Manufacturing processes can produce adverse ambient conditions that can affect employees, production uptime and product quality. Using ancillary systems with production equipment can produce excess heat in the building, sometimes increasing the ambient temperature by 20°F (11°C) or more. These temperature fluctuations can create a difficult environment for employees as well as equipment.
Selecting a Chiller
One size does not fit all when it comes to industrial chillers. Every application has unique cooling requirements, depending on the manufacturer’s recommendations as well as the process being cooled. To help size a chiller, a few questions should be answered:
- Where do you want the heat to go?
- What will you be absorbing heat with?
- How clean is the fluid?
- Is the reservoir part of the process or in the chiller?
- Is the pump part of the process or in the chiller?
- Will you need a portable, stationary, modular or split system?
- Is it a critical application that would benefit from redundancy?
- What range of temperature accuracy is required?
- Are there special process needs?
Not sure? Do not guess. Ask an expert.
When there are multiple heat-creating processes being used, a central chiller may be the best option to remove the excess heat. In addition to freeing up valuable floor space, using a central chilling system offers advantages that contribute to improving ambient conditions, product quality and production uptime.
Central chillers have the capacity to circulate water, water/glycol or oil to cool multiple processes. A central chiller unit typically is installed outdoors and can be air or water cooled. Some installations are designed as a pressurized, closed-loop system. Such systems are oxygen-free to prevent evaporation or biological growth.
The outdoor units also can 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. Higher capacities are offered if using a redundant design.
Central Chiller System Optimizes CNC Cooling
A Koolant Koolers P Series chiller is used at Voisard Tools to improve productivity and performance.
For one machine tool shop in Russia, Ohio, chillers are important to the production — especially a central chiller system. Voisard Tool manufactures solid carbide drills, step drills, reamers and end mills. The facility runs two shifts around the clock with 28 CNC machines.
The chiller is critical to regulate and maintain the temperature of the cutting oil coolant it passes through the central filtration system. The dirty cutting oil is pumped to the filtration system, where it is cleaned before being recirculated to the CNC machines. The cutting oil regulates the temperature of the parts and CNC wheel. In newer machines, the cutting oil is pumped in the motors.
“Carbide is heat sensitive. If the oil gets too hot, the carbide gets heat cracks,” said John Inskeep, production supervisor at Voisard Tool. “The danger occurs when this goes unchecked and you don’t realize you have a problem. It can lead to making a lot of bad quality products. Dependability of the chiller is a big deal.”
A CNC machine at Voisard Tools produces parts with the support of a central chiller.
Optimizing the production process prompted Voisard Tool, which is owned by Arch Global Precision, to look at all aspects affecting product quality. At a meeting with corporate executives, the high ambient temperature in the shop during production — especially in the summer months — was discussed. The team decided to upgrade to an outdoor central chiller, consolidating 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. [Prior to the change], we were running [more than] 15° hotter in the shop. Now, we are more like what the outside temperature is, which is much better.”
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The change did more than correct the ambient temperature, said Doug Voisard, vice president of operations. He added, “Our machine maintenance decreased as well after installing the central chiller.”
“The external [central] chiller definitely has helped with repeatability as well,” said Inskeep. “When we had a smaller system with multiple chillers, every system ran different [temperatures and flow rates]. The external chiller allows us to have all 16 machines on the same system. They run very similarly 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. “During 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. So, it is important that the chiller can keep the temperature within a couple of degrees.”
In conclusion, 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. A central chiller can provide many benefits to operations with multiple processes. PC
End products like these are produced by Voisard Tools’grinding process.
Differences Between Air- and Water-Cooled Condensers
Heat does not magically disappear: It has to go somewhere. Knowing your environment is crucial when selecting a chiller. This knowledge also will help you to decide between an air-cooled condenser and a water-cooled condenser.
Look at your air circulation around the chiller. Will you need an outdoor unit? Chillers must have the space to have air in and also for air to go out and circulate. It is best to prevent warm air recirculation and condenser air starvation.
Water-cooled condensers absorb heat from the process fluid and transfer it to a separate fluid source such as a cooling tower. This type of condenser has a lower condensing temperature than air, allowing more capacity. It also improves system reliability due to lower refrigerant discharge temperature. Typically, it is available at a lower cost.
Air-cooled condensers provide a refrigerant that absorbs heat from a process fluid, and the condenser ultimately discharges the heat to the surrounding air. Air-cooled condensers have either a horizontal or vertical discharge (indicated by the location of their fans). In cooler climates, adding an economizer allows energy savings by using outside air to assist in the cooling process.
Do not leave the condenser up to chance. Select the option best suited to your process environment and needs.
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