- Email: [email protected]
A big lift for the aerospace industry
A Big Lift for the Aerospace Industry Peening technology enables planes to fly lighter and longer. By Robert B. Heaton, Director/Testing Laboratory, Empire Abrasive Equipment Co.; Jack Champaigne, President, Electronics Inc.; and John T. Cammett, Metals and Ceramics Branch Chief, Air 4.9.7.1, U.S. Naval Aviation Depot-Cherry Point
he daring knights of yore somehow stumbled upon peening as a m e t h o d for saving their hides. Pounding a sword blade with a rounded h a m m e r extended the life of the weapon and, no doubt, the life of its owner as well. To this day, peening has far-reaching safety consequences as manufacturers strive to produce stronger, lighter products, particularly in the fields of automobile and aircraft production. Automobile manufacturers often peen defensively, meaning t h e y fall back on the process to strengthen a spring, gear, connecting rod, anti-roll bar, or other component that fails prematurely. Because its products travel at higher altitudes, the aerospace industry takes a more proactive approach through the development of stringent peening specifications, in which adherence must frequently be documented. Two primary factors drive Figure 1: Today's aircraft, both aerospace's attention to benefits of shot peening to fly peening details and documentation. For starters, a tight paper trail helps trace a potential part problem if a catastrophe occurs. Secondly, the industry relies heavily on shot peening technology to keep its products flying lighter and longer. Modern planes depend on the capability of shot peening to strengthen blades, roots, stators, gears, discs, combustion chambers, structural members, and many other parts too numerous to mention (Figure 1). Peening offers a big lift for the aerospace industry, but it must be tightly controlled to achieve anticipated performance gains. Because rigorous control is central to peening effectiveness, shock waves reverberated throughout the aviation i n d u s t r y w h e n three m e n associated with the St. Charles Metal Finishing Co. in St. Louis, were sentenced to jail terms in 1992 for falsi-
T
18
fying inspection reports related to the peening of parts used in 1,000 fighter planes built by McDonnell Douglas Corp. As a consequence, the Pentagon delayed acceptance of F-15 Eagles, F/A-18 Hornets, and AV-88 Harriers, as well as Harpoon and Stand-off Land-attack missiles. On civilian aircraft, off-spec or nonexistent shot peening has been cited as the cause of failures on parts ranging from engine shafts to landing gears. Recognizing the importance of sound peening practices, the FAA (U.S. Federal Aviation Administration) now assumes responsibility for educating its auditors and inspectors on shot peening and proper shot peening p r o c e s s e s in airlines, job shops, and repair facilities. In fact, one of this article's authors (Champaigne) has been i n s t r u m e n t a l in developing shot peening military and civilian, rely on the training programs now lighter and longer. a t t e n d e d regularly by FAA employees. BENEFITS OF PEENING Though peening can perform a variety of odd jobs, such as expanding undersized parts and improving oil retention, enhancing the fatigue strength of metals is its p r i m a r y role. This cold-working process relies on the action of small spheres impacting meta]s at high velocities to create plastic deformation and resulting compressive-residual-stress distributions on and beneath metal surfaces. When used to optimal effect, peening delivers truly amazing results, in-cluding fatigue-life gains in components of 10 times or more, with no decrease in applied stress limits and/or increases in maximum stress tolerances up to 40% with no decrease in life. www.metalfinishing.com
Exploiting the full potential of peening in new applications, however, can involve a substantial amount of work. Many factors-i n c l u d i n g shot size and type, coverage, intensity, and blast a n g l e s - - m u s t often be t e s t e d and optimized to a t t a i n the most productive relationship bet w e e n t h e process and component perf o r m a n c e and dura-
INTENSITY
Figure 2: M o d e m Almen gauges provide precise readings of strip deflections used to meas-
ure peening intensity.
bility. D e v e l o p i n g specifications to maximize shot peening benefits on c o m p o n e n t s not p r e v i o u s l y p e e n e d r e q u i r e s the application of theory, history, and e x p e r i m e n t , f r e q u e n t l y involving d e s t r u c t i v e testing.
