Selected articles from July/August 2006 issue published on TheFabricator.com:
Today metal tube sawing technology is light-years ahead of where it was just five years ago. Sawing machine and saw blade advancements—Special-purpose CNC tube-sawing machines, Dynamic ball-screw feed systems, Automatic Blade-changing, Carbide-tipped blades, blade coatings, Thin-kerf Blades, segmented saw Blades, optimize tube cutting.
Shielding gas is an often overlooked area of savings in tube and pipe welding. Creating a purge dam in one of several different ways can help you isolate the weld area and minimize the amount of gas and time needed to purge the weld zone properly.
Although eddy-current testing is king in the tube production industry, flux leakage is worth a look. Using a small test sample, equipment-maker InspecTech found that for 3.50-in. to 4.00-in. carbon steel tubing with wall thickness from 0.056 in. to 0.100 in., the flux leakage method found more defects and turned out fewer false alarms than the eddy-current method did.
Good sawing and maintenance practices can help alleviate problems that can occur when making angle cuts in structurals and tubing. Addressing the stock, machine setup, the blade, the cutting fluid, and the saw itself may not completely rid fabricators of problems, but it can help keep the operation profitable and relatively painless.
The cold mill pilgering process uses ring dies and a tapered mandrel to reduce tube cross sections by up to 90 percent. Because the process relies on large number of small forming steps, the result is tube or pipe that has nearly homogenous material characteristics. It is suitable for every metal.
Contrary to common opinion, a high production rate is not the key to success in making tube. Attempting to low-ball the price — while cutting corners in maintenance and upgrades -- is a poor strategy in this industry. Columnist Bud Graham provides four production scenarios that compare various rates of capacity utilization and line speed and how these affect profitability.
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