When it comes to injection molding efficiency, conventional band heaters are subpar at best, according to Kubi Kara, co-founder of APSX LLC, the Cincinnati-based maker of the APSX-PIM desktop injection molding machine.
“When we began making our molding machine—the APSX-PIM—the heater band was the only part that required maintenance or replacement,” Kara told PlasticsToday. “That’s why we focused on improving the band heaters.”
Burning out through overheating and frequent replacement are two reasons that most band heaters should be considered below the industry standard, noted Kara. Manufacturers may require a thermocouple in close proximity to the heater or internally to reduce overheating issues, but often this strategy alone does not fix the problem but only reduces the likelihood of it happening. “The outer surface of conventional band heaters may periodically rise to a higher temperature than their specified maximum limit,” Kara said. “There are also mounting errors that stretch the internal heat elements, which may cause internal damage and delayed consequences.”
Additionally, more of the heat can be lost directly to ambient air, which raises the temperature of other parts of the molding machine and within the facility, making it costlier and harder for the user to operate, Kara noted. “We have found that the connection between the heater and the barrel is not 100% tight, which is why it creates these problems,” he said.
In response, APSX designed and developed the housed cartridge barrel heater that eliminates many of the problems molders experience with conventional band heaters. The new design incorporates a cartridge heating housing made from 6061 aluminum. APSX machines the housing using the company’s CNC machining capability.
“Aluminum is good in terms of heat dissipation, so there’s no heat lost to the ambient air [as with] other band heaters,” Kara said. “With conventional band heaters, if you get your hand near the barrel, it will be hot. With ours, you don’t feel any heat when you put your hand close, meaning no heat loss.”
In the newly designed housed cartridge barrel heater, the heat is evenly distributed across the barrel because the surfaces are perfectly aligned, Kara explained. APSX machines the aluminum housing to contain the cartridge housing, which the company purchases from a supplier. Currently, the housed cartridge barrel heater is designed and manufactured in four pieces that are then assembled.
Through extensive testing of the housed cartridge barrel heater on the APSX-PIM desktop injection molding machine, APSX has eliminated the need for internal thermocouples and maximized heat retention. The new design is cost effective and provides greater durability and longevity than conventional heaters, the company said.
Starting out, APSX most likely will have “a couple of different standard-size options for molders, but if we get requests for other sizes we can customize the heater,” Kara said.
“The cost of the new housed cartridge band heater is comparable to that of a regular band heater with an internal thermocouple,” Kara added.