& COVERAGE STANDARDS
Although shot peening practitioners need not repeat the science supporting the specification, they better be on target, particularly in aerospace applications. Specifications for components as small as jet-engine turbine blades may run to many pages detailing masking requirements and separate treatments for roots and blades. A device known as the Almen strip is central to most peening specifications, despite some recent reservations about the specific correlation between strip deflection and compressive residual stress. Developed by J.O. Almen of General Motors Research Laboratories in the 1940s, the Almen strip provides a method for measuring, specifying, and duplicating peening intensity. The concept is based on the premise that a thin, flat piece of metal, mounted on the surface of a solid block, will continue to arc convexly in proportion to the kinetic energy delivered by impacting shot and resulting deformation created until "saturation" is achieved. "Saturation" is defined as the earliest point on the arc height-exposure time curve, when doubling exposure times, produces an increase of 10% or less
Clean, Peen, Finish and More
:omatically! CI is the industry's leading single-source manufacturer/supplier of the most costeffective, efficient and versatile filters for your specific spray b operation, including:
=,,y ,,,u,,- . . . . . . . . . . . . -u,ast job. Our hundreds of automated systems continue to cut costs and improve quality in applications ranging from deburring hypodermic needles to etching 6' x 15' sheets of stainless steel. Whether it's high-speed cleaning or precision peening, Empire can deliver the air-blast system to meet your needs.
• Spray booth intake filters • Diffusion media • Overspray collectors • Booth/floorprotective covering • Hardware/accessories
We
• HVAC filters
Performance Engineered A i r F ......
IlUlIIIII I n d u s t r i e s , Inc. Call: (740) 983-2552 E-maih [email protected] Visit our new website at www.colind.com
Circle 052 on reader information card or go to www.thru.to/webconnect March 2005
Have
It
All/
• A u t o m a t e d S y s t e m s • Blast C a b i n e t s • H o f f m a n Blast R o o m s • P o r t a b l e Blasters
• MACT compliant systems
, IllUUUIN°Columbus
can t r i g g e r :s in a l m o s t
F.MPIRE
TM
ABRASIVE EQUIPMENT
2101 West Cabot Boulevard, Langhorne, PA 19047-1893 Call: (215)752-8800 E-Maih [email protected] Fax: (215)752-9373 Visit: www.empire-airblast.com
Circle 019 on reader information card or go to www.thru,to/webconnect 19
Figure 3: Multiple blast nozzles provide processing flexibility by targeting different areas and facets of work surfaces.
Figure 4: An oscillating lance, which diverts shot direction sideways, peens the interiors of holes and recessed areas.
in arc height. To measure arc height, one places the peened Almen strip in an Almen gauge. Modern Almen gauges (Figure 2) resolve to 0.0001
For more information contact:
Figure 5: Programmable peening machine includes recycling equipment designed to assure consistent shot quality.
Figure 6: A stack of sieves, rotated and tapped automatically, segregate shot samples for inspection.
inch, thereby assuring sufficient accuracy and precision to properly m e a s u r e arc heights from which Almen intensity is derived.
Field kits & meters for everything from Alkalinity to Zinc as well as combination outfits for all types of water analysis.
H E N T ZIIIIIIIEIII N I HENTZEN COATINGS, INC. AEROSPACE DIVISION 6937 W. Mill Road, Milwaukee, Wl 53218 Ph: 414-353-4200 Fax: 414-353-0286 Ernail: Coatinqs(~He ntzen.com ISQ 9001:2000 Certified Circle 026 on reader information card or go to www.thru.to/webconnect
20
4-3100 ~own• MD • 21620 ~x410-778-6394 ~tte,com Circle 029 on reader information card or go to www.thru.to/webconnect
www.metalfinishing.com
Figure 7: Programmable controls enable operators to designate processing procedures by simply inputting the appropriate part-identification number.
Figure 8: Equipment manufacturers employ test laboratories to experiment w i t h various approaches for meeting customers' peening requirements at competitive costs.
INSPECTION M E T H O D S Traditionally, an inspector views the peened surface at magnification (10X to 30X) to assess coverage. Flat surfaces on softer metals are the easiest to inspect. Complex geometrical shapes or parts with holes, the most likely spots for underpeening and eventual cracking, present problems because of restricted visibility. Harder metals pose difficulties because of shallow indents, which may not be optically observable. These challenges may be mitigated with the appli-
HEAVY.METALRECOVERY Purify Recycle REASCO Modular Ion Exchange CrPur TM Chromic Acid Purification REASCO Modular Electrowinning Turn-Key Recycling Solutions
@
HAS A NEW HOM£.
and get everything it stands for.
RECOVERY ENGINEERING & S A L E S C O M P A N Y , INC. P.O. Box 297, Arvada, Colorado 80001-0297 U.S.A. TEL: 303-292-5702 FAX: 303-292-5717
www.reasco,
corn
Circle 037 on reader information card or go to www.thru.to/webconnect March 2005
UDYLITE
Automatic Machines, Parts and Service Call for ODYLITE equipment
D.I. Water Rinse Water Recovery Bath Purification E f f l u e n t Polishing Closed Loop Systems
1-800-570-0295
PEENING EQUIPMENT Peening e q u i p m e n t normally relies on either a mechanical or p n e u m a t i c system to propel shot.
