Due to the uptake in lasers and large capacity plasma cutting machine, there are not as many sold as ten years ago. However, they still have a valid place in workshops across Australia. If your product is a straight-sided steel plate, it is still the most economical way to cut.
Heavier plate shearing is strictly the domain of hydraulic machines. There are three alternative designs, four if you include Under Driven hydraulic, which we’ll exclude because it is an inferior solution for cutting thicker plate.
Most crucial factor straight out of the gate is to consider thickness capacity of the machine. We have noticed in recent years manufacturers of guillotines, particularly from China, do not reference their benchmark Ultimate Tensile Strength when stating thickness capacity. Since quite often, workshops requiring heavy guillotines may need to process tougher material, it is essential to know where you start.
Most reputable manufacturers should base mild steel capacity on Ultimate Tensile Strength of between 420 to 450 n/mm2
Stainless between 500 and 700n/mm2 depending on grade and Bisalloy or Hardox could be a lot more, so it is worth checking!
As mentioned earlier, there are three designs for 6.0mm and thicker capacity shears. Swing Beam Shear, Parallel Overdriven Shear and Variable Rake.
No particular design is the stand out winner although we do have a preference for the Swing Beam or the Variable Rake machines. The Variable Rake does offer better cycle times on material downrange in its capacity as you can reduce rake angle. But if you are cutting within a narrow range, for example, 6-10mm on a 13mm machine then the simplicity and price of the Swing Beam Shear do make it hard to beat.
On these shears of thicker steel capacity, it is worth considering ease of blade gap adjustment since the clearance between blades is critical and relative to thickness. If it isn’t easy to do or preferably an automatic function from the programmable control, then the operator may forget or be too lazy to do it, the consequences will be a poor quality cut or worse damaged blades.
A Ballscrew backgauge CNC Controlled should be standard equipment on any new shear, it should swing up out of the way at the end of its stroke to allow you to push through longer lengths if required. That way you can cut a 4.0m long plate in half if needed.
You can order both the Swing Beam and Variable Rake machines with a throat in the side frame, and this gives you the ability to slit longer lengths than can be customarily cut between the frames. In effect, you can use the machine as a big pair of scissors.
There are many other options to discuss, including handing equipment for the front and pneumatic sheet support system for the rear.