in Vol. 4 - July Issue - Year 2003
Frohn GmbH has upgraded its Technical Service Center
Typical view of the software screens with all relevant parameters and the system layout displayed
Machine operators prepare the smallest machine (single wheel) to shot peen suspension springs
Durability Test Machine - Ervin Tester
PC Terminal - controls and monitors all peening machines
In the process of writing this article, MFN was invited by Peter Beckmerhagen, the CEO of Frohn GmbH to visit their facilities in Altena and inspect the new Technical Service Center first hand. MFN would like to thank Peter Beckmerhagen for his hospitality during our visit.
Frohn GmbH is the German based headquarters for a worldwide organization. With 2 production facilities, 3 distribution warehouses, 6 offices and a network of independent distributors they provide efficient service around the globe. They are specialists in the manufacture of Conditioned Cut Wire shot, distributors of a wide variety of peening accessories and technical experts in the Shot Peening industry.
Headquartered in Altena, Germany Frohn GmbH is a world leader in the manufacture of Specialty Shot Peening Media. They also provide their customers with a wide variety of accessories to control shot peening processes.
Frohn is committed to providing its customers with a total package: media, process control and technical expertise. Nowhere is this more evident than when we take a closer look at their Research and Development Center. The R&D Center includes several wheel peening machines all built in house to exacting specifications. By designing and building the machines in house Frohn was able to incorporate an almost infinite variety of adjustment and process simulation capabilities. So important fluctuating peening parameters such as Shot velocity, Mass flow, Exposure time and Angle of impingement can all be adjusted easily.
Frohn altered the amount of shot required to charge its machines so that they can alternate varying media within a matter of minutes. Only 250kg of media is needed to guarantee a continuous flow of shot. This allows for a greater diversity and influence of parameters determined solely by the media such as Size, Shape, Hardness and Specific weight to be made almost effortlessly.
The full size wheel machines have also recently been upgraded with the latest state of the art technology developed partially in house. All of the important parameters mentioned above are now measured and monitored continually during the entire peening process.
The Peening machines are controlled by a standard PC connected to the machine control panels. The software allows the user interface to be displayed in English, French, German or Spanish. Dialogues and reports generated by the software can also be viewed and printed in your choice of languages. Once an operator has charged the machine with the chosen media and loaded the part to be peened they simply step away from the machine to set and control the peening process from the PC terminal.
The machine peening cycle time can only be set after a saturation curve has been established. Though it may seem a simple matter to choose or set the machine peening cycle a pre-generated saturation curve helps to define the parameters of the test peen process. The PA² software loaded into the PC’s operating system combined with a large assortment of dummy parts fitted with Almen test blocks aid in completing this time consuming but necessary task more quickly. After the saturation curve has been established the operator inputs the required data such as shot velocity (m/s), flow rate (kg/min), peening time (sec.) and the rpm of the revolving table or continuous pass through both of which can be simulated.
The media type and size along with the operators name and customers name are also recorded for future reference.
With all the pertinent data entered into the PC the operator simply selects “run” in the software to start the fully automated peening cycle. Once the peening wheel has reached the preset rpm for the pre determined shot velocity an electromagnetic valve then enables the flow of shot into the machine. A driver module regulates the flow of electrical current to the electromagnetic solenoid interrupting the magnetic field of the permanent magnet. The driver module and a built-in flow sensor are both connected to the PC and together regulate the flow rate with precision. The actual flow rate is displayed on the screen during the entire Shot Peening process. By feeding all of the sensors into the PC the software is able to indicate and monitor all of the values in real time as it archives every single second of the process for future reference.
Frohn also uses a miniature wheel-peening machine known as the Ervin Tester to determine durability of peening media and to compare intensities using different media under laboratory conditions. The wheel motor is equipped with a frequency inverter enabling adjustment of the shot velocity and a realistic simulation of common shot peening process parameters.
A typical use of the Ervin Tester starts by placing a media charge of 100 grams into the machine. The media is then cycled through the machine 500 times before being removed. Once removed from the machine the media is placed on a sieve with a mesh size representing the appropriate take-out size. The balance of material remaining on the sieve after screening is then weighed and the loss is recorded. New media is then added to the remainder on the screen to bring the total back up to 100 grams and the test machine is recharged once more and run for an additional 500 cycles. These steps are repeated until the accumulative media loss has reached 100 grams or more. The total number of cycles equal to 100 % breakdown of the media is now calculated via interpolation of the recorded data.
The Almen intensity of various media in varying degrees of condition can also be tested in this way. Simply removing an existing plug on the Ervin Tester and replacing it with an Almen test block can accomplish this.
The Ervin Tester has proven to be an ideal method of measure in quantifying the work life or lifespan of media and in gauging media performance. Even though the results do not correlate directly 1:1 with an existing Shot Peening process they can give a good indication of what to expect in a „real“ Shot Peening environment.
Maintaining a well equipped Research and Development center is part of Frohn’s contribution and commitment to their customers’ satisfaction. Their endeavour to meet the ever-changing needs of the Peening industry and help improve industry quality is more than clear. With over 40 years of experience and technical expertise their full-service Research and Development center provides the industry with an invaluable resource. A resource that can redefine and improve existing processes or help in developing a whole new approach.