UDYLITE SYSTEMS • FANTA SERVICE
• Heavy Metal Recovery • • • • •
cation of tracer coatings, which provide a colorful landscape of peening coverage. Computer analysis, using either contact or electromagnetic data, may be employed to minimize subjectivity. In essence, the computer approach compares a desired surface profile with an actual profile obtained after peening to determine if results fall within acceptable coverage parameters.
Circle 020 on reader information card or go to www,thru.to/webconnect 21
Mechanical systems offer energy-saving advantages in mass production. Rotating wheels with blades impart momentum directly to the shot and are capable of delivering large volumes of media at high velocity. Accessory equipment must often accompany these systems to turn or roll workpieces because the shot stream is unidirectional. Also, "hot spot" adjustments may be required because these machines produce a wide pattern in comparison to their actual work focus. Controlling shot momentum, however, is a simple matter of selecting the desired wheel speed because the "thrown" shot maintains a relatively uniform velocity. Pneumatic peening systems take two approaches, commonly known as "suction" and "pressure." The fundamental difference between the two is that a suction system relies on pressure differential created by moving compressed air to draw shot from an unpressurized storage hopper into a blast gun from which it is expelled onto the work surface. In a pressure system, the entire arrangement, including the shot-storage vessel, is pressurized. When actuated, the system feeds shot from the vessel into a pres-
surized feed line connected to blast nozzles, which focus shot on the work surface. Pressure systems have the advantage of using compressed air more efficiently than suction systems while providing more precise control of shot velocities at both high and low operating pressures. Suction systems, on the other hand, simplify the use of multiple blast guns and are normally less expertsive and easier to maintain. In both cases, however, the ability to deploy multiple blast outlets (Figure 3) capable of tracing contoured surfaces gives pneumatic systems a major edge over mechanical systems in peening parts with complex geometrical contours and with reeentrant indents or holes (Figure 4). Regardless of the system selected, peening to specifications requires proper maintenance of peeningmedia quality. Besides reducing the size, depth, and shape of indentations, degraded shot may also cut or abrade the work surface, thereby reducing desired peening effects. Even the highest quality shot begins to break up after multiple impacts, at which point its remnants must be removed from the processing equipment. Most often this cleanup is accomplished
Selling Your Company... • • • •
All Cash Deals P r e m i u m Prices O b t a i n e d Negotiating Power Personalized, Tailored Service
A corporate sale is a complex task. Our street-smart entrepreneurial approach guides you through the entire process. We are experienced, seasoned professionals, who successfully complete more acquisitions per person than any other firm. M y company negotiates a transaction structure that protects o u r clients from post-closing litigation. For additional information about our unique services, contact:
D
GEORGE SPILKAAND ASSOCIATES Merger & A c q u i s i t i o n C o n s u l t a n t s Suite 301, 4284 Route 8 Allison Park, PA 15101 412/486-8189 • email" [email protected]
www.georgespilka.corn Circle 055 an reader information card or go to www.thru.to/webcennect 22
Comparisons are good! It takes two of this popular brand filter to reach the efficiency and life of one Andreae Filter. Want to compare pricing? We do too! One Andreae Filter cost the same as one of theirs'. Enough said! .....~,~.,i!~!~ =
Ca//for a Free Filter Tri No Cost or Obligation/ 800-891-9785
........
i
......
......
Circle 051 on reader information card or go to www.thru.to/webconnect www.metalfinishing.com
with a classification system (Figure 5) that maintains correct shot-size distribution and eliminates misshapen and broken media as well as debris and foreign objects. The shot is also subjected to inspection for maintenance of shape and size according to specifications. The analysis is performed with a sample of 100 grams of shot placed into a stack of nested standard sieve screens that segregate the shot according to size. The stack of sieves is rotated and tapped (Figure 6) automatically for 5 to 15 minutes after which the amount on each screen is weighed and compared to the specifications. The shape inspection is performed on a sample of media, usually in a half-inch square field with a stereo view at 10X to 30X magnification. U n a c c e p t a b l e shapes are counted and compared to specification values for acceptance or rejection of the media.
