b'So how do you decide which is better for your shop?Vertical Versus as three-axis machines, so a fourthmoving parts, so they have fewer axis must be added later. components that can fail. Plus, they HMCs are built so the compo- are easier to work on when some-two tables that can be exchangednents are supported by the waything fails. Programming is some-automatically after the machiningstructure from underneath, unlikewhat smoother because there is cycle. This allows the operator toa VMC, in which some componentsonly one table and three axes. The load and unload parts while the ma- are cantilevered over the table. Thedifference in complexity also means chine continues to run, effectivelyHMC structure is inherently morethat VMCs are less expensive than eliminating wasted machine time.stable and rigid, which aids processHMCs of similar capability.Although VMCs can be fitted withcapability. The structure of an HMCSo how do you decide which tooling that mimics the HMCs ca- is so effective that some VMC build- is better for your shop? In many pability, they rarely come from theers have adapted the concepts tocases, the cost of the machine au-factory with autoloading tables.VMCs, but these are somewhat un- tomatically dictates the style of the Therefore, loading and unloadingconventional and very expensive. machining center purchased. The the machine introduces lost ma- VMCsarelessdesirableinlower cost of VMCs is why they are chining time into the equation. high-production environments butfound at almost every small shop. Making a lot of parts also meansexcel in other areas. When com- Volume and variation are the other making a lot of chips. Because partspared with an HMC of similar value,most significant factors. If your shop are held perpendicular to the floor,a VMC has a much larger workingsees a lot of variation and low vol-the chips made on an HMC natu- envelope. The axis travels are twoume, then a VMC is far more prac-rally fall away from the work due toor three times longer, and they sup- tical. Likewise, high volume almost gravity. Chips on a VMC have noport substantially more weight. demands an HMC to be profitable.place to go, so they must be re- It is much easier to load andIn some instances, the geome-moved with air, coolant or otherclamp large, heavy parts on VMCstry of the work dictates the course methods. If you are going to drillas they have wider doors that openof action. Some low-volume parts, deep holes or mill pockets in parts,in the front so forklifts, cranes andsuch as custom valves for petro-an HMC reduces the headaches as- other material-handling machineschemical plants, often need to be sociated with chip interference. have easy access. A VMC also occu- machined on HMCs because it is HMCs usually come preparedpies less space than an HMC. necessary to reach all sides and fix-for high-volume production withSetting up a VMC is simpler thanturing the valve body for horizontal large-capacity tool magazines, chipsetting up an HMC as well. Becausemachining is far easier.conveyors and hydraulic systems forthe front of the machine is openThe machine tool market fre-automated part clamping. Theseand the table is easily accessible,quently is presented with new de-features are almost always optionala machinist can comfortably getsigns and advances. Some stay, and equipment on VMCs. One of theinto the working area to use thingssome disappear. But the VMC re-most significant elements may belike hand tools and indicators. Ofmains one of the foundational ma-a fourth axis that allows machiningcourse, a machinist can do simi- chine tools that can be found at Filtermist_Ad_CTE_847_Layout 112/9/202:26 PMPaof multiple sides. VMCs are builtlar work on an HMC, but it is notpractically every shop. The fact that as easy since access is through aVMCs have changed little in the smaller opening positioned on thepast 20 years is a testament to their OIL MIST & SMOKE side of the working area. functionality. Cost, simplicity and a IN YOUR SHOP? VMCsarelesscomplexthanbroad range of applications have HMCs, which provides advantages.made the VMC the workhorse of VMCshavefewersystemsandthe modern shop.CTEwww.mistcollectors.com Tel: 1-800-645-4174about the author Low-Cost, Highly Efficient Mist and SmokeChristopher Tate is manufacturing engineering manager at Collectors Designed Specifically for theUnified Brands Inc. in Vicksburg, Mississippi. Contact him at Metalworking Industry [email protected] 2023VerticalMachining.indd 36 6/15/23 12:54 PM'