The world of High-Speed Machining (HSM)
and that of conventional machining are two completely different worlds. Though
they do cross over from time to time and have some similarities, they are quite
different.High-Speed Machining and Hard Milling Explained
Authored by Jim Carlin, High Speed Machining - Product Manager, Sodick Inc.
The world of High-Speed Machining (HSM)
and that of conventional machining are two completely different worlds. Though
they do cross over from time to time and have some similarities, they are quite
different.
When you ask people from different manufacturing sectors what HSM is, you will more than likely get varied opinions of how HSM is applied. Many in the production machining industries cutting soft materials such as: aluminum, brass, composite materials, and various types of plastics consider what they are doing to be HSM.
Some of the people that have helped to develop HSM have introduced other terms like:
High-Definition Machining
High-Performance Milling
Hard-Die Milling
Productive Net-Shape Milling
These terms are used to help people distinguish what HSM actually means and what the applications of HSM are. High-Definition Machining (HDM), High-Performance Milling (HPM), and Productive Net-Shape Milling are really what High-Speed Machining (HSM) is all about. The ability to produce highly defined shapes on complex parts productively while maintaining accuracy.
HSM was developed as a means to remove material quickly on complex shaped parts and in the process leave a near net shaped part. The theory behind HSM is to produce parts or molds that require as little polishing as possible. The problems with polishing are:
Time consumption - Polishing parts to remove machining marks and to improve the surface finish can require many hours. The harder the material, the longer polishing takes
High skilled labor - Polishing is often performed by highly skilled tool-makers to assure that it is done right
Loss of dimensional accuracy - In many cases geometric accuracies are sacrificed in order to achieve a required surface finish. Even the most skilled polisher can not polish as accurately as some commodity type machines can machine
HSM brings forth many challenges as
well as rewards to those who master it. As HSM can be applied to many types of
materials, in order to apply it correctly and productively the person processing
parts for HSM must have a clear understanding of HSM processing and practices.
This includes:
Knowing the limitations of the machine being used
Knowing the limitations of the material being machined
Knowing the limitations of the tool being used, both cutting tools and work-holding
Having and being able to effectively use a CAM system that is designed for HSM
Knowing the best tool paths and tool to material entry approaches to apply based on the part geometries, material hardness, and surface finish required
The impact that the development of HSM has had on machine tool designs, CAM software development, cutting tool technology, and part/tooling design is quite dramatic and impressive. One technology that spawned from HSM is hard milling or as some call it, Hard-Die Milling (HDM).
Hard Milling has been made possible through the break-through developments in machine tool design, CAM software development, cutting tool technology, and part processing knowledge. The two greatest benefits of Hard Milling are:
Shorter lead times
More accurate part shapes
Shorter lead times are achievable by
being able to machine a part complete with the material in its hardened state.
In most cases, with Hard Milling there is no need to pre-machine prior to
heat-treating. Hard Milling, in many cases, has eliminated much of the sinker
EDM work required in the manufacturing of molds and complex shaped parts. By
directly milling the shape, or as much of the shape as possible (in some cases
some details will need to be EDMed), most if not the entire sinker EDM time is
saved along with the time it takes to produce the electrodes. Hard Milling
eliminates most of the grinding required and polishing time is dramatically
reduced resulting in a more accurate part.
Hard Milling presents perhaps the greatest challenges for anyone applying HSM technology. To be successful at Hard Milling you not only have to have a complete understanding of HSM processing, you need a CAM system that is designed for Hard Milling of complex shapes, high quality tool holders and cutting tools, and, most importantly, a machine tool designed for Hard Milling.
Many machine tools being promoted for Hard Milling were designed to do general purpose machining or as solid, accurate graphite mills. Some machine, though designed for Hard Milling, lack the structure needed for Hard Milling. And some builders have simply changed the model name on the machine to reflect its use for Hard Milling when it was actually designed for lighter HSM applications.
The Sodick "MC" Series Machining Centers
The Sodick MC series machining centers were designed from the base up with Hard Milling in mind. Sodick uses a bridge-based design and combines two types of iron in the design of their mills. The base casting is made of high grade FC300 cast iron known for its impact toughness while the bridge casting is made of ductile FCD-500 spheroidal cast iron known for its strength and ability to resist temperature changes. The way system uses roller bearing linear guide ways because of the following characteristics:
High radial load capacity
Highest speed capacity
High rigidity
Vibration and shock resistance
High rotational accuracy
The spindle is a specially designed
high-frequency 40,000-RPM spindle that uses an HSK-32E holder interface. The
spindle is designed for maximum stiffness throughout the full rpm range. With
Sodick being one of the pioneers of linear motor technology in the manufacturing
of machine tools the MC series machining centers incorporate linear motors on
all three-axis. "The Sodick linear motors, combined with .03-micron (.0000012")
linear scale feed back, make the mills some of the most accurate machines on the
market," said a company spokesperson.
