With manual-operated, rotary-indexing pallet-changer systems from SMW, Equivalent Base slashed a 10-min load/unload time between machining cycles to 1 min.
Equivalent Base of Warren, Mich., manufactures a line of over 500 modular components that are the building blocks of automobile body welding, assembly, and checking fixtures. Because the company supplies components to most fixture builders in this industry, it knows the advantages of economies of scale largely through producing more parts per machine. However, chip cleaning and work loading/unloading added a 10-min cut-to-cut time between machining cycles. To drastically reduce this noncut time, the shop brought in four manual pallet changers.
A 25-min cycle time was cut to 16 min with the pallet changers. Ten minutes spent loading/unloading were slashed to just one. This lets Equivalent run 30 machine cycles, as opposed to 19.2, during an 8-hr shift — a 64% increase in machine output.
Supplied by SMW Systems and called SetupSwitchers, the units consist of a power-operated pallet-locating-and-clamping fixture that mounts on the shop's machine tool table; precision cast iron pallets; and a rotary-indexing table. This rotary table contains the off-line pallet, which is switched onto the machine table when a machining cycle ends — a process that takes no longer than 1 min.
Both pallets and clamp fixtures have hardened and ground precision locators, bushings, and rest surfaces. And the pallets repeat to within 0.0002 in.
"Once we realized the advantages of the SetupSwitchers," says Jeff Wells, Equivalent Base manager, "we equipped four of our vertical machining centers with them. On many production runs, we've actually doubled machine output. But on short runs, the system's 1-min switch time lets us change over to a new job in less than 10 min. Because of this, we reduce on-shelf inventory and respond to new orders and changing market conditions quickly."
With the system's quick changeover, Equivalent can easily interrupt a running job and be cutting a rush order within 30 min of receiving it. In addition, this interrupt advantage saves time when cutting the first part of a new job. "We stop the current job, switch pallets and machining programs, run the first piece, switch back, and resume machining the current run. There's no machine shutdown during first-piece inspection," adds Wells.
The shop has also designed a subplate fixturing system used on extra pallets stored on shelves. These pallets accept the subfixture mounting-hole patterns, so Equivalent runs a range of parts on a single pallet by simply changing subfixtures. An adjustable-height cart transports pallets between storage shelves, setup areas, and the machines. These shelves and carts are also from SMW.