Alexei Samoshkin ( Teko Competence Center, Russia)
As widely known, each refilled cartridge has its own end-user, who is not interested, which supplies were used during remanufacturing. The only thing important is that the documents printed with this cartridge be of high quality, and that the yield corresponds with the declared one.
What does the end user mean when he says “cartridge quality”? On the whole we can highlight several important factors influencing the readability of the text. These are the level of text “blackness”, the absence of grey background, the absence of printing defects (dots, spots, etc.). The yield is also important for the user, because the amount of money spent on document printing depends on it.
All those parameters can be evaluated. However, there is a question… How? No doubt every company can develop its own unique technology. But in this case it is not possible to compare your own production with the products of the others. And inaccuracy of the chosen technology can influence the legality of the evaluation. Using standard methods (to which STMC methods serve as an example) relieves you of those complexities. Teko Competence Center uses them in its work.
STMC – Reliable Methods of Printing Parameters Measurement
Standardized Test Methods Committee (STMC) is an international committee, created for finding and promoting of standardized testing methods for printer cartridge industry. It advises the usage of two standard of measuring cartridge characteristics:
- ASTM F2036 for measuring of printing density and background level;
- ASTM F1856 for measuring the yield.
It is important to remember that STMC methods do not determine, which cartridge is “good” and which is “bad”. They only give the possibility to measure printing parameters.
Let us briefly review how measurements are done according to these standards in Teko Competence Center. For testing of each cartridge the printing of defined pages in a defined order is performed until the yield is exhausted. By weighting toner hopper before testing, after testing, and after a complete toner removal, we can learn how much toner there was in the beginning, how much was spent for printing, and how much was left unused.
2 or 5 times during the test (depending on the cartridge yield) the special test pages are being printed, which are measured by densitometer to determine printing density (how black is the blackness) and the background level (how white is the whiteness). Also with various test pages it can be determined whether the cartridge has printing defects or not.
From 1 to 3 times during cartridge testing the spending of toner is being measured by the precise scales before and after printing of exactly 1000 pages with 5% filling.
From the amount of used toner and its average consumption during the whole printing cycle the cartridge resource (yield) is being calculated.
Evaluation of the Received Measurements
STMC methods do not give the answer to the question: whether the measured parameters are “good” or “bad”. Due to this fact the problem arises of how to interpret the received data.
Having many years of experience in testing under STMC guidelines, Teko Competence Center created the system of supplies evaluation. It is optimal for service centers specialists, serving as a benchmark.
During printing density evaluation the prints are compared with OEM-made, using a scale that considers logarithmical nature of density values (the percentage is calculated from reflection coefficient):
- Higher than 85% compared with OEM – “good”;
- 70-85% compared with OEM – “satisfactory”;
- Lower than 70% compared with OEM – “unsatisfactory”.
However, since any density values that are higher than 1.40 are perceived as “good” by the majority of users and are hardly differentiated by the human eye, we should switch the scale to the absolute values, if OEM printing density exceeds 1.47 (1.40 – is 85% from 1.47 on a reflection percentage). This way we get uninterrupted evaluation scale.
- >=1.40 – “good”
- From 1.32 to 1.40 – “satisfactory”
- < 1.32 – “unsatisfactory”.
We use analogous evaluation system for minimal density measured during the test.
For background level evaluation an absolute empirically matched scale is being used:
- The values lower than 2% - below measurement error;
- 3% - the borderline of the background naked eye visibility, the values below it mean “good”;
- Higher than 4% - a background visible to the eye, such values are counted as “unsatisfactory”.
For evaluation of printing defects presence a special series containing 6 test pages are being printed. Each page is designed to detect certain types of defects.
The complete evaluation of printing quality is made with the following parameters being taken into consideration:
- Average printing density throughout the whole printing cycle;
- Minimal printing density throughout the whole printing cycle;
- Average background level throughout the whole printing cycle;
- Maximum background level throughout the whole printing cycle;
- Printing defects found by the user during the whole cartridge lifecycle.
As a result, if all listed points of printing density and background level fit into “good” category, this corresponds with “3 Stars” grade.
If one point fits into “satisfactory” category, and others fit into “good”, this corresponds with “2 Stars” grade.
No more than two points fitting into “satisfactory” category and others are “good”, or one point fits into “unsatisfactory” and others are “good”, this corresponds with “1 Star” grade.
One star is taken away for each recognized drawback (significant to the end-user) unaccounted for at previous points.
If the final result has less than one star, then the product doesn’t fit into standard.
The benchmark for yield evaluation is OEM product put in the same conditions. We compare not the spending of toner but a value of the yield in pages, since the difference in toner spending might be compensated by the difference in filling weight. The evaluation scale is simple:
- The yield higher than 90% from that of OEM corresponds with “3 Stars”;
- From 80% to 90% - “2 Stars”;
- From 70% to 80% – “1 Star”;
- Lower than 70% - the product doesn’t fit into standard.
The evaluation of “the rest” supposes the reviewing of all important points not included into “printing quality” and “yield” categories. It is always recommended to check the effectiveness of toner transfer and quality of its fusing. Also all the anomalies noted during the test (conditionality of component wearing, extra noises during functioning, limited compatibility with other components, etc) should be mentioned in the report. The system of evaluation is extremely simple:
- No drawbacks noticed – “3 Stars”;
- One drawback noticed – “2 Stars”;
- Two drawbacks noticed – “1 Star”.
Teaching STMC Methods
To learn STMC methods one must contact a certified trainer. For instance, this status is being held by the head of Teko Competence Center, mr. Alexei Samoshkin. Then the specialist goes to the customer premises and performs a one-day course. This curse is for free, but the customer pays for trainer’s road and stay. Also the customer’s company must purchase equipment for testing laboratory: scales, calibration weight, densitometer, thermometer, hygrometer, densitometer padding, test pages generator.
Having completed the course the customer himself performs the testing. In case of correct usage of the test methods and correct filling of report he receives STMC certificate. For this several fees must be paid:
- Basic certification - $1000;
- Repeated certification (every 4 years) - $1000. It requires sending of a new testing report to your trainer or STM Committee for inspection.
Despite complicated procedure of getting STMC certificate, there are numerous certain advantages. For instance, with its help you can impartially compare your results with manufacturer’s (vendor’s distributor’s) tests, compare and evaluate the work of different supplies used for cartridge remanufacturing. Also there is a possibility to set tolerance for production parameters:
- For quality control of your production;
- For preparation of technical requirements during tenders and controlling the compliance.
There is also a marketing advantage – the right to use world-recognized STMC logo on your production and marketing materials. This is undoubtedly will increase the company authority, customers’ loyalty and trust.