What is a central chiller system?

Central chillers have the capacity to circulate water, water/glycol or oil to cool multiple processes. This unit typically is installed outdoors and can be air or water cooled. Some systems can be a pressurized, closed-loop system that is oxygen-free to prevent evaporation or biological growth. 

These outdoor units can also be built with economizers to utilize free cooling and N+1 redundancy to support facility growth and expansion. Generally, central water chillers are offered in capacities from 5 to 180 tons or more if using a redundant design.

For one machine tool shop in Russia, Ohio, chillers are important to the production, especially when using a central chiller system. Voisard Tool manufactures solid carbide drills, step drills, reamers and end mills. The facility runs two shifts 24/7 with 28 CNC machines. 

Chillers are critical to maintain coolant temperature that is originating from the central filtration system. The chiller regulates the temperature of the cutting oil in the filtration system. The dirty cutting oil is pumped to the filtration system and returns clean cutting oil to the CNC machines. The cutting oil regulates the temperature of the wheel of the CNC and the parts and in newer machines, the cutting oil is pumped in the motors. 

 “Carbide is very heat sensitive and if the oil gets too hot, the carbide gets heat cracks,” said John Inskeep, Production Supervisor at Voisard Tool. “The danger is when it is unchecked, and you don’t realize you have a problem, you can make a lot of bad quality products. Dependability of the chiller is a big deal.”

Voisard Tool, which is owned by Arch Global Precision had a meeting with its corporate executives who noticed the high ambient temperature in the shop during production, especially in the summer. The decision was to use an outdoor central chiller, consolidated the existing chillers and moving the heat outside. 

“Installing the external chiller helped because the ambient temperature in the building stayed consistent,” Inskeep said. “It really helped our workforce in the summer when the outside temperature was in the 90s. We were running +15 in the shop, now we are more like what the outside temperature is and much better. It was worth it in that aspect.”

Doug Voisard, Vice President of Operations added, “Our machine maintenance decreased as well after installing the central chiller.”

“The external (central) chiller definitely has helped,” said Inskeep. “When we had a smaller system with multiple chillers, every system ran different (temperatures and flow rates). The external chiller allowed you to have all 16 machines on the same system. They run very similar because they are dialed into the same temperature holding the same fluctuation. The operator who is used to running machine 1 can come down and run machine B7 and he is dealing with the same temperature fluctuations.”

Maintaining a consistent temperature is critical as well as being able to handle heat load fluctuations. 

“On a daily use, we need the chiller to be within a couple of degrees for our 28 grinding machines,” Inskeep said. “When lights are out over a weekend, we continue to run a few grinding machines and all the heat goes to the chiller. The heat load can go to four machines within 30 minutes and it is important that the chiller can keep the temperature within a couple of degrees.”

A central chiller will provide the most benefits with multiple processes. Using a central chiller has helped Voisard Tools improve the ambient temperature for the employees in the shop as well as improving uptime for production and the overall quality of the products.