Abrasive Wear Tests
Overview of Abrasive Wear Tests
This Section aims to provide a general overview of abrasive wear test methods for evaluating wear characteristics of liner samples. Because there are many individual testing procedures, there is no claim to completeness. Instead, the principles are briefly explained, as well as several advantages and disadvantages of general test rig build ups are shown.
Particle On Disc Test
Test Principle:
The particle on disc test is transferred from the classical pin on disc test to determine abrasive wear characteristic of solids. A single particle is fixed to a special holder and a normal force acts on the particle. The disc consists of the liner sample material and rotates at a constant speed.
Advantages:
- Exactly defined sliding conditions between the particle and the disc
- Not standardized for usage of particles, but high correlation of the procedure to pin on disc standard, e.g. ASTM G99, DIN-50324
- Only a small amount of bulk material is needed (several particles, less than 1 kg)
Disadvantages:
- Fixed particle is representing less industrial application case due to no free interaction between particles and liner sample
- Preparation of the individual particle samples, including the suitable fixation to a holder can be very time consuming
- High number of individual experiments is necessary to obtain a representative wear coefficient for the entire bulk material
Dry Rubber Wheel Test
Test Principle:
The wheel has a rubber sheath and rotates with a constant velocity. The bulk material falls due to gravity from a funnel in the gap between the wheel and the liner sample. A normal force acts on the liner sample and press it against the rubber wheel and the bulk material inside the gap. The particles are pressed into the rubber and slide along the liner sample without rotation.
Advantages:
- Defined sliding conditions between the particle and the liner sample
- Standardized procedure according to ASTM G65
- Easy to handle in laboratory scale and small amount of bulk material required
Disadvantages:
- Pressed in particles representing less industrial application case due to no free interaction between particles and liner sample
- Limitation of the suitable bulk materials to fine grained materials with low particle size variation. The standard abrasive bulk material is sand
Abrasive Wear Pot Test
Test Principle:
One or more liner samples are fixed to the end of the rotor. The rotor in placed in a pot filled with bulk material, so that the samples are surrounded by bulk material. For the test the rotor rotates with a defined velocity. Furthermore, samples can be rotated to their own axis to determine different angles. There are also others in which a lid is seated on the bulk material. This can be acted upon with an additional force.
Advantages:
Relatively easy to prepare and use in laboratory scale
- Only a relatively small amount of bulk material is needed (several kilos)
- Standardised Procedure according to german VDI 4472 to mainly determine wear factor in compare to a reference liner sample
Disadvantages:
Superposition of different wear mechanism of sliding and impact wear are possible during testing
- No clear distinction between sliding and impact possible
- Relatively high wear of the bulk material or frequent change of the bulk material necessary
Linear Belt Wear Test
Test Principle:
The linear sliding wear test consists of a belt conveyor that conveys the bulk material under the liner sample with a constant linear velocity. The test enables the investigation of various loads by placing weights on top of the sample (holder). In order to realize a conveying in the cycle, the bulk material is conveyed from the end of the belt conveyor to a bunker at the beginning of the belt via further conveyors.
Advantages:
Free interaction between bulk material and liner sample surface representing close to industrial application case
- A wide range of bulk materials can be used with just nearby no limitation regarding grain sizes.
- Constant linear speed profile across the cross section of the liner sample.
Disadvantages:
High amount of bulk material is necessary (up to several 100 kg depending on the test rig size)
- Great effort for the construction of the trainer to realize a conveyance of the bulk material in the circuit
- Large dust emission possible
Ring Through Wear Test
Test Principle:
The test stand includes a rotating annular trough with outer diameter ranging from one to several meters, in which the bulk material is located. The receiving trough conveys the bulk material bed below the liner sample. Hence, a free interaction between the bulk material and liner sample surface is allowed. The test enables the investigation of various loads and speeds. By inserting an additional plow, even mixing of the bulk material can be made possible during the tests.
Advantages:
Free interaction between bulk material and liner sample surface representing close to industrial application case
- A wide range of bulk materials can be used with just nearby no limitation regarding grain sizes.
- Simultaneous examination of different liner samples is possible.
- Smaller test rig size in comparison to linear belt wear test including smaller amount of bulk material necessary (depending on the through diameter)
Disadvantages:
High amount of bulk material is necessary (up to several 100 kg depending on the test rig size)
- No constant speed profile across the cross section of the liner sample
- Large dust emission possible
