ROTARY PAD PRINTING APPLICATION
Training programme initiated reduction of solvent use by 140 litres per week and increased production from 21,000 units per week to 63,000 per week.
HELP!!! SOS….. We were called into a company who had taken delivery of a 7 colour rotary pad printing machine. We think our engineers need training, we were told. The machine is stopped more than it’s running and our client is screaming for production. (The machine should have been running at 3000 per hour, 24 x 7). They had tried the normal route of asking all the various consumable suppliers to come in and give them “free” advice but found they were being given conflicting information and as they tried out each piece of new advice things just got worse.
As with all our training sessions we started off with the principles of the process. We almost didn’t get any further. One of the engineers piped up with “well why have we always got ink left on the pad, we are constantly thinning the ink but it just dries more quickly?” During the next break I went with some of the engineers to look more closely at how the machine was performing. Sure enough the ink was very thin and there was ink left on the pad but you could also see the solvent evaporating from the ink. It was immediately obvious to me that they were using the wrong solvents but I don’t mix well with inks although they seem very partial to me. If I get within feet of ink I end up walking away covered in it so I decided to carry on with the theoretical training and get my partner to fix the problem, (nothing like passing the buck). A quick phone call and she was on her way.
Carol’s first task was to persuade the production manager to let her stop the machine, not an easy task especially when you can’t say how quickly the problem will be fixed and they have their customer screaming for product. Once she had agreement the first thing she did was to watch the machine running and talk with the operator about the problems and what they had tried to solve the problems.
Having listened and analysed what she thought was the problem Carol then produced a plan. She decided to tackle the image that was giving the most problems, which was extremely small and fine text. Carol thought that the solvent that was being used was evaporating too quickly so before stopping the machine she did a very quick and simple check. This was to see if the ink being left on the pad was wet or dry. It was dry as she expected.
 The first job was to clean down the ink pump (an hours work in itself). After reading the Technical Data sheets on the ink and solvents she selected two solvents a fast drying solvent and a retarder. She mixed a ratio of 80% thinner to 20% retarder and very carefully weighed the solvent mix and the ink. Rather than mixing the full 3 litre quantity required for the ink pump she decided to run the ink in an ink tray, generally only used for sampling. The improvement was immediate and after the machine had been running for an hour with stops only to adjust the other colours the operator and production manager were desperate to change all the inks over to this mix but Carol forever the pessimist would not agree to changing them all in one go. They agreed to select one of the images that were totally the opposite of the first as this was a large solid area.
One of Carol’s concerns was that because the ink was using a slower drying solvent mix that they might not dry the ink before the next print. The second ink mix also demonstrated immediate improvements in print quality and consistency after running for an hour with out problems it was agreed that the machine would be stopped for a complete changeover.
I must admit it was with some trepidation that I returned to the print shop at the end of the day and I nearly turned round and walked away when I saw the machine was not running. Just as I was deciding whether to make them aware of my presence I was spotted and there was no turning back. The production manager rushed over saying “great now you’re here you can help us clean down.” Exactly what I had been trying to avoid from the beginning! For a guy who had hardly had two words to say to me earlier he never stopped chatting, by the time the cleaning had been completed I knew in minute detail what had been done during the day by Carol. Two hours later all the pumps had been cleaned and replenished with the new ink mixes. I’ve never dared ask Carol how she felt as the start button was pressed, all I know is that I would have preferred not to be there, what if it didn’t work after all this time? After the machine had been running for 45 minutes with no stops at all (totally unheard of), we started to get a steady stream of visitors to the department. By now it was 8.00 p.m. Then I couldn’t believe my ears, Carol is giving instructions to the shift engineer to add more of the solvent at hourly intervals. What the hell is she doing what if it all goes wrong now? If looks could kill I would have had her lying in her coffin at this moment. She calmly gives him her mobile number with instructions to call her if he has any problems. In all honesty I was torn between the success that had been achieved and the possibility it might all fall apart after we left. At 11.30 p.m. Carol got the dreaded call from the engineer “I just thought I’d let you know we haven’t stopped the machine yet and I’m thinking of charging admission fees to all the people coming in to look at the miracle.”
Problems are not always solved as quickly as this but if you follow these basic steps you won’t go far wrong:-
- Watch how the machine is running.
- Write down the possible variables.
- Decide how you can eliminate each of these variables.
- Decide what order to eliminate them in.
- Make sure you have any tools and consumables you may need to hand.
- Make sure you have a note pad and pen to hand.
- Keep notes on exactly what adjustments you have made and number the samples accordingly.
If you make an adjustment and the problem gets worse reverse the adjustment. |
CASE STUDIES
We have many examples of positive outcomes from companies we have delivered training to. Some appear to be extreme but all are true.
OPTIMISATION OF SQUEEGEE USE – Training programme initiated a saving on squeegee use of £11,000 per annum.
ROTARY PAD PRINTING APPLICATION – Training programme initiated reduction of solvent use by 140 litres per week and increased production from 21,000 units per week to 63,000 per week.
AN OBDURATE SCREEN PRINTER – Hey Ho, you can't win them all. The client was unable to maintain consistent quality for a new contract. |
