Research Article
Design and Experimental Implementation of a CNC Milling Process for a Pneumatic Cylinder Base
Issue:
Volume 10, Issue 2, December 2026
Pages:
36-48
Received:
12 July 2026
Accepted:
23 July 2026
Published:
17 August 2026
Abstract: Pneumatic-cylinder bases contain planar interfaces, stepped regions, hole patterns, and threaded features whose relative accuracy directly affects assembly and sealing performance. This study develops and experimentally implements a milling-oriented process-planning framework for a representative cylinder-base component. The workflow links functional requirements to datum selection, operation sequencing, cutting-tool selection, computer-aided manufacturing (CAM) programming, toolpath verification, and shop-floor execution. The component was modeled and programmed in Mastercam 2022. The adopted sequence comprised face milling, contour and pocket milling, center drilling, drilling, tapping, chamfering, and final inspection. A D60 face mill, end mills, 4.2 and 6.8 mm drills, spot drill, chamfer tool, and M5/M8 taps were used. The NC programs were verified through graphical simulation before machining on a Manford CNC machining center. An aluminum blank available in the workshop was used to demonstrate the process, although the original design was intended for gray cast iron. The completed component reproduced the required overall geometry and hole arrangement and was suitable for assembly trials. Visual inspection, however, revealed cutter marks and a surface condition inferior to the original specification; therefore, sealing performance and long-term load capacity were not claimed. The results show that a design-to-CAM process chain can reduce programming ambiguity and provide a reproducible route for low-volume production, while also demonstrating that material substitution and the absence of quantitative surface-metrology data must be explicitly considered when assessing manufacturing conformity. Accordingly, the experimental evidence should be interpreted as verification of workflow implementation and qualitative geometric feasibility, not as quantitative qualification of dimensional accuracy, surface integrity, or pneumatic function.
Abstract: Pneumatic-cylinder bases contain planar interfaces, stepped regions, hole patterns, and threaded features whose relative accuracy directly affects assembly and sealing performance. This study develops and experimentally implements a milling-oriented process-planning framework for a representative cylinder-base component. The workflow links function...
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Research Article
Effect of Sliding Speed, Load, and Lubricant Viscosity on the Friction Behaviour of Soft Porous Lubrication
Duc Hieu Nguyen*
Issue:
Volume 10, Issue 2, December 2026
Pages:
49-62
Received:
12 August 2026
Accepted:
24 August 2026
Published:
9 September 2026
Abstract: This study examines how sliding speed, applied load, and lubricant viscosity govern the friction behaviour of soft porous materials under dynamically evolving compression. Soft porous lubrication can generate load support while reducing friction by combining solid-matrix deformation with pore fluid pressurisation, but most existing theoretical models assume fixed compression and cannot capture the coupled response of real bearing systems. To address this gap, a modified Mini Traction Machine (MTM) was used, in which a cone-shaped upper specimen was paired with interchangeable soft porous samples on the lower disc, allowing the porous layer to compress and recover freely during operation rather than being held at a fixed thickness. Six porous materials — four open-cell polyurethane foams and two woven fibrous substrates, spanning a range of thicknesses and pore sizes — were tested dry and under water, glycerol (5% and 10%), and PEG 400 lubrication, across sliding speeds of 5-120 mm/s at constant load and normal loads of 1-7 N at constant speed. Dry friction coefficients ranged from approximately 0.1 (thin woven material) to 0.65 (thick open-pore foam), and results show that, contrary to predictions from steady-state, fixed-compression theory, friction did not consistently decrease with increasing sliding speed or applied load; for most materials the friction coefficient changed only marginally or even increased, indicating a self-regulating feedback loop in which rising pore pressure increases fluid lift, which in turn reduces compression and limits further pressure build-up. Introducing a liquid lubricant markedly reduced friction relative to dry contact, cutting the friction coefficient of the thinnest woven material from roughly 0.10 (dry) to as low as 0.02 with PEG 400 lubrication — a reduction of approximately 80% — although the benefit of increasing glycerol concentration plateaued beyond 5%. These findings demonstrate the limitations of fixed-compression theoretical models for soft porous lubrication and highlight the need for dynamic, compression-free testing protocols when selecting lubricant formulations and operating conditions for advanced low-friction, long-life bearing designs.
Abstract: This study examines how sliding speed, applied load, and lubricant viscosity govern the friction behaviour of soft porous materials under dynamically evolving compression. Soft porous lubrication can generate load support while reducing friction by combining solid-matrix deformation with pore fluid pressurisation, but most existing theoretical mode...
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Research/Technical Note
Assessment of Fatigue Life and Stress in Conventional and Hybrid 6206 Ball Bearings by Theoretical and Finite Element Analysis
Issue:
Volume 10, Issue 2, December 2026
Pages:
63-70
Received:
4 April 2026
Accepted:
25 April 2026
Published:
12 November 2026
Abstract: Ball bearings are essential in mechanical systems. Fatigue life and stress distribution affect performance and reliability of system. Recently hybrid bearings have attracted attention because they may have advantages over traditional steel bearings, such as reduced friction, better wear resistance, and a longer service life. This study gives a comparative analysis of the analytical and real-life simulation fatigue life of 6206 deep groove ball bearings for conventional (AISI 52100 steel) and hybrid (AISI 52100 races with Si3N4 ceramic balls) specification. The main goal of this research is to find the fatigue life and stress behaviour of both types of bearings under similar operating conditions. The study calculates analytical life using the ISO 281 bearing life equation, and the stress distribution in bearing is evaluated using finite element analysis in ANSYS Workbench. The results show that the hybrid bearings have about 30% longer fatigue life compared to conventional steel bearing based on analytical calculations. finite element analysis shows that hybrid bearing experiences a higher von Mises stress due to the ceramic balls but it also shows lower maximum principal stress indicating reduced subsurface stress and improved fatigue resistance. The relation between analytical and ANSYS life estimation shows close agreement, with a life ratio of 1.30 (analytical) and 1.32 (simulation), respectively. In conclusion, hybrid bearing shows higher fatigue life, good stress distribution and suitable for high-load or high-speed applications where longer life and reduced friction is required.
Abstract: Ball bearings are essential in mechanical systems. Fatigue life and stress distribution affect performance and reliability of system. Recently hybrid bearings have attracted attention because they may have advantages over traditional steel bearings, such as reduced friction, better wear resistance, and a longer service life. This study gives a comp...
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