Special-application tooling gives punch presses more function
August 9, 2005
New types of punch press tooling make it possible to perform many secondary fabricating operations on the turret press as well as standard punching—in some cases eliminating additional equipment and part handling, and reducing machine downtime. Not only are new part features possible on the turret press using these new tools, the reduced costs fabricators may achieve by using these tools to may make the tools a variable in DFM.
This special-purpose tool punches self-locking, spring-loaded tabs that snap into prepunched holes, thereby eliminating the need to weld connecting joints.
The concept of design for manufacturability (DFM) has been around for more than a decade, but recent advances in punch press tooling design can help facilitate DFM initiatives. New types of punch press tooling make it possible to perform many secondary fabricating operations on the turret press as well as standard punching-in some cases, eliminating additional equipment and part handling and reducing machine downtime. Not only are new part features possible on the turret press using these new tools, but the reduced costs fabricators may achieve by using these tools may make the tools a variable in DFM.
During the early stages of design, fabricators should analyze the turret press capabilities and the tools available for fabricating the needed parts. Quality is a constant. But knowing what new special-application tooling is available also can shed new light on the overall manufacturing process, particularly in light of the requirements to reduce costs and manufacturing time.
Secondary operations can be consolidated, in some cases, by using special-application tooling in a turret press. Examples of secondary operations that can be performed on the press include welding, cleaning, painting, press brake bending, and hinging.
Some small parts made of thin sheet metal can be bent by hand after using a turret tool that produces bend lines.
By eliminating the need to queue and move parts from the press to another machine, the fabricator can reduce non-value-added time, which is one of the central tenants of lean manufacturing.
Tooling That Fabricates Connecting Joints. A special-purpose punch tool can produce self-locking, spring-loaded tabs that snap securely into prepunched holes (see Figure 1), thereby eliminating the need for welding connecting joints, in some cases, such as those in electrical boxes. Through good planning, multiple-component assemblies can be reduced to a single, prepunched component that folds and locks together.
Another advantage of this tool is that it allows the fabrication of "welding-challenged" prepainted and other surface-sensitive material. Therefore, the tool can help eliminate additional finishing operations, such as painting, powder coating, and electroplating.
A special-application tool shears parts from sheets.
Tooling That Creates Bend Lines. Fabricated metal parts often require bending, an operation most often done using press brakes. Certain simple bending operations, particularly on small parts made of light, thin( up to 0.059 in.) material, can be done quickly by hand after using a tool that produces preprogrammed bend lines on the material surface (see Figure 2). The tool creates the lines with CNC punch precision and speed. Parts then can be bent by hand as they come off the turret press without the need to use a press brake.
The tool is especially suitable for components with small internal features that would be difficult to reach with conventional press brake tooling. In addition, components that can be shipped flat and then bent at the destination, such as electrical and electronic enclosures and heating, ventilation, and air-conditioning components, are suitable, because this approach often reduces shipping volume and transport costs.
Names, assembly codes, serial numbers, and etchings can be embedded with a marking tool.
Tooling That Shears Parts From the Sheet. Edge quality is an important consideration when using a turret press tool to shear sheet metal, especially for extended lengths (see Figure 3). A special-application tool shears parts from sheets and provides consistent quality and edges that are free of overlap marks and have minimal burr. Using the programming capabilities available on turret presses, a fabricator can use this tool to eliminate separate shearing operations on many projects.
Examples of components that this tool is suitable for are decorative covers and appearance-critical components on consumer appliances such as ranges, stoves, and furnaces.
Tooling That Marks Parts. Names, assembly codes, serial numbers, and etchings can be embedded permanently in sheet metal parts with a marking tool (see Figure 4). Companies with quality programs requiring part traceability now can do this on their turret presses, eliminating downstream labeling, tagging, and other forms of part identification. Using the turret press NC program, fabricators can mark part traceability data such as pallet numbers, sequential serial numbers, time, and date permanently into the material at a specified location on the part.
A special-application turret press hinge tool allows fabricators to form knuckles on a part, eliminating the need to attach hinge components.
Components used in the aircraft, military, and electronic enclosure industries regularly require a batch number to ensure traceability. Electrical enclosures often must have important safety or operating instructions indelibly marked to conform to local and state regulations. This tool is very useful for these applications.
Hinge Tooling That Creates Knuckles. Fabricated metal enclosures and similar cabinetry that require hinges can be fabricated with integral hinge knuckles (see Figure 5). Using a special-application hinge tool on the turret press, fabricators can punch many different types of knuckles of different lengths and diameters. This omits the need to attach hinge components or to weld and can eliminate the need for separate hinges, fasteners, spot welds, or assembly operations.
Tooling That Makes Threaded Holes. Another special-application tool designed to thread prepunched holes or extruded holes adds versatility to a turret press (see Figure 6). The tool uses standard taps and collets to thread a range of hole diameters in stainless steel, mild steel, and aluminum. This eliminates threading operations by hand or on separate machines.
Another special-application tool threads prepunched or extruded holes which eliminates hand or machine threading as a separate, secondary operation.
Tooling That Fabricates Mounting Holes. Finally, a type of special-application tool that fabricates mounting holes is suitable for rack positioning in electronic enclosures (seeFigure 7). This tool, with multiple points, makes many holes faster than single-point punching tools. It is designed to reduce downstream assembly time and the need for additional assembly components.
Each of these special-application tools can save time and costs by eliminating secondary operations, including assembly, and by reducing the number of part components. By combining more than one of these tools in a fabrication process, fabricators can save even more time and cost, for example, by marking parts with the part-marking tool for part traceability and using the tool that punches spring-loaded tabs.
A type of special-application tool that fabricates mounting holes is designed to reduce downstream assembly time and the need for additional assembly components.
Tooling, while seemingly expensive, may be the least expensive way to improve manufacturability when compared to labor rates and machine capital and operating costs.
The potential improvement to be gained from special-application tooling depends on part design, material, tooling, and the turret machine's capabilities, as well as operator abilities.
Operator programming ability and creativity play a role in extending the performance range of the turret press and tooling.
Experienced press operators willing to work with tool manufacturer designers and customer service personnel can find new ways to get more out of their turret press equipment using special-application tools.