Elsevier

Surface and Coatings Technology

Volume 284, 25 December 2015, Pages 365-376
Surface and Coatings Technology

Wear study of structured coated belts in advanced abrasive belt finishing

https://doi.org/10.1016/j.surfcoat.2015.10.040Get rights and content

Highlights

  • We studied belt finishing by varying the abrasive belt morphology, the cycle time and the speed rotation.

  • The effects of the number of revolution on belts' wear and surface roughness have been discussed.

  • Abrasive belts wear have been studied by SEM observations and an energetic analysis.

  • We have introduced the surface roughness multiscale analysis.

  • Some guidance has been found in order to improve the functionalization of the surfaces manufactured by belt finishing.

  • The relationship between the belt morphologies and the workpieces surface roughness has been studied.

Abstract

Advanced belt finishing process is remarkably simple and inexpensive. The principle of operation is simple: pressure-locked shoes platens circumferentially press an abrasive coated belt on a rotating workpiece. This abrasive machining process reduces significantly surface irregularities subsequently improving geometrical quality and increasing wear resistance and fatigue life. It is therefore extensively used in automotive industry to superfinish crankshaft journals. However, the major industrial issue about this manufacturing process is its efficiency and robustness.

One of the most promising ways to solve this issue is to control the distribution and morphology of the abrasive grits. Recently a new generation of abrasive belts coated with structured and shaped agglomerate grits has been commercially available. These structured coated belts with mastered cutting edge orientations promise to be more efficient as they have a better wear resistance compared to the traditional coated abrasive belt. Therefore, this work aims to discuss these assumptions and to establish the link between three structured coated belts, the surface finishes and the physical mechanisms which govern their wear performances. In particular a parametric study, based on the cycle time and the rotation speed, is lead in order to analyze the potential of each structure in terms of surface roughness improvement, wear resistance and consumed energy.

The experimental results have demonstrated that, depending on the abrasive structure considered and for a same number of revolutions, modifying the cycle time or the rotation speed can lead to different surface finishes and belt's wear.

Introduction

Friction is one of the major issues of mechanical engineering, especially in the automotive engines. One of the ways to reduce friction is to act on surface morphology. In practice, this is achieved either by using anti-friction coating technologies and texturing technology, or in a more traditional way by reducing surfaces roughness with one or multi-step finishing process [1], [2].

In a passenger car engine, about 30% of the total frictional loss is accounted by the bearings alone [3]. The process engineering departments working on this key organ have to maintain specific geometrical specifications and very strict surface finishes. In this context, the abrasive belt finishing is surprisingly simple and economical [4]. During the process, pressure-locked shoe-platens circumferentially press an abrasive coated belt on a rotating workpiece. Commonly, this finishing process also includes a low frequency oscillatory movement of the workpiece and belt finishing arm in a direction parallel to the rotations of the workpiece. This abrasive process is used extensively in the automotive industry to superfinish crankshaft journals and pins, which reduces surface irregularities, improves the geometrical quality, and increases wear resistance and fatigue life. However, in practice, belt finishing is a highly complex process.

The performance of this process depends on a large number of variables (grit density, shape and size, oscillations frequency, normal force, contact surface, lubrication fluid type, belts feeding, etc.). It makes its optimization particularly difficult. Moreover, the poor mastery of the active contact area and the abrasive characteristics [4], [5], [6], [7], [8] complicate the physical understanding. The crankshaft superfinishing also needs several steps of belt-finishing while successively decreasing the grit size, which involves substantial manufacturing and investments costs. Lastly, the conventional belt finishing machines used in the industry does not ensure sufficiently a good dimensional flexibility and also a change of the diameter of the workpiece necessarily implies a change of the shoes. Several technologies exist to partially solve these issues. Some of them propose to modify the shoes (geometries, material, servo pressure of the inserts), while others change the abrasive belt (grit's morphology, grit's material) or the global kinematic of the apparatus (high oscillations frequency, radial micro-vibration).

In our previous work, we studied, in the same process configuration, the link between grits' morphology, the surface finish of belt-finished workpieces, and the physical mechanisms which govern their wear performance [9]. We found that a coating with slanted grits had the advantage to ensure a good clipping of roughness profile while preserving valleys depth and thus, preserving the retention capacity of the surface roughness. The belt composed of pyramidal agglomerated grits allowed a very good reducing of the roughness amplitude while having a good wear resistance. Moreover, we saw that dense structures of grits could obstruct the chip's evacuation, generating unpredictable results in terms of roughness. The present study thus aims to extend our previous one by varying the cycle time and the rotation speed.