PROCESS CONTROLS Peening can be controlled manually, automatically, or somewhere in between. Today, even the tightest specifications on a simple p a r t can be achieved
w i t h i n the confines of a p e e n i n g cabinet. By adding various accessories, such as nozzle oscillators, p a r t fixtures, flow-control and m o n i t o r i n g devices, and p r o g r a m m a b l e nozzle-motion controls, repeatability becomes an easily documented reality. The growing v e r s a t i l i t y offered by increasingly effective programmable controls continues to draw more manufacturers and job shops toward peening in-house where they have a tighter grip on quality control. At the same time, producers of peening equipment are responding to demand by tailoring products to m a r k e t needs. As a case in point, an FAA-certified repair center for jet-engine parts w a n t e d to bring precision-peening work on disks and hubs in-house without stressing finances for new machinery. R e q u i r e m e n t s for the peening s y s t e m included automated features to control air pressure, media quality, shot-flow rate, processing times, and blastnozzle movements, plus the ability to peen exterior slots and interior holes on components of various sizes. Other features, such as fault sensors, pressure regulators, flow monitors, and shot classifiers, were You've got anodizing problems. We've got anodizing solutions custom-designed to meet your needs, your delivery schedule and your cost parameters. First, we listen to your requirements. Then, using state-of-the-art Computer Aided Design, our engineers input those requirements as part of the design process to produce whatyou need to precisely fit your operation, whether it is tlt~niHmor ~h]mim]m r~k~ cwfn~tonor~ And ~nlvinonrnhlom~
VULCANIUM° Northbrook, IL 60062 USA Toll-free: 888-922-0052 (outside IL) • Direct: 847-313-4843 E-Marl: [email protected]
www.¥ulcanium.com Circle 031 on reader information card or go to www.thru.to/webcoanect M a r c h 2005
Circle 048 on reader information card or go to www.thru.to/webconnect 23
implemented not only to assure tight quality control, but also to open avenues for the repair shop to accrue future, and possibly more demanding, new business. Because the machine was equipped with programmable controls (Figure 7), part changeovers could be accomplished in a matter of minutes once processing parameters had been established and stored in the controller.
"The FAA Elevates Shot Peening," The Shot Peener, 18(2):4-7; 2004. Heaton, R.B., "Shot Peening," Metal Finishing, 87(7)25-31; 1989. U.S. 5235517; 1993. Heaton, R. B., "Meeting Shot-Peening Specs while Controlling Equipment Costs," Metal Finishing News, 3, 14-15; November 2002.
BACK TO THE LAB Aerospace peening specifications normally evolve from trial and error based on destructive tests, including mechanical testing and X-ray diffraction residual-stress measurement. As indicated previously, finding the right mix of peening parameters requires a lot of science. Aircraft designers continue to expand the envelope of"lighter, stronger, and longer" by exploiting the potential of shot peening to enhance component performance and durability. Manufacturers of peening equipment also spend many hours in test facilities (Figure 9) to produce machinery capable of meeting production specifications. Often, equipment proposals alone require extensive testing with sample parts to develop reliable, cost-effective, and creative approaches that exploit the growing capabilities of programmable controls. Because this technology provides a reliable and flexible means for automating--and repeating--critical peening processes, it has been a boon to practitioners as well as those of us who rely on the benefits of peening every time we fly.
Robert Heaton, during 30 years at Empire Abrasive Equipment Co., has contributed to the design of shotpeening systems and has worked closely with a number of major US. aircraft component manufacturers and airlines to develop peening specifications, operator training programs and automated peening systems. He currently directs laboratory operations at Empire. He can be contacted at (e-mail) [email protected].
REFERENCES O'Hara, P., "Dyescan Tracers as a Quality Control Tool for Coverage Documentation in Controlled Shot Peening," (SAE 850708); 1985.
