MACHINING CENTERS
Tips For Buying A Machining Center written by: Bruce Redenz of Madison Tool, Inc.
When buying a used vertical or horizontal machining center, many factors need to be taken into consideration. Modern control technology, combined with improved machine design and construction equal almost limitless potential for multi-axis and multi-function machining. Part complexity, job and part quantity, material to be machined, loading and unloading of machine, programming aptitude, and availability of qualified personnel are all important variables when choosing between a vertical or horizontal machining center. Horizontal machining centers offer better chip clearance under typical use because they have gravity on their side – chips fall out of cavities during machining, offering many advantages in-the-cut. Whether horizontal or vertical configuration, pallet change systems offer the ability for operators to be loading and unloading parts while the machine is in-cycle, as well as the ability to maintain multiple work-holding and fixturing set-ups on a single machine. Driven by the need for increased profitability and value-added services, four and five-axis machining has become part of routine capacity for many CNC machine tool users. Feedrates, rapid traverse rates, and spindle speeds have become faster, driven by the desire to machine hardened steels, graphite, and composites, with spindle speeds of 12,000, 18,000, 25,000 RPM and higher becoming common. For heavy cutting, geared headstocks offer maximum torque and horsepower through the entire spindle speed range. Standard-pressure and high-pressure coolant through-the-spindle ensure powerful and consistent chip clearance, offering longer tool life and better surface finish. So you've made the decision on which configuration, horizontal or vertical, best suits your work load, shop floor layout, and your shop talent's ability to set-up, program, and run. You now find yourself actively shopping for a used CNC machine. Adhering to disciplined research, inspection, and shipping guidelines will help you avoid common pitfalls and costly – if not disastrous – challenges. Inspect a used machine under power, talk to the operator(s) if possible, and inspect maintenance records. Does the environment where the machine is currently in service practice preventive maintenance and best practices in manufacturing methods and quality control? Is the shop clean? Do the employees seem to take a general pride in the place they work, and the parts they produce? These are all excellent indicators of how the machine has been cared for, and how many years of usable life it has remaining. Listen to the spindle bearings, table motion – particularly in rapid modes – and thrust bearings. Are the ballscrews in good shape? Are all lubrication systems, filtration components, and chiller(s) working properly? If proper inspection of the machine tool is beyond your scope, consider hiring a qualified CNC repair and inspection technician. The modest investment in due diligence may save you not only money, but the immeasurable loss of valuable production time after re-installation of the machine tool. Control technology is critical in selecting a used CNC machine. Is the control still supported? Are drives and servo motors readily available, at practical cost? Are parts stocked in your area, or do they come from other parts of the country or world when needed? Like anything that combines motion and motors, your CNC machine will require occasional repair. Minimize future downtime by selecting a well-supported machine, backed by a strong technical and field support network, even if it means a modest augmentation of your budget during the selection process. Lastly, make sure your used CNC purchase is properly decommissioned before transport. Consult machine manuals, the OEM, or a regional distributor to determine what measures need to be taken to properly prepare the machine for loading and shipment. Do motion axes need to be secured with specialty brackets? Does the seller still have them? Do any counterweights need to be secured? Does anything have to be removed to clear a door opening, or a highway height restriction? Are personnel at the plant or storage facility where the machine originates capable of decommissioning the machine? If in doubt, consider hiring a service technician to perform the preparation, or sending your own maintenance team into the facility to conduct the pre-loading checklist on your behalf. Sometimes, the best people to decommission a CNC machine are the ones who will be reintroducing it to service at its new location. If you, as the buyer, are responsible for loading and shipping arrangements, talk to distributors or technicians in the seller's area to determine not only who the most affordable machinery movers are in a particular area, but who are the most respected. Work with an established trucking company, well-versed in specialized transport, with adequate tarps, chains, and straps, and quality air-ride equipment. Ask to see their certificate of insurance. Buying a used CNC vertical or horizontal machining center can be a mostly hassle-free process when a few important steps are adhered to during pre-purchase research and inspection, and during decommissioning of the machine tool from its previous facility.
About the Author: Bruce Redenz has spent the past 24 years buying, selling, appraising, moving, and troubleshooting metalworking machinery. He and his business partner are co-owners of Madison Tool, Inc., a stocking dealer of CNC machinery in south-central Wisconsin. In his free time, he is proud to volunteer for community outreach groups, and enjoys distance cycling, hiking, fishing, and the great outdoors. Bruce can be reached at 608-850-6730 Ext 103. 12
June 2015
LOCATOR
Check the latest listings online: www.LocatorOnline.com
9653: FADAL VMC4020AHT, 20" X 40" X 20" TRAVELS, RIGID TAPPING, 7500 RPM, 88HS MULTIPROCESSOR CONTROL, 21 ATC, 40 TAPER, 2004
9689: FADAL 4020-HT VMC 40" X 20" X 20" TRAVELS, 88 HS CONTROL, 5TH AXIS, CAT 40, 22.5 HP AC, 24 ATC, 220/440 V, RIGID TAPPING, 1997
9167: MILLTRONICS VMD30A, 70" X 30" X 26.5", 24" X 70" TABLE, 20 ATC, 40 TAPER, CENTURION 5 CNC CONTROL, 1996
Wisconsin Metalworking Machinery, Inc. 2207 S. West Ave., Waukesha, WI 53189 Phone: 262-548-6080 Fax: 262-548-6094
sales@wismet.com * www.wismet.com listings e t e l p om
of
ters n e C g in Machin ... For c
age 60 go to p
NIIGATA SPN-50 Horizontal Machining Center Fanuc 16iM, 60 ATC, CAT50, Coolant Through
Madison Tool, Inc. Waunakee, WI (608) 850-6730 BruceR@MadisonTool.com Please tell advertisers you found their machines in LOCATOR
LOCATOR
June 2015
13