Written by Sujith Ail and Rohit Shetty July 8, 2016

Purandara has been manufacturing molds for label and carton processors for 7 years, even though the company has been in the printing industry for more than 25 years. Recently, the Cochin-based company invested in a new mold plate laser cutting system from Suntex, Japan, and modern CNC engraving technology for the manufacture of hot stamping or embossing molds.

The investment aims to provide laser cutting punching dies and CNC engraving hot stamping and embossing dies.

"Because mold manufacturing is a niche industry, the machine installation base is very low. Because of the small number of machines, it is difficult for machine manufacturers to set up services in India," said Raju N Kutty, Managing Director of Purandara Laser Technologies.

Purandara's mold manufacturing plant is located in Cochin City, covering an area of ​​4,000 square feet, with 23 employees in the workshop. Currently, the company caters to southern India.

Technical know-how Suntex's machine is equipped with FANUC laser technology, which can flexibly set the laser power, pulse cutting mode, and the distance between the nozzle and the mold plate during the cutting process. Kutty said: "The new technology allows us to cut layouts in a faster and more user-friendly way. The laser speed is twice that of traditional machines and can achieve straight double cutting. In addition, the technology does not require any additional training for customers. "

Kutty said that in terms of engraving technology, due to the conditions in the market, there are some restrictions. "Documents used for embossing and bronzing are usually difficult to produce on CNC engraving because they are more suitable for making films and then chemically etching the mold."

If you compare the international standard competition between a single carton and a corrugated carton, many of Purandara's carton manufacturing customers have made significant investments to improve quality and maintain quantity. Purandara is taking small steps every year to fulfill its promise by manufacturing quality tools. "The quality of tool manufacturing is about technology and craftsmanship. With money, you can invest in technology, but you can't buy craftsmanship," Kutty emphasized.

The market scenario has experienced many changes in the requirements of molds. Issues such as price cuts or negotiations plague manufacturers, causing mold manufacturers to cut corners in order to survive. In addition, tool production is a small batch business. On the other hand, various technological advancements have opened up new ways to increase the business portfolio. Kutty said: "Today, we see that the packaging market is more attractive in terms of mold consumption. In the commercial sector, there is an increase in demand for complex designs, such as wedding cards and album covers."

Tech gyaan: Q&A with Raju Kutty

PWI: Compared with the traditional process, what is the difference in the preparation time of the laser mold manufacturing process? RK: There is not much difference. The laser machine takes a few minutes to charge, nothing more. The bottleneck lies in the tools, because this is the work of the craftsman. 

PWI: What is the life of a mold made with a steel ruler? RK: It depends on the condition of the machine and the bed, the abrasiveness/tensile strength of the material, the material of the ruler, and many such factors. Under normal circumstances, any mold can be expected to have hundreds of thousands of impressions, provided it is ready. It is also possible to re-cut the mold at one time. We have had an example where a customer was able to obtain 300,000 impressions for production runs. In some cases, the mold failed within 1,000 impressions. 

PWI: How do you ensure that the mold is safe during transportation? RK: The Thermocol packaging on the top and bottom and the kraft paper around it are good enough. Damage to the mold during transportation is rare. 

PWI: What are the tolerances maintained by the mold? RK: In general, we keep the tolerance within 0.25 mm. 

PWI: What is the relationship between the blade angle and the die-cutting material? RK: The blade angle depends on the tensile strength of the material. High tensile strength materials like PVC (especially when the laminate is inside) require more shearing forces than ordinary cardboard or even corrugated cardboard. In order to achieve this higher cut, ruler manufacturers manufacture rulers with lower bevel angles. So you have a basically sharper inverted V-shaped outline. Manufacturers also provide additional polishing according to such rules to achieve additional hardening. We apply such rules to plastic cartons, gaskets, internal laminated cartons, and such challenging tasks. These rules are expensive, and mold costs are also higher. 

PWI: What are the minimum and maximum embossing heights that can be achieved? RK: Engraving can be done on a 7mm brass block, and the same depth can be achieved. The embossing depth of a typical folding carton is 0.7 mm or sometimes less. The depth of the carving is usually determined by the geometry of the work. 

PWI: How to eliminate angel hair or burrs during die cutting? RK: Due to improper die cutting, angel hair is formed in the carton. In the mold, this requires the use of smaller angle rules, and the use of harder profile rubber in areas prone to dust formation. But this also involves a dimension of the machine. The hardness of the board and the age of the bottom plate are also a factor in this situation. In the areas where you have blank separations, we see a tendency to form angel hair, so we use special rubber in the blank separation areas. 

PWI: What types of ejector glues are used for die cutting? RK: Various rubbers are used in the die-cutting process. For example, we use high Shore hardness rubber in complex areas where waste paper tends to accumulate during the production process. For regular use, there are many soft rubbers to choose from. Corrugated cardboard again uses a special soft rubber. 

PWI: What is the thickness of the tool used by the CNC engraving machine to make the mold? RK: The thickness of the tool starts from 0.1mm, which can be determined according to work needs.

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