Lapping Performance Research Articles

Research on composite pattern design and lapping performance of fixed abrasive pads controlled by multi-physical fields

The present work provides an innovative method of composite pattern design for fixed abrasive pads, addressing issues such as machining non-uniformity and passivation blockage arising from uneven lapping flow, pressure, and velocity fields in lapping. First, a multi-physical field modeling method is provided, a material removal distribution model and evaluation criteria for the performance of the abrasive pad are established, and the reliability of this model is validated. Second, based on the model, a composite pattern abrasive pad coupled with a spiral groove and concentric micro groove is designed. Comparative experiments are conducted with the grid abrasive pad. The results show that the clogging and passivation performance of the composite pattern abrasive pad is improved, and the pressure distribution is optimized. Compared with the grid abrasive pad, in the pressure range of 20 N–70 N, the surface roughness Ra of sapphire is reduced by 6.4 %–25.42 %, defects such as brittle fracture pits and scratches on the workpiece surface are reduced, and the surface quality of the workpiece is significantly improved. The material removal rate is between 0.23 μm/min to 0.34 μm/min. This confirms the effectiveness of optimizing abrasive pad pattern design based on multi-physics fields. The research results provide a novel approach for abrasive pad pattern design with engineering application value.

Performance analysis and mechanical determinants of the opening lap of the team sprint in elite-leveltrack cycling.

The team sprint (TS) is a three-lap pursuit and the most revered event in track sprint cycling. The opening lap of the TS is an important determinant to the overall performance. But despite it being the most controlled and repeatable task in track sprint cycling, very little data are available to better understand the performance of the opening lap. The aim of this study was split into three-parts: part one, to better understand the profile and the indices thought to be determinants of the opening lap of the TS in elite sprint track cyclists. Part two of the study examined all available timing splits (15, 65, 125 and 250m) from 36 standing-start laps. Part three of the study examined the peak torque outputs and peak power outputs of different various starts performed over a 3-month period. The results showed time to 125m exhibited a near perfect relationship with starter lap performance. Very strong relationships were seen with 15 and 65m split times and final lap performance. Peak torque of the lead starting leg and peak power output were shown to be highly predictive 15m, 65 and 125m performance in training. These data suggested the first 15m is highly important and predicts a disproportionately high level of final opening lap time performance. Therefore, it is likely that peak power output normalised to system mass and peak torque of lead leg is a strong determinant of overall performance in the TS.

Investigating the efficiency and reliability of different lap-splice configurations in NSM BFRP rods for strengthening RC beams

The use of near-surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement has shown great promise for flexural and shear strengthening of reinforced concrete (RC) members. However, the continuity of NSM FRP rods is often interrupted due to length constraints, necessitating lap splices to transfer forces between spliced rods. The performance of lap splices depends on design configuration factors, including anchorage shape, splice length, and connection method. This research describes an experimental investigation into the bond behaviour and failure mechanisms of various lap splice designs for NSM basalt FRP (BFRP) rods in RC beams. The parameters investigated were end anchorage shape (straight or Embedded Through-Section (ETS) anchors), and connection type (overlay rods or face-to-face with FRP sheet wrap). A total of 8 simply supported RC beams strengthened with different NSM BFRP lap splice configurations were tested under four-point bending. The load-deflection response, strain distribution, and failure modes were evaluated. Test results showed that beams with NSM FRP rods with ETS anchors exhibited higher bond strength and ductility than face-to-face connections. The outcomes of this study can help optimize lap splice design and detail provisions for NSM FRP systems in future strengthening applications.

The influence of the types of cluster composite abrasives on the performance of fixed abrasive pads in processing quartz glass

