Automakers, appliance manufacturers and other companies engaged in high-volume manufacturing typically rely on coil-fed stamping lines for their blanking operations. Although fast and efficient, these systems require significant investment in dedicated tooling to produce the desired shape. This reduces flexibility while increasing manufacturing lead time, both of which are growing concerns in this day of routine, often rapid product changes and lower production quantities.
On the other end of the blanking spectrum sit flat-bed lasers. Here, a human, robot or tower system loads single sheets of metal into a CNC-controlled laser cutting machine, after which the blanks must be sorted and separated from the skeleton holding them in place. Though infinitely flexible, the problem here is one of speed – laser cutting systems with their need to trace every linear inch of a part profile can’t compete with a stamping press’s one-hit-and-done capability. In addition, loading one sheet at a time into a machine is nowhere near as fast (or cost-effective) as feeding from coil stock.
Wouldn’t it be great if a Goldilocks alternative were available, one that offers the flexibility of laser cutting with the speed and cost-effectiveness of coil feeding? Such a blanking system would be a game-changer for metal service centers, OEMs and their tier suppliers that have neither the time or resources to invest in dedicated stamping tools nor the quantities to justify the expense, but can’t compete at higher volumes by processing individual sheets through their laser cutting machines.
According to James Gamache, sales engineer with the TruLaser Group at TRUMPF Inc., this middle-of-the-road solution is now available. The company’s recently introduced TruLaser 8000 Coil Edition boasts an 8-kW or 12-kW TruDisk laser, a cutting area of 4,000 mm by 2,500 mm (157 in. by 98 in.), and a 6-axis robot for removal and sorting of blanks weighing up to 100 kg (220 lbs.). As the name indicates, the system is equipped with a winder that carries coil stock up to 2,000 mm in diameter and an Arku brand precision leveler and conveyor belt system.
To learn more, Stamping Productivity had the opportunity to ask Gamache questions about the new system, chief among them being whether the TruLaser 8000 Coil Edition truly delivers “the highest productivity and best part costs for series production” as the company claims.
Stamping Productivity: Tell us how the TruLaser 8000 Coil Edition works. What’s the material flow?
Gamache: As you can imagine, there’s a coil and straightener at one end of the machine feeding material into the laser. The laser then cuts the nest, and a conveyor transports the blanks and skeleton to a robot-tended unloading table, which separates everything and disposes of the scrap. At the same time, the laser is busy cutting the next nest. It’s a continuous, single-direction flow, which is one of the reasons why this machine is so productive – there is no time lost waiting for a pallet change or parts picking like there is with a sheet-fed 2-D laser cutting machine, nor is there a need for micro-tabbing.
StP: Is there an ideal part and part size?
Gamache: The TruLaser 8000 Coil Edition is generally for larger parts that are somewhere in the middle of the road complexity-wise, say anything larger than 200 mm by 300 mm (8 in. by 12 in.). The reason for the complexity statement just now is that you probably don’t want to blank parts with a million holes or hugely intricate profiles that take a long time to cut. The machine is perfectly capable of that kind of work, but the idea is to keep that coil moving.
StP: Similarly, what’s the ideal part quantity? Who stands to gain the most by investing in the TruLaser 8000 Coil Edition?
Gamache: It’s hard to put an exact figure on that, but let’s say lot sizes of 1,000 parts and higher. No laser cutting system will be as productive as a stamping line, which can probably produce one and a half to two times more parts per shift, but it will definitely be a lot more flexible as well as faster and easier to change over. This makes it easy to slide in a prototyping job or rush order or for situations where quantities are increasing and the company has decided to put the job on a traditional stamping line, to use the laser cutting system as a bridge machine until the hard tooling is ready.
The difficulty with a stamping line is that you can achieve very high production levels, but your investment cost is also very high. Unless you have the order quantities to amortize that investment, the TruLaser 8000 Coil Edition will quite possibly be a more cost-effective solution.
StP: Understanding that cost reductions are dependent on part geometry, production quantities, type of material, etc., approximately how much can a manufacturer save by going to coil?
Gamache: A good rule of thumb is that coil stock is roughly 15 percent less expensive per pound than sheet stock. That’s a nice savings, but there’s much more to consider. Coil stock provides the opportunity for what’s known as infinite nesting. Let’s say you have five parts nested on a 60-in.-by-120-in. sheet; by moving to coil stock, you can nest continuously, eliminating much of the waste that would otherwise occur at the ends of a flat sheet. This improvement in material utilization can easily provide another 15 percent in savings.
StP: That sounds like a big benefit, but does it throw a monkey wrench into the nesting process?
Gamache: It’s true that nesting on a coil-fed machine adds a bit of complexity, but our team has addressed this through our TruTops Boost software. As a result, the programming is actually quite similar to how you would program a flat sheet laser cutting machine, which is easy and user-friendly. The only additional step is the unloading cycle, which relies on an integrated robot to remove the parts from the skeleton and stack them on a nearby table. But even that step is largely automated because the software knows where to pick parts and which suction cups to use on the universal gripper.
For any shop able to program a punch press or 2-D laser, it will all be very familiar and easy to get a handle on. Either way, you don’t have to be a programming expert.
StP: Why did TRUMPF turn to Arku for the precision leveler and conveyor? Aren’t they a competitor?
Gamache: They aren’t a competitor although they do provide levelers to other companies. As such, they have a great deal of experience in coil handling and blanking, which is why we partnered with them on this system and others. Actually, we produced our first coil-fed laser in 2002 as a custom solution and they were part of that, so we’ve been working with them for a long while. One big advantage of this current solution is that you don’t need to dig a looping pit like you do with a coil-fed stamping line. Instead, this system uses a 1,500-mm length of buffer material, which accomplishes the same thing but at a much lower investment cost.
StP: Who’s the ideal customer? Is it laser shops struggling with higher production quantities or automakers and other high-volume manufacturers dealing with frequent changeovers?
Gamache: Interestingly enough, it’s a mix of everybody. As you indicated, we’re seeing great interest from automotive and agricultural OEMs as well as job shops that might have a large order and are looking for ways to increase productivity. For the latter, a coil-fed laser cutting machine is especially advantageous because it provides them with a great deal of flexibility while allowing them to reduce part cost.
StP: Is there a big learning curve in terms of material handling, strategizing purchases and so on? What are some things to watch out for?
Gamache: It’s definitely different than buying flat sheet. One important consideration is that you will want to use that whole coil of material. It’s a big spend, and you have to buy it all upfront, so cash flow could also be a factor. Yes, you can use half of it now and set the rest aside for later, but then you have to band it up and store it somewhere, not to mention the logistics of moving a big coil of material. The ideal situation would be to put the coil on the machine, completely run it out and then move on to the next one. This machine can consume a lot of material, and if you want to maximize your investment, you’d better plan on keeping it well-fed.
