BN-20 - Print Head Questions

[SEW]

The BN-20 uses one DX7 print head?

A DX7 has 8 channels with 180 nozzles per channel (so 1440 nozzles in total), resulting in a maximum dpi of 1440?


What is the average life expectancy specification (in dots per print head or dots per nozzle?) for a BN-20/DX7 print head under standard operating conditions and standard maintenance, please?


Also, CMYK usage of the BN-20/DX7 is about 0.005 cc/inch^2 for C and Y and 0.01 cc/inch^2 for M and K (rectangular print area, single "colour" use), respectively?

Thanks in advance!

 

[Solventinkjet]

Yes it uses the DX7 head.

Yes 1440 max resolution.

Life expectancy about 6 billion shots give or take a billion or 2.

Don't try to estimate ink usage based on the print head. The general rule is to think about what a full coverage prints price per square inch of ink is. You will get between 0.20 to 0.40 per square foot for cost. Now charge based on that even if it is or isn't a full coverage job and don't forget the other costs.

 

[El Barto]

I've had a DX7 go to pot after about 3.5 billion and I have two with over 20 billion now that still print great. A couple of things to keep in mind is that some colors are harsher than others (I've heard that it's the cyans that go first, which is what I saw), and also that some colors will print 3 or 4 times as much as others. I use 3 M and Y for every 1 C and B. My shot counts reflect this on both of my ecosol printers.

After all that, VanderJ summed it up nicely. Six billion is what people expect on average. It just might take you a decade to get there on some channels.

Also, if you're using Versaworks the log will tell you ink usage for each job. It won't break it down into channels, but it will tell you the total amount.

 

[SEW]

Thanks a lot for the replies!

Some follow up questions:

When you say around 6 billion shots that's for the whole print head, per channel or per nozzle?

Are the 8 channels color specific, i.e. 2 particular ones exclusively used for C, another 2 only for Y, another 2 only for M and the final two for K?

Thanks again in advance! Much appreciated!

 

[El Barto]

Sorry man, but you can disregard my post. I misread yours and was referring to a completely different head. Too much work here to be goofing off on forums, I suppose.

 

[Solventinkjet]

6 billion per channel so if 1 channel hits 6 billion it is considered at it's life expectancy. The head does not know what color ink is in what channel so there is no specific color for a channel. Your machine dictates what the color configuration is. If you put the wrong color in the wrong spot, it will still print but the colors would be wrong.

 

[SEW]

Thanks again for the answers/feedback!

The following might be a bit artificial, but just to get my head around it.

From what I understand, for a simple rectangle print of 1 inch by 1 inch in one color (full yellow or full cyan) at 1440 dpi, the DX7 needs about 0.0052 cc/inch^2.

The DX7 uses 8 channels, each with an average life expectancy of 6 billion (6 000 000 000) operations per channel.

For the example I assume that each channel gets equally used and would lead to the following?


the head: 1440 dots / inch

each channel: 1440/8 = 180 dots / inch

each channel contributes to an area
of 1 inch x 1 inch: 180*180 = 32400 dots / inch^2

maximum print area per channel
with 6 billion life time operations: 6000000000/32400 = 185185.185 inch^2

channel life expectancy equals that of the
head, so max. print area per head: 185185.185 inch^2

ink consumptions of 0.0052 cc/inch^2,
so life time ink consumptions per head is about: 963 cc

That's not even 4 cartridges of ink and so I assume the above is wrong and I might not see the tree for the forest?

Some things I could think of:
Is the 6 billion maybe per nozzle and not per channel? This would add a factor of 180, which would obviously be quite significant.
Is getting from that 1440 dpi to 1440*1440 = 2073600 dpi^2 in this actually wrong and for dot prints? If so, how do I get from dpi to dpi^2?
Do dots not equal channel operations? I assumed here with 1440 dpi, 8 channels of 180 nozzles each, each nozzle activates once, so each channel as a whole once for a dot.

Thank a lot again in advance!

 

[Solventinkjet]

It is impossible to figure out exactly how your head is going to function using math. It may give you a vague idea but there are too many variables.

I saw a customer's shot count the other day. They run their machines hard for two seasons a year and then slow down for the rest. In 2 years the magenta and yellow channels were around 2 billion shots where the black channels were only at 700 million.

In general I see 3 to 5 years life expectancy on these heads. I have one customer who has 2 VJ1624s and on one printer the head lasted 2 years and the other one is still going at 4. I have spoken with many people who have gotten 7+ years out of a head. Manufacturing inconsistencies, environment, usage, head strikes, maintenance consistency etc. all effect the life of the head and not just shot count.

 

[SEW]

Thanks for the reply, very much appreciated!