Locating matrix on a Heidleberg cylinder die cutter
I have a 22x30 Heidleberg cylinder die cutter. It cuts 918 and scores are 895 vertically and 900 horizontally. When I makeready a job the vertical knives usually are cutting and most of the horizontal knives need to be patched on the carbon spot makeready about 3 to 6 thousandths. So I am pretty confident that the press packing s correct. Problem is when I try to locate matrix on the cylinder on the horizontal scores it takes several attempts for it to locate properly and I am wasting a lot of matrix. Once I lay matrix down on the scores I throw machine on impression one revolution. I have been doing this for years and have never had this problem before.I have been on this press for 2 months now. I use Cito, CCM and Schreiner matrix, doesn’t matter they all do it. The cylinder is clean and I have tried dropping kerosene in the hole next to counter. Any help would be appreciated
It almost sounds like the machine is bearing off on the vertical matrix and not laying enough pressure to adhere the horizontal matrix. You may want to run your horizontal matrix onto the cylinder first. If you are working on a die-cutting jacket for this work, make sure the jacket is pristinely clean. When I’ve had problems with matrix adhesion, it usually pointed toward cleanliness—or old matrix where the glue is getting weak.
If almost sounds like your are concerned that the cylinder is not coming down on impression sufficiently. There should be an adjustment below the door on the side that sets the cylinders resilience to pressure. You might want to set it for least resilience when running the matrix on.
You have to be sure to put the press on impression before the swing are takes a sheet. If you don’t time this right the position of the cylinder to the bed will be slightly off. I dunno if this is as important when positioning score matrix but it’s worth looking into.
Mike
Are you saying to put the machine on light form instead of heavy form to locate the matrix? I normally run the die cutter on heavy form on the run, but will try light form when applying matrix if that is what you mean. Also I forgot to mention this happens even when I have just a single score locked up going horizontal or paralell to the gripper
I will make sure I check where swing arm is next time.Thanks
I assume you are flipping the trips on the swing arm into the off position (down) to hold the machine in impression ?
if you really find this is happening only in odd spots around the form and is random you can always get the odd bit to transfer by putting a smallstrip of tissue along the rule and sandwich it between the rule and matrix , it will be stuck in the locator after the transfer it wont fall into the machine .
As an after thought…. you have the right matrix width in relation to your rule width , if the rule is too wide it will stick hard into the locator ,this i have encountered many times and when i find things tight the strip of tissue often helps .
The matrix goes up on the cylinder but when I hit a sheet you can see the score isn’t cleanly pushing the paper into the matrix. The score looks distorted at the edge where the paper starts to push into the channel. Also tried putting on light form before putting matrix up, that didn’t work.
It is not unusual for the leading edge of a cylinder Crease to dig in a wee bit where the first contact occurs with vertical rules , if the matrix doesnt go beyond the end of the rule this can also leave a small indent at 90deg to the crease , on a complicated carton it is not unusual that you have to scrape the end or sand the ends of the matrix to stop some of the distorting that sometimes occurs .
I have never seen any point in having higher rules across the bed and lower rule down it . I have always impressed on my advice that you use low rules and a bed plate with tissue or whatever when necessary , i prefer 21.80mm crease rule and with that 22.30mm score (cutting) . I make no allowance for the weight requirement across the cylinder other than i put one line of hard sellotape along the backs of all the horizontal rules that are cutting . If the run is a long one and long to my way of work is 5000 impressions and up then i may use .001” steel shim instead . Typically i use 2/3point rules for most folder work up to 450gsm , packaging being often thicker and needing a wider matrix then 4point rule is more helpful if you have the right guage of matrix .
If you are able try the approach without the extra height on the horizontals and you will find that you may not have quite enough height on the crease . If youare creasing thin stock you need narrow rule and matrix or the crease will not have a definate bias . If you take a pull of the job with no matrix up you should not see any crease rule indent in the job when all the cutting rules are doing their bit .
I’ve run across the same issue with my Heidelberg cylinder.
Other than keeping the cylinder spotless I’ve also put a sheet or two under the chase. Then I remove the sheets once the matrix transfers.
Mike
it sounds like your machine is an automatic impression machine and it needs the impression mechanism resetting so that the cylinder sits down to its correct position on the first revolution rather than taking 3 or 4 revolutions to achieve its correct position, if we can be of any assistance please call whittenburg inc, 615 212 0015.