Jack Champaigne is president of Electronics Inc., a developer of control components used in shot-peening equipment. He has been instrumental in creating training courses for peening practitioners and FAA inspectors. He plays an active role on SAE committees for shot-peening specifications and is a member of the International Scientific Committee on Shot Peening. Champaigne can be contacted at (e-mail) [email protected]. John Cammett works with the U.S. Navy to analyze aircraft-component failures and develop remedial solutions. During 25 years with private companies, including General Electric, he studied many aspects of metal fatigue in aircraft engines. He is a past chairman and current member of A S M International. Cammett can be contacted at (e-mail) john.cammett@navy, mi. IT/[
/ / ~ Kushner Electroplating School "Training ElectropJaters Since 1947"
" ' "
WEBRING TRAININGTO YOU V' V' V' V'
Focuson topics critical to your tasks ~ Industryrecognizedtraining materials No travel expenses or time away from your plant Training materials suitable for future reference
Call, f a x or e-mail f o r i n f o r m a t i o n a n d free q u o t a t i o n t
L
Circle 025 on reader information card or go to www.thru.to/webconnect 24
,
732 Glencoe Court, Sunnyvale, CA 94087 (408) 749-8652 • Fax (408) 749.0176 E-maih info@platingschool,com www.platingschool.com
Circle 028 on reader information card or go to www.thru.to/webconnect www.metalfinishing.com
he daring knights of yore somehow stumbled upon peening as a m e t h o d for saving their hides. Pounding a sword blade with a rounded h a m m e r extended the life of the weapon and, no doubt, the life of its owner as well. To this day, peening has far-reaching safety consequences as manufacturers strive to produce stronger, lighter products, particularly in the fields of automobile and aircraft production. Automobile manufacturers often peen defensively, meaning t h e y fall back on the process to strengthen a spring, gear, connecting rod, anti-roll bar, or other component that fails prematurely. Because its products travel at higher altitudes, the aerospace industry takes a more proactive approach through the development of stringent peening specifications, in which adherence must frequently be documented. Two primary factors drive Figure 1: Today's aircraft, both aerospace's attention to benefits of shot peening to fly peening details and documentation. For starters, a tight paper trail helps trace a potential part problem if a catastrophe occurs. Secondly, the industry relies heavily on shot peening technology to keep its products flying lighter and longer. Modern planes depend on the capability of shot peening to strengthen blades, roots, stators, gears, discs, combustion chambers, structural members, and many other parts too numerous to mention (Figure 1). Peening offers a big lift for the aerospace industry, but it must be tightly controlled to achieve anticipated performance gains. Because rigorous control is central to peening effectiveness, shock waves reverberated throughout the aviation i n d u s t r y w h e n three m e n associated with the St. Charles Metal Finishing Co. in St. Louis, were sentenced to jail terms in 1992 for falsi-
T
18
fying inspection reports related to the peening of parts used in 1,000 fighter planes built by McDonnell Douglas Corp. As a consequence, the Pentagon delayed acceptance of F-15 Eagles, F/A-18 Hornets, and AV-88 Harriers, as well as Harpoon and Stand-off Land-attack missiles. On civilian aircraft, off-spec or nonexistent shot peening has been cited as the cause of failures on parts ranging from engine shafts to landing gears. Recognizing the importance of sound peening practices, the FAA (U.S. Federal Aviation Administration) now assumes responsibility for educating its auditors and inspectors on shot peening and proper shot peening p r o c e s s e s in airlines, job shops, and repair facilities. In fact, one of this article's authors (Champaigne) has been i n s t r u m e n t a l in developing shot peening military and civilian, rely on the training programs now lighter and longer. a t t e n d e d regularly by FAA employees. BENEFITS OF PEENING Though peening can perform a variety of odd jobs, such as expanding undersized parts and improving oil retention, enhancing the fatigue strength of metals is its p r i m a r y role. This cold-working process relies on the action of small spheres impacting meta]s at high velocities to create plastic deformation and resulting compressive-residual-stress distributions on and beneath metal surfaces. When used to optimal effect, peening delivers truly amazing results, in-cluding fatigue-life gains in components of 10 times or more, with no decrease in applied stress limits and/or increases in maximum stress tolerances up to 40% with no decrease in life. www.metalfinishing.com
Exploiting the full potential of peening in new applications, however, can involve a substantial amount of work. Many factors-i n c l u d i n g shot size and type, coverage, intensity, and blast a n g l e s - - m u s t often be t e s t e d and optimized to a t t a i n the most productive relationship bet w e e n t h e process and component perf o r m a n c e and dura-
INTENSITY
Figure 2: M o d e m Almen gauges provide precise readings of strip deflections used to meas-
ure peening intensity.
bility. D e v e l o p i n g specifications to maximize shot peening benefits on c o m p o n e n t s not p r e v i o u s l y p e e n e d r e q u i r e s the application of theory, history, and e x p e r i m e n t , f r e q u e n t l y involving d e s t r u c t i v e testing.
& COVERAGE STANDARDS
Although shot peening practitioners need not repeat the science supporting the specification, they better be on target, particularly in aerospace applications. Specifications for components as small as jet-engine turbine blades may run to many pages detailing masking requirements and separate treatments for roots and blades. A device known as the Almen strip is central to most peening specifications, despite some recent reservations about the specific correlation between strip deflection and compressive residual stress. Developed by J.O. Almen of General Motors Research Laboratories in the 1940s, the Almen strip provides a method for measuring, specifying, and duplicating peening intensity. The concept is based on the premise that a thin, flat piece of metal, mounted on the surface of a solid block, will continue to arc convexly in proportion to the kinetic energy delivered by impacting shot and resulting deformation created until "saturation" is achieved. "Saturation" is defined as the earliest point on the arc height-exposure time curve, when doubling exposure times, produces an increase of 10% or less
Clean, Peen, Finish and More
:omatically! CI is the industry's leading single-source manufacturer/supplier of the most costeffective, efficient and versatile filters for your specific spray b operation, including:
=,,y ,,,u,,- . . . . . . . . . . . . -u,ast job. Our hundreds of automated systems continue to cut costs and improve quality in applications ranging from deburring hypodermic needles to etching 6' x 15' sheets of stainless steel. Whether it's high-speed cleaning or precision peening, Empire can deliver the air-blast system to meet your needs.
