Roller Hearth Furnaces

• If temperature uniformity is a high concern, consider asking for options with inner doors at the entrance and/ or exit ends of the furnace. Choose a company with experience in building inner doors as this feature is exposed to significant stress & temperature fluctuations. Poorly designed or poorly manufactured inner doors can case significant downtime.
• Analyzing the quality of rolls, bearings, seals and drives supplied in a roller hearth can be a daunting and technical task. Rolls need to be suitable for: load, sizing, temperature and speed. The roll construction is a critical feature for high temperature roller hearths; some rolls are water cooled (above 1800°F furnace temperature). The roll journal is the portion of the roll that comes through the seal and insulated furnace wall and is supported by a high temperature bearing assembly. The bearing must allow for roll expansion at elevated temperatures. Strength of materials for various alloys is a critical criterion for roll construction. TIR or “total indicated run-out” is a measure of a rolls straightness and concentricity. For high torque conditions a DS or “double-single” sprocket configuration is commonly employed. Some low-cost suppliers will skimp in this area and only drive the top or a single sprocket, this design is less robust and is not recommended for heavy industrial loads. The conveyance of the load through the system is usually reliable and trouble free for decades of use, if the manufacturer gets the design right.
• To rapidly heat-up the processed workload, recirculating fans are needed. Fans allow the temperature uniformity to be of a closer tolerance in the affected chamber portion. This feature is critical if automotive, aerospace or military specifications need to be passed. TUS (temperature uniformity surveys) will not be passed if fan design and flow volumes is not correct. Heat transfer by convection is greatly improved for temperature ranges from 200°F to 1450°F, this allows furnaces to be shorter for treated part heating. Make sure the fans are of the highest quality and are built for the purpose you need. These fans are super important.     
• Spare parts stock and thorough maintenance recommendations. Unless you are buying a duplicate of a furnace that you already own or specifying large amounts of component equipment to match those of your other lines, consider adding on a full spare and ware parts list for the furnace to your order. Bundling this in early can save you money, as suppliers can buy extra components when they buy the furnace’s original components at a good price. As with any new piece of equipment, your maintenance and production teams will go through a learning curve during the first 6 months. As time goes on, necessary wear and spare parts will become more obvious. But in the beginning, it pays to get a full stock of recommended parts to have on hand during the first year. 
• Think long term; consider a design that allows for flexibility. Roller hearths are typically purchased to fulfill the treatment needs of one to two known parts that will be manufactured steadily for many years. Regardless of the type of parts that your company makes, it pays to think about buying a roller hearth that can be modified in the future to treat different parts a decade from now. Many of our customers in the automotive & aerospace world are thinking about the long term when they buy. By starting the conversation with your supplier early, you can buy a piece of equipment that can be more easily shortened or lengthened through the addition or subtraction of modules in the future. Quench systems, system speed, temperate, and many other features can all be designed with the possibility of cost effective future modification; making your company more competitive in the long run. Most of CEC’s continuous processing equipment accommodates change easily as our customer’s offerings change.
• Heating element selection options. Significant advances have been made in both the electric heating elements and burners used in industrial furnaces. Efficiency is much higher than it was ten years ago. It is likely that the choice between gas and electric has already been made by your organization, but it pays to buy from a company that is deeply familiar with a large variety of burners and who is up to date on the latest in burner technologies. At CEC, we have decades of experience with every major burner producer. This allows us to accommodate customers who own a significant amount of one brand of burners in their existing installations. Our long-term relationships with burner companies also allow us to offer competitive prices on the heating elements for your furnace, and on any spare parts that should be kept on hand.
• PLC Controls, SCADA, Part tracking, Tray tracking, CQI-9 and 2750 requirements and capabilities offer a myriad of roller hearth system controls choices. The choices should be confirmed in your purchasing specification. Level one control offers automation of the machine or system at the machine site. Level two control offers the same control at a remote location such as a control room. Level three control allows the machinery production to be monitored all the way to the accounting office, shipping area or where the network connects. Your specification should clearly describe your controls need. 

What to look for:

• Durability. Some purchasing supervisors fail to recognize the possibility that a quality roller hearth could or should outlast the part contract that it is designed to fill. Accounting related to payback done by your company for the purchase of a roller hearth may only be based on five to ten years of use. In such a scenario, the cheapest machinery available for purchase may seem the most attractive. CEC invites customers and potential customers to look well past the first ten years when they consider roller hearth furnaces as many of our products have been run almost continuously for twenty to thirty years with minimal downtime for maintenance and modification to accommodate a new type of part.
• Support. Look for a company with a history of installing and servicing machines in your geographic area. In CEC’s case, we have demonstrated our ability to support customers throughout most of the world. We have offices in China, Switzerland, the USA, and Mexico, and have developed additional relationships with third party furnace maintenance companies over the past sixty years. CEC has dozens of employees all over the world who stand ready to support our installations if something goes wrong.

• Suppliers who cannot prove that they have installed & designed several dozen roller hearth furnaces. Why is this a big deal? Unexperienced companies may offer very low prices, or agree to poor or unfavorable terms just to get a job type that they have not previously built. There are vast differences between small and large continuous systems. Experience in a smaller, or more standard roller hearth systems does not whatsoever guarantee success in a large or custom application. Insist on visiting some installations and seeing some pictures of similar jobs to the one you are quoting. If pictures can’t be provided or visits can’t be arranged, start looking somewhere else.
• Companies without sufficient liability insurance. Why should supplier have this? Roller hearths are dangerous pieces of equipment. No matter what promises are made, a company without liability insurance puts itself and you at risk.
• Companies with unhealthy financials or histories of being bought and sold. CEC has been around since 1959 and has been family & employee owned for its entire history.  We have a strong track record of weathering economic storms and excellent prospects for the future. Watch out for companies with a history of management and ownership changes. Make sure that the company supplying your roller hearth is financially sound. Quality and support very often falter in companies who exhibit problems in these areas. It is important to select a company who will be around to support you and your equipment over the long haul.