• Tribology and Lubricants
• /
• v.23 no.5
• /
• pp.195-200
• /
• 2007

This paper presents the friction induced scuffing and wear defects analysis of a pin bushing bearing based on the chemical composition using a scanning microscopy (SEM) and an energy dispersive X-ray analyzer (EDX). The SEM/EDX system, which may provide good information on the surface thermal defects and chemical compositions, provides impurities such as an aluminum, a silicon, a ferrous component and an oxygen, especially. The EDX measured results show that the oxygen may reduce the strength and a hardness of a pin busing, which may lead to a scuffing and a seizure on the rubbing contact surface. The current technology fabricated by a sintering for a pin bushing bearing should be modified or changed to reduce the oxygen composition and the impurities in pin bushing materials.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.227-228
• /
• 2002

One of the serious challenges in developing rotary compressor with HFC refrigerant is the prediction of scuffing times and wear amounts between vane and roller surface. In this study, the tribological characteristics of sliding surfaces using roller-vane geometry of rotary compressor were investigated. The sliding tests were carried out under various sliding speeds, normal loads and surface roughness. During the tests, friction force, wear scar width, time to failure, surface temperature, and surface roughness were monitored. Because severe wear was occurred on vane surface, TiN coating was applied on sliding surfaces to prolong the wear-life of vane-roller interfaces. From the sliding tests, it was found that there was the optimum initial surface roughness to break in and to prolong the wear life of sliding surfaces. Depending on load and speed, the protective layers, which were composed of metallic oxide and organic compound, were formed on sliding surfaces. Those would play an important role in the amount of friction and wear between roller and vane surfaces.

• Tribology and Lubricants
• /
• v.18 no.6
• /
• pp.418-424
• /
• 2002

The basic concept of ‘gear profile modification’ is to change a part of the involute profile to reduce the load in that area and appropriate profile modifications can help gears to run quietly and resist scoring., pitting, and tooth breakage. In this study, the modification of tooth profile to make a smooth transmission of the normal loads in spur gears has been developed. The modified tooth profile has been determined by the total deflection at contact points. We also compared our results with other experimental results.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.267-272
• /
• 2001

The effect of characteristic of surface roughness and roughness patterns on frictioin was studied experimentally in boundary lubrication with reciprocating tribometer. Roughness was changed from Ra=0.2 $\mu\textrm{m}$ to Ra=1.2 $\mu\textrm{m}$. Three roughness patterns-transverse, oblique, longitudinal- were tested for various load. Ra=1.0 $\mu\textrm{m}$ roughness showed lower friction coefficient and transversal pattern showed lower friction and high scuffing load in the test conditions.

• Tribology and Lubricants
• /
• v.16 no.5
• /
• pp.357-364
• /
• 2000

In this study, the sliding wear in spur gears, using Archard's wear model, is analyzed. Formulas of tooth sliding wear depth along the line of action are derived. The tooth profile is modified Id make a smooth transmission of the normal loads and the cylinder profile for reducing the pressure spike is suggested. The sliding wear rate is calculated with these profiling results. We expect these modification methods to contribute to the reduction of sliding wear not only in the root, but the tip of tooth and tooth edge.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.9
• /
• pp.1005-1012
• /
• 2014

Gears are critical elements in automobiles, and their use as power transmitting machine elements in engineering applications is quite extensive. In the areas of contact between gear teeth, the condition of a gear is likely to deteriorate due to contact fatigue, wear, material defects, lubrication failure, etc. Thus, it is necessary to monitor its condition to ensure smooth power transmission. Gear teeth deterioration causes failures such as abrasive wear, scuffing, pitting, and spalling. These failures lead to a higher level of vibration signals in the gear system. This paper presents the results of an experiment on the surface fatigue wear of a spur gear system. The correlation between the estimated specific film thickness, statistical parameter of the vibration signals, and Stribeck curve was considered in this study.