Section snippets

Nomenclature

    tc

    cycle time (s)

    N

    rotation speed (rpm)

    Nr

    revolutions number of the sample

    Nrc

    characteristic revolution number

    D

    initial workpiece diameter (mm)

    R

    initial workpiece radius (mm)

    L

    belt finished width (mm)

    Rpk

    reduced peak height (ISO 13565) (μm)

    Rk

    core roughness depth (ISO 13565) (μm)

    Rvk

    reduced valley depths (ISO 13565) (μm)

    C

    circularity (μm)

    Ma

    multiscale arithmetic roughness average (μm)

    MPS

    Multiscale Process Signature

Experimental procedure

In this work, three abrasive structures are considered. Their behaviors during belt finishing are determined by measuring the surface roughness, the circularity gains, the consumed energy, the belts' wear and the generated chips. An extensive discussion based on physical explanations underlines the behavior of three abrasive structures when the cycle time or the rotation speed increases.

The belt finishing test rig consists of a conventional lathe (power of 9 kW) and a superfinishing apparatus

Workpiece surface finish

The relative reductions (gain ratio) of the functional roughness parameters Rpk, Rk and Rvk (ISO 13565 standard) were assessed in order to estimate the surface finishing improvements. These parameters are all based on the analysis of the Abbott–Firestone curve (see Fig. 4), which is simply a plot of the cumulative probability distribution of surface roughness height [10].

Rpk, Rk and Rvk are particularly relevant when characterizing textured surfaces since they allow to well describe the

Conclusions

This paper shows all the effects of the abrasive belts structure during a one step belt finishing. The tests conducted have demonstrated that, at the same number of revolutions, modifying cycle time or rotation speed can lead to a different surface finish, belt's wear, and consumed energy depending on the abrasive morphology considered.

With Type I and III abrasive structures, we see that the number of revolution is not sufficient to explain the roughness modifications and the results follow

References (13)

There are more references available in the full text version of this article.

Cited by (22)

  • Advances in grinding tools and abrasives

    2022, CIRP Annals
    Citation Excerpt :

    Accordingly, friable abrasives are prone to form new sharp cutting edges during engagement with the workpiece but this has the drawback of higher wear rates of the grinding tools; this aspect is also influenced by the bond's strength on which the abrasive is embedded (see section 2.2). For widely used coated abrasives, such as found in fixed abrasive pads and abrasive belts, agglomerated diamond abrasives could be leveraged to improve processing efficiency and stability thanks to its micro-cutting and self-sharpening capabilities [44,171,200]. Open-porous sintered CBN abrasive wheels show the capabilities of long stable duration as pores provide chip storage space and abrasive self-sharpening [67].

  • Preparation and characterization of coated abrasives with domed pyramid thermosetting polyurethane/epoxy/diamond composites by roller embossing: Wear performance

    2021, Diamond and Related Materials
    Citation Excerpt :

    For instance, polymer-matrix composites (PMCs) with abrasives help in making material removal uniform across difficult-to-machine material such as 304 stainless steel [4]. Meanwhile, structure plays an essential role in wear performance to promote the evacuation of chips and the flow of coolant, and tools coated with a structure comprised of half-spherical shaped and pyramid-shaped agglomerates could retain a durable grinding capability [5,6]. Moreover, super abrasives could provide superior wear resistance in comparison to conventional abrasives and especially suitable for structured and textured tools [7,8].

  • A strategy on generating structured plateau surface by the sinusoidal oscillatory lapping of the grinding wheel with the phyllotactic pattern of abrasive grains

    2021, Journal of Manufacturing Processes
    Citation Excerpt :

    In order to reduce the frictional resistance of parts, some scholars have begun to do a lot of work on the morphological characteristics and manufacturing method of structured surfaces. Among them, the research on the friction reduction mechanism and manufacturing method of the structured plateau surface has always been the subject of people's attention [4,5], such as plateau honing of engine cylinder liners [6–8], superfinishing of bearing grooves [9,10], abrasive belt superfinishing on the surface of cylindrical parts such as crankshaft journals and rollers [5,9–12] etc. The plateau surface with a cross-texture structure surface of the parts, which can improve fluid dynamic pressure effects during part work, is generated by honing or superfinishing to reduce friction and mechanical power consumption.

  • Comprehensive investigation into the effects of relative grinding direction on abrasive belt grinding process

    2021, Journal of Manufacturing Processes
    Citation Excerpt :

    2D roughness parameters of Ra, Rsm, Rq, Rsk and Rku were selected [25] and plotted in Fig. 6. According to Fig. 6(a), two curves of Ra for both up/down grinding represent a mainly continuous descending trend because of the continuous abrasive belt wear [25,26]. Those trends go down quickly before the third experiment and then enter a relatively slow decline phase, which corresponds to the phase change mentioned above in Fig. 5(a).

  • Investigation on secondary self-sharpness performance of hollow-sphere abrasive grains in belt grinding of titanium alloy

    2020, Journal of Manufacturing Processes
    Citation Excerpt :

    But its mitigation on abrasive wear was inconspicuous. Surface coating technique could significantly promote the wear resistance and fatigue life of abrasive belt [23]. However, the non-renewability of coating resulted in that this technique had little improvement on the grinding of difficult-to-machine materials like titanium alloy.

View all citing articles on Scopus
View full text