| Between diminishing factory orders and increasing | | | | sit down with you and discuss the specific needs of |
| labor and energy costs, companies that use plate | | | | your business. There are many issues that need to |
| metal in their fabricating processes are finding their | | | | be addressed, many of which a purchasing manager |
| profit margins increasingly pinched. | | | | may not initially foresee. |
| Yet, manufacturers must still invest in new production | | | | 3. Stay within ideal operating parameters of the |
| equipment -- whether to replace obsolete equipment | | | | machine |
| or to take advantage of new business opportunities | | | | It is recommended that manufactures identify what |
| -- in order to remain competitive. | | | | material and what thickness represent their highest |
| Manufacturers must make careful assessments when | | | | volume of work. Then (a company) can deliver a |
| evaluating the addition of new plate-rolling equipment. | | | | machine that will camber to that specification, thus |
| Debt capital is still available to purchase new | | | | conserving valuable production hours and eliminating |
| machinery, but paying back the loan will not yield a | | | | large amounts of scrap. |
| satisfactory return on investment unless the | | | | Quality rolling machines are usually cambered at 50 |
| equipment adds value to the production. | | | | percent of the full-rated value of the machine. Hence, |
| Unfortunately, many buyers end up purchasing | | | | a 1-inch machine is cambered to roll 1/2-inch plate at a |
| equipment that lacks the capability and flexibility to | | | | nearly perfect edge. Disregarding this important fact |
| meet production volumes and tolerances, simply | | | | can result in out-of-spec product that the customer |
| because they don't understand all available options | | | | will not accept. Problems most commonly arise when |
| and considerations. | | | | rollers attempt to push the upper limits of their plate |
| In an effort to help manufacturers optimize plate | | | | roll. If 5/8-inch plate is rolled through a 1-inch-rated |
| rolling operations, 5 key considerations are offered in | | | | machine, a small degree of barrel effect will likely |
| order to choose a proper plate bending machine. | | | | occur. This may or may not be an acceptable margin |
| 1. Factor in the properties of the material to be rolled | | | | for error. However, when plate thickness |
| Even though drawings call for a plate to be rolled | | | | approaches the upper end of a machine's rating, then |
| down to the same dimensions, a tougher material will | | | | severe defects can occur. Unless corrected with a |
| require a much higher-rated rolling machine. In | | | | shim, it will not be sellable. Conversely, when very thin |
| absence of such considerations, defects will result | | | | material is rolled through a machine rated for very |
| and the manufacturer will end up with excessive | | | | thick plate, the finished product may come out |
| scrap. | | | | tighter in the center than at the ends. Again, time |
| Today's steel is much stronger and requires more | | | | consuming shimming is necessitated to correct for |
| strength to bend. Thanks to detailed classifications by | | | | this "hourglass" effect. |
| the American Society of Mechanical Engineers, | | | | 4. Carefully consider bending diameters |
| countless varieties of steel abound: A36, A516 grade | | | | The tighter the diameter, the more bend pressure |
| 70, Hardox 400/500 series and AR 200/300 series, | | | | required. For instances where thick material must be |
| for example. And these different steels require | | | | rolled into tight inside diameters (ID), the diameter of |
| varying pressures to roll. | | | | the top roll and the layout of the machine can make |
| A metal's temper and yield strength must be | | | | the difference between a product whose cylindrical |
| matched with the customer's application to correctly | | | | edges meet and one that won't close. |
| determine the specifications of the plate roller. This is | | | | As a rule of thumb, most machines can roll plate at 1 |
| especially important since steel characteristics have | | | | 1/2 times the upper roll diameter. Hence, given a |
| changed drastically over the past couple of decades. | | | | 10-inch-diameter top roll, inside diameters as tight as |
| What was once known as mild steel no longer exists. | | | | 15 inches can be obtained. However, new machines |
| 2. Work with an equipment dealer that is willing to | | | | that incorporate planetary guides are able to keep |
| discuss your specific plate-rolling needs | | | | approximately 50 percent more area of the plate |
| Customers must know the correct questions to ask, | | | | under bend-pressure during the rolling operation, |
| in order to get the correct answers. Each | | | | thereby achieving ratios of 1.1 times the upper roll |
| manufacturer faces unique challenges, and through | | | | diameter. This creates a 30 percent advantage on |
| systematic querying an astute sales representative | | | | tight diameters. |
| can determine exactly what equipment will work best | | | | All machines achieve precise measurements at 50 |
| for their process. | | | | percent of the full-rated value. Therefore, given a 1.1 |
| Manufacturers must also carefully consider whether | | | | roll geometry, a 3/8-inch machine with a 10-inch top |
| they wish to roll conical or parabolic shapes to take | | | | roller can consistently roll 3/16-inch plate to 11-inch ID |
| advantage of a broader market. Hydraulically | | | | without any barrel defect. |
| operated four-roll machines are ideal for this type of | | | | 5. Incorporate both side and vertical supports to |
| work by eliminating surface scarring, thereby | | | | prevent unwanted bends |
| decreasing the need for grinding the lamination | | | | Adequate support requires both side and vertical |
| (bullnosing) on the minor diameter edge of a cone. | | | | roller-supports, as designed by the manufacturer of |
| Accurate conical rolling is further achieved through | | | | the plate-rolling machine. Once employed, plate rolling |
| features such as torsion bar parallelism, as opposed | | | | becomes a one-man job instead of two. This frees |
| to electronic systems or proportional value systems | | | | up valuable manpower that can be re-routed to other |
| that merely maintain a theoretical balance. Finite | | | | jobs. |
| parallelism allows the machine to be adjusted to its | | | | When rolling a cylinder, once the inside diameter is |
| full conical tilt and back to parallel in only five seconds. | | | | more than 200 times greater than the thickness of |
| Customers need to discuss issues such as inside | | | | the material, the weight of the material becomes |
| diameters, material type, tolerances and the desired | | | | sufficient to bend the cylinder as it exits the top roll |
| shape of the finished product. As an example, some | | | | and gets further away from the machine. Without |
| products, such as those found in the pressure vessel | | | | proper support, unwanted radii result. Purchasing a |
| industry, demand a maximum of 1 percent | | | | machine with both side and vertical roller supports |
| out-of-round on their diameters or they are | | | | easily solves this problem.Some manufacturers |
| considered defective. By using an underpowered | | | | attempt to skimp on this ancillary equipment by |
| plate roller, too much of a barrel effect can render | | | | resorting to "makeshift" support such as a forklift or |
| such a product useless and quickly erase any | | | | overhead crane. However, this shortcut ties up the |
| potential profit margin. | | | | use of equipment that can best be utilized elsewhere. |
| Matching plate-rolling equipment to the specific needs | | | | Because it cannot adequately support the material, |
| of a manufacturer requires attention to detail. It is | | | | unforeseen bends can still appear. |
| imperative that the dealer you work with is willing to | | | | |