Dental abrasive disk integrity

Requirement

The resistance to slippage of the eyelet crimp at the centre of a dental abrasive disk is a key measure of the quality of the product. The test is to check for any relative rotational slippage between the two components under an applied torque. An improved process was implemented with a quick-change custom fixture, an automated test program and the added capability to export the data results for further analysis and SPC monitoring.

A global supplier of medical equipment manufactures dental finishing disks for shaping, contouring and polishing. The product is comprised of a flexible, abrasive-coated disk and a crimped metal eyelet at its centre—where it connects to the mandrel/hub of the dental instrument during use. The company wanted to improve its overall process for testing the integrity of the disk. 

The test involves applying a pre-set torque to the eyelet and then making a visual check to see whether it has slipped relative to the abrasive disk. Two disk sizes of 3/8” and 1/2" diameter needed to be tested using the same test system and gripping fixture.

Solution

Mecmesin designed and manufactured a custom fixture for rapid batch testing of the different sizes of abrasive disk on a Vortex-i (now replaced by the VortexPro range) automated torque tester. Prior to testing, the specimen is marked across both disk and eyelet to clearly indicate if breakaway occurs. A clamp secures the outer disk, and a conical probe engages the eyelet to exert the appropriate torque. The Emperor software used at the time controls the Vortex-i torque tester to apply the specified torque at a constant 5.0 rev/min. After the test, the specimen is removed from the fixture and the marks checked for indication of rotation of the abrasive part against the eyelet. If representative samples show sufficient resistance to breakaway under the applied torque, the batch can be accepted. If not, then adjustments to the crimping machine can be made.

The software enables the test data to be automatically exported to Excel® for reporting and further analysis—another requirement of the solution.

VectorPro continues our software family with the added functionality of database architecture to conform to 21 CFR Part 11 compliance for medical industries.

Test equipment

• Vortex-i torque testing system with ITC 1.5 N.m sensor (replaced by VortexPro and VectorPro software)
• Emperor fully programmable torque testing software
• Custom-designed upper probe - tapered to hold the eyelet
• Special lower clamping fixture - double-sided to suit both sizes of abrasive disk