Demands are increasing for high-quality
manufacturing processes in the production of complex molds with superior
finishes. With high-tolerance shape and surface requirements in such areas as
micromachining and medical applications. It is becoming more imperative that the
required surface finishes be achieved during the actual cutting process. To
accomplish this, depth direction needs to be improved in the machining process
of precision components.
Makino engineers have completed months of testing on enhancements to mold surface finishes in order to determine the best solution available to eliminate the thermal displacement and abrasion that causes this effect. And they have come up with a new patent-pending process to ensure superior surface finishes without slowing down operations.
Testing Solutions
In advanced technology machines with built-in
automatic tool changers (ATCs), where surfaces are often milled by different
tools, there is a detectable and measurable occurrence of difference in the
spindle thermal displacement. Makino engineers say this is caused by the slight
inaccuracy of tool change positionings and different spindle speeds, and by
minor occurrences of tool abrasion.
Although the extent of these surface differences is very small, they can cause problems when the polishing process is shortened or eliminated. Various processes were tested by Makino engineers to minimize such slight differences.
It was discovered in testing that one method to negate this impact requires the use of tools that do not easily act abrasive in the finishing process. This requires that one tool be used for the entire machined surface finishing process.
However, most operations and processes do not allow for the potential of just one tool to finish the entire machined surface of the mold. The diameters of the tools used to machine such molds are becoming smaller, and varieties are needed at different rotation speeds to properly finish such molds.
Makino Solution
Makino engineers have developed a solution to
enable better position control. They have designed a patent-pending "Hybrid
Automatic Tool-Length Measuring System" that is available on its precision Hyper
2J, V22 and V33 high performance vertical machining centers.
The key is to measure the position of the tip of the rotating tool at the submicron level. "Measuring the tip of the tool in a highly accurate and stable manner is vital, taking the expected thermal displacement caused by spindle rotation into consideration," said a Makino spokesperson.
Measuring by a contact sensor is an appropriate method to achieve high accuracy measurement, as cutting oil or chips do not easily affect it. There is also a method for measuring accurately by a non-contact sensor, as well as a combination of processes.
Hybrid Measurement System
The measurement system invented by Makino
engineers, which is referred to as the Hybrid Measurement System, is actually
the combination of the contact and non-contact measuring options. The tip of the
tool is brought in contact with the low contact; pressure-contact sensor while
the spindle is stopped. The effect of vibration can thus be minimized and the
position of the tool tip is measured accurately.
The spindle with the tool in place is rotated at a speed used during the machining process, and a non-contact sensor measures the position of the spindle end. By measuring the end of the spindle, which has specified shape and accuracy as a machine component, it is possible to measure the position, accounting for thermal displacement caused by the spindle rotation in a highly accurate and in a stable manner.
The control unit then determines these two measurements, and the calculation result is regarded as the position of the tool tip. The obtained position of the tool tip is then used as tool data during the machining process.
Case Studies
The following case study describes how the Hybrid
System measures the tool tip position, and the measurement results are used as
tool data during the machining process.
On a Makino V33, six different types of tools were used, with various spindle speeds and axis feed rates for the roughing and semi-finishing. Five different types of tools were also used for the finish machining process.
Before each process began, the Hybrid System measured the position of each tool tip, and the measurement result was used as tool data during the machining process. The level differences between the machined surfaces finished by five different tools and the reference plane were all within one micron, as measured by the roughness meter.
Additional Tests
In a similar test with the Makino V22 vertical
machining center, four different types of tools were used for roughing and
semi-finishing processes, and six different types of tools were used for the
finish machining process.
The NAK80 40 HRC workpiece was 60 x 45 x 25 mm, and was machined in 2 hours and 39 minutes using a rotating R2.0 ball end mill at a speed of 20,000 min-1. A portion was machined by using a rotating R1.0 ball end mill at a speed of 40,000 min-1.
The level difference between the two surface portions that have been machined by two types of tools at speeds of 20,000 min-1 and 40,000 min-1 were both within one micron.
In another V22 test seven different types of tools were used for the finish machining process of a television mold. Also using a Hyper 2J fine precision vertical machining machine the Hybrid System, two different types of tools were used for the roughing and semi-finishing.
The latter was machined by a R1.0 ball end mill at a speed of 20,000 min-1, 30,000 min-1 and 40,000 min-1. The level difference among those portions machined at different speeds is within one micron.
Conclusion
These results clearly indicate the high precision
process and capability of the Hybrid Automatic Tool-Length Measuring System
machining. Level differences were quantitatively evaluated, and were determined
to be extremely small despite the different tools and speeds employed.