To enhance the material removal rate (MRR) and surface quality of quartz glass lapping, a new method is proposed utilizing a fixed cluster composite abrasive pad (FCCAP) for processing quartz glass. Firstly, cluster composite abrasives (CCA) with a particle size of 28 μm were prepared using the normal temperature and pressure sintering method, including cluster Al2O3-diamond composite abrasives (CADCA), cluster diamond-diamond composite abrasives (CDDCA), and cluster SiO2-diamond composite abrasives (CSDCA). Secondly, using CCA as the abrasive and relying on ultraviolet curing technology, three types of FCCAP were prepared: fixed cluster Al2O3-diamond composite abrasive pads (FCADCAP), fixed cluster diamond-diamond composite abrasive pads (FCDDCAP), and fixed cluster SiO2-diamond composite abrasive pads (FCSDCAP). Simultaneously, to validate the performance of the prepared FCCAPs, three types of fixed single crystal abrasive pads were prepared using the same process with single crystal Al2O3 (SCA), single crystal diamond (SCD), and single crystal SiO2 (SCS) with a particle size of 28 μm. Using quartz glass as the processing object, lapping experiments and friction and wear experiments were conducted, with MRR, surface roughness Ra, and coefficient of friction (COF) selected as evaluation indexes to compare and study the lapping performance of the six pads. FCCAP demonstrated higher machining efficiency, with FCDDCAP achieving the highest MRR of 3.611 μm/min. Additionally, after FCCAP lapping, the surface roughness Ra of quartz glass is lower, to some extent repairing surface damage such as large scratches. Among them, FCSDCAP achieved the lowest surface roughness of 91.564 nm. Finally, FCCAP exhibits superior friction and wear performance, with FCSDCAP samples having the highest average COF of 0.127. Under the same abrasive particle size conditions, FCCAP has better processing capabilities, enabling efficient lapping of quartz glass.

The wear behavior and lapping performance of fixed abrasive pad for acidity and alkalinity of lapping fluid in lapping quartz glass

The wear behavior and lapping performance of fixed abrasive pad for acidity and alkalinity of lapping fluid in lapping quartz glass

Investigation on microstructural evolution and local mechanical performance of friction stir lap welded AA6061-T6/ AA7075-T6 joints

The current study uses the friction stir lap welding (FSLW) technique to successfully fabricate two layered dissimilar AA6061/AA7075 joints. A defect-free joint with superior interfacial properties was obtained at the optimized process parameters (tool rotational speed / transverse speed) of 850 RPM/ 55 mm/min. The detailed investigations of microstructure evolution, crystallographic texture, and strength correlation were performed using the field emission scanning electron microscope (FE-SEM), optical microscope (OM), electron backscattered diffraction (EBSD), Vickers microhardness, nano-indentation, and miniature tensile tests. EBSD analysis reveals the presence of a significant grain refinement at the bottom (3.65 µm), middle (4.58 µm), and top region (6.34 µm) of stir zone (SZ) compared to AA6061 (42.56 µm) and AA7075 (34 µm) base metals. An increasing trend in the fraction of high angle grain boundary (FHAGBs) and recrystallization fraction was noticed from top to bottom of the build within the SZ. Continuous dynamic recrystallization (CDRX) with the gradient in strain, strain rate, and temperature leads to these microstructural variations within the SZ. The microhardness study shows a decrease in microhardness in the SZ due to thermal softening and precipitate dissolution at higher temperatures. Appreciable interfacial material mixing leads to remarkable strength, ductility, and strain-hardening behaviour within the SZ, especially at the interface section. Pole figures (PF) reveal the presence of major shear texture components (B/B̅, and C) with some minor presence of A1*/A2*and A/A̅ that confirms the presence of higher strains within the SZ. The dominant presence of recrystallization textures components (like cube {001} 〈110〉, Goss {011} 〈100〉, and P {011} 〈122〉 ) within the SZ confirms the presence of the CDRX mechanism.

Удосконалення механізму притирання вільним абразивом за допомогою використання силікатного складу

The results of an experimental study are presented that explain and confirm the mechanism of lapping friction surfaces with a silicate abrasive composition.
 It is shown that the stability of the silicate lapping paste over time can be achieved by introducing ferric trichloride (FeCl3), which in this case is a thickener of liquid glass and also has high hygroscopic properties. The adhesive properties of the silicate paste are improved by the addition of lubricant 1-13. This grease was chosen due to its water solubility. To increase the abrasive ability of the silicate paste, an abrasive powder was introduced. 
 It was found that the lapping performance of the silicate composition and the quality of surfaces are higher than when treated with the «KT» paste, which is currently used for lapping automobile engine valves. Based on the results of the study, the mechanism of lapping friction surfaces with a silicate paste is presented. The mutual movement of the surfaces results in cutting and scratching of the highest peaks of the bumps by the abrasive grains. When silicon oxide (SiO2) is added to the abrasive material, its particles are coated with silicon oxide. This is because liquid glass solutions have a high adhesive force and low surface tension. At the points of contact between the abrasive particles, the temperature rises, and since there is SiO2 around the abrasive, when the latter enters the contact zone, amorphous silica (SiO2) is formed. Since the abrasive grains are coated with a silicon oxide film, SiO2 penetrates into the cavities of micro-irregularities and adheres to the surface under repeated exposure to the abrasive. Thus, the surface to be treated is saturated with silicon oxide, which leads to an increase in its quality after grinding with a silicate composition.
 It has been proven that high surface quality is formed by amorphous silica. To confirm this mechanism, chemical and X-ray spectral analyses of the samples were performed, which showed the presence of SiO2 on the treated surface and a "strong bond" of silicon compounds with the metal surface layer. 
 It was found that the high quality of the surface is also due to the shape of abrasive particles and wear products. It has been confirmed that with the variable movement of surfaces relative to each other, abrasive grains take on a new position each time. At the same time, they are worn from all sides and acquire a rounded shape, and are simultaneously enveloped by a SiO2 foil.

