When we complete the payment and provide the design documents, the production of the bags will already begin out of sight. The first step in production is to make molds.
Qingdao Xintongda Plastic Products Co., Ltd., one of the leading manufacturers of flexible packaging in China, has been providing superior flexible packaging solutions to customers across various industries over the past three decades. This means that our mold making level is also industry leading.
Next, let me introduce the specific production process of the mold for you.
1.Color separation
When we get your design, the first thing we need to do is color separation. As we all know, all colors are blended by CMYK. So our designers need to separate the colors, calculate the mixing ratio of colors in each part, and make suggestions on whether spot colors should be used for some colors according to the printing difficulty of the design.
After this step is completed, our designer will make a final confirmation picture for you, and all the required colors will be marked so that we have a clear idea of the number of molds required. In addition to the basic mold, there will also be white, spot color and matte special templates.
We will also use digital printing of a paper copy to show the printing, but the effect of design printing on paper and bag is completely different, so it can only be used for reference and to check whether there are changes in the position and content of the design.
After you confirm the final design picture, we will officially enter the mold production process.
Tips：
1. In addition to the standard CMYK, we usually add a white mold, which is not only to provide the white pattern in the design, but also to make the overall printing effect of the bag better and clearer after printing the white, which can also make the design more three-dimensional. If you want the design to look more metallic, we can choose aluminum foil material while not printing all white, so as to achieve a metallic effect.
2. Spot color:
Usually we recommend the use of spot color for two reasons: one is to save the mold, if only a certain part of the color is mixed by other two colors, then we can choose spot color, so as to reduce the color mixing, save the cost of the mold.The second is to ensure the accuracy of the printing color. In some large-area color blocks or areas with a lot of color mixing, spot colors are recommended in order to prevent these parts from changing due to the adjustment of the color proportion of other parts, which will affect the final printing effect.
2.Preparation of the mold before carving
All the materials are of the same size, so we need to calculate the width and circumference of the mold according to your design, and then we will cut the materials according to this to make them the size we need.
Next, we will put it into our automatic process. First, the mold after cutting needs to be corrected. The purpose of this is to ensure that the mold is in a circular motion during the printing process, so as to ensure that all the printed content can be accurately printed on the bag during printing.
After correction, we’ll plug both ends of the material. The robot will choose the width of the material at each end based on the width of our printing machine.
Then we need the process of polishing and dynamic balance correction. Polishing is to make the surface of the material smoother, so that some pollutants do not affect the subsequent carving. Dynamic balance correction is also to ensure the smooth operation of the mold in the subsequent printing process. We can ensure the dynamic balance of the mold by adding counterweight blocks of different weights.
At this point, all the preparatory work has been completed.
3.The carving of a mold.
（1）Copper plating
First of all, we will add serial number on the edge of the mold, including the date, serial number of the whole mold and serial number of a single mold, so that it can not only be more convenient and accurate when it is put into the printing machine, but also we can also look for it according to the serial number to determine its storage location faster when we need it in the subsequent production.
After that, we need to electroplate a layer of copper on the mold, copper plating is a key process of mold processing, its quality directly affects the quality of the mold. Usually we require that the surface of the mold after copper plating is smooth and delicate, and there is a matching hardness with the electronic engraving machine. Copper plating process usually adopts copper plating process of copper sulfate electroplating solution. Under the action of direct current, after countless electrode reactions, a layer of copper is plated on the surface of the mold.
Hardness and brightness are key factors of copper plating. The hardness is low, the dot configuration is not good, the hardness is high, the carving is difficult, the carving needle is easy to break. The surface of the copper layer should be bright and smooth, uniform thickness, fine crystallization, which has strict requirements on the content of copper sulfate in the plating solution, the content of sulfuric acid, the temperature of the solution, the current density and the PH value of the electrolyte.
(2) Chrome plating
Once the copper plating is complete, we use a laser engraver to carve the pattern on the mold. This is the specific process: We will evenly coat the surface of the mold with an anticorrosive adhesive, engraving machine laser beam will make the design part of the adhesive layer instantly vaporized,, non design part of the adhesive layer still exists, this process is also called laser engraving film. Then put the mold in the corrosion tank with ferric chloride corrosion liquid corrosion,the design part of the adhesive layer due to be opened, so it is corroded into a concave network hole, the non text and text part of the adhesive layer is still retained, and then wash off the non text and text part of the adhesive layer with cleaning liquid, so the design of the sculpture is completed.
After finishing the carving of the mold, we also need a layer of chrome plating to ensure that the mold will not wear too much in long-term use. The unstable chromium plating process causes the difference in the chromium layer and hardness of the mold, the different wear degree of the mesh wall, the different surface finish, the different wetting tension, resulting in the inconsistent formation and transfer of ink film, which leads to the difference in color reduction. This requires us to polish the mold again. Polishing can make the layout form oblique plate pattern, play a blocking role in the high-speed flow of ink, but also polish off the edge of the engraving dot burr, so as to achieve better printing effect.
After completing this step, the entire mold production process has been completed.
(3)Printing test
Next, our mold workshop will use a small printing machine to print some samples for inspection, ensure that the printing positions of all molds are correct and corresponding. If there is no problem, we can install the mold on the printing machine and start the formal printing.
Usually the service life of the mold is 200 km to 250 km, after which the printing effect will become worse due to wear. At this point we can choose to re-carve the mold. We can use special reagents to etch the metal on the surface of the mold, then re-sand and carve, repeating the previous steps. It is worth mentioning that the printing effect of the re-carved mold is not as good as that of the new mold, so if the cost is acceptable, we usually recommend making a new mold.
That’s about all the details of mold making.
Qingdao Xintongda Plastic Products Co., Ltd covers an area of 6,000 square meters, with near 30 years production experience. Xintongda boasts state-of-the-art equipment, fully enclosed, dust-free, pollution-free sanitary conditions that meet the standards of food packaging production and the workshops which have passed the certifications of IS09000, QS, FDA, CE and BRC. All these help its products always maintain high reputation in the industry and gain unanimous recognition from a great number of customers both at home and abroad..
Our company always adheres to the principle of reputation first, quality first, and customer first. We will provide the best service to users both at home and abroad with the most excellent quality, the most favorable price and the fastest delivery speed. Sincerely look forward to your visits and inquiries!
