It’s ironic. Tell a shop owner or production engineer to mount a mechanical 3-jaw chuck on a CNC lathe and they’ll look at you as though you’re wearing a duck on your head. Why do they then turn around and put old-fashioned, hand-cranked vises on vertical machining centers? A basic hydraulic vise setup for a VMC can cost between $1,700 and $4,000—roughly the same price as a hydraulic workholder on a lathe—and provide far more reliable and consistent clamping than mechanical units. So what gives?
According to Mike Antos, application engineer at Cleveland-based workholding and lifting products manufacturer Jergens Inc., fewer than 10 percent of shops use hydraulic vises on their machining centers. This lack of acceptance is due largely to shops going with what they know. “Most machine shops have always used mechanical vises,” he said. “There’s a comfort factor there. Then along comes the vise salesman and the word ‘hydraulics’ comes up. That can be somewhat intimidating.”
There’s nothing to be scared of. Hydraulic systems make your car stop at red lights. They compact the trash you put on the curb and raise the seat when you’re getting a haircut. Installing a hydraulic pump and plumbing a few lines is no more complicated than fixing a leaky toilet seal.
Machine tool builders are partially to blame for the lack of acceptance of hydraulic vises. The cost of a chuck and the hydraulic system to power it are already rolled into the price of most CNC lathes—if they weren’t, shop owners might be inclined to pull out their red Sharpie and strike them off the purchase order. But if builders were to equip that shiny new machining center with a hydraulic vise, you can bet a Ben Franklin that machinists would use it.
Read the rest: http://www.ctemag.com/aa_pages/2014/140502-Workholding.html