Kzell Metals, Inc.
K-zell offers state of the art custom CNC drilling and milling services. Call us today for more information!
At K-zell Metals, Inc we have over 30+ years of experience as a well-established metal fabrication contract manufacturing and job-shop firm. We are equipped to handle projects for a wide array of customers across various industries. Our combination of equipment, processes, capabilities, quality control, and industry knowledge provides us the opportunity to manufacture a wide variety of products with great precision for a reasonable cost.
One of the most important considerations of part design when Rotary Draw Bending specification is required is the bend radius (FYI, we are always taking centerline as a standard) relative to the material alloy. The minimum bend radius that an alloy can tolerate has to do with the elongation % of that alloy. As an example, typical Hot Rolled ASTM A513 ERW (Seam welded mild carbon steel tube) has a range of elongation but as a minimum, runs about 25% - 30% (Mill Test Reports will usually note this specific to the tube when purchased). This elongation allows for a relatively small D bend usually on order of about 2D – 3D. On the other side of the spectrum is 6000 series aluminum (6061-T6 and 6063-T52) which has a typical minimum elongation % of 10% - 12% meaning that a minimum bend is around 4D – 5D to avoid fracturing and breaking. Generally speaking you will find that the MTR’s (Mill Test Reports) of 6000 series aluminum tube will have quite a bit higher elongation % than what the typical minimums are but it is always dangerous to design around the upper end of the available elongation % as that material can become sparse or non-existent over time which may require heat treatment before and after forming (annealing and solution treating) which will add considerable time and cost to a part.
Both initial pinch and pyramid rolling machines leave a flat section at the beginning and the end of the radiused material. Initial pinch rolls leave a smaller flat section than the pyramid rolls. If flats are not acceptable the leading and trailing edges can be performed either in the rolls or on a press brake in separate operations to minimize the length of the flat sections. It is virtually impossible to eliminate all of the flat prior to welding the long seam. After welding, it is sometimes possible to re-roll the cylinder and further reduce the flats.
Parts processed with CNC cutting systems may have dimensional variations as a result of the mechanical components on the particular system, the cutting process and the material being cut. The robotics of the particular cutting system has both repeatability and location tolerances. The cutting process may not cut truly perpendicular to the surface of the plate. The speed and direction of the cut also influences the kerf width. The material may move on the table as the part heats up from the cutting process causing dimensional deviations. Tolerances for laser cut parts vary by material type, part size and cutting parameters. In general most parts can be held within +/- 0.015”. Please, inquire about special fabrication tolerance or tolerances on parts with any dimension over 36”.