August 10, 2004
Over the past several years the sheet metal fabrication industry has witnessed a number of technological advancements in both machines and tooling. Machines are now capable of punching, cutting, and bending faster and more accurately than previously imaginable.
Despite these innovations, even the most advanced shops encounter bottlenecks in their press brake areas. While these bottlenecks cannot be attributed to a single factor, fabricators can make several changes to help reduce lengthy setup times, increase efficiency, and improve overall productivity.
Fabricators today are faced with small runs and tight tolerances for most of their jobs. It is common for a shop to run 15 setups per shift—many shops run significantly more. Operators who specialize in complex press brake setups are becoming increasingly difficult to find, and most shops rely on each operator to set up and run his or her own press brake.
Implementing standard operating procedures (SOPs) facilitates consistency and helps to reduce multiple setup parts and the resulting scrap. These SOPs not only help shops minimize press brake setup times, but also increase consistency in bend sequences for all operators and reduce part variations produced by individual operators.
Setup Sheets. One of the steps press brake operators can take to reduce setup times on recurring jobs is to use setup lists. Setup lists or sheets document the tools being used for each application and other notes about the specific job and should be used every time that job recurs.
Photos. Shops should consider recording tool locations and special stops with snapshots. These photos also can be used for reference in future applications.
Open-position Loading. Another important procedure is loading tools only with the machine in the fully open position. This provides greater access to the workspace and a safer work environment for operators.
Shops also should consider adopting procedures and tooling systems that permit their operators to perform frequent tasks, such as loading and unloading tools, more quickly and efficiently.
Auxiliary Tool Features. Many progressive-tool systems incorporate punch holders, push-button safety clips (see Figure 1), quick-change 2V dies (see Figure 2), and power clamping systems (see Figure 3) that allow tools to be changed very quickly by a single operator. These systems also help operators to function more independently and efficiently without compromising their safety.
|Devices such as push-button safety clips (blue buttons in Figure 1), quick-change 2V dies (Figure 2), and power clamping systems (Figure 3) allow tools to be changed quickly by a single operator, and simplify setups.|
Sectionalized Tooling. Precision-ground sectionalized tooling components built to the required bend length eliminate the time required to cut tools to a specific size. Precision-ground tools also reduce or eliminate the need for shimming. Sectionalized tooling is lightweight to facilitate handling, which reduces physical strain and operator fatigue and lessens the likelihood of accidents. Precision-ground tools also have hardening and surface enhancements to lengthen their life.
Tool Identification. Most tools are now being laser-etched with pertinent information, making it easier for operators to identify, organize, and reorder tools quickly. This information typically includes the catalog number, tip angle, radius, V openings, length, and tonnage ratings.
Tool Storage. The use of cabinets for organizing and storing tools offers the dual benefits of improved safety and better inventory management. An organized storage system eliminates the need to scour racks of tools to find a custom length. This level of organization also allows managers to monitor tools more vigilantly to ensure high-quality inventory and to identify worn and damaged tools, as well as determine how and when these worn or damaged tools are to be replaced.
New press brakes offer advanced functionality and many features that can help operators run them more efficiently. Operators who master these new machine control capabilities can use these functions to increase performance.
Job Tool Specifications Storage. One common feature on most new CNC press brakes is the ability to store job specifications and all relevant job information, such as tool type, location, and bend sequence. CNC capabilities also allow the operator to store and access tool libraries, making it easier to manage tool inventories.
Material Thickness Sensing. When using precision-ground tools, press brakes now can sense changes in material thickness and make bend calculations on-the-fly, reducing overbent and underbent parts.
3-D Graphics and Bend Simulation. These features allow operators to reduce errors by showing them the part being flipped or turned on the control screen as it is formed, eliminating scrap from incorrectly formed parts.
Common shut height tools eliminate the need for custom risers and special shims to force tools to close simultaneously.
Offline Programming. Programming the machine while offline saves setup time because the operator doesn't have to program the machine to run the part. The engineering staff can set the program for a part and download it to the brake.
Common Shut Height. Common shut height tool lines are designed to simplify complex staged tool setups with plug-and-play capabilities. Common shut height tools were developed with the advent of CNC vertical movement of backgauges. Vertical CNC is required to use the common shut height concept accurately, because common shut height is achieved by keeping the bottom of the die opening at the same height from the top of the die holder. As the die opening gets larger, the overall die height must enlarge correspondingly (see Figure 4). That is why this tool style eliminates the need for custom risers and special shims to force tools to close at the same time.
Small, complex parts often require offsets, 90-degree bends, and flattening, a setup that ususally requires multiple machines or setups to complete. Staged or common shut height tools allow this operation to be finished in one handling on one brake. Using common shut height tools, the operator can place 30-degree tools, offset tools, flattening blocks, and gooseneck tools on the same die holder and produce a finished part.
Fabricators who use press brakes currently face complex issues. High raw material costs make it imperative that every blank yields a good part. Shops willing to adapt the way their press brake areas operate can reduce setup times, derive greater productivity, and reduce scrap rates.
Developing and implementing well-designed SOPs, making better use of storage and inventory systems, leveraging machine functionality, and maximizing human resources are just a few possible approaches to help press brake shops become more efficient and productive.
Shawn Shultz is a product specialist, press brake tooling, for Wilson Tool International® Inc., 12912 Farnham Ave., White Bear Lake, MN 55110, 800-445-4518, fax 800-539-4590, firstname.lastname@example.org, www.wilsontool.com.
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