New Gear Peening Research Laboratory at the University of Newcastle Design Unit sponsored by USF Surface Preparation Group
New Gear Peening Research Laboratory at the University of Newcastle Design Unit sponsored by USF Surface Preparation Group
Keywords: Peening, Research, Surface preparation
A new laboratory dedicated to research into the shot peening of automotive gears and transmission systems, has been opened recently at the Gear Technology Centre, operated by the Design Unit of the School of Mechanical and Systems Engineering at the University of Newcastle upon Tyne (Plate 1).
Shot peening (or peening) is a process used widely to enhance the fatigue resistance of metallic components that are subject to cyclic stresses –gears and transmission shafts being typical examples. The process has been employed for many years in the aerospace industry for treating highly stressed parts to prolong their operating life, and is being utilised increasingly in both the motor sport and performance production car fields. It is the modern-day technological equivalent of the use of a "ball peen" hammer to increase the strength of armour and swords favoured by medieval blacksmiths.
Plate 1New Gear Peening Research Laboratory at the University of Newcastle Design Unit sponsored by USF Surface Preparation Group
The new facility is sponsored and part funded by the USF Surface Preparation Group, with additional support from the Engineering and Physical Sciences Research Council (EPSRC). Two USF Surface Preparation Group companies, in particular – Impact Finishers and Vacu-Blast International – have worked closely over the past 2 years with Dr Brian Shaw, Head of Materials Engineering at the Newcastle Design Unit, on the optimisation of shot peening parameters. The result of this project, which was under the leadership of Impact Finishers' Technical Specialist, Franck Petit-Renaud, is expected to prove of immense value for process control in the production environment. Ongoing projects at the facility will further this research work and investigate other aspects of gear peening together with the measurement and control of the peening process.
As part of the USF Surface Preparation Group's support package, the facility has been equipped with the very latest vacu-blast "Ventus 150P AXT" programmable shot peening machine, which enables the peening process to be very precisely controlled and monitored.
Official opening
The new gear peening facility was officially "launched" at a Champagne reception at the University of Newcastle, by Andrew Carmichael, the USF Surface Preparation Group's Vice President – UK Distribution and European Business Development.
Speaking at the event, Mr Carmichael said: "Close collaboration of this kind between manufacturing industry and university engineering design departments plays a vital role today in the development and application of improved and new production technologies."
"Projects like the one we have been involved with recently – the optimisation of shot peening parameters – bring the researcher into closer contact with the practicalities of the real-world production environment and, at the same time, help design and production engineers from the manufacturing sector to look beyond the commercial and everyday confines they are often subject to, and become involved in aspects of pure research – the development of which will hopefully benefit them in the future."
"We are very happy to be able to support this facility, by both providing the necessary equipment and loaning personnel, and confidently expect the results that emerge over the ensuing months and years to prove of immense value, not only to the automotive industry, but also to the surface engineering world as a whole."
Gear Technology Centre
The Design Unit Gear Technology Centre, part of the School of Mechanical and Systems Engineering at the University of Newcastle upon Tyne is a self-funding research, development and design group in the field of mechanical power transmission, working for industry and Government. It was founded in 1970 and has 24 full time staff. As well as the new USF-sponsored laboratory, the unit has five other dedicated laboratories and well equipped mechanical, materials and electronics workshops.
The shot peening process
Any metallic component that is subjected to cyclic stresses within its elastic limit can benefit from the shot peening process.
Although the process is applied using highly controllable, usually programmable, machines, the basic peening principle has been around for centuries. Medieval blacksmiths discovered that shaping metal by hammering significantly improved the strength of armour and swords. "Peened" armour offered increased resistance to penetration and sword blades survived longer before fracturing. This is the origin of the "ball peen" hammer.
Nowadays, the hammer has been replaced by precisely manufactured round steel shot, glass or ceramic beads, which are propelled at the component in a controlled manner utilising a compressed air stream or, centrifugally, by means of a vaned wheel.
The shot peening process works by introducing residual compressive stress in the surface of the component. The compressive stress helps to prevent crack initiation, as cracks cannot propagate in the compressive environment generated by peening.
Compressive stresses are generated when the impact of each particle of shot on the component produces a small indentation. It follows that if the surface has been dented then the material beneath the dent has been compressed. Peening generates not just one dent but many thousands over the surface. Eventually the component becomes encased in a compressively stressed layer.
The benefits of the process have been well proven – both with components operating in a highly-stressed but relatively short-lived environment, such as motor racing, and for critical parts with a much longer and predictable operating life in aeroengines and aircraft structures.
