High Temperature, Lean Manufacturing
The market for high-temperature ovens, operating between around 400ºC and 600ºC, is heating up, says Scott Miller, marketing manager at Carbolite (Watertown, WI). High-tech materials manufacturers use large ovens in this temperature range to produce high-tech materials and coatings. The R&D labs supporting new materials development employ much smaller units, with volumes of 30 to 60 liters, to test product ideas and troubleshoot manufacturing.
Energy efficiency in high-temperature ovens is a must. “Insulation drives the unit’s ability to support the heat it generates and to reduce the energy [needed] for maintaining temperature,” Miller comments.
Heat distribution and temperature uniformity are not as problematic for common laboratory ovens (think glassware drying) as for high-temperature “process” ovens, where samples are often sensitive to temperatures and heat distribution. Phase changes that occur during materials curing, particularly for large-area samples, are highly dependent on reaching and holding a particular temperature.
What to look for
That is why Miller advises potential buyers to validate both the uniformity of the “heating envelope” in high-temperature ovens and the recovery time for reestablishing heat uniformity when the unit is opened. “For materials processing, proper venting of volatile organic compounds is an absolute must. Otherwise it will not be safe to open the door.”
Users should also get some idea from the vendor about radiant heat from the oven shell. This is a function of efficiency and directly affects lab comfort and operating costs. “Units should follow standards for maximum external case temperature,” Miller adds.
"Customers should also consider their desired process temperature, controller functionality, and overall processing conditions,” says Kim Meyer, product manager for Thermal Technology at Despatch Industries (Lakeville, MN). “There are many different options for temperature control based on the required process—for example, if a customer needs to ramp and soak or if a customer is running at uniform temperature.”
Despatch manufactures forced convection ovens, from the most straightforward designs to models with microprocessor-based controllers with full data logging and reporting.
Users should also consider whether they require a special atmosphere—for example, nitrogen, oxygen-enriched, or argon, or HEPA-filtered clean process air. “They also need to think about the potential presence of flammable solvents when determining which oven best fits their needs,” Meyer says.
Customers often expect quick delivery on small laboratory ovens. Most manufacturers stock basic models to meet this need, but customers still need to wait for made-to-order ovens that meet special needs.
In June 2013, Despatch implemented new manufacturing techniques based on “kanban,” a form of lean manufacturing, which it claims has reduced lead times for specialty ovens by 50 percent or more. The company has restructured its manufacturing facility to allow for in-lining of production equipment and assembly stations that improve flow and minimize production time. Through this approach parts are automatically replenished as they are used, thus reducing inventory costs and lead times.
“We have reduced delivery times for large standard ovens from eight weeks to four weeks; cabinet ovens with Class A and high-temperature requirements are delivered in two weeks; and our laboratory models ship from the factory in three days,” states Jeff Bell, Despatch product manager.