FAQ
General Peening Process
What is peening?
Peening is a cold working process where media is propelled onto the surface of components to induce a thin layer of compression to reduce the initiation and propagation of crack thus improving the fatigue life of the components.
Why peening?
Peening increase fatigue life of components without increasing their weight.
What is fatigue life of a component?
Number of low level loading cycles that a component can sustain until a crack initiates and grows to a critical levels.
What is the difference between peening, flapper peening, roto peening, needle peening?
These peening processes have the same objective to induce a thin layer of compression on the surface of components but use different methods to do this. Conventional Peening uses air pressure or wheel motion to propel the media. Flapper peening, also known as roto peening, uses rotating flaps with rows of tungsten carbide balls to strike the surface. Needle peening uses tungsten carbine needles that are moved up and down perpendicularly to impact the surface.
What material can be peened?
All metal components can be peened. Aluminum, steel, hardened steel, titanium, Inconel, etc.
What components can be peened?
Most metal components can be peened although peening is often reserved for critical structural members. Example include Lower Wing Skins, Landing Gears, Wheels, Critical Structural Members, Ribs, Spars, Flap Tracks, Engine Components, Disks, Blisks, Blades, and many more.
What is peening intensity?
Peening intensity is a measure of the force of impact of the media against the surface of the component.
How do I measure intensity?
A method to measure peening intensity was defined many years ago by a man named Almen. This method uses the deformation, or arc height, of thin strips of metal called Almen strips to measure the force of impact of the media. This deformation of the thin strip depends on many factors such as hardness of the shot peening media, the velocity of the shot peening media, the angle of impact of the shot peening media, the flow rate of the shot peening media (amount of impacts). Intensity is found by generating a saturation curve and calculating the intensity from the curve. Almen Strips are most commonly used to find intensity but new methods are now available to measure the velocity of the media (Velocity Meter) or to measure the impact force directly (E-Strip®).
What is an Almen Strip?
Almen strips are made of SAE1070 spring steel and are classified into three types based on thickness: A, N, and C. An Almen strip is peened on one side only. The residual compressive stress from the peening will cause the Almen strip to bend or arc towards the peened side.
What is a saturation curve?
A saturation curve is a method to determine peening intensity. Almen strips are exposed to a shot stream for varying amounts of time with all other parameters fixed. The arc height of the almen strips are plotted verses exposure time. A best fit curve is generated through the points. The first point on the line (not necessarily a data point) when time is doubled at which the arc height increases by 10% is called the saturation point and is defined as the intensity.
What is the Shockform Saturation Curve Solver?
The Shockform Saturation Curve Solver (SSCS) is a user friendly application that will quickly and easily plot your saturation curve data and find the peening intensity using the 10% rule. No more confusing Excel spreadsheet to fiddle with! The SSCS can be used for conventional peening and for rotary flapper peening.
Why sometimes we see 8A and 20A?
Intensity is often measured in thousands of inches (0.008A) but is often called out as 8A. This can lead to confusion since measurements can also be made in millimeters for the metric system where an 0.008A inch becomes 0.203A mm.
What is coverage?
Coverage of the surface of a component is defined as the percentage of the surface impacted or dimpled by the shot peening process. In the shot peening process, a full or 100% coverage is often requested although it is only a theoretical limit. A coverage of 98 % is defined as full coverage and if often mandatory.
How can I measure coverage?
Coverage is determined by visual inspection of the surface using a 10x, 20x or 30x magnifier.
Why do some drawings asks for 100% coverage and other 200%?
A 100% coverage is usually required for fully automated peening while 200% coverage is required for manual peening. A 200% coverage does not change the depth or properties of the compression layer. It is more like a safety factor when peening.
How do I calculate 100% or 200%?
Coverage to 100% is determined by visual inspection of the surface using a 10x, 20x or 30x magnifier. A 100% coverage is defined as complete dimpling of the surface. To reach 200% coverage, the time required to reach 100% is noted and applied again to the surface. For example, if 2 minutes of peening were required to reach 100% coverage as inspected using a 10x, 20x or 30x magnifier then an additional 2 minutes of peening would be required for 200% coverage.
2 minutes of peening = 100% coverage
2 minutes + 2 minutes = 100% + 100% = 200% coverage
Why is certain drawings call for time and other coverage?
All recent specifications and drawings define coverage by surface inspection using a 10x, 20x or 30x magnifier. When the inspection of the peening surface with magnifier reveals full coverage, peening is complete. Some older specifications determined coverage time by factoring the time to reach intensity on the Almen strips. This method falsely assumes that the component peened is made of the same material as the Almen strip and will therefore require a time proportional to the peening time on the Almen strip.
Why is time not the reference?