Simulation and Experimental Study of Non-Resonant Vibration-Assisted Lapping of SiCp/Al.

SiCp/Al is a difficult-to-machine material that makes it easy to produce surface defects during machining, and researchers focus on reducing the surface defects. Vibration-assisted machining technology is considered an effective method to reduce surface defects by changing the trajectory and contact mode of the abrasive. Aiming at the problem of SiCp/Al processing technology, a vibration-assisted lapping device (VLD) is designed, and elliptical motion is synthesized by a set of parallel symmetrical displacement output mechanisms. The working parameters of the device were tested by simulation and experiment, and the lapping performance was verified. Then, the effects of removal characteristics and process parameters on surface roughness and lapping force were analyzed by simulation and experiment. Simulation and experimental results show that frequency and amplitude that are too low or too high are not conducive to the advantages of NVL. The best surface quality was 54 nm, obtained at A = 8 μm and f = 850 Hz.

Optimisation of free-abrasive assisted lapping process with vitrified bonded diamond plates for sapphire substrates

To improve the processing performance of vitrified bonded diamond fixed-abrasive lapping plates for processing sapphire substrates, a free-abrasive was added to the lapping slurry to enhance the self-dressing ability of the lapping plate to achieve efficient and high-quality processing of sapphire substrates. The processing effectiveness and mechanism of a free-abrasive assisted fixed-abrasive lapping plates (FAAFALP) lapping process for sapphire substrates were analysed and revealed via a single-factor experiment. To optimise the lapping process of the FAAFALP of sapphire substrates with good overall performance (high material removal rate (MRR), minor surface roughness (Ra) and big lapping plate wear ratio (η)), the effects and the optimal parameters combination of the lapping pressure, lapping speed and free-abrasive concentration on MRR, Ra and η of lapping-processed sapphire substrates were investigated using orthogonal experiments. Furthermore, the experimental results were combined with process parameters to establish a regression model. The multi-evaluation index optimisation problem was transformed into a single-index optimisation problem via the grey relational analysis (GRA) to evaluate each parameter's performance comprehensively. The results revealed that an MRR increased by 22.2 % to 2.48 μm/min, the smallest surface roughness Ra of 0.141 μm, and the lapping plate wear ratio η relatively increased to 14.88 was obtained when a free-abrasive of SiO2 with a particle size of 14 μm was added into lapping slurry. Compared with no free-abrasive lapping process, free-abrasive can significantly improve the lapping plate's self-dressing ability and enhance the sapphire substrates' processing effect. The lapping speed, lapping pressure and free-abrasive concentration had different influence degrees on MRR, Ra and η. The established regression equations predicted the response values of MRR, Ra and η to be 99.87 %, 99.06 % and 98.59 %, respectively, and the relative errors between the predicted and actual measured values were <12 %. With increased lapping speed, MRR initially decreased but subsequently increased, and Ra and η gradually decreased. MRR and η continuously increased with increased lapping pressure, whereas Ra decreased. With increased free-abrasive concentration, MRR, Ra and η initially increased but subsequently decreased. Comparing the optimised results obtained by intuitive analysis, the parameters optimised via the GRA were used to obtain sapphire substrates lapping with an MRR of 3.81 μm/min, Ra of 0.133 μm and η of 20.4, and the overall lapping performance was better 42.92 %, 102.90 % and 43.60 % than that of intuitive analysis for MRR, Ra and η. Therefore, combining orthogonal experiments and GRA can provide new ideas for optimising the FAAFALP lapping process for sapphire substrates.

