Abstract
Mass finishing is amongst the most widely used finishing processes in modern manufacturing, in applications from deburring to edge radiusing and polishing. Processing objectives are varied, ranging from the cosmetic to the functionally critical. One such critical application is the hydraulically smooth polishing of aero engine component gas-washed surfaces. In this, and many other applications the drive to improve process control and finish tolerance is ever present. Considering its widespread use mass finishing has seen limited research activity, particularly with respect to surface characterization. The objectives of the current paper are to; characterise the mass finished stratified surface and its development process using areal surface parameters, provide guidance on the optimal parameters and sampling method to characterise this surface type for a given application, and detail the spatial variation in surface topography due to coupon edge shadowing. Blasted and peened square plate coupons in titanium alloy are wet (vibro) mass finished iteratively with increasing duration. Measurement fields are precisely relocated between iterations by fixturing and an image superimposition alignment technique. Surface topography development is detailed with ‘log of process duration’ plots of the ‘areal parameters for scale-limited stratified functional surfaces’, (the Sk family). Characteristic features of the Smr2 plot are seen to map out the processing of peak, core and dale regions in turn. These surface process regions also become apparent in the ‘log of process duration’ plot for Sq, where lower core and dale regions are well modelled by logarithmic functions. Surface finish (Ra or Sa) with mass finishing duration is currently predicted with an exponential model. This model is shown to be limited for the current surface type at a critical range of surface finishes. Statistical analysis provides a group of areal parameters including; Vvc, Sq, and Sdq, showing optimal discrimination for a specific range of surface finish outcomes. As a consequence of edge shadowing surface segregation is suggested for characterization purposes.
Highlights
Engineering surfaces polished by mass finishing are often pre-processed by blasting and peening to satisfy production or mechanical requirements
Media surface roughness was identified as a process variable for component surface texture by Wang et al [2] and a media running in period is recommended to achieve consistent results
During processing a peripheral coupon region experiences a deficit in mass finishing media action due to an ‘edge shadowing’ effect. This deficit can be considered as part of the total mass finishing work, as a balance to the surplus of media action seen in the significant radiusing of surface corners
Summary
Engineering surfaces polished by mass finishing are often pre-processed by blasting and peening to satisfy production or mechanical requirements. Surface texture specifications are typically reached before all the residual pre-processing pits are removed from the surface. Finished surfaces are said to be ‘stratified’ (though not necessarily functionally so) being composed of a predominant plateau with sparse pits. Mass finishing is a diverse process group, of which polishing applications form a major part. A fluidized media bed in a vessel often flushed with a wetting agent forms the processing environment see figure 2
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