Time to reach intensity is no longer used to define coverage because the material of the Almen strip is seldom the same as the material of the component. If the component material is softer than the Almen strip material, the component will be over peened and if the component material is harder than the Almen strip material, the component will be under peened. The method where a magnifier is used will result in the proper coverage for the component material.
How do I prepare the surface before peening? Can I peen over paint?
Peening can only be performed on clean surfaces without paint, coatings, grease, dirt or oil. The surface must also be free of corrosion and damage for maximum efficiency.
Where can we use flapper peening?
Flapper peening is often used to re-peen small areas where the surface compression from the original peening was damaged or removed. Flapper peening can be used on most metallic components as long as the tungsten carbide balls on the flaps can properly impact the surface of interest. The best tool for flapper peening is the FlapSpeed® PRO developed by Shockform.
Where can we use needle peening?
Just like flapper peening, needle peening was developed to re-peen small areas where the surface compression from the original peening was damaged or removed. The difference is that needle peening does not produce FOD and can be used on fully assembled aero-engines. Needle peening can be used on most metallic components as long as the tip of the tungsten carbide needles can properly impact the surface of interest. The best tool for needle peening is the Spiker® developed by Shockform.
Can I use flapper peening or needle peening to peen large surfaces?
Peening larges surfaces with flapper or needle peening tools is not recommended because it would take too much time. That being said, peening a fully assembled component using loose media with compressed air of wheel methods requires bagging to avoid media flying everywhere, masking to peen only the area of interest and cleaning after peening to remove all loose media. These three steps often require more time than flapper peening or needle peening.
Products FlapSpeed® Controller
What is a FlapSpeed®?
The FlapSpeed® PRO is a flapper peening tool that will help you find the right peening parameters for a certain peening intensity and will ensure that the selected RPM is maintained throughout the peening process.
When can I use the FlapSpeed® PRO?
The FlapSpeed® PRO can be used whenever a drawing, engineering order, technical document or manual calls for flapper peening.
Boeing Spec BAC5730-2 says that if I use the FlapSpeed®, I don't need to do a Saturation Curve. Why?
Extensive testing at Boeing has demonstrate that using a FlapSpeed® controller to continuously monitor and adjust the RPM during the flapper peening process produces very repeatable results in terms of intensity. It is therefore no longer necessary to produce a saturation curve and find the intensity when using the FlapSpeed® controller.
Can I use the FlapSpeed® with metrics or imperial intensity and with different voltage?
The FlapSpeed® Controller works at all voltages between 110v and 220v and can display results in inches and millimeters.
Can I do A, N and C range with the FlapSpeed®?
Yes it is possible to A, N and C type intensities with the FlapSpeed®.
Why do I have a USB key on the FlapSpeed® controller?
The USB key on the FlapSpeed® controller allows the operator to save reports and Saturation Curves and print them from a computer.
Do I need to calibrate the FlapSpeed® controller?
The FlapSpeed® controller needs to be calibrated on a yearly basis.
Can I send you the handpiece only for calibration?
It is necessary to have the handpiece and the controller to perform a good calibration.
What intensity can be achieve with flapper peening in general?
With flapper Peening it is possible to achieve intensities from 0.004A to 0.0165A inches. This corresponds to a rotational speed from 1500 rpm to 6000rpm.
What is the range of intensities that the FlapSpeed® can achieve?
The FlapSpeed® can achieve all intensities possible with flapper peening.
What is the correct RPM for the intensity I want to reach?
The correct RPM is the rpm that will provide you with the intensity you are seeking.
Do I need to generate a Saturation Curve?
It is preferable to generate a new saturation curve for a new job unless an existing saturation curve can be used. In flapper peening, a saturation curve is necessary for each operator.
Why is there different flaps and what's the difference between the different types of Flaps?
Three different flaps exist. The small one has a dimension of 9/16 x 1 inch, the middle one has a dimension 9/16 x 1 ¼ inch and the large one has a dimension of 1 x 2 inch. The middle sized flap is the most common one and allows you to reach intensities from 0.004A to 0.012A inch. The smaller flap allows you to reach lower intensities while the larger flap allows you to reach higher intensities.
Why is there different mandrels and what's the difference between the different types of Mandrels?
Mandrels are made to work with one of the 3 flap size. They also come in different lengths to facilitate access to hard to reach locations.
Why is there a magnetic holder?
The standard holder with the screws cannot be used for flapper peening because the balls on the flaps get dislodged when hitting the screws. A magnetic holder was invented for flapper peening.
The flap keeps sliding out of the mandrel. What should I do?
The mandrel needs to be squeezed with pliers at the flap location to firmly hold the flap in place. Pliers are provided with the FlapSpeed® controller.
I am not getting the intensity predicted by the FlapSpeed® at a specified rpm. What should I do?
