Ástæður fyrir alvarlegu sliti á tannhjólsinnstungunni eru sem hér segir:
(1) The greater the adhesive wear load and the higher the surface temperature, the more serious the adhesion phenomenon. For metal materials with a certain hardness, wear tests are performed under different pressures to obtain a graph of the relationship between wear rate and pressure. When the pressure reaches more than 1/3 of the hardness of the material, severe wear will occur. According to the stress distribution diagram, it can be seen that the maximum stress contact point is the maximum pressure, and its value is 884.4 MPa. Because the quenching hardness of the chain socket is HRC4852, the corresponding hardness value is 4800MPa. Therefore, the pressure is far less than 1/3 of the material's hardness, so adhesive wear is not the main form of sprocket wear.
(2) Slit á þreytu í snertingu
The friction pair of the sprocket and the chain is an alternating contact stress, which is prone to fatigue pitting on the friction surface. The index for judging the contact fatigue strength of metals is the contact fatigue limit, that is, the maximum stress at which pitting corrosion does not occur under a certain number of stress cycles. The contact fatigue limit of 40Cr is σ0H=HRC17 plus 200 after surface quenching treatment, and σ0H=1016MPa is calculated. According to the stress distribution diagram, the maximum stress value of the sprocket socket is 884.4 MPa. Its value is very close to the allowable contact fatigue limit of the sprocket surface, and it is easier to cause pitting failure at the maximum stress. However, due to the poor lubrication conditions of the sprocket and the chain, pitting corrosion is too late to form and has caused wear. At this time, the main form of damage is wear rather than pitting. Contact fatigue wear is the main form of sprocket wear, which basically determines the service life of the sprocket.
(3) Slípiefni
Vegna þess að keðjan kemst óhjákvæmilega í snertingu við duftkol, er lítið magn af duftkoli á henni, sem er komið að snertipunkti keðjunnar á keðjuhjólinu. Duftkolið inniheldur smá skarpan sand sem veldur því að yfirborðsefni keðjuhjólsins fellur af meðan á núningsferlinu stendur. Þetta er slípiefni. Slitefni tengist hörku núningsefnisins og hörku slípiefnisins. Af línuriti um áhrif slípiefnishörku á slit má sjá að þegar hörku slípiefnisins er nálægt hörku núningsefnisins mun það valda miklum-hraða sliti á núningsefninu. Vegna þess að kolduftið er blandað með smá beittum sandi er þetta líka ein helsta ástæðan fyrir því að hraða sliti keðjuhjólsins.
