Vibratory Stress RelievingVibratory Stress Relieving

An Alternative to Thermal An Alternative to Thermal Stress RelievingStress Relieving

Presented by

Vibratory Stress Relieving (Africa)cc

Applications of Vibratory Stress RelievingApplications of Vibratory Stress Relieving

During ManufactureDuring ManufactureBefore rough machining, milling or grinding Before rough machining, milling or grinding operations.operations.Before final machining, milling or grinding Before final machining, milling or grinding operations.operations.Following various stages of fabrication.Following various stages of fabrication.On completion of fabrication & welding.On completion of fabrication & welding.Following heat treatment or hardening. Following heat treatment or hardening. Following straightening operationsFollowing straightening operationsFollowing repairs and before reinserting into Following repairs and before reinserting into service.service.Periodically for preventative maintenance.Periodically for preventative maintenance.

Types of ComponentsTypes of ComponentsPlate.Plate.Bar.Bar.Weldments.Weldments.Castings.Castings.Forgings.Forgings.Extrusions.Extrusions.Machined Components.Machined Components.Fabrications. (up to 200t)Fabrications. (up to 200t)Composites.Composites.Plastics. (including pipe)Plastics. (including pipe)

Benefits of using VSR include:•It can give equal stress reduction and stability to thermal stress relieving.

•If applied after rough machining or semi-finishing, accuracy is only limited by the accuracy of the finishing method.

•It can be used upon materials not treatable by thermal stress relieving.

•Time savings of approximately 50:1.

•VSR is brought to YOU, the component does not have to leave your works.

•Treatment capabilities of up to 200t

•No distortion, loss of hardness or yield strength of materials

Materials on which VSR can be used:Materials on which VSR can be used:

Low and medium carbon hot rolled steel. Low and medium carbon hot rolled steel. Low and medium carbon steel alloys.Low and medium carbon steel alloys.Tool steel alloys.Tool steel alloys.High strength steel alloys.High strength steel alloys.Cast irons including grey, nodular and mechaniteCast irons including grey, nodular and mechaniteAluminum and aluminum alloys.Aluminum and aluminum alloys.Stainless steels.Stainless steels.Exotic metals including gold, titanium, inconel, and magnesium.Exotic metals including gold, titanium, inconel, and magnesium.Powdered metals including tungsten carbide and stellite.Powdered metals including tungsten carbide and stellite.

Poor Applications for VSR:Poor Applications for VSR:Cold rolled steelCold rolled steelBurned edgesBurned edgesCopper and high copper content alloysCopper and high copper content alloysMaterials where mechanical properties need to be altered. Materials where mechanical properties need to be altered. Severely cold worked steels.Severely cold worked steels.

Vibratory Stress RelievingVibratory Stress Relieving V’s V’s No Stress No Stress ReliefRelief

It has been estimated that 50% of all the components that should be stress relieved are notIt has been estimated that 50% of all the components that should be stress relieved are not

Often the reason cited for skipping stress relieving is based upon the desire to avoid unwanted side effects associated with heat treatment.Often the reason cited for skipping stress relieving is based upon the desire to avoid unwanted side effects associated with heat treatment.

Common unwanted side effects include:Common unwanted side effects include:

► Distortion.Distortion.► Scaling.Scaling.► Change in material properties. Change in material properties. ► Lengthy time restraints.Lengthy time restraints.► Further reasons are time, cost and size limitations associated with furnace sizes.Further reasons are time, cost and size limitations associated with furnace sizes.

Omitting stress relieving involves a risk.Omitting stress relieving involves a risk.

► The risk is in hoping that no problems will arise normally cracking, distortion, or a reduction in the component life cycle.The risk is in hoping that no problems will arise normally cracking, distortion, or a reduction in the component life cycle.► A bigger, often forgotten risk, is any of the above will often generate dissatisfied customers.A bigger, often forgotten risk, is any of the above will often generate dissatisfied customers.► As VSR does not cause any of the mentioned unwanted side effects and the process is virtually limitless in size and weight capabilitiesAs VSR does not cause any of the mentioned unwanted side effects and the process is virtually limitless in size and weight capabilities not stress relieving is unnecessary.not stress relieving is unnecessary.

