Purandara has been manufacturing dies for label and carton converters for a period of seven years, even though the company is in the print industry for over 25 years. Recently, the Cochin-based company has invested in a brand new die-board laser cutting system from Suntex, Japan as well as in contemporary CNC engraving technology for making foiling or embossing dies.

The investment is aimed to provide laser cut punching dies and CNC engraved foiling and embossing dies.

“Since die-making is a niche industry, the installation base of the machines is low. It becomes difficult for the machine manufactures to set up their services in India due to low number of machines,” informs Raju N Kutty, managing director, Purandara Laser Technologies.

Purandara’s die making factory located in the Cochin city is spread across 4000 sq/ft area, with 23 employees manning the shopfloor. Currently, the firm caters to the southern part of India.

Technological know how
The machine from Suntex is equipped with Japanese Fanuc laser technology and allows the flexibility in setting parameters like laser power during cutting, pulse cutting mode, nozzle distance from the die-board, among others. Kutty says, “The new technology enables us to do layout cutting in a faster and more user friendly way. The laser speed is twice that of the conventional machines and can achieve straight double cutting. Plus the technology does not require any additional training to the clients.”

According to Kutty, when it comes to engraving technology, there are a few constraints because of the conditions existing in the market. “The files prepared for embossing and foiling are often quite difficult to produce on CNC engraving as they are more suitable for making films followed by chemical etching of dies.”

If comparison is made with respect to the competition from international standards in mono cartons and corrugated boxes, many of Purandara’s carton manufacturing clients have made serious investments to improve quality and maintain the volumes. Purandara is taking small steps every year to fulfill its commitment by making quality tools. “Quality in tool making is about both technology and workmanship. With money you can invest in technology but workmanship cannot be purchased,” stresses Kutty.

Market scenario
The requirement for dies has gone through a lot of changes. Problems like price reduction or negotiation plague the manufacturer and makes die-makers to cut corners in order to survive. Also, the tool production is a low volume business. On the other hand, various technology advancements have opened up new avenues leading to increase in the business portfolio. Kutty says, “Today, we see more traction in the packaging market with regard to die consumption. While in the commercial space there is an increase in demand for intricate designs, for example, in case of wedding cards and photo album covers.”

Tech gyaan: Q&A with Raju Kutty

PWI: What is the difference in the make-ready time for laser die-making process when compared with the conventional ones?
RK: There is not much of a difference. Laser machines take a few minutes to charge up and that's about it. The bottleneck is in tooling as this is a craftsman's job. 

PWI: What is the life of die manufactured with steel rule?
RK: This depends on condition of the machine and the bed, the abrasiveness/tensile strength of the material, material of the rule, many such factors. Typically a couple of lakh impressions can be expected from any die assuming that it has been prepared well. Re-knifing of dies is also possible once. We have had instances where a customer has been able to obtain production run of three lakh impressions and in some cases the die failing within 1000 impressions also. 

PWI: How do you ensure that the dies are safe during transportation?
RK: Thermocol packing on top and bottom and craft paper all around is more than good enough. Damage of dies during transit is few and far between. 

PWI: What is the tolerance maintained by the die?
RK: By and large we maintain tolerance within 0.25mm. 

PWI: What is the relationship between blade angle and the material to be die-cut?
RK: Blade angle depends on the tensile strength of the material. A high tensile strength material like PVC (particularly if the lamination is inside) requires larger shearing force than normal board or even corrugated board. In order to achieve this higher shearing, rule makers manufacture rule with lower bevel angle. So you have a basically sharper inverted V profile. Manufacturers also provide additional ground finish on such rules to achieve extra hardening. We use such rules for plastic cartons, gaskets, cartons with inside lamination and such challenging jobs. These rules are expensive and dies also cost more. 

PWI: What is the minimum and maximum height of embossing that can be achieved?
RK: Engraving can be done on 7mm brass blocks and the same depth is achievable. Typical folding cartons embossing depth is 0.7mm or sometimes less. Depth of the engravings is often determined from the geometry of the job. 

PWI: How to eliminate angel hairs or burr that occurs during die-cutting?
RK: The angel hair is formed in cartons due to improper die-cutting. In the die, this requires smaller angle rules to be used and harder profile rubbers to be used in such areas where dust formation tends to happen. But there is also a dimension of the machine involved in this. Hardness of the plate and age of the base plate is also a factor in causing this. In areas where you have blank separation we see a tendency of angel hair formation and therefore we use special profile rubbers in blank separation areas. 

PWI: Types of ejection rubber that are used for die-cutting?
RK: There are various rubbers used in the die-cutting process. For example, we have high shore hardness rubbers inside intricate areas where paper waste tends to get accumulated during production runs. For regular use, lots of soft rubbers are available. Corrugated board again uses a special soft rubber. 

PWI: What is the cutting tool thickness used by the CNC engraver to manufacture the die?
RK: Thickness of tool starts from 0.1mm, which can be decided based on the job requirement.