Avoid Ironworker Abuse

Know your material, and use enough power

High Tensile Strength Material

High-tensile-strength material and specifications for thicker, stronger structural components than specified a few years ago are demanding more tonnage from ironworkers. Photo courtesy of Neiman Machinery.

Materials passing through ironworkers are getting tougher. Economic pressures and material advances can both lead to fabricators using material with a tensile strength that demands more fabricating force.

Less expensive plate, produced with fewer quality controls which can lead to a higher-than-anticipated Rockwell rating, may be substituted for a specified material to save a few dollars. High-strength, low-alloy steel—lighter, stronger, and less expensive than A36—is creeping out of the automotive realm and into components fabricated for a variety of industries.

Building codes in some areas, for example, the earthquake-prone regions, are calling for thicker, stronger, heavier materials than specified just a few years ago.

Bending, shearing, and punching parts from these tougher materials take more hydraulic brawn.

Packing a Punch

Equipment manufacturers are continually introducing ironworkers with more capacity to meet the highstrength- material challenge. Plasma, and recently plate lasers, can blast holes in thick plate. But these tables can be a pricey way to produce holes. Ironworkers are affordable, can get the job done, and are frequently seen operating alongside their more expensive counterparts.

High-tonnage ironworkers packing hydraulic power from 150 to about 242 short tons (about 136 to a whopping 220 metric tons) are meeting the challenge. The power rating depends on the manufacturer.

Compare Apples to Apples

Jerry Kroetch, president of Scotchman Industries, Philip, S.D., said that it is important to be aware of which measurement system is used in machine specifications to get an “apples-toapples” capability comparison. “On ironworkers the tonnage rating is based on the punching station. Look at the diameter of the hole that equals the thickness of material and the tonnage recommended by the manufacturer to punch the maximum round.”

Unfortunately, fabricators don’t always recognize—or acknowledge— a need for additional tonnage. Too often they try to power through jobs that shouldn’t be processed on their machines. Bottom line, ironworkers are frequently abused.

The punch process, which demands the most power, is where the majority of problems will occur if a machine is pushed beyond its tonnage rating. Compared to the punch, said Kroetch, most of the other stations require a fraction of the machine power to function. And features built into some stations are designed to prevent overload. That doesn’t mean, however, that operators don’t challenge the limits.

“When you have a machine designed to shear a 6-in. by 6-in. by ½-in. angle iron, a larger piece of angle won’t fit in the cavity. So in theory, you can’t overload. But it is amazing what fabricators will try to do when they have an application that needs more power than the machine offers. They might gamble that shearing a piece beyond the machine limits won’t break the machine. It’s a 50/50 shot.”

Material Cavities

Material cavities in some ironworker stations, such as the angle iron shear, safeguard against overloading by physically limiting the thickness or dimensions of material that can beloaded. Photo courtesy of Neiman Machinery.

Ironworker Abuse

“Pushing beyond the limits can result in premature wear on the machine or broken parts,” said Kurt Neiman, president of Neiman Machinery, Newmarket, Ont., distributor of the Geka line of ironworkers. “I’ve seen customers overload machines, cause premature wear, and instead of fixing the problem, they’ve continued using the machine. The result was a broken main slide.”

Damage can come in many forms: machine stress that causes parts to wear before their time, broken fasteners in the machine frame, shattered tooling, or compromised safety guards that can fail to protect the operator.

Automatically triggered hydraulic bypasses give ironworkers some protection against overloading. “The beauty of the hydraulics is that there is a built-in bypass, so if you try to punch or shear more than the machine is rated for, it’s going to stall. It’s going to shut down, and that eliminates breaking the machine,” said Kroetch. “As far as the part goes, the worst thing that would happen would be an indent to the material being punched rather than a hole.”

Tonnage charts, available with most machines’ technical manuals or online, rely on standard tensile strengths to calculate recommended tonnages. If a material has a different ultimate tensile strength than those addressed in the charts, tonnage requirements can be calculated using formulas provided by equipment or tooling manufacturers. Although the formulas may vary slightly depending on the source, they will provide a suggested tonnage based on general calculations.

Some tooling configurations can reduce the tonnage needed to create a punched feature. For example, a chisel point or a rooftop punch can reduce the tonnage required to produce the hole and also lessen shock and vibrations created by the impact of the process.

Accumulation of Errors

Even when operating within specified limits, machines can be overworked and put at risk.

“I call it an accumulation of errors that can lead to overload,” said Neiman. “Using a dull punch or not lubricating will require more tonnage to go through the same piece of steel than a sharp, lubricated punch. If a machine isn’t maintained properly, that can also adversely affect the performance and require more tonnage. Then add trying to work with material with a tensile strength higher than expected. You are working your way up to an overload situation. The old cliché that says a chain is only as strong as its weakest link certainly comes into play here.

“Whether a customer is not aware of trying to punch material that requires more power than the machine has, or if he just turns a blind eye to it, it will cause a problem. Machines bought 10 years ago aren’t able to keep up today,” said Neiman. “They just don’t have the tonnage for the jobs.”

www.neimanmachinery.com

www.scotchman.com

High Tonnage Ironworkers

Manufacturers are introducing highertonnage ironworkers to create parts from high-tensile-strength materials. Photo courtesy of Scotchman Industries.