Benefits of stress relieving (VSR) are many but briefly the common ones include:Benefits of stress relieving (VSR) are many but briefly the common ones include:

► A reduction in distortion following machining (up to 93%).A reduction in distortion following machining (up to 93%).► A reduction in machining time (up to 40%) by eliminating extra cuts or a lower cutting speed and rate due to distortion of the workpiece.A reduction in machining time (up to 40%) by eliminating extra cuts or a lower cutting speed and rate due to distortion of the workpiece.► Prevention of delayed distortion caused by a non stress relieved component undergoing an “ageing process” in service.Prevention of delayed distortion caused by a non stress relieved component undergoing an “ageing process” in service.► A reduction in cracking, brought on by high residual stresses being reduced and a reduction in the “critical crack propagation rate”.A reduction in cracking, brought on by high residual stresses being reduced and a reduction in the “critical crack propagation rate”.► Prevention of premature failure in service.Prevention of premature failure in service.► Proven reductions in residual stress of up to 72% Redistribution of surface strains of 100%.Proven reductions in residual stress of up to 72% Redistribution of surface strains of 100%.► Satisfied customersSatisfied customers..

Apart from a proven track record dating back to the late 1930,s and many thousands of satisfied users worldwide. (Our database of VSR users in South Africa exceeds 800!)

HOW DOES ONE KNOW THAT VSR WORKS?

The above bar diagram has been drawn from the original data in the DTI / ERA (UK) research project which lasted almost two years and has been authenticated by Dr. Phil Aplin of ERA .

This clearly shows the effectiveness of Vibratory Stress Relieving

Ongoing research and testing is being carried out both in South Africa and overseas to prove the effectiveness of VSR. Detailed here is some of the equipment and components with strain gauges attached

Following are some photographic examples of some Following are some photographic examples of some of the many components treated on a daily basis by of the many components treated on a daily basis by

our on site-service teamsour on site-service teams

The VSR service is available in all provinces of The VSR service is available in all provinces of South AfricaSouth Africa

Treatment of various impellors following manufacture & prior to balancing

On-Site treatment of vibrating screens & feeder pans

Assorted Screen Components being VSR Treated

The treatment of machined components prior to final machining

A wide selection of components are treated on a daily basis by our on-site service teams

Sections of an automotive body panel press VSR treated in Durban for Toyota SA

Assembly tables and jigs fabricated VSR treated and then machined customers include

Toyota SA, BMW, Delta, Land Rover , Audi and Delta

Heavy fabrications subjected to VSR treatment on completion of fabrication

Examples of various buckets VSR treated following repairs

Crusher sections after weld repairs VSR treated before machining

Sheave wheels rough machined VSR treated on-site

•The largest component treated by VSR in South Africa (and possibly worldwide) was a train tippler manufactured by DCD Dorbyl for Saldanha Steel.

•Treatment of each item was before final machining.

•The main frame was 119,000kgs with each end ring weighing 40,000kgs.

•VSR has the capacity to treat a 200t component but this is normally impossible owing to lifting restraints in workshops or in the field.

Rough machined bases

Rough machined bases

•Military and aerospace components make up some of the more interesting aspects of service work in terms of the specialised materials used in their manufacture.

•VSR is utilised by most manufacturers of aerospace and military components worldwide owing to the security classification of some of the components and the type of materials used in manufacture

A Heavy Vehicle Simulator manufactured by Denel for the fatigue testing of road surfaces.

•One of these machines is often seen around the Johannesburg area testing major road surfaces.

•All critical load bearing items of this unit were treated using Vibratory Stress Relieving prior to assembly.

Underground Mining Vehicles after repair / manufacture

Owing to the mixture of materials used in their construction VSR offers the best option for the stress relieving of mining equipment

Roq Tuff 50B 43A

VSR is used extensively on lifting equipment from rope drums to ladle lifting hooks and overhead crane sections

The effects of different frequencies on a component can often be seen by the formation of “node lines”. These can be highlighted by scattering loose material such as sand onto the component whilst treatment is in progress

Small and lightweight components are treated by means of a vibrating table

Items for water plants manufactured both for SA and for export

Dead Sea Desalination Project (Sulzer)

Rand water Board (Batemans)

Ladles (cast & fabricated) and water cooled furnace sections

Haulage Equipment and wheel rims