Thomas S. Weir is punching product application specialist for LVD Strippt.Click image to enlargeby Thomas S. Weir 

Reduce downtime, increase productivity and get better punching and forming results

 

A well-planned turret layout is a simple investment to realize the best punching outcomes. A few key considerations can make all the difference in planning the most efficient turret layout. 

1) Fill all stations, even if they’re not used

Empty stations are potential catch points for the worksheet. The corner of a worksheet can catch on the pocket of an open station, particularly with larger C or D 51 to 89 mm (2.0-in. or 3.5-in.) stations. If the sheet catches on an empty station, it stops moving but the machine does not, quickly making scrap of the workpiece. For this reason, it’s best to fill all the lower stations, even those that will not be used:

  • Use special blank dies 
  • Fill empty stations with unused cutting dies

Keeping all stations loaded is an easy way to avoid a catch hazard that may result in more than just wasted material. In heavier gauges, a worksheet that’s caught on a station may damage or destroy the tool or upset the turret alignment (scissor the turret), requiring machine downtime to realign the turret and/or a possible service call. 

2) Consider positioning and use of forming dies
As punch presses are increasingly used for forming to reduce or eliminate secondary operations, your turret layout may call for forming tools. Countersinks, embosses, electrical knockouts and louvers are commonly used forming tools.   

Forming dies (i.e. form-up tools) are usually taller than standard cutting dies simply because of the action they need to perform. The die height is the height of the form to be produced. Because of their height, forming tools have a greater risk of colliding with the worksheet or causing other issues. To prevent problems:

  • Keep space between forming dies. Forming dies too close to each other can result in sheet distortion. This is caused because the worksheet is not able to push down on the adjacent die, forcing the sheet to rollover. 
  • Don’t position cutting tools too close to forming dies. Doing so can lead to sheet distortion because the workpiece sits higher on a forming die than a standard die. The forming die may cause the sheet to lift up at an angle, which can result in the sheet dimpling when it’s punched. For very high forming dies, it may be best not to use the stations on either side of the die. 
  • Place parting tools as far from forming dies as possible.
  • Be aware that forming dies can break micro-joints as the sheet moves over them. Micro-joints (fine, interconnecting tabs) separate parts nested in a workpiece and make it easy to remove (shake out) the parts from the processed sheet. As the worksheet moves on the machine table over tall forming dies, the vibration of the motion can break the small (micro) tabs. If using high forms in your turret layout, you may need to increase the size of the micro-joints to increase their strength. 
  • Consider sheet movement and position tools. As the sheet enters the turret space, the first tool it meets should not be a forming die, a potential catch hazard. Instead, plan your layout to make it easy for the sheet to sit above the first die it encounters (ideally, a standard tool).
  • Remove forming dies when not being used to prevent possible part distortion, prevent potential collision (when you’ve forgotten you’ve left forming dies in the turret and are running a new job that does not require them), and reduce scratching on the underside of the worksheet (important if you’re producing parts in polished stainless or for applications like architectural or medical that require highly cosmetic parts).

3) Pay attention to keyways
For shaped tools, ensure tools are keyed to the correct angle. If the turret layout doesn’t match the part program, you will not produce good parts. 

  • Most turret stations can be keyed at 0° and 90°
  • Some stations have special keyways of 45° and 135°
  • Make use of adapters if needed. Size B 32 mm (1.25-in.) tools can be used in indexable C or D stations

Both job shops and OEMs can benefit from planning a punch press turret layout. Giving thought to tool use, placement and orientation prevents mistakes, accidents and waste – which is more critical than ever in today’s manufacturing environment. SMT

Thomas S. Weir is punching product application specialist for LVD Strippit.

 

Elliott Matsuura Canada Inc.

Based in Oakville, Ontario, Elliott Matsuura Canada Inc. has been supplying and supporting quality machine tools to the Canadian metal cutting industry since 1950. Elliott carries a full range of metalworking machinery,

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