Shop for bakeware at Crate and Barrel. Browse a variety of metal, glass, ceramic and silicone bakeware for cakes, cookies, pies and more. Order online. The National Wildlife Federations family of magazines include National Wildlife, Ranger Rick, Ranger Rick Jr., and Ranger Rick Cub. Dont Use Chalkboard and Magnetic Paint Until You Read This. How important is sheet and plate steel flatness This article examines flatness of steel, discussing the outcome of combining temper passing and leveling in the same line. It also provides the outcomes of experimentation on steel that has been leveled, temper passed, and both. Furthermore, it gives a few real world examples of who is using this process and what they are saying about it. Figure 1 Hot rolled sheet coils generally reveal some or all symptoms of poor flatness. Steel has the tendency to cling to its original shape and molecular composition. Why Because it was given a unique configuration when it was rolled, cooled, and coiled at the steel mill. In its natural state, steel is not at all flat. In fact, a hot rolled sheet coil generally reveals some or all symptoms of poor flatness see Figure 1. For example, 7. 2 inch wide material with a 1. PSI yield strength can have a crossbow of 2 to 1. These shape imperfections must be removed to produce a high quality steel sheet that is not only flat, but will remain flat during such subsequent manufacturing operations as laser, plasma, and punch cutting. Astra5_2.gif' alt='Sheet Metal Nesting Program' title='Sheet Metal Nesting Program' />How can I keep woodpeckers from pecking my house The persistent tapping and drumming of woodpeckers, sapsuckers and flickers make them very noisy and destructive. What sheet metal shops wish you knew Batch size, setup, and thickness Better understanding of fab leads to better decisions in CAD. Lets focus on batch size. GB/powernest-demo-comparison.jpg' alt='Sheet Metal Nesting Program' title='Sheet Metal Nesting Program' />Temper passing, in conjunction with a roller leveler, cut to length TP CTL line, can be an alternative for improving these conditions. What Is Temper Passing Temper passing is compressing flat steel under very high pressure between two work rolls to flatten and elongate it see Figure 2. A cold reducing process, temper passing also called temper rolling or temper pass strives to decrease the material thickness between 1. At this percent reduction or lengthwise elongation, temper passing increases the material surfaces yield strength and improves its finish. Both integrated steel mills and coil processors have used temper pass processing extensively. Initially, it was used in coil to coil processing as a way to improve surface finish, equalize surface stresses, and help reshape the incoming raw material. What Is Leveling When material is leveled, it is compressed or stretched about its neutral centerline see Figure 3. As the fibers of the steel pass between two alternating, opposing rolls, they are bent in. The center of the material is in an elastic condition and wants to remain in its original condition, while the surface of the material has been stressed beyond its initial yield point. Because the reverse bending actions have stressed the surface, the material is unable to return to its initial near flat shape, and opposing forces now are present in the material. This results in material that is flat but contains large amounts of internal stress. These stresses are released when the sheet is processed into parts using mechanical or thermal processes. Combining Temper Pass and Leveling in One Line. When temper passing and leveling are combined, the increased surface yield strength created by temper passing allows the subsequent leveling to increase the extension of the material through the neutral axis without exceeding the surface yield point. This allows the surface of the sheet or plate to revert to its original condition while minimizing the internal trapped stresses. Figure 4. Experiments at Hoogovens Steel Corus, of the Netherlands have shown that processors need to achieve 1. Any result outside of this range will likely produce an unacceptable product. TP CTL Lines Already in Place. The idea to use temper pass rolling mills in conjunction with leveler, cut to length lines was not addressed until the late 1. Robinson Steel successfully installed its first line. This integration allowed the steel processor not only to remove inherent rolling stresses but also to remove coil set more easily. Today North American fabricators routinely request temper passed steel. At least 1. 6 temper pass lines currently are in operation or under construction. All of these mills have a four high designone main roll and one backup roll on the top and bottomexcept for one, which has a two high designone roll each top and bottom. It is interesting to note that no known TP CTL systems are installed outside North America at this time. Steel producers and processors in Europe and Asia instead are flattening products by controlling alloy content and using specialized, carefully controlled rolling practices. Quantifying the Value of TP CTLA variety of thicknesses and material types were studied by Steel Warehouse Co. For the study, material was processed on a temper level line. To minimize experimental variability, the same coil of steel was used to produce both TP CTL and non temper pass sheets and plates. This was accomplished by disengaging the temper mill once the. Both portions of the coil then were shipped to participants in the experiment for fabrication. Two categories of parts were tested using both temper passed, leveled and leveled only sheet. The first category was composed of production parts familiar to the fabricator. Data Link Protocol Ethernet Fast Ethernet Driver. The second category included difficult parts known to be highly sensitive to residual stresses in the steel. Some of these parts were long and narrow and, thus, subject to coil set. Others contained large windows that were. Low carbon C1. 01. HSLA grades 5. 0 and 8. Material thicknesses were 1. The widths used were 3. After the parts were cut, they were measured on large, flat granite surface plates with a feeler gauge to determine the largest gaps on both the length and width. The results were recorded and converted to a flatness specification in inches per foot of deviation from flat. Test Results. The results were organized into part length flatness, thickness flatness, part width flatness, and overall flatness by material thickness and grade. Length flatness was defined as deviation from flat measured in inches per foot of rolling direction. Similarly, width flatness was the deviation measured across the rolling direction, again expressed in inches per foot. Overall grade flatness was. Length flatness showed the most marked improvement using TP CTL see Figure 4. With TP CTL, flatness was improved 1. C1. 01. 0 and 5. 5 times in grade 8. In other words, as the yield strength of the material increased, the flatter the material became when TP CTL was used. This illustrated that higher strength materials, which had a much higher surface yield. Figure 5. This length flatness measurement demonstrated the process well because the leveler did not have enough force to exceed the surface yield strength of the material yet coil set was removed effectively. The second significant improvement was better thickness flatness with TP CTL. It was found that thinner materials were improved more by TP CTL than thicker materials see Figure 5. At thicknesses of 14 in. TP CTL decreased the flatness deviation more than 8. This result occurred because thicker material requires more force. Figure 6 shows the results of measuring width flatness. It should be noted that it is difficult to squeeze the edges of the material as much as the center, because when the steel is originally rolled, the center of the material is thicker. This is because the rolling mill uses that crown to aid tracking in the mill. Under the huge forces applied, the temper mill rolls. This contributed to the marginally out of flat numbers observed. Parts cut closer to the sheet edges exhibited more out of flat conditions than those cut from the middle two thirds of the material. Figure 7 combines the results of the three measurements. The most improvement was in the grade 8.