Toothbrush tester for bristle stiffness and pull-out resistance

Solution

Motorised tensile test stand
Custom grips to suit the each individual test requirement
Graphing software

Benefits

Single testing station for multiple tests
Soft, medium, firm grading quantified
Data capture and results comparable to international test standards
System usable by production staff in the factory environment with maximum reproducibility

Requirement

3 parameters needed to be tested on a range of toothbrushes;

Stiffness of bristles according to ISO 8627, 1987/BS5757
Strength of a single bristle
Strength of a tuft of bristles

The equipment needed to be simple to operate for production staff, robust enough for a factory environment with extremes in temperature and offer the ability to perform all 3 tests with the minimum of 'set-up' time.

Solution

A VersaTest motorised test stand adapted with accessories and sensors was used to perform each test.

According to the ISO 8627 bristle stiffness test, the toothbrush has to be mounted in a holder and rubbed against a metal grid at a speed of 200 mm/min. The grid is attached directly to a 100 N S-Beam Loadcell which detects the stiffness of the bristles as they travel over its surface. The graph of force/deflection was recorded using DataPlot-X software. Soft bristles will show a low force compared to hard bristles.

A surgical clamp with serrated jaws was used to hold the bristle for the 'single bristle' pull test. Forces in the region of 10-15 N were required to remove the nylon bristle from the polypropylene toothbrush head.

For the 'tuft' pull test, a set of bristles were held in a pin-chuck and connected to a 200 N S-Beam sensor, via a flexible chain link. Removal forces for the complete tuft were in the region of 50-70 N.