|
A tube cutting laser machine can offer significant productivity advantages over traditional tube and pipe cutting methods by reducing secondary operations such as drilling, punching, and deburring, and a laser helps simplify welding setups. Another factor in productivity is the machine’s ability to handle material—specifically, the time it takes to remove a finished tube and load the next tube. For example, if a process makes four parts from each tube, and each part takes 12 seconds, the total time to process those four parts is 48 seconds. If the process of loading the next tube takes 20 seconds spark-to-spark (the time between the last spark of the last cutoff to the first spark of the next tube), the actual cycle time is about 30 percent greater at 68 seconds (17 seconds per part).
The material feeding system has a big effect on output as well as machine flexibility, which is increasingly important as lot sizes and inventory levels continue to shrink, demanding quick changeover. To maximize the green-light time, the two main feeding system considerations are a bundle feeder and a magazine feeder.
Bundle Feed System
A number of tube laser systems come equipped with bundle feed systems. As the name implies, this system accepts an entire bundle of tubing at once. The laser processes a full bundle of tubes without interruption and without operator intervention, making these systems suitable for high volumes. Higher-end systems are fully automatic; less advanced models require some manual setup.
If a job is completed but the bundle is not, tubes remain in the queue, and this can lead to a significant amount of changeover time. The operator must stop the machine, stop the bundle loader, manually remove the tubes from the loader, reband the tubes, pick up the bundle, and return it to the storage area. Meanwhile, the machine sits idle.
Magazine-style Loader
A multiposition magazine-style loader can accommodate several tubes of raw material (some systems can accept up to 11 tubes). In this system, the user loads individual tubes manually from a material handling cart. Some systems offer seam detection; others do not.
The magazine-style loader offers the advantage of easy changeover because material is not stored inside the machine. When a job is finished, the operator removes any remaining sticks of pipe from the magazine manually, returns them to a material handling cart, and the machine is ready for loading the next batch of material. If several material handling carts are available, the next bundle of material could be staged on a cart near the machine so production of the next job can begin immediately. Any leftover pipe is banded offline, so removing remaining material doesn’t have much affect on the machine’s uptime.
Because it’s able to accommodate a quick changeover, a magazine-style material feed system is suitable for small to medium lot sizes.
How They Compare
To identify which feed system best fits your needs, consider common material types and thicknesses you encounter, part quantities, and lot sizes.
Footprint. A bundle-type system usually has a significant footprint. Most machines with a bundle loader are more than 20 feet wide by 24 ft. long. Depending on the shop’s setup, the large footprint might require a facility expansion or a significant reorganization of the shop floor.
A magazine system typically has a compact design, usually 8 by 24 ft. at the infeed. A laser machine equipped with a magazine feeder generally is half the size of a tube laser with bundle feeder.
Access. A bundle load system requires access from two sides of the machine. One side of the machine has the operator’s console; the other side has the bundle loader. In addition, some bundle feed systems are not designed for fork truck access, so crane access is necessary.
On machines equipped with a magazine feeder, the only necessary access is at the front of the machine. As a result, the machine can be installed near a wall.
Setup. Depending on the machine model, setup when using a bundle loader can be automatic or require some manual steps.
When using a magazine feeder, the operator must load tubes manually. The machine then feeds them, one after the other, for processing. Some magazine systems present a part beneath the carriage while it is moving, so that it is ready to raise as soon as the carriage reaches the load position; other systems require two motions to complete this action.
Part Quantities. A bundle feeder is suitable for large batches and long part runs. For short runs or small batches, and part kitting, a magazine-style loader offers a high degree of flexibility to transition from one job to the next.
Material Type and Thickness. Because bundles are loaded by a crane, hoist, or other lifting device, a bundle loader handles heavy-duty materials, eliminating the possibility of operator fatigue. The manual loading process of a magazine feeder means that the operator might need assistance when processing heavy stock.
Job List. The bundle feeder is best for planned jobs and not designed for unanticipated work orders. Breaking into the cutting schedule goes against a bundle loader’s strongest point: the productivity it achieves when running full bundles consistently.
A magazine loader is the opposite in this regard. It can accommodate unplanned rush jobs interspersed with scheduled work. Unloading and reloading aren’t difficult or time-consuming.
Operator Attention. A bundle feed system offers cost savings through continuous, uninterrupted production without the need for operator intervention; a magazine-style loader requires frequent operator intervention to run an equivalent lot.
Lights-out Operation. True lights-out operation is possible with a bundle loader, but it is limited by the loader’s capacity, the material handling capacity on the tube laser’s outfeed side, and the simple fact that tubes don’t stack like sheet metal. If it takes 68 seconds to process one tube from spark to spark and the bundle feed system holds 300 tubes, it can run 5.6 hours unattended.
Lights-out operation is not possible when using a magazine-style material feed system.
Cost. Many tube laser machines come integrated with the bundle feed unit. This is why these systems tend to have a higher price tag. If a system is purchased without a bundle loader, this option can be added later to complement the magazine loader.
Two Feeding Systems Feeding One Machine
A bundle feed system can be added to a tube laser with a magazine-style loader so that the machine can most effectively handle high-volume production and high-diversity needs. A magazine loader with the capability of bundle loading off the back side of the machine offers maximum flexibility, which translates to high productivity. For example, if the user were running a large batch of tubes from the bundle feeder and received a rush job of just a few tubes, the user can load the tubes from the front of the machine, change the program, and make the new (rush) parts. When the tubes are finished, the user can return to the previous program and run tubes from the bundle feeder again.
Ultimately, the best material feed system is the one that best handles the user’s mix of parts—high volumes and infrequent changeovers, low volumes and frequent changeovers, kit production, or some combination of these.
- The 18th China(Guangzhou ) Int’l tube
& pipe Processing Equipment Exhibition
|
