Dear Franco

The Pin-on-disk or ball-on-disk would be fine as long as the manifestation of tribology exists, i.e., friction, wear, and lubrication. For faster results, the Pin-on-disk would be recommended in a comparison to the ball-on-disk.

Thanks fpr the reply.

Franco

Each test has its own advantage (for example it is possible to achieve high speed ) and a lock of it (moving forward does not allow it back). What we want is important. Most often used pin-on-plate test.

I'm looking to the most general purpose testing machine.

Hello, dear Franco! It depends what the task you have for decision. The friction schema pin-on-ball can be used if you want to define the loads limitation for the tested material. But if the task is determing the friction coefficient, then the friction schema pin-on-disk is more preferable. I do my experiments on the machine with pin-on-disk schema and recieve some tribotechnical characteristics, like friction coefficient in dependance from the load and used lubricant, wear and so on.

Hello Franco! if you are searching for some general purpose tribometer there are some machine that can be adapted to several configurations depending on what you have to test for instance SRV from Optimol industries can be an example but there are several others.

Dear Franco,

Your quastion is too general. Everything depends on your experimental goal. However, comparing pin-on-disc and ball-on-disc I would choose the first one, as ball-on-disc has one important disadvanteges - increasing contact area in coarse of a test, i.e. experimental coditions are not constant.

Regards

I think ball on cylinders for boundary lubrication at extreme Hertzian pressure will be the best when testing oils. Whereas 4 ball test for grease to test it under spectrum loading will be very good. Pin on disk is good to test coating using scratch test.

please specify what you need and I will help you.

Pin on Disk is suggested and most of the researchers have published using this equipment.

I suggest both

acc. to my view pin on disc apparatus is more suitable as compare to ball on disc.

It depend on the lubrication or coating you are using specially if you are running a boundary regime test.

Dear Franco,

For general purpose pin on disc is most suitable. Ball on disc is suitable for lubrication condition.

We can not specify which is the best from my experience pin on disk is good for lubricant in the boundary regime, 4 balls test is good for grease under high pressure , ball on cylinders is good for HDL tests and boundary. So it depends on what you are doing and be consistent with the protocol.

DearFranco,

Adding a new dimension,

trapping of heat & wear debris is crucial factor for COF and wear,

POD and BOD both have different nature if come to trapping of heat and wear debris

it depend on, what are you looking for???

Again I answered this before and said that alldepend on the materials and lubricant used

Pin on disc test would be preferable for tribology. Other type of tests can be performed based on the material.

Based on my experience, ball-on-disk is method based on the ASTM Standard D4172-94 Method for Wear Preventive Characteristics of Lubricating Fluids. Basically, this method is appropriate to test the performance of lubricants under the same testing conditions. At the end of the test, the performance can be measured based on the wear scars left on the steel balls after the test. Since the steel balls have a point contact, based on Hertzian stresses, a light normal load can be applied during the test to cause high contact stresses. Pin-on-disk, is a different type of test aimed to measure the tribological performance of other type of materials, for instance hard coatings, polymer coatings, polymer against metals (steel, aluminum cast iron) or even metal against metal. This test has the advantage that you can test the tribological interface at different lubrication regimes (boundary/mixed, hydrodynamic, etc) and even recreate a Stribeck curve for the tribopairs. Also this interface, is useful to study the wear behavior of different interfases and other phenomena such as scuffing, galling, under certain testing protocols.

I agree with @Emerson. Usually, we use pin on disc for material testing and ball on disc for lubricant testing.

Most of the time when we are doing ball/pin on disc test, the ball/pin is the counter body. The counter body is chosen depending on the application. The disc is of the material on which we have put coating. The disc can as well be a standard material depending on the application.

Say, for example, you want to study the efficacy of minimum quantity lubrication with different cutting fluids while turning Ti64 with uncoated tungsten carbide insert. As an initial study, you want to run tribometry test. Then you may choose tungsten carbide as the ball/pin. Getting tungsten carbide balls of a specific composition may be easier than pins. The disc would be of Ti64. And we would have done ball-on-disc rather than pin-on-disc.

For evaluating the performance of coatings also, we have primarily used ball-on-disc as availability of balls of standard material (alumina, tungsten carbide, bearing steel, silicon nitride etc) and diameter is easy as compared to pins.

According to the application we have to choose the wear test. For example, Brake pad application we have to select an abrasion tester.

Thank you.

Dear Franco,

the selection of a tribotest largely depends on the application you wish to model and the contact conditions you wish to achieve, therefore I would say that there is no such thing as “the best tribometry test” but rather that it is possible to find the best solution for a specific purpose.

Ball/disc type of tribometers are typically used for highly loaded lubricated contacts due to the very high contact pressures achieved in these contacts. However, if you wish to model an application with lower contact pressures, measure hydrodynamic friction or analyse tribological phenomena under more specific conditions, you need to turn to other solutions.

Generally, in the last years, the focus has shifted from the simple ball/cylinder/disc type of testing towards more complex and close-to-real-application geometries and testing conditions. I would say that according to the “Categories of tribological testing” as defined by H. Czichos in his book “Tribologie-Handbuch” (in German) – many adaptations of the original representation can be found here or there (see e.g. https://www.researchgate.net/profile/Hayder_Al-Maliki/publication/317426637/figure/fig1/AS:503228919971840@1496990532421/Overview-of-the-tribology-test-categories-of-DIN-50322-base-on-8_W640.jpg) – we have moved from category VI to categories V and IV. Consequently, an increasing number of testing equipment producers have started offering a wide range of sample geometries and holders to allow for more application-oriented testing covering a larger spectrum of testing conditions.

For more information on “application-oriented tribotesting”, you can check some of our papers with examples of tribometer setups for various applications and testing conditions:

• Cold metal forming: https://doi.org/10.1016/j.triboint.2017.04.052
• Low-pressure polymer contacts: https://doi.org/10.3390/lubricants7020017
• Ice friction: https://doi.org/10.3390/lubricants7120106
• Paper contact: https://doi.org/10.1108/ILT-02-2020-0064
• Elastomer contact: https://doi.org/10.3390/lubricants5040045
• Gaseous atmosphere: https://doi.org/10.1016/j.triboint.2016.02.022

Best regards,

Igor

I fully agree with Igor. There is not the best (universal) tribotest. Tribological testing always shoud be individually fit to real friction and wear conditions. In this contest Igor's recomedations are very usful.

Well elaborated by Igor Velkavrh

Dear Fransco

I prefer ball on disc method to measure wear of the fabricated part because this method will give you more realistic prediction of wear than Pin on Disc. However, I am using Pin on disc to estimate the wear of EDMed samples as this method has less arrangement and available. But you have to make a fixture with complex design based on method arrangement. Furthermore, You have to choose your lubricant based on your application. I am using Hanks solution as the lubricant.

I hope the narrated information will assist you.

Best regards

According to the application we select the tribometer. Please elaborate your question what application you are targeting. Then only it is possible to give you right suggestion.

It depends upon the application of the specimen to be tested.

First, you need to figure out the extent of wear the surface might undergo.

If the wear is extensive then a pin-on-disk might give good indicative results whereas for ageing wear or at elevated temperatures a ball on disk can give better indicative results.

depends on what type of contact, lubricant film you want to investigate in this tribotest. Pin on disc mostly for wear test, friction test.

Depending upon the type of contact of your material with the counter material in your application as in both cases( pin on disk and ball on disk), friction and wear values will be different

I think one of the important factor in selecting the wear test is the application of the alloy you are testing.