• Spray booth intake filters • Diffusion media • Overspray collectors • Booth/floorprotective covering • Hardware/accessories
We
• HVAC filters
Performance Engineered A i r F ......
IlUlIIIII I n d u s t r i e s , Inc. Call: (740) 983-2552 E-maih [email protected] Visit our new website at www.colind.com
Circle 052 on reader information card or go to www.thru.to/webconnect March 2005
Have
It
All/
• A u t o m a t e d S y s t e m s • Blast C a b i n e t s • H o f f m a n Blast R o o m s • P o r t a b l e Blasters
• MACT compliant systems
, IllUUUIN°Columbus
can t r i g g e r :s in a l m o s t
F.MPIRE
TM
ABRASIVE EQUIPMENT
2101 West Cabot Boulevard, Langhorne, PA 19047-1893 Call: (215)752-8800 E-Maih [email protected] Fax: (215)752-9373 Visit: www.empire-airblast.com
Circle 019 on reader information card or go to www.thru,to/webconnect 19
Figure 3: Multiple blast nozzles provide processing flexibility by targeting different areas and facets of work surfaces.
Figure 4: An oscillating lance, which diverts shot direction sideways, peens the interiors of holes and recessed areas.
in arc height. To measure arc height, one places the peened Almen strip in an Almen gauge. Modern Almen gauges (Figure 2) resolve to 0.0001
For more information contact:
Figure 5: Programmable peening machine includes recycling equipment designed to assure consistent shot quality.
Figure 6: A stack of sieves, rotated and tapped automatically, segregate shot samples for inspection.
inch, thereby assuring sufficient accuracy and precision to properly m e a s u r e arc heights from which Almen intensity is derived.
Field kits & meters for everything from Alkalinity to Zinc as well as combination outfits for all types of water analysis.
H E N T ZIIIIIIIEIII N I HENTZEN COATINGS, INC. AEROSPACE DIVISION 6937 W. Mill Road, Milwaukee, Wl 53218 Ph: 414-353-4200 Fax: 414-353-0286 Ernail: Coatinqs(~He ntzen.com ISQ 9001:2000 Certified Circle 026 on reader information card or go to www.thru.to/webconnect
20
4-3100 ~own• MD • 21620 ~x410-778-6394 ~tte,com Circle 029 on reader information card or go to www.thru.to/webconnect
www.metalfinishing.com
Figure 7: Programmable controls enable operators to designate processing procedures by simply inputting the appropriate part-identification number.
Figure 8: Equipment manufacturers employ test laboratories to experiment w i t h various approaches for meeting customers' peening requirements at competitive costs.
INSPECTION M E T H O D S Traditionally, an inspector views the peened surface at magnification (10X to 30X) to assess coverage. Flat surfaces on softer metals are the easiest to inspect. Complex geometrical shapes or parts with holes, the most likely spots for underpeening and eventual cracking, present problems because of restricted visibility. Harder metals pose difficulties because of shallow indents, which may not be optically observable. These challenges may be mitigated with the appli-
HEAVY.METALRECOVERY Purify Recycle REASCO Modular Ion Exchange CrPur TM Chromic Acid Purification REASCO Modular Electrowinning Turn-Key Recycling Solutions
@
HAS A NEW HOM£.
and get everything it stands for.
RECOVERY ENGINEERING & S A L E S C O M P A N Y , INC. P.O. Box 297, Arvada, Colorado 80001-0297 U.S.A. TEL: 303-292-5702 FAX: 303-292-5717
www.reasco,
corn
Circle 037 on reader information card or go to www.thru.to/webconnect March 2005
UDYLITE
Automatic Machines, Parts and Service Call for ODYLITE equipment
D.I. Water Rinse Water Recovery Bath Purification E f f l u e n t Polishing Closed Loop Systems
1-800-570-0295
PEENING EQUIPMENT Peening e q u i p m e n t normally relies on either a mechanical or p n e u m a t i c system to propel shot.