Sodick's new linear motor driven high speed machining center has compact design requiring very little floor space. Its' rigid structure results in a high-dynamic response with a 1G axis acceleration rate and a 40,000 RPM spindle speed. The machining center is available is in two sizes. The MC430L and MC640 models have a 16" X 14" x 8", and 24.5" x 16" x 12" respective axis travels.
The use of linear motor technology in HSM is a natural. Unlike conventional machining that generates high axis loads due to heavy cutting depths performed at low spindle rpm and low feed rates, HSM applies shallow cutting depths at high spindle speed and high feed rates. Backlash in a ball screw system limits how much "gain" can be used to control the positioning of the axis. Since "gain" is a measure of the control systems responsiveness, it can be a very limiting factor in a machine tools design. Linear motor drives can be controlled at many times the gain of rotary motors. This allows the machine to position, contour, and interpolate more accurately at high feed rates.
For more information contact:
Jim Carlin
Sodick Inc.
1605 North Penny Lane
Schaumburg, IL 60173-4555
847-310-9000
Fax: 847-252-8521
Southwest
TX
Chaparral Machinery
3435 Roy Orr Blvd. #100
Grand Prairie, TX 75050
972-313-1987
Fax: 972-313-1984
E-mail: dstilley@chaparralmachinery.com
Allied Machine Tools
P.O. Box 2166
Stafford, TX 77497-2166
281-565-8700
Fax: 281-565-8686
Champions Machine Tools, Inc
1151 E. Cypresswood
Spring, TX 77373
281-355-9220
Fax: 281-353-3299
TX, NM
CNC Precision Machines MTS Co.
1392 Vista Granada Dr.
El Paso, TX 79936
915-592-3161
Fax: 915-778-0102
AR, LA
Cardinal Machinery
P.O. Box 341245
Memphis, TN 38184
901-377-3107
Fax: 901-377-4855
OK
Sodick Inc.
1605 N. Penny Lane
Schaumburg, IL 60173
847-310-9000
Fax: 847-310-9011
KS
CJ Smith Machinery
P.O. Box 14338
Lenexa, KS 66285
913-498-1020
Fax: 913-498-1198
Southeast
FL
Myer Precision Sales & Service, Inc.
P.O. Box 915326
Longwood, FL 32791
407-774-8893
Fax: 407-862-3287
GA
Sunbelt Associates
5071 Hampton Lake Dr.
Marietta, GA 30068
770-565-7996
Fax: 770-565-5796
NC, SC
McWilliams Sales & Service, Inc.
6600-A North Park Blvd.
Charlotte, NC 28216
704-598-6616
Fax: 704-598-6789
VA, WV
Production Machinery Associates Inc
207 High Point Road
Williamsburg, VA 23185
757-258-5800
Fax: 757-258-4900
E-mail: productionmachinery@cox.net
TN, MS
Cardinal Machinery
P.O. Box 341245
Memphis, TN 38184
901-377-3107
Fax: 901-377-4855
TN
Cinton Machine Tools
P.O. Box 339
Cross Plains, TN 37049
615-654-0500
Fax: 615-654-0500
Northeast
CT, MA, ME, NH, RI, VT
Joe Klier
Brooks Associates, Inc.
77 Accord Park Drive, Unit C-3
Norwell, MA 02061
781-871-3400
Fax: 781-871-4969
E-mail: brooksmachinery@comcast.net
S. NJ, DE, MD, E. PA, DC
Forrest Jacobs
Jacobs Machine Sales, Inc.
2823 Ady Road
Forest Hill, MD 21050
410-879-6520
Fax: 410-838-3352
E-mail: jmachine@clearviewcatv.net
W. PA
Ken Niemeier
Barney Machinery Company
1114 Parkway View Drive
Pittsburgh, PA 15205
412-787-3737
Fax: 412-787-1968
E-mail: kniemeier@barneymachinery.com
Upstate NY
Kevin McCarthy
2SQ Machine Tools
575 Ludwig Avenue
Buffalo, NY 14227
716-893-3643
Fax: 716-893-3673
E-mail: kmccarthy@2sq.com
N. NJ, NY (Long Island)
Rick Fiorillo
Shore Machine Tool Sales
437 River Street
Oceanport, NJ 07757
732-222-9414
Fax: 732-222-9201
E-mail: shoremach@aol.com