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Punching

Punch press vs. laser

By Russ Olexa

Head to head, which is best for a shop, or do both offer the perfect blend?

Are lasers slowly gaining in use as punching falls to the wayside? Or do they both still have a place in a fabricating shop? Could a perfect piece of fabricating equipment be a punch press/laser combination? Or is it still better to have both types of equipment on the shop floor?

President Jim Vining of Salem Metal Fabricators Inc. has found that both punch presses and lasers have their place in his fabricating shop. But he also notes, at least in his shop, that times are changing and one piece of equipment is doing less work than the other. After working as a machinist in the late 1960s at his father-in-law's screw machine company, Vining started doing sheet metal fabrications, and in 1970 he established Salem Metal Fabricators located in Salem, Mass. He built up the sheet metal work, and as time went by customers increased. Eventually the company moved to a larger facility in Middleton, Mass., where he now has 30,000 sq. ft. and 40 employees.

Salem has a diversity of clients, but much of its work is for medical products. One common part they produce is a sheet-metal frame for a portable defibrillator. To get contracts, Vining says that two afternoons a week he sees existing customers. Also, for the last 15 years, they've had two manufacturers' representatives that have worked with them bringing in major accounts.

"Funny as it sounds, we've had so much work in the last five years that we actually have a moratorium on new accounts," he says. "Sounds crazy but we're that busy. We want to be able to service the accounts we have and make every attempt to stay on schedule. We're told that in this local New England area that between 25 and 35 percent of the sheet metal shops have gone out of business because of the fallout from 9/11."

To process sheet metal, Vining uses five Amada and two DiAcro press brakes. He also has an Amada 644, 1,800-watt laser with a 40-in.-by-40-in. table and a Mitsubishi 3015 LVP 3,500-watt laser with a 5-by-10-ft. table. His Mitsubishi laser has a material handling system that moves sheet material in and out of the machine.

"Quite often the sheets are rather heavy so to manipulate the stock on the machine is quite helpful," Vining says. "The material handler places the sheet in the same exact location every time and it keeps our labor costs down. If you don't have a sheet handler then you need a forklift, and it's a time-consuming thing to accurately put the sheet on the machine. So I would suspect that you would probably lose some uptime waiting to hand load each sheet on the machine prior to cutting."

Lot sizes average between 35 and 50 pieces per run, but they have done jobs involving up to 10,000. They run mild steel, aluminum and stainless stock from 0.10 in. thick up to just under a 1/4 in., but the Mitsubishi laser can cut up to 1-in. mild steel.

Blending technologies
"Punching has always been faster, but within the last 15 years lasers are rapidly catching up," Vining states. "Years ago lasers really couldn't compete with a punch because a punch could generate lots of round holes, slots, vents, louvers and other forms. Lasers were generally used for configurations that the punch couldn't do or for shapes that you wouldn't want to produce the costly punching tools for. Lasers have come a long way with their software and power increases. We utilize both our laser and punch for the best methods. This allows us to make a job the most economical way we can."

Mike Morissette, punching and press brake product manager at Trumpf says, "There will always be a need for punching, primarily because punching offers functions that can't be duplicated unless they're through secondary operations. For instance, forming is a big one. If you have any type of part that requires forming, it automatically dictates that it needs to be punched. By forming, I mean extrusions, bumps, countersinks, counterbores, tapping, anything along this line. These are typical applications for a punching machine. What a company really needs to be looking at is combining operations because it makes for a more efficient process and a less expensive part."

Asked if there are part-size limitations and configurations that would lend itself more to a punch over a laser, Vining says, "Simple parts generally go with the punch, because it can do square corners, ovals and rounds and these types of configurations. When you get into large radiuses and tiny slotted areas for bend clearance, a laser is a lot more convenient. Lasers are great for long slots, clearance areas, radii, special irregular shapes that you don't have tooling for or that you wouldn't want to nibble out. Once you're familiar with what both machines can do, you can quickly look at a drawing and know exactly what each machine can do for you. Now that we have the fast 3,500-watt Mitsubishi laser, quite often if the job has radii or irregular shapes, we don't even punch it any more because we can do the round holes, the slots and everything on that part a lot faster than using both machines. A lot more of our parts are being transferred to the laser today."

Jerry Rush, executive manager of products at Amada America, says, "I think lasers came on really strong about eight years ago when there was already a substantial turret punch press population. But we've seen a resurgence in punch press sales. I think the population of old punching machines is being replaced because of their age and changes in technology. In the last few years there have been some significant technology changes in punch presses in the overlap area between presses and lasers. These new technologies have made turret punch presses more appealing as an alternative to a laser."

What's the best process?
Once a part comes in, how is it looked at to determine which process is more economical?

"If it has more common hole sizes that we have punches for, it's going to go to the punch," Vining says. "If it has more radii and curves and shapes to it than what the punch can accommodate, it has to go to the laser. Some parts fall right in the middle. So we use the best of both worlds; we'll punch all the holes to quickly get those out of the way, then we'll transfer the sheets into the laser. And rather than buy special tooling and put it into the punch, we'll put it into the laser and finish up the job with its capability for radii and irregular shapes. Sometimes it's best to use both machines for what they're good at."

