High-accuracy production-line colour metering

Citation

(2000), "High-accuracy production-line colour metering", Pigment & Resin Technology, Vol. 29 No. 6. https://doi.org/10.1108/prt.2000.12929fad.009

High-accuracy production-line colour metering

High-accuracy production-line colour metering

Keywords Minolta Industrial Instruments, Sensors, Colour, Measurement

Minolta Industrial Instruments (Plate 4) is offering a high-accuracy, non-contact sensor for production line colour control. The spectrophotometer is said to provide stable measurements over long-term use making it ideal for a wide range of process applications.

Plate 4 Minolta offers a choice of portable and benchtop colour meters for the paint industry and for finished products

According to Minolta, its CF-1440 On-line Spectrophotometer is designed for colour measurement at heights of up to 100mm above a production line and across a maximum width of 385mm. It can reportedly be set to measure one, three or four 40mm diameter points across the axis of the meter. When used for single point measurement the minimum measurement interval is 0.6 seconds. Three other modes enable three- or four-point measurements at defined positions across the axis in a single rapid scan. This is thought to ensure consistency across the width of the product.

The CF-1440 operates under PC control, connection being via an RS-232 port. It claims measurement across the full visible spectrum from 400nm to 700nm, with a 20nm pitch. Internal calibration is performed during each scan measurement to ensure the stability of colour measurement over a long period of time. A distance sensor corrects fluctuation in intensity of illuminance on the specimen's surface caused by fluctuations in the specimen's height. This reduces the distance fluctuation to within E* _ab0.25.

Minolta are also offering a range of portable and benchtop spectrophotometers and tri-stimulus calorimeters for the measurement of colour within the paint industry or of painted products at prices to suit most applications.

The Minolta CM-508d is a portable spectrophotometer that fits in the hand and weighs just 1.3kg. Its ability to be switched to include or exclude the specular component of reflected light reportedly increases its versatility to account for gloss finishes. Measurements of spectral and calorimetric values, absolute or difference, can be displayed graphically and numerically on the in-built LCD screen. While capable of storing up to 200 sets of measurement and target data, this is expanded to 1,350 sets with the optional plug-in memory card. An RS-232 port enables downloading of recorded data to a PC or unloading of data for comparison on the shop floor.

The CM-508d has an 8mm diameter measuring area and utilises d/8 geometry (diffuse illumination and 8 viewing) which is reported to meet the ISO and DIN standards for reflectance measurements as well as CIE d/0 recommendations and ASTM t/0 and d/0 standards. The wavelength measurement range of the instrument is said to be from 400nm to 700nm with a 20nm pitch. It claims maximum operational reliability as it has the minimum number of moving parts and utilises a pulsed xenon arc lamp capable of more than a million flashes.

The lower cost Minolta CM-508i is very similar in function to the CM-508d but does not offer exclusion of the spectral component measurement. For work in the laboratory, Minolta has two highly accurate benchtop spectrophotometers, the CM-3600d and CM-3500d, which are believed to be ideal for controlling colours during the formulation and manufacture of liquids and powders. To enhance the results obtained from the spectrophotometers, Minolta offers SpectraMagic Quality Control Software, which has a wide range of functions including graphical displays, calorimetric data, indices, tolerancing, statistical analysis and an e-mail facility to allow fast transfer of data. Predictive colour matching software is also available. For Point-of-Sale paint colour comparisons, Minolta offers a hand-held, low-cost Computerised Electronic Colour Fan (CECF), to provide colour matches to manufacturers' paints, and a CR-300 tri-stimulus calorimeter. Minolta can provide full systems solutions to its customers as well as offering training courses and re-calibration of equipment.

Details available from: Industrial Instruments Operation, Minolta (UK) limited. Fax: +44 (0) 1908 618662; e-mail: twalker@minolta.co.uk