UDYLITE SYSTEMS • FANTA SERVICE
• Heavy Metal Recovery • • • • •
cation of tracer coatings, which provide a colorful landscape of peening coverage. Computer analysis, using either contact or electromagnetic data, may be employed to minimize subjectivity. In essence, the computer approach compares a desired surface profile with an actual profile obtained after peening to determine if results fall within acceptable coverage parameters.
Circle 020 on reader information card or go to www,thru.to/webconnect 21
Mechanical systems offer energy-saving advantages in mass production. Rotating wheels with blades impart momentum directly to the shot and are capable of delivering large volumes of media at high velocity. Accessory equipment must often accompany these systems to turn or roll workpieces because the shot stream is unidirectional. Also, "hot spot" adjustments may be required because these machines produce a wide pattern in comparison to their actual work focus. Controlling shot momentum, however, is a simple matter of selecting the desired wheel speed because the "thrown" shot maintains a relatively uniform velocity. Pneumatic peening systems take two approaches, commonly known as "suction" and "pressure." The fundamental difference between the two is that a suction system relies on pressure differential created by moving compressed air to draw shot from an unpressurized storage hopper into a blast gun from which it is expelled onto the work surface. In a pressure system, the entire arrangement, including the shot-storage vessel, is pressurized. When actuated, the system feeds shot from the vessel into a pres-
surized feed line connected to blast nozzles, which focus shot on the work surface. Pressure systems have the advantage of using compressed air more efficiently than suction systems while providing more precise control of shot velocities at both high and low operating pressures. Suction systems, on the other hand, simplify the use of multiple blast guns and are normally less expertsive and easier to maintain. In both cases, however, the ability to deploy multiple blast outlets (Figure 3) capable of tracing contoured surfaces gives pneumatic systems a major edge over mechanical systems in peening parts with complex geometrical contours and with reeentrant indents or holes (Figure 4). Regardless of the system selected, peening to specifications requires proper maintenance of peeningmedia quality. Besides reducing the size, depth, and shape of indentations, degraded shot may also cut or abrade the work surface, thereby reducing desired peening effects. Even the highest quality shot begins to break up after multiple impacts, at which point its remnants must be removed from the processing equipment. Most often this cleanup is accomplished
Selling Your Company... • • • •
All Cash Deals P r e m i u m Prices O b t a i n e d Negotiating Power Personalized, Tailored Service
A corporate sale is a complex task. Our street-smart entrepreneurial approach guides you through the entire process. We are experienced, seasoned professionals, who successfully complete more acquisitions per person than any other firm. M y company negotiates a transaction structure that protects o u r clients from post-closing litigation. For additional information about our unique services, contact:
D
GEORGE SPILKAAND ASSOCIATES Merger & A c q u i s i t i o n C o n s u l t a n t s Suite 301, 4284 Route 8 Allison Park, PA 15101 412/486-8189 • email" [email protected]
www.georgespilka.corn Circle 055 an reader information card or go to www.thru.to/webcennect 22
Comparisons are good! It takes two of this popular brand filter to reach the efficiency and life of one Andreae Filter. Want to compare pricing? We do too! One Andreae Filter cost the same as one of theirs'. Enough said! .....~,~.,i!~!~ =
Ca//for a Free Filter Tri No Cost or Obligation/ 800-891-9785
........
i
......
......
Circle 051 on reader information card or go to www.thru.to/webconnect www.metalfinishing.com
with a classification system (Figure 5) that maintains correct shot-size distribution and eliminates misshapen and broken media as well as debris and foreign objects. The shot is also subjected to inspection for maintenance of shape and size according to specifications. The analysis is performed with a sample of 100 grams of shot placed into a stack of nested standard sieve screens that segregate the shot according to size. The stack of sieves is rotated and tapped (Figure 6) automatically for 5 to 15 minutes after which the amount on each screen is weighed and compared to the specifications. The shape inspection is performed on a sample of media, usually in a half-inch square field with a stereo view at 10X to 30X magnification. U n a c c e p t a b l e shapes are counted and compared to specification values for acceptance or rejection of the media.
