Ammar Ahsan

Mr. Ammar Ahsan

orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 September 2020 in Production Engineering
Verified
Journal Article
Open access
PDF file
SBStefan Böhm
Stefan Böhm
AAAmmar Ahsan
Ammar Ahsan
JKJ. Kröger
J. Kröger
JWJ. Witte
J. Witte
In recent years surface texturing of the cutting tools has proved to improve tribological characteristics at tool/chip and tool/workpiece interface and help to reduce cutting and feed forces as well as tool wear. Most, if not all, of the studies have focused on subtractively made textures whereby the material is removed from the surface. This study investigates the performance of additively made surface structures whereby hard ceramic particles are dispersed in the form of dome shaped textures on the surface of the cutting tools using solid state millisecond pulsed laser (pulsed laser implantation). Dry cutting tests were performed on ductile cast iron. The results show a greater reduction of process forces with implantation of flank face as compared to rake face. Both cutting and feed forces were reduced by 10% compared to the non-structured tool. In addition, the tool life increased by a factor of 3 whereas the average flank wear reduced by as much as 80% and cutting edge rounding by up to 60%.

AAAmmar Ahsan
Ammar Ahsan
IKIgor Kryukov
Igor Kryukov
SBStefan Böhm
Stefan Böhm
The effect of micro patterning of cemented carbide surface using nanosecond diode pumped solid-state pulsed laser on the strength of induction brazed carbide and steel joints has been investigated. Surface patterns increase the total surface area of the joint and, for an originally hydrophilic surface, increase the wettability of a liquid on a solid surface such that, instead of building droplets, the liquid spreads and flows on the surface. Microcomputed tomography (µ-CT) was used to observe the filler/carbide interface after brazing and to analyze the presence of porosity or remnant flux in the joint. Microstructures of the brazed joints with various surface patterns were analyzed using scanning electron microscopy. The strength of the joints was measured using shear tests. Results have shown that the groove pattern on the surface of carbide increases the joint strength by 70–80%, whereas, surface patterns of bi-directional grooves (grid) reduced the joint strength drastically. Dimples on the carbide surface did not show any improvement in the strength of the brazed joints compared to samples with no surface pattern.

Verified
Journal Article
Open access
PDF file
AAAmmar Ahsan
Ammar Ahsan
KKKyle Kenney
Kyle Kenney
JKJonas Kröger
Jonas Kröger
SBStefan Böhm
Stefan Böhm
In a bandsaw machine, the blade guides provide additional stiffness and help to align the blade near the cutting region. Typically, these are either in the form of blocks made of carbide or ceramics or as sealed bearings. Abrasive particles, generated while cutting hard and brittle materials like natural stones, settle between the contact surfaces of the guides and the blade causing wear and premature failure. The hydrostatic guide system, as presented in this work, is a contactless blade guiding method that uses the force of several pressurized water jets to align the blade to the direction of the cut. For this investigation, cutting tests were performed on a marble block using a galvanic diamond coated bandsaw blade with the upper roller guides replaced by hydrostatic guides. The results show that the hydrostatic guides help to reduce the passive force to a constant near zero in contrast with the traditional guides. This also resulted in reduced surface roughness of the stone plates that were cut, indicating a reduction in laterial vibration of the band. Additionally, it has also been shown that using hydrostatic guides the bandsaw blade can be tilted to counter the bandsaw drift, opening opportunities for further research in active alignment control. This original research work has shown that the hydrostatic guide systems are capable of replacing, and in fact, perform better than state-of-the-art bearing or block guides, particularly for stone-cutting applications.

22 January 2020 in Preprints.org
Verified
Preprint
Open access
AAAmmar Ahsan
Ammar Ahsan
JKJonas Kröger
Jonas Kröger
KKKyle Kenney
Kyle Kenney
SBStefan Böhm
Stefan Böhm
Bandsaws either use fibre or ceramic block or sealed bearings as blade guides. This works well for cutting metals, wood and plastics. However, highly abrasive particles generated while cutting stones, settle between the contacts of the blade and the guides causing wear and premature failure. Hydrostatic guide system as presented in this work, is a contactless blade guiding method that uses force of several pressurized water jets to keep the blade cutting in a straight line. For this investigation, cutting tests were performed on a marble block using a galvanic diamond coated bandsaw blade with the upper roller guides replaced by hydrostatic guides. The results show that the hydrostatic guides help to reduce the passive force to a constant near zero in contrast to the bearing guides. This also resulted in reduced surface roughness of the stone plates that were cut. Additionally, it has also been shown that using hydrostatic guides the bandsaw blade can be tilted to counter the bandsaw drift. This original research work has shown that the hydrostatic guide systems are capable of replacing and in fact perform better than the state of the art bearing or block guides specially for stone cutting applications.

7 January 2025
Verified
Book Chapter
Open access
PDF file
AAAmmar Ahsan
Ammar Ahsan
MKM. Kahlmeyer
M. Kahlmeyer
EFE. Fedotov
E. Fedotov
SBS. Böhm
S. Böhm
State of the art in tooling for cutting granites are sintered grinding tools having synthetic diamond grains bound together in metal matrix usually a cobalt copper alloy. Routers for CNC machining of stone surfaces come in various forms such as face milling tools, end milling cutters, edge profiling tools etc. and have either segmented or continuous grit. Characteristic of the grinding processes the material removal rates are relatively low and inefficient compared to geometrically defined tools such as milling tools for metal or wood. In this study, a milling tool with four vacuum brazed polycrystalline diamond inserts have been used to machine Nero Assoluto Granite. The cutting edge of the brazed PCD tips were laser ablated using ultrashort pulsed lasers to form round and chamfer micro-geometries. Wet milling of granite plates was carried out at constant cutting and feed speed to study the effect of various edge geometries on the tool wear as well as cutting forces. The results showed that the cutting edges with laser ablated chamfer resulted in the smallest tool wear as well as the lowest average cutting force and therefor make a decisive contribution to energy and resource efficient machining processes.