Electric performance of hybrid busbar joints under service and high voltage conditions

This paper is focused on hybrid busbar joints with a twofold objective of understanding the differences in electrical resistance under service conditions and evaluating their performance when subjected to hazardous high voltages. Three different types of joints fabricated by conventional bolting, friction stir spot welding and injection lap riveting are selected and two different experimental setups are used to allow the hybrid busbars to be tested up to high voltage electrical discharges of 30 kV. The work is an enhancement of previous experimental and numerical investigations of the authors in the field with results showing no signs of damage or catastrophic failure when the different types of busbars are subjected to high voltage electrical discharges. Results also confirm the good overall performance and advantages of injection lap riveted hybrid busbar joints against bolted and friction stir spot welded.

Synthesis and lapping performance of a detonation nanodiamonds slurry by a SPS deagglomeration technology

In order to obtain a simple and efficient technique to prepare detonation nanodiamonds (DNDs) lapping slurry, deagglomerate DND powders by a spark plasma sintering (SPS) technology was proposed in the present study. The effect of SPS treatment temperature on the surface characteristics and dispersion properties of DND powders in deionized water have been studied. The best deagglomeration of DND powders with the peak particle size distribution of 79 nm is achieved for the DND that treated by SPS at 500 °C. The DND dispersed water solution is used as lapping slurry for the four ceramics (Al2O3, AlN, Si3N4, and 3Y-TZP) with different mechanical properties. The material removal rate and surface quality of the four ceramics in lapping process were also examined and compared, in which showed the highest material removal rate for 3Y-TZP and the lowest for Si3N4. The surface roughness of the four ceramics can be decreased to <10 nm by lapping sequentially with slurry of diamond grit size of 3, 0.5, and 0.1 μm and DND slurries successively. Compare to Al2O3 and AlN, 3Y-TZP and Si3N4 ceramics show lower surface roughness. And a lowest roughness of Ra 3.4 nm is achieved for 3Y-TZP. In lapping of AlN ceramic, Al(OH)3 is formed due to the hydrolysis reaction, which is produced shallow pits with the size of grain.

Analysis of pacing and kinematics in 3000 m freestyle in elite level swimmers

ABSTRACT This study aimed to determine elite swimmers’ pacing strategy in the 3000 m event and to analyse the associated performance variability and pacing factors. Forty-seven races were performed by 17 male and 13 female elite swimmers in a 25 m pool (20.7 ± 2.9 years; 807 ± 54 FINA points). Lap performance, clean swim velocity (CSV), water break time (WBT), water break distance (WBD), stroke rate (SR), stroke length (SL) and stroke index (SI) were analysed including and excluding the first (0–50 m) and last lap (2950–3000 m). The most common pacing strategy adopted was parabolic. Lap performance and CSV were faster in the first half of the race compared to the second half (p < 0.001). WBT, WBD, SL and SI were reduced (p < 0.05) in the second half compared to the first half of the 3000 m when including and excluding the first and last laps for both sexes. SR increased in the second half of the men’s race when the first and last laps were excluded. All studied variables showed significant variation between the two halves of the 3000 m, the highest variation being obtained in WBT and WBD, suggesting that fatigue negatively affected swimming kinematics.

Performance of Steel Bar Lap Splices at the Base of Seismic Resistant Reinforced Concrete Columns Retrofitted with FRPs—3D Finite Element Analysis

This paper examines analytically the design criteria for the composite retrofit of reinforced concrete (RC) columns with a short lap splice length of steel rebars inside the critical region. The advanced potential of pseudo-dynamic three-dimensional (3D) finite element (FE) modelling is utilized to investigate critical design parameters for the required carbon fiber-reinforced polymer (FRP) jacketing of RC columns with a rectangular cross-section based on the experimental lateral force-to-drift envelope behavior of characteristic cases from the international literature. The satisfactory analytical reproduction of the experimental results allows for the systematic numerical investigation of the developed stress along the lap splice length. The maximum lateral force and the horizontal displacement ductility of the column, as well as the maximum developed tensile axial force on the longitudinal bars, their variation along the lap, the bar yielding, and the plastic hinge length variation, are considered to determine the seismic behavior of the columns. For the first time, cases of smooth bar slip together with delayed bar yielding or without bar yielding are identified that may be recorded through a “ductile” P-d seismic response. Such pseudo-ductile response cases are revisited through suitably revised redesign criteria for adequate FRP jacketing.