Obtaining a low intensity at a specific RPM can be caused by a few things. The flapper peening technique of the operator might be at cause because de flap is too high from the surface of the Almen strip. This is common for new operator. Lowering the flap closer to the surface of the Almen strip will increase intensity. Another common issue is that the flap is old and flimsy. A new flap will usually generate better results in line with the predicted intensity in the FlapSpeed® controller.
I have one or more tungsten carbide balls missing from the flap after some light usage, what is going on?
It is normal for tungsten carbide balls on the flap to become dislodged with peening usage. This will be accelerated if the peening is performed at high rpm or if the geometry of the part being peened has edges that catch the balls as they rotate.
Where can I find more information about the FlapSpeed®?
Shockform is the original equipment manufacturer (OEM) of the FlapSpeed® controllers. Visit our web site at www.shockform.com of call us at (450) 430-8000. During regular business hours, someone is always available to talk to you.
How can I reach you if I have technical issues?
Call us (450) 430-8000 or send us an email at sales@shockform.com and we will help with your technical issue.
Products Spiker® Needle Peener
Do I need to calibrate the Spiker®?
Calibration of the Spiker® is required on a yearly basis.
Can I send you the handpiece only for calibration?
It is necessary to have the handpiece and the controller to perform a good calibration.
What is the range of intensities that the Spiker® can achieve?
With Spiker® Peening it is possible to achieve intensities from 0.004A to 0.014A inches.
What is the correct pressure for the intensity I want to reach?
Simply select the intensity required in the Spiker® graphical user interface and the unit will propose a pressure to achieve that intensity. Generate a saturation curve to verify that the proposed pressure is the right for our technique and peening conditions.
Do I need to generate a Saturation Curve?
It is good practice to generate a saturation curve to verify that the pressure and peening parameters selected will provide the required peening intensity.
Do the tungsten carbide needles wear out, and do I need to change them?
The tungsten carbide needles on the Spiker® will wear eventually. Once their total length is out of tolerance, they have to be replaced with new one.
How do I replace the tungsten carbide needles?
The needles can be changed simply by opening the head of the handpiece. Detailed instructions are given in the user manual.
Can the needles fall out of the head?
Under normal conditions, the needles cannot fall out of the head.
How do I know when the contact cap is worn out and how can I replace it?
The contact cap had wear line just like tires to indicate when they need replacement.
The sensors keep activating the alarm. What can I do?
The sensors track the movement of the needles. The sensors might become dirty with time. Open the head and gently clean the sensors for better performance. Detailed instructions are found in the user manual.
Where can I find more information about the Spiker®?
Shockform is the original equipment manufacturer (OEM) of the Spiker® needle peener. Visit our web site at www.shockform.com of call us at (450) 430-8000. During regular business hours, someone is always available to talk to you.
How can I reach you if I have technical Issues?
Call us (450) 430-8000 or send us an email at sales@shockform.com and we will help with your technical issue.
Products SmartPeen®
What is the difference between a SmartPeen® and other pressure pot?
The SmartPeen® mobile peening unit allows you to save and select recipes directly from the controller. It controls and continuously adjusts the pressure and media flow rate in real time. The SmartPeen® also includes a reclaim system that will leave you work area much cleaner.
Do I need to calibrate the SmartPeen®?
Calibration of the SmartPeen® is required on a yearly basis.
What is the range of intensities that the SmartPeen® can achieve?
This depends on the media selected. With small media, very low intensities in the N scale can be achieved while the use of large media can provide high intensities in the C scale.
What is the correct pressure and media flow rate for the intensity I want to reach?
Several different combinations of pressures and media flow rates can provide a particular intensity for a specific type of media. Testing will allow you to select the best parameters for your application.
Do I need to generate a Saturation Curve?
The SmartPeen® mobile peening unit includes a saturation curve solver to generate saturation curves. It also allows you to save your saturation curve with a specific recipe. When reusing an existing recipe, it is not necessary to generate a new curve. Only a intensity verification of one point on the curve is necessary.
How much media should I fill the SmartPeen® with?
The SmartPeen® mobile peening unit has sensors to show when the pressure pot is full or empty.
How can I use the SmartPeen® without the vacuum function?
Yes it is possible to use the SmartPeen® unit without the vacuum function when connected to a cabinet.
Where can I find more information about the SmartPeen®?
Shockform is the original equipment manufacturer (OEM) of the SmartPeen® mobile peening unit with vacuum reclaim. Visit our web site at www.shockform.com for more info or call us at (450) 430-8000. During regular business hours, someone is always available to talk to you.
How can I reach you if I have technicals issues?
Call us (450) 430-8000 or send us an email at sales@shockform.com and we will help with your technical issue.