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Humans have known to be involved in reproducing handwritten texts and graphics as early as 220 A.D. Man saw the advantages of printing which made it possible to relay and distribute the information at hand. Printing, singularly impacted the expanse over which the information could be reproduced and with the invention of the Printing press in 1400’s this simply grew. All through these centuries up till today, printing has made major advances using the latest technology available. Even with the introduction of internet in the early 90’s that could distribute information faster and further than print, it showed no signs of slowing down.

Screen Printing

Screen printing is one such method of printing that was invented in the early 1900’s that still finds its place today. It has become the go-to method when it comes to producing beautiful typography and imagery. This method involves distributing ink over a surface on which the image needs to be printed. A stencil is made on a netted screen that allows the ink to spread through and produce the required image. This is how it gets its name “Screen Printing”. The process is a highly skilled one where correct amount of ink needs to be spread using a mechanism called a “Squeegee”. It is nothing but a rubber blade that spreads the ink evenly over the stencil thereby producing the print on the surface.

Screen Printing

Photo courtesy of RENU

Issues with current method

Over the last century this field has experienced major advancements but has come with its own pitfalls. Work has been done to improve the equipment and the inks used but the process still experiences issues which affect the quality.

While producing the image, a constant pressure and speed need to be applied by the operator to evenly distribute the ink over the surface. Although the process of swiping the squeegee over the surface can be repeated multiple times, these repetitive actions increase the time spent per image. This certainly is not beneficial when the operators have a large order to fulfill within a given time frame.

Also any change in the pressure applied or the speed at which the squeegee moves produces the same image with varying results. Moreover human errors and fatigue always play an important role in manually operating methods. Let alone the accuracy and precision with which the images need to be reproduced repeatedly. Better qualities of prints are observed when the operators are less fatigued.

This variation in quality over large numbers increases the rate of rejection of the final product. This in-turn affects the profits made by the printing company. It is not beneficial in today’s scenario of cut-throat competition where companies go extra lengths to save every dollar.

RENU Electronics helps automate the process

A popular printing company that manufactures screen printing equipment was approached by their customers. Their customers wanted a solution that would eliminate at least some of the pain points which were responsible for low productivity while using the manually operated techniques. This printing company got in touch with RENU for help with a solution that could bring together automation equipment to make the process of screen printing affordable, fast and easy. The challenge was to design a machine that would not compromise on quality regardless of the number of repetitions the screen had to go through. This had to be rather improved. 

Programmable controller

FL004 Low Cost PLC

Photo courtesy of RENU Electronics

An industrially robust micro-controller based PLC had to be used this purpose. The aim was to utilize as little space as possible for the control system circuitry in order to maintain the compactness of the whole system. The controller had to be installed in a very small area. For this purpose RENU provided the FlexiLogics®-FL004, one of our newest offerings. This PLC gave them the freedom to use 8 Digital Inputs along with 6 Digital Outputs in a small form factor. Other features of this PLC include support for high speed counters and PWM outputs that can generate signals as high as 10kHz. The FL-004 is a cost effective solution as compared to the other PLCs in the market.

Touchscreen HMI

Since the machine had to be compact, the designers did not have enough space for operating buttons and switches. Also no machine that had been made for this purpose of printing had built-in touch-screen controls for the operators. By integrating a touch-screen HMI, it gave the operators the ease to control the machine in various Auto/Manual modes. More features could be added onto the HMI with use of multiple screens like alarm conditions and other control options. FlexiPanel®- FP2043T provided by RENU was selected for this purpose. It’s compact size of 4.3” and easy communication with the PLC over the RS-485 interface at a low cost, made it the best option for use in here.

Using products by RENU Electronics which are high in efficiency and low on power consumption, the designers were able to design the product that consumed only 0.5 units/hr of electricity. This was a major breakthrough achieved in terms of power consumption.

Direct Impact

There was a rise in both quality and quantity of the final print that was seen after using this machine. The companies could increase the throughput of their production up to 1550 prints per hour. Even at its slowest operating speed, the machine was able put out about 500 prints per hour. This was observed as a massive rise in production when compared to the manual process which could achieve only up to 100 prints per hour using manual methods.

Screen Printing Device

Photo courtesy of RENU

One of the important objectives of any production house is to strive for zero rate of rejection in terms of quality. The rate of rejection that was consistently observed to be around 10,000 ppm in the manual process was brought down to 0 ppm after using this machine.

There were also significant savings in ink that were used in production as the machine precisely controlled the amount of ink that had to be injected at every swipe.

Esis distributes RENU Electronics PLC’s and HMI’s in Australia, for automating any kind of physical industrial process. Check out the range on our RENU Electronics HMI and PLC page, or simply call us to discuss your requirements. 

Article Courtesy of RENU Electronics. 

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