Experimental study on lap behavior of CFRP indented bars in UHPC

The lap behavior of Carbon Fiber Reinforced Polymer (CFRP) indented bars in Ultra-High Performance Concrete (UHPC) were investigated based on pullout test under direct tension on 27 specimens in total. The test variables include splice length, UHPC strength and stirrup ratio. The lap failure mechanism of CFRP bar embedded in UHPC and the influence of test parameters on lap performance were analyzed. Test results showed that the failure modes, pull-out and rupture of CFRP bar, in those lap-spliced specimens were governed only by the splice length of the CFRP bar embedded in UHPC. The pullout failure was caused by the shearing off of indented ribs on the surface of the bars and the fracture failure was governed by the tensile strength of the bars. The bond strength of lap-spliced indented CFRP bars in UHPC is mostly dependent on the shear strength of indented ribs on CFRP bars, little on the UHPC strength and stirrup ratio. For CFRP bars with a 2480 MPa tensile strength and a 9.8 mm diameter (d), a splice length of 30d in UHPC can fully develop the tensile strength of the bar. A simplified equation for predicting the critical splice length of CFRP bars in UHPC was proposed. Compared with the results on anchorage of CFRP bars in UHPC, the critical splice length of CFRP bar in UHPC was 1.45 times the corresponding anchorage length.

Effect of material structure on spinel machinability in its fixed abrasive lapping

Clarifying the effects of material properties on the lapping performance is helpful in optimizing the lapping processing and revealing the lapping mechanisms. In this study, the microstructures of single-crystal spinel (SS) and polycrystalline spinel (PS) were observed by a microscope after being etched with H3PO4 at high temperature. Automatically controlled micro-hardness testing and analysis systems were used to measure the hardness and crack length of SS and PS wafers. On this basis, the fracture toughness and critical cutting depth were estimated. And, a series of lapping tests were conducted to evaluate the effects of crystals on its machinability with a fixed abrasive pad (FAP). After lapping, the size distribution of collected debris was measured by using a laser particle analyzer. The debris and selected posts of FAP were observed by using a scanning electron microscope. Experimental results indicate that the different microstructures and hardness characteristics between SS and PS result in different average cutting depths, which finally affect the lapping debris sizes, FAP surface conditions, and its machinability.

Optimisation of Lapping Process Parameters for Single-Crystal 4H-SiC Using Orthogonal Experiments and Grey Relational Analysis.

Lapping is one of the standard essential methods to realise the global planarization of SiC and other semiconductor substrates. It is necessary to deeply study the mechanism to obtain SiC lapping process parameters with a strong comprehensive lapping performance (i.e., high material removal rate (MRRm), small surface roughness (Ra), and low total thickness variation (TTV)). The effects of the lapping process parameters and their interactions on lapping performance for SiC were investigated using orthogonal experiments; the effects on the MRRm, Ra, TTV, and optimal parameters under the conditions of a single evaluation index were investigated using intuitive analysis (range analysis, variance analysis, and effect curve analysis). The entropy value method and grey relational analysis were used to transform the multi-evaluation-index optimisation into a single-index optimisation about the grey relational grade (GRG) and to comprehensively evaluate the lapping performance of each process parameter. The results showed that the lapping plate types, abrasive size, and their interaction effect had the most significant effects on MRRm and Ra, with a contribution of over 85%. The interaction between the lapping plate types and abrasive size was also found to have the most significant effect on TTV, with a contribution of up to 51.07%. As the lapping plate’s hardness and abrasive size increased, the MRRm and Ra also gradually increased. As the lapping normal-pressure increased, MRRm increased, Ra gradually decreased, and TTV first decreased and then increased. MRRm, Ra, and TTV first increased and then decreased with increasing abrasive concentration. Compared to the optimisation results obtained by intuitive analysis, the process parameter optimised by the grey relational analysis resulted in a smooth surface with an MRRm of 90.2 μm/h, an Ra of 0.769 nm, and a TTV of 3 μm, with a significant improvement in the comprehensive lapping performance. This study reveals that a combination of orthogonal experiments and grey relational analysis can provide new ideas for optimising the process parameters of SiC.

