing for tight machining and tight tolerances during high-speed machining operations. Because there is no table overhang, X-axis pitch and yaw are eliminated. The spindle centerline-to-column distance also is minimized, offering further rigidity. The machine’s heavily ribbed cast iron construction is said to provide long tool life and part surface finish. The combination of twin screw-type conveyors and a caterpillar conveyor also ensures complete chip removal with little manual cleaning, the company says. Additionally, finite element analysis (FEA) is used to design each bridge mill, simulating the effects of real-world conditions, including vibration, heat, fluid flow and other physical impacts.

Machines include the DMC 900-1500H small-frame bridge mill series, which features a fixed column with moving table; X-axis travel from 35.4" to 59.1", Y-axis travel of 35.4"and Z-axis travel of 30"; and table load capacities ranging from 6600 to 13,200 lbs. The DMC 1600-3100H medium-frame series offers a fixed-column construction with moving table; X-axis travel from 63" to 161.4", Y-axis travel of 51.2" and Z-axis travel of 31.5"; and a table load capacity of 13,200 lbs.

Several DMC versions offer multi-axis and five-face solutions. The 2100S-6100 SH S series offers a fixed-column moving table with X-axis travels from 82.7" to 240.2", Y-axis travel of 70" and Z-axis travel of 31.5", while the 3100P-6100PH P series features the same fixed-column moving table with longer travels of 122" to 240.1" in the X axis, 90.5" in Y and 31.5" in Z. Table load capacities range from 22,000 to 26,400 lbs and 22,000 to 35,20 lbs, respectively.

The large DMC 4000 series can handle 44,000 lbs of table load with an X-axis travel of 118" through 236", Y-axis travel of 110.2" to 189", Z-axis travel of 31.5" to 42" and W-axis travel of 39.4" to 78.7" on a fixed-column moving table. Finally, the SDMC series includes custom-made, unlimited size, sliding double-column, multi-axis, five-face moving-column and fixed-table gantry mills with X-axis travels ranging from 157" to 720", Y-axis travels of 72" to 236", Z-axis travels from 31.5" to 42", and W-axis travels from 39.4" to 78.7". Table load capacity is 614 lbs/ft2.

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