With the increasing demand for higher quality films with more accurate gauge profiles, Macro has responded with the development of its ACCUPRO gauge control systems for blown film dies. Macro has developed both Automatic (ACCUPRO-AD) and Semiautomatic (ACCUPRO-SD) die gauge control systems. The Semiautomatic system is a lower cost alternative to the Automatic system. These systems will deliver tighter gauge control that results in better film quality, lower scrap rates, resin savings, and facilitate quick order changes.
Both systems consist of closely spaced cartridge heaters placed around the circumference of the outer die lip of the blown film die. The purpose of these heaters is to selectively set the temperature of the different zones around the outer die lip. The systems utilize a capacitance or beta ray gauge-scanning device that automatically takes thickness measurements as it oscillates continuously around the bubble. These measurements are automatically displayed and updated on a high-resolution computer monitor.
Automatic Gauge Control System (ACCUPRO-AD)
When the system notices a deviation from a preset thickness value, it will automatically make small temperature adjustments. If a thick spot is noticed it will increase the temperature of the cartridge heater at that particular zone. This will lower the thickness at that particular spot as the film will tend to downgauge more because of reduced melt viscosity at that particular spot. If a thin spot is noticed, it will do the exact opposite, i.e. it will decrease the temperature, which will tend to increase the thickness. The response time of the ACCUPRO-AD is very fast.
Manual Gauge Control System (ACCUPRO-SD)
In the semiautomatic system, an operator monitors the gauge profile on the computer screen and manually adjusts the cartridge temperature setting of each zone according to the readout.
These systems are extremely user friendly and can be mastered in a few hours. They can be specified with new blown film dies or easily retrofitted into existing dies. Improvements in gauge variation of 50% or better are typical when compared to conventional die systems. For example, a 2-mil (50µ) film, which typically has a gauge variation of ±7%, can now be manufactured with a gauge variation of only ±3.5 %.
