Testing in industrial life is routine and mundane thing but some tests you remember esp when its impact results in out proportion saving to bottom-line. Surface preparation with abrasive blasting is carried out in many activities like coating. Use of right abrasive results in right quality & best economy. I would like to share one such pleasant experience about Ervin test.
It is very small equipments consists of a wheel with two blades, a target and a re-circulating device-just like a miniature version of shot blasting machine.
Ervin test machine enables us evaluation of quality of metal abrasives esp durability [life] and transmitted energy [impact energy] of abrasives under controlled conditions, which are two key measures of the value and quality of metal abrasive. Durability of abrasives are determined by number of passes against the target that are required to reduce the abrasive to unusable size ie 100% replacement by test quantity.
We had calibrated the system using S-550 calibration standard shots and then tested abrasives available at our end, results were as follows:
[No.s of passes to replace 100%]
|calibration standard- SS 550||2946 [2900+-50 as per standard]|
|A-grit GP 25||2893|
|A-shots SS 330||3043|
|B-grit GP 25||1091|
Supplier A & B were both good name in industry B-shots gives half life compared to that of A-shots and B-grit gives one third life compared to that of A- grits. Results at that time were shocking, but resulted in very hefty saving in surface preparation cost.
This facility may be utilized for evaluation of shot and grits and for new vendor development.
It can also be used with a frequency inverter to establish optimum shot velocity of abrasive mix.
Thus Ervin test with simulation of real shot blasting process, helps to demonstrate media properties such as hardness, size, density and durability and how their interaction, determines the efficiency of energy transfer and the economy of abrasive cleaning process.