Different Causes of Gear Tooth Failure: Bending Failure and Wear Failure

DIFFERENT TYPES OF GEAR TOOTH FAILURE

Failure is the fact, there is nothing in this word which can’t fail. Here we are going to see types of gear tooth failure and reason behind it. So let’s get started without wasting much time.

Þ     Failure of the gear tooth is mainly classified into two types. 1^st is BENDING FAILURE & 2^nd is WEAR FAILURE. Wear failure is further classified into another sub failure like PITTING FAILURE, SCORING FAILURE, ABRASIVE FAILURE, CORROSIVE FAILURE, etc.

BENDING FAILURE:

Ø  I f repetitive bending stress on gear tooth is more than breaking strength of gear tooth in this case a crack is produced on the surface of gear tooth initially, which finally results into bending of gear.

Ø  In another word we can say that amount of load which is faced by gear tooth repeatedly is more than the strength of gear tooth to withstand against the load in this case bending occur. If bending occurs, gear will fail.

Ø  By using the material with high bending strength can avoid bending failure. Proper module and fillet radius provision can also reduce bending failure.

              PITTING FAILURE:

Ø  There are two types of pitting failure. 1^st is initiative pitting, and 2^nd is destructive pitting. Initiative pitting is not that harmless, it is reversible, and it won’t result in failure of entire gear.

Ø  But in other had negative pitting results in failure of full gear. It occurs when HARTZ’S CONTACT STRESS is more than connection strength of material. By making equipment with high contact resistance material this failure can be avoided, but once this failure starts then, it’s not reversible like initiative pitting.

             SCORING:

Ø  When oil film on the surface of the gear tooth is worn out, and when engagement occurs there is metal to metal contact which results in failure of teeth, this type of failure is known as scoring.

Ø  Scoring occurs due to improper lubricants and incorrect method to apply it.

           ABRASIVE FAILURE:

Ø  If lubricant is not properly filtered before using it on the surface of gear then impurities in it is responsible for the abrasive failure. Particles in unfiltered oil rub against the surface of two mating gear which caused worn out of gear surface and leads to failure of gear.

           CORROSIVE FAILURE:

Ø  When there is a use of metal then there is corrosion. Corrosion is oxidation occur on the metal surface. So if your gears are made of metal then corrosion well take place sooner or later.

Ø  To avoid failure due to corrosion, one should make gear from material like steel, nonferrous metal, nonmetal. To cover gears from the atmosphere or to provide proper lubricant is also one of the ways to avoid corrosion failure.