As a growing manufacturer, we require initial certification for our suppliers as well as continued assessment visits. However, printing and electrical are two areas that require a specialist to assist me (we can't be good at everything, right?:))

However, we have struggled with the establishment of acceptance guidelines for 4-color process printing. Our packaging is quite challenging with color gradients, process printing on small fonts, and registration issues.

Can someone provide me some reasonable guidelines that process printers use to determine "how good" there processes are. To me it seems highly dependent on the setup operator (even though we have reviewed the color shift over time).

Ultimately, what do I need to look for to a) certify the vendor b)provide specifications for our component.

This has bothered me for some time :frust:

Can someone provide me some reasonable guidelines that process printers use to determine "how good" there processes are. To me it seems highly dependent on the setup operator (even though we have reviewed the color shift over time).


Hi K3nny,

Being from a print shop I hear ya!! We tend to focus heavily on regular flood prints as oppossed to CMYK...but we do our fair share of those too. Sorry, I have no real answer for you due to the intricacy of the process...we can use all the densitometers, spectrophotometers, light booths, etc...but nothing will compare to the human eye when it comes to printed graphics. As long as the reg. marks are lined up in 4-colour you should have a near perfect print (assuming the screens and art is accurate...lol)

I hope you can get some ideas from this link (http://newsmedianet.com.au/home/titles/title/Specifications.jsp?titleid=505#4colour).

Many years ago I worked in a "system module office furniture" company, where colour matching was an issue in terms of "customer needs", the office systems could be added or parts replaced over many years and each time the colour had to match.

To ensure we have a defined standard and colour "tolerances" we used what I believe were called - Munsell Color Tolerance Sets these Master color standards defined the range around the perceives colour dimensions of:

Hue - the name of the colour family, such as red or blue.

Value - the lightness or darkness of a colour.

Chroma - the intensity or strength of a colour.

The cards were ideal for visual assessment having windows to place over your samples to judge the measure of the colour against its "tolerance".

Needless to say a control light source, angle of viewing and distance (arms lenght) was used,the inspection personnel had sight tests yearly - this provide a control method, that could be documented in a simple "works instruction"

Had a quick look on the web - if you search on "Munsell colour" information appears.

I used to work in supplier quality for Lionel Trains and owned all of the packaging/artwork products. It is not an easy thing to deal with due to the subjective nature. Also with the fanatical nature of our customers who bought model trains as a collectors item, they were the most picky. Many would buy $1000+ toy trains and never open the box, so the box had to be perfect.

First define a specification of what is acceptable. We had things like "no voids larger than 1/64"" and "no more than one void in X square inches". You can get mylar templates made to use a checks.

When you find rejects make sure you get them back to the supplier to use as training/visual aids. Digital pictures might work too.

It is probably not practical for your supplier to do 100% visual inspection on packaging, but make sure they have good sampling plans in place.

We also always ordered extra packaging as our assembly people would act as the final quality check. We made sure we had enough extra boxes so that if we rejected some we could still finish the production run. Rejects were credited and samples returned to the supplier.

Our requirements pushed the edge of what printing technology could do, so we had to rely on sorting. Not the best plan in the world, but all we could do.

We also deal with a great deal of printing. We have been moving away from standard printing (silk screen, off-set,etc.) and moving more and more to digital printing. This eliminates the registration issues that are present when doing CMYK in silkscreening or other standard methods. Unfortunately, this doesn't eliminate the colour issue.

What we have done to try to reduce this issue (almost impossible to eliminate) is to provide the supplier with a "light", "heavy" and "target" sample of the range we are willing to accept. This is generated during our product development (and vendor evaluation) stage. This has resulted in much better quality from our suppliers as well as better understanding of the pricing for our customers (i.e. there is a cost for producing within a tight tolerance).

Unfortunately, all the machines in the world cannot simulate the human eye and how the brain translates this information. We have had too many cases where the "measuring devices" indicated acceptance of the colour, but everyone agreeing that the colour was not acceptable. We are relying on the human eye but at least it is controlled to some degree.

John

Does the electronic files have the appropriate "under color build", in CMYK?
What kind of stock? What is the Imposition on the sheet? Please provide a little more detail. I think I can help you on this one.
Patriot1

While Im new to the printing industry (2 years) I find that most pressmen will argue for art over science in verification of printing. They will state that only the human eye can detect flaws but this is extremely subjective. To reduce subjectivity I have employed various tools.

We employ an AVIA Mnuemonics system which can detect 4 pt broken text. Our Clinical and Pharmaceutical customers have a zero tolerance for broken text. The smallest piece of dust on a plate will destroy a press run so housekeeping is paramount to the pressmans success. We also use this system in comparing customer proofs to epsons/film before plates are made. This becomes our master file for all reprints and for checks throughout the press run.

We have a database that points the operator to correct annilox rollers to use for each job. These are checked at sign in.

For color we are purchasing an X-rite spectrophotometer which can not only provide a Delta reading but grades color in the CMYK scale. One of our sister companies has employed the strategy of placing spectrophotometers at the press with the correct settings for a job and colors scales saved on the quality drive based on the CMYK scale. A quick comparison before sign in can save the operator much embrassment.

For printing the ink is a main suspect in most color defects so along with experation dates and climate control for storage of inks we have imposed on waterbase inks both a viscosity test and a Ph test to ensure the ink will apply properly.

Now if the ink is right and the plates are right and everything is in registration and you are still having problems that leaves the substrate (note: we work in a climate controled environment which can and will affect printing). Different substrates can also affect the application of ink in which case we use dyne pens to determine surface energy. If the surface energy is to low than the ink will not adhere.

So little by little I have removed some of the art from the pressman with scientific detection on the front end which has not been well recieved by them but our customers are reaping the benifits.

Does the electronic files have the appropriate "under color build", in CMYK?
What kind of stock? What is the Imposition on the sheet? Please provide a little more detail. I think I can help you on this one.
Patriot1

We are specifying a retail product on SBS sheetfed stock (I'd have to look up the sheet specs and I do not have these specifications at home). For similarity of design, take a look at:

http://www.medela.com

The product features:

1. Dual Gradients (Gold merges into light gray). Images within the gradient.
2. Imposition is simple with one design per sheet.

Greetings,

We too had the same problem that you have stated. We resolved the issue by implementing " Proofing and Printing to Standards". There are a lot of International Standards out there but we discovered that what suited us best was the ISO 12647 family of standards. There is a lot of information available on this on the internet and there is a firm in UK which goes by the name of Mellow colour who can help you on this. Try this ! Colour can be quantified , measured and controlled to a large extent . Am attaching some mails along with this which may help.

Regards

Arunmenon