PROCESS CONTROLS Peening can be controlled manually, automatically, or somewhere in between. Today, even the tightest specifications on a simple p a r t can be achieved
w i t h i n the confines of a p e e n i n g cabinet. By adding various accessories, such as nozzle oscillators, p a r t fixtures, flow-control and m o n i t o r i n g devices, and p r o g r a m m a b l e nozzle-motion controls, repeatability becomes an easily documented reality. The growing v e r s a t i l i t y offered by increasingly effective programmable controls continues to draw more manufacturers and job shops toward peening in-house where they have a tighter grip on quality control. At the same time, producers of peening equipment are responding to demand by tailoring products to m a r k e t needs. As a case in point, an FAA-certified repair center for jet-engine parts w a n t e d to bring precision-peening work on disks and hubs in-house without stressing finances for new machinery. R e q u i r e m e n t s for the peening s y s t e m included automated features to control air pressure, media quality, shot-flow rate, processing times, and blastnozzle movements, plus the ability to peen exterior slots and interior holes on components of various sizes. Other features, such as fault sensors, pressure regulators, flow monitors, and shot classifiers, were You've got anodizing problems. We've got anodizing solutions custom-designed to meet your needs, your delivery schedule and your cost parameters. First, we listen to your requirements. Then, using state-of-the-art Computer Aided Design, our engineers input those requirements as part of the design process to produce whatyou need to precisely fit your operation, whether it is tlt~niHmor ~h]mim]m r~k~ cwfn~tonor~ And ~nlvinonrnhlom~
VULCANIUM° Northbrook, IL 60062 USA Toll-free: 888-922-0052 (outside IL) • Direct: 847-313-4843 E-Marl: [email protected]
www.¥ulcanium.com Circle 031 on reader information card or go to www.thru.to/webcoanect M a r c h 2005
Circle 048 on reader information card or go to www.thru.to/webconnect 23
implemented not only to assure tight quality control, but also to open avenues for the repair shop to accrue future, and possibly more demanding, new business. Because the machine was equipped with programmable controls (Figure 7), part changeovers could be accomplished in a matter of minutes once processing parameters had been established and stored in the controller.
"The FAA Elevates Shot Peening," The Shot Peener, 18(2):4-7; 2004. Heaton, R.B., "Shot Peening," Metal Finishing, 87(7)25-31; 1989. U.S. 5235517; 1993. Heaton, R. B., "Meeting Shot-Peening Specs while Controlling Equipment Costs," Metal Finishing News, 3, 14-15; November 2002.
BACK TO THE LAB Aerospace peening specifications normally evolve from trial and error based on destructive tests, including mechanical testing and X-ray diffraction residual-stress measurement. As indicated previously, finding the right mix of peening parameters requires a lot of science. Aircraft designers continue to expand the envelope of"lighter, stronger, and longer" by exploiting the potential of shot peening to enhance component performance and durability. Manufacturers of peening equipment also spend many hours in test facilities (Figure 9) to produce machinery capable of meeting production specifications. Often, equipment proposals alone require extensive testing with sample parts to develop reliable, cost-effective, and creative approaches that exploit the growing capabilities of programmable controls. Because this technology provides a reliable and flexible means for automating--and repeating--critical peening processes, it has been a boon to practitioners as well as those of us who rely on the benefits of peening every time we fly.
Robert Heaton, during 30 years at Empire Abrasive Equipment Co., has contributed to the design of shotpeening systems and has worked closely with a number of major US. aircraft component manufacturers and airlines to develop peening specifications, operator training programs and automated peening systems. He currently directs laboratory operations at Empire. He can be contacted at (e-mail) [email protected].
REFERENCES O'Hara, P., "Dyescan Tracers as a Quality Control Tool for Coverage Documentation in Controlled Shot Peening," (SAE 850708); 1985.
Jack Champaigne is president of Electronics Inc., a developer of control components used in shot-peening equipment. He has been instrumental in creating training courses for peening practitioners and FAA inspectors. He plays an active role on SAE committees for shot-peening specifications and is a member of the International Scientific Committee on Shot Peening. Champaigne can be contacted at (e-mail) [email protected]. John Cammett works with the U.S. Navy to analyze aircraft-component failures and develop remedial solutions. During 25 years with private companies, including General Electric, he studied many aspects of metal fatigue in aircraft engines. He is a past chairman and current member of A S M International. Cammett can be contacted at (e-mail) john.cammett@navy, mi. IT/[
/ / ~ Kushner Electroplating School "Training ElectropJaters Since 1947"
" ' "
WEBRING TRAININGTO YOU V' V' V' V'
Focuson topics critical to your tasks ~ Industryrecognizedtraining materials No travel expenses or time away from your plant Training materials suitable for future reference
Call, f a x or e-mail f o r i n f o r m a t i o n a n d free q u o t a t i o n t
L
Circle 025 on reader information card or go to www.thru.to/webconnect 24
,
732 Glencoe Court, Sunnyvale, CA 94087 (408) 749-8652 • Fax (408) 749.0176 E-maih info@platingschool,com www.platingschool.com
Circle 028 on reader information card or go to www.thru.to/webconnect www.metalfinishing.com