Morissette adds, "As lasers increase in speed, the gap between punching and lasers gets smaller. Then you have to look at the cost of operation also. How much does it cost to actually make that part? If the edge quality from punching is satisfactory, then it becomes a pure cost standpoint. Punching is still a more cost efficient process. So this will keep punching alive."

Rush says, "If you're doing different material types from thick to thin, stainless to aluminum, highly complex geometry and really low lot sizes, there can be some advantages with lasers. But when it comes to how many operations you can do in sheet metal, then this clearly favors the turret punch press because it can bend up parts, extrude, tap, create louvers and countersinks, etc. If you want to do a lot of different things in sheet metal, then a punch offers more flexibility than a laser does."

Nick Ostrowski, division manager of marketing at Amada America, says, "With our new punch press technologies, we've addressed some of the advantages that a laser once had over a punch press such as the elimination of burrs and the achievement of smooth contours. Now these operations are available on a turret punch press with better results than ever before."

One of Salem's three Amada punching machines has a 40-station tool holder, one with a 58-station and one with a 31-station. Two machines have auto-index, and one is a straight, in-line machine for simpler jobs. The largest part that they can punch is a 4-ft.-by-8-ft. full sheet at up to a 1/4 in. thick.

Salem also has a diverse assortment of specialized punch tooling, but doesn't buy much of it any longer because of the lasers. Vining will only put the cost into tooling if he has a very large run that will justify the cost, something in the range of 500 parts or more and a continuous order.

Starting out
But what would be best for a fabricator just starting out in the business? Vining says, "If you're just starting out, you're going to start with simple parts. With these types of parts, I would say a smaller, used turret punch press would be a good choice. If you get laser work along the way, you can always farm it out. As you grow, you can grow into a laser. Then you'd eventually have both. But in general, simple work can be accomplished pretty well with a turret punch press, especially with an auto-index and some minimal specialized tooling. The laser, I would think, would come later."

"Machine costs are directly related to capability, speed and capacity," says Morissette. "So when you're looking at costs between a punch and laser, you're really talking apples and oranges. If you need a part that's over 1/4 or 3/16 in. thick, than you have to go with the laser. If you drop below this area, then you should look at both processes."

If you compare Trumpf's punching and laser cutting machines, the cost differential is significant enough to make a difference for a shop that might just be starting out.

Another piece of equipment that could prove vital for a shop is a combination laser/punch press. "The benefit of this equipment is that it melds both technologies together," Morissette says. "So whatever you need to do to a part, forming, tapping or punching, you have it. This will allow you to get the lowest cost per part and also the most functionality from a machine. So it really is the best machine available right now."

One drawback of this type of equipment is material thickness. Trumpf's punch and laser combo only goes up to 5/16-in.-thick material.

"I think the main reason people are looking at the punch and laser combination machines is that they want to eliminate tool set-up," Rush adds. "They see the advantages of having punches that can form, extrude and tap and the advantages of using a punch for hole intensive parts. Also they see the laser as a device that can create any geometry. So when you look at both of them and combine them, you can achieve total automation in the setup for a huge range of parts that also have different material thickness." FFJ

Deburring just got simpler
Every metal fabricator has found that after punching and laser cutting, sheet metal often needs to be deburred. For Salem Metal Fabricators Inc., just about every part they produce needs to be either deburred or grained, especially for stainless steel parts. Doing this manually was time consuming and labor intensive. Over the years, the company invested in graining machines, but they did a poor job in taking burrs off.

Originally the company had a single-head (one-belt) graining machine. This put an inline grain on the part to make it look good and did take off the surface burrs, but it left sharp edges on the part. Salem would then do secondary operations to make the part acceptable to the customer.

Today's graining/deburring machines have multiple heads, from two to four. This offers more versatility for a finished product. They also offer a wider opening, from 3 ft. to 4 ft., for larger or more parts to be put through.

"As our company grew our customers wanted parts that were grained for aesthetics and deburred," Vining says. "We needed a new machine that would give us greater capability and versatility. We started doing the research over a period of about six months and approached several manufacturers. The end result was that we felt more comfortable with a SteelMaster four-head graining/deburring machine from AM Machinery Sales.

With the new SteelMaster equipment, Salem found that they were eliminating many secondary operations and minimizing or eliminating labor-intensive deburring operations. Vining says, "We can finish a product faster with less cost, and it gives us an immediate payback for this four-head machine. In fact, we don't have to use all four heads, we can use one, two, three or all four as needed. This saves us costs in the long run. We regulate the number of heads on the machine based on the parts we're putting through. On some parts we might use a single head. But when we need that versatility, we're able to run all four heads and usually get the desired result from a machine like this versus the method that we used to use on a single head machine, which was feeding the same part through multiple times.

"The training is more extensive on this machine, because there is more to learn; more adjustments, and more capability," says Vining. "Once you grasp the machine, you realize how much more you can do with it and how much more product in an eight-hour day you can push through it. You not only have more parts done, you have better quality parts."

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