Excavator Bucket Tooth Failure Analysis
The Excavator bucket tooth have to bear heavy loads of materials like soil, rock and subjected to abrasion wear due to the abrasive nature of soil particles. Its tooth got damaged due to abrasive wear and impact load. This paper deals with review of Excavators bucket tooth analysis to find out its actual failure.
Abrasive Wear, Hard Facing, Digging Force, Tooth Development
Rapidly growing rate of industry of earth moving machines is assured through the high performance construction machineries
with complex mechanism and automation of construction activity.
An Excavator bucket is an attachment for heavy equipment which is designed to be used in site excavation. Buckets can be attached to Excavators, tractors, cranes, and similar types of equipment.
Excavator buckets are made of solid steel and generally present tooth protruding from the cutting edge, to disrupt hard material and avoid wear-and-tear of the bucket. The excavator bucket tooth have to bear heavy loads of materials like wet soil and rock and also subjected to abrasion wear due to the abrasive nature of soil particles when tooth acting to break up material Generally alloy steel is used to make an Excavator bucket tooth and hard facing of some wear resistant materials can be applied on the material of bucket tooth, so that its life will improve against abrasive wear.
The direct contact of metallic components with the soil constituents
requires the employment of alloys that have both good toughness
and abrasive resistance. High values of hardness are also needed
in those surfaces over which the extracted materials move and even
harder materials to manufacture the mineral milling equipment.
Due to these reasons. A careful analysis should be preformed to
select appropriate materials in this field.
Nowadays, an excavator tooth has to be replaced after approximately
a working week, causing an elevated cost which represents an
important economic factor in the mining industry
II. Calculation of Excavators Bucket Force
Digging force has a key effect on the dynamic behavior of the
bucket wheel drive system .
The methodology adopted is to find maximum
Digging force for the given cylinder pressures, and this is done
using Design View. The second stage is to find the forces at all
pivot points of the attachment, this is done using MathCAD.
• Calculation of Digging and Breakout Force
• Digging Force (RX)
The digging force is the available force at the tip of the bucket tooth created by the stick cylinder(s). Maximum digging force is
calculated with dimension “a” at its maximum and with the bucket in a position calculated for maximum Breakout force.
It is established that the development of cutting tooth could be improved by using finite element analysis. This technique is applicable to compare different types of tooth easily. It leads to an assessment of the effect of the main parameters on the behavior of the geometric configuration of the tooth. Consequently the results of finite element analysis show that the head of tooth is the most critical point and so we conclude that high strength steel will be adequate because of the extreme loads. The obtained results can be useful in practice.
IV. Bucket Tooth Development
The objective was to elaborate a testing and planning methodology ensuring the verification of the new components (buckets, tooth)
developed . Following the review of the excavators’ cutting structures used until then having more advantageous features than those of the earlier ones.
The most important features among these are listed below.
V. Failure of Bucket Tooth
The excavator bucket tooth which fail due to abrasive wear and
impact load is protected against abrasive wear by using four
different types of hard facing materials using manual metal arc
welding process .
A tooth of a Digging of an excavators is working member which
is subjected to an intensive abrasive were during operation
and to heavy impact and static loads which determine its
service life. A tooth of excavators buckets performance two
main functions: It plunges into rock; it brakes-up the rock and
guide the broken particles of rock into the excavators bucket.
When a tooth of an excavator digging bucket plunges into the
rock, a flow of particulate rock moves along its top surface, the
flow of particulate rock at the starting portion of the tooth of a
comparatively short length being of laminar nature . The flow
of particulate rock then leaves the tooth surface which results
in a material increase, from twenty to forty times, in resistance
to penetration of the tooth in the rock. To lower this resistance,
the portion of the tooth surface adjacent to the portion where the
laminar flow of particulate rock leaves the tooth is made concave.
The flow of particulate rock at this portion changes from laminar
to turbulent so as to determine a positive formation of vortices
in the boundary layer of particulate rock which is adjacent to
the top surface of the tooth at the concave portions. The major
part of coarser particulate rock moves over the vertices of the
boundary layer. Therefore, intensity of abrasive wear of the tooth
is determined by the character of movement of particulate rock
in the boundary layer. Excavator Bucket Tooth Failure Analysis
The SAE provide the breakout and digging force. For maximum
Breakout force condition but for autonomous application it is
important to understand. Which are improved bucket geometry
for more efficient digging and loading of material and heavy duty
robust construction for increased strength and durability . Excavator Bucket Tooth Failure Analysis
III. Geometric Modeling & Description
In order to investigate the distribution of stresses in the cutting tooth, author set up a finite element model. Consider the solid model shown in fig. 1, consisting of a holder, a part from the cutting edge and an optimized cutting tooth. The cutting tooth is jointed into the holder as a removable piece. The holder is actually a steel rectangular structural tube, and of course it is possible the remaining parts of structure are made of a different
kind of steel. SK60RC Digger Rock Tip
3D Solid Models of Excavator Bucket Tooth
The finite element mesh of cutting tooth is of free type using 10-node tetrahedral elements and so this solid structure is divided into 25 937 finite elements. The geometrical model of tooth is illustrated in fig. 2. The mechanical properties of steel used in linear elastic finite element analysis are also taken: Young’s modulus (E) is 205×103 MPa and Poisson’s ratio (ν) is 0.29. This material behavior is assumed to be linear elastic until the effective stress reaches proportional limit and in this region the stress-strain relation is represented by Hooke’s law.