Shot Peening Media
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Transcript of Shot Peening Media
What is Shot peening ? Shot peening is a cold working process used to
produce a compressive residual stress layer and modify mechanical properties of metals.
It entails impacting a surface with shot(round metallic, glass, or ceramic particles) with force sufficient to create plastic deformation.
It is similar to sandblasting, except that it operates by the mechanism of plasticity rather than abrasion: each particle functions as a ball-peen hammer.
In practice, this means that less material is removed by the process, and less dust created.
Shot Peening Media In this time has 5 Media of shot peening that used in
markets. There are
Cut wire shot
Cut wire shot heat treatment
Steel shot
Ceramic shot
Fine particle shot
Cut wire shot Cut wire shot is created by cutting drawn steel wire to
lengths approximately the same size as the width of the wire. The resulting wire is then rounded to remove the sharp edges.
It has many shape such as Cylindrical, Rounded , Spherical.
Cut wire shot (Cont.) Advantages
Tends to wear down into smaller diameter rather than fracture into particles with sharp edges.
Produces uniform results due to its consistency in size, shape, and hardness.
More durable (longer life) than cast steel, glass, and ceramic shot.
Available in carbon steel and stainless steel.
Ability to achieve the highest intensity.
Easiest to maintain spherical particles.
Disadvantages High material cost
Limited sizes
Cut wire shot heat treatment It is created like cut wire shot but bring it to heat
treatment before used.
Advantages
It has advantages same cut wire shot but it has more durable (longer life) than cut wire shot.
Disadvantages
It has prepared difficult more than cut wire shot.
High material cost and Limited sizes.
Steel shot Steel shot are created by atomizing molten steel, then
heat treating and sieving the resulting material.
Such as Cast steel beads, Hi-Carbon steel beads, Stainless steel beads, etc.
Steel shot (Cont.) Advantages More durable (longer life) than glass and ceramic shot
Available in carbon steel and stainless steel
Ability to achieve the highest intensity
Easiest to maintain spherical particles
Disadvantages More difficult than cut wire shot to maintain spherical
particles
Less durable than cut wire shot
High material cost
Ceramic shot In this days have 2 type that used, there are
Glass shot
Zirshot
Glass shot Zirshot
Glass shot Glass shot is created by atomizing molten soda lime, then
sieving the resulting material.
Advantages Available in wide range of sizes
Low cost material
Inert material, will not cause ferrous contamination or leave residue on work piece .
Environmentally friendly
Disadvantages More difficult than steel media to maintain spherical
particles
Less durable than steel and ceramic media
Zirshot
Zirshot is ceramic shot that have compound between ZrO2 , SiO2 and Al3O2
Advantages
Density in the middle of the range between glass and steel : process versatility.
Smooth surface : not abrasive
Round shape : high peening ability
Chemically inert : no contamination
High mechanical strength and hardness level : high impact efficiency, weak consumption rate
High impact strength versus glass beads and steel beadsZirshot (Cont.)
Glass beads explode generate dust which is sticking to the beads. After 10 cycles, only glass dust is remaining.
In the meantime, this dust is sticking to the beads, and they become aggressive.
Steel shot is wearing and breaking according to its hardness, generating dust. Hardness, shape, hardness and smoothness.
Ceramic beads are breaking into pieces, but not wearing. They produce no dust and keep their initailsize, shape, hardness and smoothness.
Zirshot (Cont.)
Zirshot (Cont.) Disadvantages
High material cost
Can not distort close-tolerance parts.
[5]
Fine Particle Shot Peening (FPSP)
Fine particle shot peening is fine, powder like spherical media (20-200 µm in diameter) thrown against metal surfaces at speeds of more than 100 m/sec.
The typical hardness of FPSP media, which can be metallic, ceramic or glass, is 750-1000 HV.
The machine used in the process is a modified pneumatic shot peening system. Like conventional shot peening.
FPSP improves fatigue strength and stress corrosion fracture resistance. Its greatest additional benefit is that it produces a very smooth surface finish.
Fine Particle Shot Peening (Cont.) Shot peening advantages
Greatly improves strength and fatigue resistance.
Well-known process that is relatively inexpensive to implement.
Has substantial research and quality controls to enhance its value.
Media and equipment are readily available.
Creates a pebbly surface that is advantageous in certain applications.
Shot peening disadvantages
Pebbly surface finish isn’t suitable for all applications
Can distort close-tolerance parts
Fine Particle Shot Peening (Cont.) Fine particle shot peening advantages
Improves surface hardness and wear resistance Ultra-smooth surface is ideal for bearings,seals,
or close-tolerance areas Will not distort close-tolerance parts Will not damage soft or fragile parts
Fine particle shot peening disadvantages Limited availability in U.S. and Europe. Media can be difficult to use and few equipment
and media manufacturers are experienced with it. Limited depth of compression might make it unsuitable
for some applications.
In present Fuji Kihan Company and Fuji SeisakusyoCompany have patented a fine particle peening process that they market to the Japanese automotive.
They have licensed this technology to over 130 companies and 80% of these are Japanese auto and auto part manufacturers. Japan also has a FPSP Society.
It has several papers for research and development FPSP such as “Fatigue Property Enhancement by Fine Particle Shot Peening for Aircraft Aluminum Parts” by A. Inoue,T. Sekigawa and K. Oguri with Mitsubishi Heavy Industries presented According to the abstract :
Fine Particle Shot Peening (Cont.)
Fine Particle Shot Peening (Cont.)
Fatigue life of conventional shot peened aluminum parts was increased by several times, while that of FPSP aluminum was increased by more than 10 times compared with that of as-machined.
The compressive residual stress on FPSP surface covered adequately with uniform dimples is higher than that on shot-peened surface.
Fracture surface observation revealed that the fatigue crack of FPSP samples originate at the subsurface layer, which shows the high compressive residual stress at very near the surface and the less-roughened surface prevents crack initiation from the surface.
FPSP can improve fatigue life more than shot peening, which shows fatigue crack initiates from small flaws and laps on the surface created by shot peening.
Fine Particle Shot Peening (Cont.)
Life Cycle / cycleS-N Data (63 μ in finish)
Reference Gillespie,R.D. Shot peening media,Its Effect on Process Consistency and
Resultant Improvement in Fatique Charateristics.Premier shot company,Cleveland,Ohio,USA.
Kathy Levy . The Shot Peener Winter 2010, Special Application Review: Fine Particle Shot Peening. Page 4-6
http://en.wikipedia.org/wiki/Shot_peening
http://www.indmetfin.com/Services/ShotPeeningMedia.aspx
http://szhlda.51ev.org/group-Abrasive-Tools/544157/Ceramic-shot-peening-surface-treatment.html
http://www.zirpro.com/