How Clean Is Clean?

A feature article in a recent issue of Products Finishing asked the same question as the headline of this story (March 2008). The article then went on to describe multiple standards and methods for determining the level of cleanliness of your parts, ranging from simple water break testing to complicated elemental and particle analysis using scanning electron microscopes and other sophisticated equipment.
A German supplier of precision cleaning and surface inspection equipment now has its own answer. Advanced Clean Production GmbH (ACP; Esslingen) says its PartSens device is the first ever to allow direct measurement and documentation of particulate contamination on component surfaces.
The device features a large measuring probe that ACP says significantly expands the potential range of applications, enabling rapid cleanliness checks of, for example, sheet metal blanks and automotive body panels. The probe has a measuring surface of 20 × 15 mm and allows for efficient, random sample testing of component surfaces for particulate cleanliness, according to the company. It can detect particulate contamination with sizes down to 25 µm, and measurement can be performed either manually or automatically.
The PartSens inspection system has a measuring surface of 20 x 15 mm and is equipped with optical filters that produce high-contrast images of surfaces being inspected. The result is precise, reliable measurement of particulate cleanliness on a variety of flat and shaped sheet metal surfaces.
The system works by using direct side lighting to illuminate the surface being inspected. Integrated optical filters produce images with extremely high contrast, assuring reliable inspection even under difficult conditions such as inspection of surfaces with complex geometries.
Testing is a simple procedure consisting of passing the measuring probe over the surface to be inspected. An integrated video display allows real-time visualization of the surface under test, and the number of particles, along with their size, orientation and position is represented in the live image.
The company says the instrument lets users reach reliable conclusions regarding the number, the size and size distribution of particles on the inspected surface. The system lets users program particle count, size and other characteristics in accordance with customer-specific requirements, documenting the required cleanliness of part surfaces. And, ACP says, the fact that measurement results are available immediately allows users to react without delay to problems, thus avoiding expensive rework and scrap.
Documentation of test results is via an integrated thermal report printer. Measured values and live images can also be saved to a USB memory stick for documentation and later analysis at a PC.
In automotive plants, inspecting sheet metal blanks before press forming is a typical application for the new measuring system, according to ACP. The company says a large U.S. automobile manufacturer is already using the system to inspect auto body panels for cleanliness before painting. Further applications include monitoring of production environments and examination of the degree of cleanliness achieved during cleaning.
source pfonline.com/articles/1208tn1.html