I'd hope so, whatcha got in mind? Feel free to PM too~
Thanks!
OK, here are some ideas. Cron has very little substantive info about their CtP's imaging. Which is a bother. So these suggestions are designed to help test the imaging system. Pick and choose from the following menu according to your priorities.
1 - If you cannot attend the plate imaging test then have them load the "Periscope" app (it's free) on a smart phone or tablet. You should do the same. It allows them to broadcast the test live over the internet so you can watch them perform the test.
2 - Create a file to test for plate to plate imaging registration. This is to give you an idea as to how well the plates will fit when mounted on press or require press adjustments to make fit. Also, how well a replacement plate will fit to an existing set (e.g. if a plate is damaged and needs replacing).
This is a 4 page black and white document. The size of the document should be the size of the maximum plate size that you will be using. Use AM screening at 120 lpi.
Page 1 is full coverage 30% K. Page 2 is the same 30% K but with about 1" cropped from the top. Page 3 is the same 30% K but with about 2" cropped from the top. Page 4 is the same 30% K but with about 3" cropped from the top.
Something like this (exaggerated for clarity):
While using the Periscope app (so you can watch the test being conducted) have them image page 1 only. Do not process the plate. Then reload the plate and image page 2. Again do not process the plate. Then reload the plate and image page 3. Again do not process the plate. Then reload the plate and image page 4. And process the plate. Have the operator sign the plate and have it sent to you.
After receiving the plate inspect it. Since the halftone dots are identical for all 4 exposures there should not be any lighter or darker areas. No moirés. Under a loupe you should only see single round dots in the 4 corners and center of the image. Doubled dots would indicate poor fit.
3 - While on the Periscope app so you can watch the test being done, have the Cron operator take out a new plate. Then have him use Scotch tape to make an X on the back of the plate starting at each corner. This is to give you an idea as to how well the laser focussing system manages variations in plate to laser distance. Expose the plate at whatever lpi you normally use. Remove the tape and process the plate. You should not see an X - just an even 30% tone across the plate. If you see any signs of the X that means represents a "hot" spot on the plate which in production might be caused by a small bit of debris between the back of the plate and the drum it's mounted on for exposure.
The laser system that exposes the plate in a CtP system has an impact on the consistency of the halftone dots that make up the image on the plate and therefore the consistency and integrity of the final presswork. The more well focussed, and hence sharper, the beam of exposing energy the more consistent the resulting halftones will be.
The four main ways that laser energy is focussed on a CtP device in order from basic to most sophisticated (I couldn't find where Cron specifies which system they use).
a) Depth of field. It is similar in concept to how depth of field works in a camera. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on each side of the focused distance, so that within the depth of field, the unsharpness is imperceptible under normal conditions. Typically requires constant calibration to maintain imaging consistency.
b) Hard focus. The laser is focussed for the particular plate when the CtP system is initially set up. This method is not able to cope with issues of variations in plate media thickness or as plate surface to exposure focus point changes. Hot spots and/or banding may appear.
c) Auto focus. The laser does an auto-focus for the particular plate each time just before actual imaging begins. This method is not able to cope with issues of variations in plate media thickness or as the plate surface to exposure focus point changes. Hot spots may appear.
d) Dynamic auto focus. The laser continuously adjusts focus for the particular plate during actual imaging. This method is able to cope with issues of variations in plate media thickness or as the plate surface to exposure focus point changes. Hot spots are unlikely.
During the CtP manufacturing process the geometric accuracy of the CtP drum on which the plates will eventually be mounted and imaged is measured.
4 - Geometric correction.
This is only important if you will be using more than on CtP device - whether that device is local or remote.
Imagine a grid wrapped around the CtP's imaging drum. In a perfect world the grid would have perfect integrity. And be identical on every CtP. In reality - the CtP drums are never perfect cylinders. For those CtP devices that have geometric correction, software distorts the bitmap that will be imaged on the plate in order to compensate for differences in the geometry of the imaging drum on the CtP device. Geometric correction also provides CtP device to CtP device integrity so that the plates from different machines will be as identical as possible.
5 - Thermal compensation
Aluminum plates expand and contract with temperature change as much as film does - about 0.5mm across a 1m plate (typical 8-page size) for every 5°C (9°F) temperature change. That 5°C change in temperature will result in a half row of dots @ 175 lpi misregistration plate to plate which can result in the need for the shop to reimage all four plates in a process job even if only one is actually needed. If feasible, plate page 1 of your 30% test file twice on the plate but imaged at different temperatures. Without temperature compensation, the change in plate size due to the ambient temperature change may result in a misregistration of the image.
Thermal compensation, for those devices that have this capability, corrects for ambient temperature variations by scaling the bitmap in such a way that it is as if the plates were always imaged at a single temperature. If the CtP doesn't have this capability then it will need to be installed in a temperature controlled environment.
6 - Ask to have a private sit down talk with the technician who will be servicing your Cron CtP. No sales or management at the table so he can be candid with you. Ask questions like: What training have you had? Was it sufficient? Is it updated as devices are updated? How is documentation? Clear? Correct? Complete? What are the most common issues you encounter? How quickly are issues resolved. Are replacement parts well stocked locally? Can I service the machine myself for the some of the issues? What about remote diagnostics? Is there a 24/7 call center? What support do I receive if I'm hard down and can't make plates?
I'm sure you can think of more.
That should get you started. Good luck.