• Tribology and Lubricants
• /
• v.1 no.1
• /
• pp.20-29
• /
• 1985

많은 윤활 부품의 성능과 수명은 초기작동기간에 금속표면에서 일어나는 현상들에 의하여 좌우된다. 특히 혼합마착구역(Mixed film region)에서나 윤활막의 두께가 몇십 마이크론의 정도가 되는 EHD(Elastohydrohynamic)윤활구역에서 작동하는 경우엔 더욱 중요하다. 이러한 경험적 현상에 의해 상대운동하는 두마찰면의 초기 작동과정을 길들이기(run-in, breaking-in)라고 부르고 "마찰 부분의 형상이나 마모 및 윤활 마찰특성이 향상되어가는 과정" 으로 정의한다. 보통 길들이기 과정이 끝나면 표면 모양은 더이상 변하지 않고 마모나 마찰 특성이 일정하게되며 이 단계를 정상 상태라고 부른다. 길들이기과정이 중요시되는 것은 이 과정에서 마모는 정상 상태보다 심하고 Scuffing 혹은 Scoring현상이라고 부르는 마찰면 손상의 가능성이 항상 존재하기 때문이다. 이 현상은 보통의 마모나 부식 또는 피로파손의 형태와는 달리 갑작스런 발생으로 부품이나 기관의 부분적 혹은 완전 파손을 유발함으로써 설계나 제조 과정에 문제를 제기하는 요인으로 오래전부터 알려져 왔다.부터 알려져 왔다.

• Journal of Power System Engineering
• /
• v.13 no.6
• /
• pp.102-109
• /
• 2009

A retarder, as a supplementary brake system that is not friction-based, is frequently used in heavy-duty vehicles generally to slow the vehicles down on inclines. The electric retarder mainly used in a heavy-duty bus is generally placed between the transmission and the axle. The rotor inside the retarder system is attached to the axle. The operation of the retarder within a driven vehicle generates reverse torque due to coast driving force on hypoid gears in the differential gear system. By the reverse torque, scoring or scuffing on the hypoid gear teeth may directly occur. The scoring may be generated due to excessive contact stresses on the tooth surface. In this study, tooth contact stresses and contact patterns were analysed in order to investigate on the tooth scoring phenomenon using a finite element analysis program T900 in which the Hertzian contact stress formula was taken. Backlash, wear and surface finish were considered in the finite element simulation on the scoring.

• Tribology and Lubricants
• /
• v.9 no.2
• /
• pp.1-8
• /
• 1993

기어가 비교적 큰 하중과 고속의 운전상태에서 사용되는 경우 되풀이 응력에 의한 피로를 대상으로 하는 면압이나 굽힘강도 이외에 치면에서 발생되는 긁힘이나 융착(瀜着) 또는 용착(溶着)을 대상으로 한 스코어링(scoring) 강도를 고려하여야 한다. 스코어링은 주로 치의 이끝 부분에서 접촉방향으로 긁힘이 나타나는 손상으로 특징지워진다. 미국기어제조협회(AGMA)에서는 윤활막 파손에 의한 금속과 금속과의 접촉에 기인하여 발생되는 여러형태의 손상, 예를 들면 scuffing, seizing, galling 등을 광범위하게 스코어링으로 통칭하고 있다. 미국계통의 기술분야에서는 스코어링을 고온 스코어링(hot scoring)과 저온 스코어링(cold scoring)으로 구분하고 있다. 고온 스코어링은 고속 운전시 표면의 섬광온도(flash temperature)에 기인한 용착과 접촉방향으로 재료를 이탈시키는 형태를 나타내고, 저온 스코어링은 저속의 기어에서 윤활막 파단으로 표면에 줄질(filing)한 듯한 손상이 발생되는 것을 나타낸다. 유럽에서는 고온 스코어링 손상은 스커핑이라 하고 저온 스코어링손상만을 스코어링이라 부르고 있다.

• Tribology and Lubricants
• /
• v.12 no.4
• /
• pp.60-70
• /
• 1996

Scuffing and severe wear of the highly stressed sliding components have been very critical problems in the development of a rotary compressor. In order to improve durability and reliability of the compressor, plasma ion-nitriding was applied on the shaft and the vane surface. The effects of different treatment conditions on the mechanical and tribological properties of the ion-nitrided surfaces were investigated. Ion-nitrided surfaces showed better tribological performances than untreated surfaces. The best wear performance was observed when the shaft was nitrided in the condition of 450$\circ$C, 7 hours, $N_2:H_2=1:4$ gas mixture by forming a ductile nitrided layer which has $\gamma'$ phase microstructure. As nitrogen gas pressure increased, $\varepsilon$ phase layer was formed. This hard phase layer was observed to be more beneficial for the vane in reducing friction and wear.