OPC Drum Wear Measurement
DeFelsko Coating Inspection Application Notes
 
 

DeFelsko manufactures hand-held, non-destructive coating thickness gages that are ideal for measuring the wear of Organophotoconductor (OPC) Drums.

Measurement Challenges

OPC drums require accurate non-destructive measurements to facilitate critical reuse and wear analysis decisions.  The coating thickness of OPC drums, while varying between manufacturers and products, is typically around 50 μm (2 mil).  Since even a few microns (tenths of a mil) of OPC wear may be considered significant, repeatable measurements on the curved surface of an OPC drum are critical in attaining accurate results.

Dry Film Thickness Measurement Solutions

The simplest and most cost effective way to non-destructively measure OPC coating thickness is with our PosiTector 6000 NAS series.   The NAS probe is specifically designed for high resolution measurement of nonconductive coatings (OPC) on non-ferrous (aluminum) substrates.  Though capable of measuring up to 625 μm (25 mils), the NAS probe is most accurate and provides its highest resolution under 100 μm (4 mils).  This optimum probe range is well within the expected OPC coating thickness of most manufacturers. 

When the customer identifies their application as “OPC Drum Measurement”, DeFelsko includes a custom fit plastic V-Groove adapter for the probe.  The groove in the adapter is designed to fit a broad range of OPC drum sizes offered by various manufacturers.  As shown in the images below, the adapter ensures the probe is consistently positioned perpendicular to the surface of the OPC drum, optimizing accuracy and repeatability.  When measuring, the plastic adapter also protects the OPC coating from physical damage that could be caused by the stainless steel probe.  

Prior to measuring the OPC coating, it is important to zero the probe on an uncoated drum to minimize the effects of the curvature and any existing base coating on the aluminum drum.  Note that for accurate measurements, the OPC surface should be smooth, clean and free of toner.

 

OPC Drum Wear Measurement     OPC Drum Wear Measurement

 

Free Consultation

For current pricing or to order these instruments, please contact us by telephone (315) 393-4450, fax (315) 393-8471, or e-mail techsale@defelsko.com.  If you require more technical information or have questions relating to your particular application, we encourage you to take advantage of our years of experience to recommend the best gage for your application.

 

Background on OPC

What is the Application?

The OPC (organophotoconductor) drum is the most expensive component of a toner cartridge and drives the entire print process.  The OPC drum consists of a nonconductive (organic) coating on a nonferrous (aluminum) substrate.  An OPC drum is used in an abrasive environment in which its surface is worn down by toner, wiper blades, and paper dust.

Why measure?

The life expectancy of an OPC drum is considered depleted when 5 to 15 microns (0.2 to 0.6 mils) of coating has been worn away.  As the amount of wear approaches half of its original thickness, automatic scrap decisions are often made.  Thus, the ability to measure OPC coating enables remanufacturers to maintain quality standards while maximizing the use of each OPC drum. An added benefit of taking a quick measurement to determine suitability for reuse is that the decision to scrap can be made prior to further processing such as cleaning, polishing or coating.

The ability to measure OPC wear also enables a remanufacturer to optimize their purchasing decisions of other cartridge components.  The most cost effective components for each manufacturer and model of OPC drum cartridge can be determined by monitoring the wear effects of various wiper blades, lubricants, toners, OPC overcoatings and paper types.   To monitor wear effects on OPC coatings it is recommended to record several measurements along the length of a new OPC drum. After experimental testing or actual customer usage, retake measurements in the same areas and record the new thickness values.  Subtract the before and after values to calculate the amount of OPC film thickness wear.   

Where is the market?

Remanufacturers of print and copier cartridges are the primary market for measuring OPC coatings.  As the cartridge printer continues to mature in the market place it is expected to come under heavy pricing pressures.  A remanufacturer capable of measuring OPC thickness has the additional information necessary to make decisions in a competitive marketplace.

DeFelsko would like to acknowledge the following article by Lester Cornelius as a source of technical information OPC Wear: A Predictable Variable” from Recharger Magazine in January, 1998

 

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