Validating high-performance polymers
Challenge
Polymers are widely used in high-performance applications such as electronic coatings and medical implants and are finding increasing use in precision instruments incorporating sophisticated plastic optics. Plastic optics readily provide more complex optical shapes than glass and need to be accurately manufactured and well characterised in shape and surface profile to ensure their performance.
Micro surface features and other small height change measurements (profilometry) are used to control manufacturing and quality assurance processes. These delicate measurements are usually made with a thin probe in contact with the surface of the material being measured. The weight of the probe requires careful control so that it doesn’t damage the material or cause material build-up on the probe itself, both of which effect the measurements. This is particularly difficult to achieve for polymers that are relatively soft and can be easily distorted by the measurement process. Improvements to the profilometers used to measure polymers would support an increased understanding of their properties and allow more-effective exploitation in innovative products.
Solution
The EMRP project Dynamic mechanical properties and long term deformation behaviour of viscous materials developed algorithms for profilometer contact probes, which enable correction for the distortions created during surface measurements of soft materials such as polymers. The project team produced well-characterised step height change reference materials and used these to compare surface contour measurement methods. This has enabled the development of new calibration methods with well characterised uncertainties for profilometry measurements.
Impact
Mahr GmbH, a leading manufacturer of measurement equipment, used the step height reference materials to assess its profilometer’s performance when measuring polymers. The knowledge gained through this assessment, along with the project’s correction algorithms have helped Mahr to optimize the measuring force of its profilometers. This significantly reduces surface damage and measurement problems caused by material accumulating on the profilometer probe itself. Applications include measurements of plastic optics, as well as diamondturned moulds for optical components.
The profilometer correction algorithms developed by the project have been incorporated in the DIN 32567 standard. This ensures wider access to these data correction techniques for instrument manufacturers and will ultimately lead to improved profilometry data for their customers.
- Category
- EMRP,
- Industry,