Our dream was to design a pad printing machine that anyone could use just by pushing a button! No time-consuming adjustments, no unnecessary waste of product, high accuracy and repeatability the first time. And we succeeded! We created and patented the Automatic Colour Registration ACR module.
Pad printing is an indirect printing technique in which a product is printed with an image engraved in a printing plate. The printing plate is inked using our closed ink system and the ink, from the printing plate, is transferred to the product using a flexible silicone pad.
Multi-coloured images are obtained by printing several single-colour images next to or on top of each other.
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Starting with a (pad) printing project requires 2 steps.
Step 1 is the development of a pad, a printing plate and determining the right ink for optimal printing results.
The appearance of the print on the product should meet the expectations. This can be a purely visual requirement, using one or more colours to achieve the desired print, as in a beautiful print on a cosmetic perfume bottle.
Or it can also be a functional print, where precision is more important than the visual aspect of the print, such as when printing graduation scales on a syringe or numbers on a dose counter.
Printing International will take care of these print-technical developments and realises in-house print trials and specific developments on your products.
Contact us for additional information to co-develop your specific printing needs.
Step 2 is the setting-up of the machine for the actual printing.
Before we talk about the innovation we are introducing, let’s talk about common practices and implications for the (pad) printing industry.
Procedure before the introduction of our patented technology:
After mounting printing plate(s), ink and pads, machine setup involves putting printing plates and pads in place referenced to the product that needs to be printed. As printing accuracy may need to be as good as a few hundreds of a millimeter, this may be a cumbersome task. Not only will it require specific skills from the operator and strict procedures to follow, it will also take time and require some number of products that will be used throughout the setup process and will be wasted for commercial purposes.
Existing pad printing equipment may require typically “a few minutes” for each print unit to be adjusted. The mechanical positioning systems used to position printing plates and pads could be difficult to access or use in an easy way and high-precision positioning systems come definitely not cheap.
Problems encountered before introduction of our patented technology:
Do you have to throw away too much badly printed products ?
Have you had the problem that the responsible for operating you pad printing equipment is unavailable and nobody else is able or willing to setup the printing machine ?
Does it take too much products to setup your printing equipment so that the return on a printing job is difficult to calculate or even seems economically not viable ?
Are you dreaming of first-time-right (FTR) printing equipment ?
With our patented technology, setting up the machine will require an operator only putting on the printing plates and pads.
The actual setup or calibration of the machine is fully automatic. At the touch of a button, the machine runs through several steps that involve measuring the position and orientation of product container, printing plate and pad. Based on the measurements, the position and orientation of printing plate and pad is adjusted so that the print will be perfectly aligned with the product.
This reduces the set-up time for each printing module to just a few seconds and not one single print is needed, so no waste of products!
For automatic running of the system, the pad print modules need to be equipped with electronically controlled axes. The system should be able to reference the product fixture and each of the printing plate modules in X,Y and rotation to the printing position. The same holds for product fixture and pads.
Product fixture, printing plate and pad should have accurate position reference markers.
To identify the position and orientation of the markers of product fixture, printing plate and pad, a vision sensor is required. The resolution of the camera depends on the positioning accuracy requirements of the print on the product. Special care is taken to capture the image(s) in optimal conditions. This may require specific illumination, lenzes and stable positioning of the vision sensor.
Our pad printing machines are mostly controlled using a PLC. As an OEM partner of Siemens since 2008, all our machines are equipped with Siemens PLC, drives, motors and HMI. The PLC is used to control the axes during machine operations. A separate processor, to which the machine is connected, is used for calibration purposes.
The machine should be equipped with print units compatible with the ACR module.
The machine should be equipped with pad(s), printing plate(s) and product container / product fixture / product jig compatible with the ACR module. Ink would only be necessary to visualize the printing result. As such, it is NOT required for the calibration / setup of the machine.
Upon pushing the calibration button, the camera needs to take a picture of the markers on the product container, printing plate and pad. Based on calibrated information about the different movements of the product container, printing plate and pad, the system calculates the target positions of any of these for taking the image with the pad on the printing plate and depositing the ink with the pad on the product.
This step is repeated for any combination of printing plate, pad and product fixture of interest during the production cycle.
Would you like to see what this ACR is capable of doing ? Take a look at the video we made in which 2 printing units are calibrated to print onto a common product container.
While this setup procedure would take a few minutes for a trained operator/supervisor, the system is capable doing it in about 25 seconds, including the theoretically not-necessary printing and control step.
The prints of the 2 printing units are registered within +/-0.01 mm and angular accuracy is excellent.
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