This Hybrid System testing indicates that extremely high-quality machined surfaces can be obtained. Makino engineers note, "With these superior and more accurate surface finishes, polishing and bench time can be eliminated."
Mark Rentschler
Makino Inc.
7680 Innovation Way
Mason, OH 45040
800-552-3288
Fax: 513-573-7360
Southwest
TX
Mike Johns
Andy R. Plassenthal
Wesley Davenport
Texas Machinery Company
11875 Forestgate Drive
Dallas, TX 75243
877-477-7340
Fax: 972-231-2815
OK
KOMT
3695 East I-240 Service Road
Oklahoma City, OK 73135
405-670-1111
Fax: 405-670-6664
E-mail: okc@komt.com
LA
Clint Wenzel
Oliver Van Horn Co.
4100 Euphrosine St.
New Orleans, LA 70150
504-210-3040
Fax: 504-822-2449
E-mail: Clinton_Wenzel@jcwenzel.com
NM
Moncktons Machine Tools, Inc.
928 Canvas Back Rd.
Rio Rancho, NM 87144
505-891-8845
Fax: 505-994-3579
E-mail: hmorrismmt@aol.com
Southeast
NC, SC, VA
Dan Beckman
President
Beckman Precision, Inc.
415 Brookshire Road
Greer, SC 29651
864-801-8181
Fax: 864-801-8180
Sam Owens
Vice President
Beckman Precision, Inc.
160 Ringneck Trail
Mooresville, NC 28117
704-664-1627
Cell: 704-906-5973
Fax: 704-664-9545
E-mail: sowens@beckmanprecision.com
Western NC & SC
Chris Beckman
Beckman Precision, Inc.
415 Brookshire Road
Greer, SC 29651
877-510-6884
Cell: 864-346-9668
Fax: 864-801-8180
E-mail: cbeckman@beckmanprecision.com
Eastern VA & Northeast NC
Bob Hodge
Beckman Precision, Inc.
1316 Elmwood Drive
Colonial Heights, VA 23834
804-520-4200
Cell: 804-720-2198
Fax: 804-520-0602
E-mail: bhodge@beckmanprecision.com
Eastern SC & Southeast NC
Charlie Inderrieden
Beckman Precision, Inc.
396 Blue Stem Drive 58A
Pawleys Island, SC 29585
843-979-0576
Cell: 843-450-5991
Fax: 843-979-0582
E-mail: cinderrieden@beckmanprecision.com
Central NC & VA
Larry Jordan
Beckman Precision, Inc.
454 Cooper Farm Rd
Statesville, NC 28625
704-876-3885
Cell: 704-904-8045
Fax: 704-876-0417
E-mail: lwjordan@bellsouth.net
AL, GA, MS, TN
Bill Myers
SST
26762 Success Drive
P.O. Box 708
Madison, AL 35758
256-309-0404
E-mail: bill.myers@singlesourcetech.com
AL, Upper MS
Jack Nash
SST
2030 Vestavia Park Lane, Apt. B
Vestavia Hills, AL 35216
205-824-2899
Cell: 205-612-9371
Fax: 205-824-2899
E-mail: jack.nash@singlesourcetech.com
GA
Bud Cowan
SST
4282 Marci Street
Snellville, GA 30039
770-267-9044
Cell: 678-227-2588
Fax: 770-267-9044
E-mail: bud.cowan@singlesourcetech.com
TN
Hale Reider
SST
865-250-9344
E-mail: hale.reider@singlesourcetech.com
FL
Bob Arthur
Arthur Machinery, Inc.
5903 Johns Rd.
Tampa, FL 33634
813-887-4455
Fax: 813-887-4456
E-mail: sales@arthurmachinery.com
Northeast
MA, CT, ME, NH, RI, VT
Able Machine Tool Sales
800 Silver St.
Agawam, MA 01001
413-786-4662
Fax: 413-786-5056
E-mail: sales@ablemts.com
NJ, MD, E. PA, Long Island
Automation Solutions, Inc.
882 S. Matlack St., Suite 204
West Chester, PA 19382-4956
610-430-3670
Fax: 610-430-3675
E-mail: inquire@asi-pa.com
NY, CT, DE, DC, ME, MD, NJ
EDM Sales & Supplies, Inc.
965 Ball Ave.
Union, NJ 07083
800-336-7283
Fax: 908-964-9585
E-mail: edmsave@edmsave.com
NY
Meagley Machinery, Inc.
4863 Enders Rd.
Manlius, NY 13104
315-682-1884
Fax: 315-682-5319
PA, WV
Perseo Erie Machine Sales, Inc.
1416 Liberty St.
Erie, PA 16502
800-900-9117
Fax: 814-456-8447
E-mail: info@perseoerie.com