Assessment of the inter-lap stability and relationship between the race time and start, clean swim, turn and finish variables in elite male junior swimmers’ 200 m freestyle

ABSTRACT The aims of this study were to: (1) assess the stability (mean and normative) of the lap performance, and a set of clean swim and turn variables of junior male swimmers in the 200 m freestyle, and; (2) verify the relationship between the start, clean swim, turn, and finish phases in the 200 m freestyle. Seventy-six individual races in the 200 m freestyle at the 2019 long-course LEN European Junior Championships were analysed. Start, clean swim, turn, and finish variables were assessed. The lap performance showed a significant variance. The highest variation was verified between the first and third lap (Coefficient of Variation = 7.37%). The clean swim and the total turn also presented a significant variance. Normative stability indicated a moderate to very-high stability for all variables. All phases of the race had significant correlations with the final race time (p < 0.001). The total turn (i.e., the total time spent to perform the turn), specifically turn #3, showed the largest correlation with the total race performance. The significant correlation between all phases of the race and the final race time indicates that coaches and swimmers should customise the swimmers’ preparation and race strategy at major international competitions, based on the individual characteristics of each swimmer.

Characteristic of SiC Slurry in Ultra Precision Lapping of Sapphire Substrates

A method is proposed in this paper to prepare a SiC slurry with SiC particles selected by an ultrasonic-assisted elutriation method to reduce substrate surface damage caused by abrasive particles during lapping. Sapphire substrate lapping experiments were carried out using the prepared SiC slurry, and the lapping performance of the slurry was analyzed. The experimental results show that the SiC particle size is a factor that directly affects the material removal rate and surface roughness Ra, of sapphire substrates. When a SiC slurry with a particle size of 630 nm was used, the material removal rate was 508 nm/h, and the surface roughness Ra was 1.9 nm; increasing the slurry concentration and the platen rotating speed can improve the material removal rate. In addition, the agglomeration of SiC particles in the slurry depends on the pH of the slurry. Efficient precision lapping of sapphire substrates can be achieved by selecting appropriately sized SiC particles and by adjusting the slurry pH to control the agglomeration and dispersion of SiC particlesto further reduce the scratches on the substrate surface during the lapping process.

Surface Quality Improvement by Using a Novel Driving System Design in Single-Side Planetary Abrasive Lapping.

For the traditional single-side planetary abrasive lapping process particle trajectories passing over the target surface are found to be periodically superposed due to the rational rotation speed ratio of the lapping plate to workpiece that could affect the material removal uniformity and hence its surface quality. This paper reports on a novel driving system design with combination of the tapered roller and contact roller to realize the irrational rotation speed ratio of the lapping plate to workpiece in the single-side planetary abrasive lapping process for the improvement of surface quality. Both of the numerical and experimental investigations have been conducted to evaluate the abrasive lapping performance of the novel driving system. It has been found from the numerical simulation that particle trajectories would theoretically cover the whole target surface if the lapping time is long enough due to their non-periodic characteristics, which can guarantee the uniformity of material removal from the surface of workpiece with relatively high surface quality. The encouraging experimental results underline the potential of the novel driving system design in the application of the single-side planetary abrasive lapping for the improvement of the surface quality in terms of surface roughness and material removal uniformity.

Determinant physiological factors of simulated BMX race

Evaluating the physiological demands of BMX cycling on a track provides coaches with the information required to prescribe more effective training programmes. To determine the relative importance of physiological factors during simulated BMX race, 12 male riders (age 19.2 ± 3.5 years, height 1.76 ± 0.06 m, mass 68.5 ± 4.3 kg) completed a maximum aerobic capacity (V̇O2max) test in a laboratory, and a week later, completed six laps on a BMX track interspersed by 15 min passive recovery. Peak power, immediate post-lap V̇O2peak, blood lactate, and heart rate were measured in each lap. Peak power to weight ratio was significantly correlated with lap time, however, the strength of this association decreased in each subsequent lap. Mean V̇O2peak was greater than 80% of laboratory-measured V̇O2max in every lap, indicating a strong contribution of the aerobic energy system during BMX racing. This study also identified that mean blood lactate was significantly associated with lap time, which showed the importance of the anaerobic energy system contribution to BMX race. Despite the short period of pedalling during BMX racing, both aerobic and anaerobic energy systems are important contributors to lap performance. Coaches should consider maximising both anaerobic power and aerobic capacity to improve riders’ overall performance in multiple laps.