Your newsletter for tips on selecting manufacturing technology.
- Tom Grasson - question of the month
- Tips on selecting - the right machine tool
- Hot products
- Manufacturing education and training - education at the machine tool?
Please e-mail Tom your questions, suggestions, or comments.
- Here are some general considerations:
- Show the OEM/distributor sales-engineer parts and part drawings. If he can't help, OEMs typically have technical-support personnel that can.
- Make sure the machine tool model is available. If there is a wait, ask if the machine can be delivered in a reasonable time or will take several months or longer.
- Question whether an authorized distributor is nearby to set up, service, and support the new machine and if repair/service parts are readily available and affordable.
- Inquire if operator training and free telephone assistance is part of the package.
- Check the duration of the machine's warranty and where warranty work comes from.
- Find a supplier that warrants the machine for at least a year.
Here are considerations specific to VMCs:
- Determine the reason for buying the machine -- is it a first machine for a start-up shop or a first step into CNC machining? Also, consider the application -- a machine useful for high-speed positioning in an automotive application won't necessarily be good for high-speed contouring for a die/mold application.
- Ask at what Y-axis travel a machine shows noticeable side-thrust deflection, which could result in chatter.
- Make sure the construction dampens vibration and the axis configuration provides stiffness, rigidity, thermal stability, accuracy, and full-axis travel support.
- Check the machine design has minimal distance to the cutting edge, no axis stackup and overhang, and a table center of gravity within the guideways. Ballscrew size, pitch, and servomotor capability also impact machine accuracy, axis thrust, stiffness, and rigidity.
- Linear guides or boxways? In choosing, let the application be the deciding factor. Linear guides deliver fast cutting speeds and low friction. Boxways deliver slow cutting feeds and deep, heavy cuts. However, this line is blurring -- today's linear guideways are more rigid, and new coatings are delivering faster feeds for boxway machines.
- Decide on type of chip and coolant containment. Fully enclosed splashguards prevent flying chips and coolant from escaping during high-speed machining. But enclosures must provide easy access for loading and unloading.
- Make sure the VMC spindle is stiff and rigid. Factors impacting this include number, size, type and location of bearings, preloading techniques, balance, and sensitivity to vibration. Smaller 40-taper spindles usually come in high-rpm models for light, fast cuts, while the 50-taper spindles are for heavy cutting. According to some builders, the most versatile spindle speed is 8,000 rpm because it handles heavy cuts, and, although not the fastest, can also deliver light, fast cuts. The main thing to remember is the higher the rpm, the more delicate the spindle.
- Take into account productivity features such as rapid-traverse rates, cutting federate, toolchange time, and spindle spool-up/spool-down times.
- Find out what type of control the machine has and ensure it's widely used, reliable, easy to operate, powerful enough, and easy to upgrade. What elements of the control change out, does it take a day or a few hours, and can a local distributor perform the upgrade? What are the measurable benefits of speed increases and programming functions, and what is the true CPU MHz speed?
- Consider options such as programmable coolant nozzles, chip-auger systems, 4th and 5th axis rotary tables, automatic toolchangers (ATCs), and pallet changing. Investigate how complicated and reliable the ATC is and what size tools it can handle. For pallet changing, the machine control and automatic-pallet-changer pushbutton station should support setup of multiple pallets of work as well as the production operation from the front of the machine.
Manufacturing Education and Training
Education at the machine tool?
Even the best repairman can't remember all procedures for troubleshooting and fixing every machine tool in a plant. Now operators don't have to page through old manuals or ask their coworkers. They get needed information right at the machine as part of Automatic Feed Co. Inc.'s Automation Integration Manager (AIM) modular software system. A graphical, keyword-searchable SQL-based database provides links to all electrical, mechanical, hydraulic, and pneumatic prints, and equipment-manufacturer machine repair and maintenance manuals. Operators can view the PDF documents on-line, or print them from the screen. This software was designed with help from shop-floor personnel. For more information, call (419) 592-0050, or visit aim-analytical.com
Coming in March's issue: AMERICAN MACHINIST V.I.P Edition tips on selecting manufacturing technology will focus on fixturing.
For questions or comments, e-mail Leslie Gordon. To learn how to reach this newsletter's thousands of qualified readers, e-mail Christian Webb or call him at 216.931.9501. Subscribe to this newsletter or manage your account. Unsubscribe only. © 2005 Penton Media Inc., 1300 E. 9th St., Cleveland, OH 44114. Read our privacy policy.