Secondary work on turret punch presses

The biggest challenges facing today's sheet metal fabricators are a shortage of skilled labour and how to reduce or eliminate waste in manufacturing. With the right tooling, CNC punching machines can perform a variety of operations traditionally considered as press or press brake work or performed as secondary work in stand-alone stations.

What types of operations are we talking about? How can they benefit you? If your production process includes threading holes, adding hinges, creating safe edges, deburring, countersinking, marking, creating fasteners, or making 90-degree bends, your punch press can save you time and money. You can do all of these and more in your turret punch press. There is no need for time-consuming, costly secondary operations. Following are some examples of such tools.

When a component requires a thread, metal bushes or inserts typically are used. This usually requires a machine or apparatus to fix them into the sheet, which means transporting parts to a separate work area for completion. Both costs are eliminated if the thread can be made directly on the punch press.

In-machine tapping tools produce stable, reliable threads in sheet metal at a fraction of the cost of inserts and bushes. The first step is to make an extrusion, followed by the initiation of the thread forming tool. Threads produced in this way are roll formed rather than cut, resulting in increased strength and resistance for longer life and consistent performance.

An alternative to tapping is a thread form. These vary in size to accommodate small screws or plastic inserts that are found on some household appliances.

In the past, including a hinge in a metal product required several manufacturing steps. First, a length of piano hinge was purchased. Then, the hinge was cut down to size and moved to a work area. The metal product was also moved to the work area so the hinge could be welded onto it. Last, the welds needed to be cleaned up to remove the leftover scale from this process.

Now hinge tools can be used right in the punch press to eliminate much of this labour-intensive, time-consuming process. Creating a hinge in the punch press typically requires two tools. The first tool is used to wipe up the pre-punched knuckle. The second tool curls the tab over. One-hit hinge tools are also available for certain applications.

When sheet metal is cut or punched, the resulting edge often is sharp or burred. If additional handling is needed, these sharp edges present an obvious safety risk. Sharp edges and burrs can also be dangerous if cables or hoses are going to be passed through the hole. Traditionally, a rubber or plastic insert or grommet was added, usually by hand, in an assembly area away from the punch press. Alternatively, components are deburred using a separate deburring machine.

For a lean company, there are obvious wastes involved in these processes: transporting the materials, performing a secondary process, and taking up an employee's time and effort to perform an extra task.

These wastes can be eliminated by doing the work on the punch press. A deburring tool works by coining a small chamfer on the cut edge of the part using a unique ball assembly, flexibly moving in straight lines or arcs – even acute angles and very small radii.

Creating a hinge in the punch press typically requires two tools. The first tool is used to wipe up the pre-punched knuckle. The second tool curls the tab over. Images: Wilson Tool

If a countersunk screw location is required rather than a screw thread, coining tools are available that can produce an accurate, precise countersink in seconds.

The old-fashioned method of carrying parts from the punch to a machine to drill the countersink requires much more time and unnecessary effort.

In the punch press, countersinks are done quickly and precisely in one stroke of the punch. Tools are made to your exact specifications, producing a clean countersink that requires no deburring.

You have several options for part marking in your punch press. One sheet marking tool, for instance, provides a range of sheet marking options. It can be used for both sheet scribing and dot-matrix marking on many materials, eliminating the need to change tools every time you need to make a different mark.

Another tool allows you to mark materials using ink. It is equipped with an automatic airtight mechanism, eliminating the need to replace a lid after each use to preserve the ink. It can also use a selection of 10 different colour options.

With an identification stamp tool you can mark multiple numbers, letters, and various symbols without ever taking the tool or the sheet off your machine. It eliminates secondary handling costs and ensures consistent marking.

Fastening parts typically requires a labour-intensive assembly process like spot welding, screwing, or clipping and often demands separate hardware. Connective forming tools for the punch press allow you to create fasteners directly on the part and avoid time-consuming secondary operations. Connective forming tools fall into two categories: common tools you’ve likely used for other purposes, and those that are made specifically for fastening.

Using a scratch tool as a sheet stop eliminates the need to spot weld the back of the sheet. Then there are familiar forms that double as connectors: bridges, louvres, and half-shears are convenient, cost-effective sheet- stopping tools.

Not all bends need to be done on a press brake; bending in the punch press eliminates secondary operations as well as material handling and transport. In some applications, bend heights of 1 in. are possible.

For example, one tool employs a rotating cam built into the lower unit of the die, with the machine stroke mimicking a press brake cycle. The tool, with its lower-cam design, allows for heights not typically achievable in a punching machine. On a turret press, the operation is not limited by the tool having to travel above or beyond the form as would be the case with a traditional lance and form of 90 degrees or even with a 90-degree wipe.

A deburring tool works by coining a small chamfer on the cut edge of the part using a unique ball assembly, flexibly moving in straight lines or arcs – even acute angles and very small radii.

As you can see, with the right tools, your punch press can help eliminate the need for costly, labour-intensive secondary operations, saving you time and money.

Susan Erler is product manager, Punching/My Account, at Wilson Tool International, 12912 Farnham Ave., White Bear Lake, Minn. 55110, 651-286-6154, [email protected], www.wilsontool.com.