THE IDM ink rub tester from IDM Instruments has been designed for determining the abrasion resistance of printed material, labels, folding cartons, corrugated boxes, inserts, circulars and other packaging material that has graphics.
This instrument is based on, and is equivalent to, the Sutherland rub tester as specified in ASTM D5264. The following tests can be executed on the tester: dry rub, wet rub, wet bleed or transfer, wet smear, functional rub.
The significance of the ink rub procedure is to differentiate between strong and weak ink films as well as their adhesion to container board and the container boards resistance to rubbing and scuffing.
The IDM tester is essentially a motor driven device for moving a weighted test specimen over a printed or unprinted sample through an arc of 8.5° ±0.5° approximately 3.9cm for a predetermined number of strokes.
The stroke comprises one to-and-fro motion of the test weight. Test speeds can be selected from fixed speeds of 42 and 85 cycles a minute. Both speeds are accurate within 2 per cent.
Weights of 908g ±45g (2lb) and 1816g ±90g (4lb) are provided each having 51.6cm2 (8in2) of contact area. With these dimension and weight, the relative pressures produced are 1.7kPa (0.25psi) for the 908g weight and 3.4kPa (0.50psi) for the 1814g weight.
The test weights are fitted with neoprene pads 0.32mm thick with compressibility such that 172kPa ±34kPa shall compress the pad to half of its original thickness.
With a very easy operation, the result of scuffing on samples of undamaged areas of the test piece are easily determined and can be used in the decision on the suitability of an ink for certain applications.