On high-volume packaging work the problem is usually not cutting but separating and stacking the cut work cleanly at machine speed. On BOBST-type automatic lines two tools beside the cutting die take on that task: stripping, which removes the waste, and blanking, which delivers the blanks to the pallet. Both are made from the same drawing and to the same dimensions as the cutting die.
What is different about BOBST work
On a flatbed press the die’s job ends when cutting and creasing are done; the sheet is taken off by hand and the waste is picked out by hand. On an automatic line the sheet moves on to the stripping and delivery stations as soon as it leaves the cutting station; if the die is not matched to those stations the line stops, however clean the cut.
A BOBST die is therefore treated as a set, not a single tool: the cutting die, the upper and lower stripping and blanking tools and, where needed, the blanking grid and pusher unit. A matched set shortens make-ready; a mismatched set asks for operator intervention on every stroke.
- Cutting speed is not the only measure of success; stripping and stacking count too.
- If the waste does not separate the line stops, and cut quality does not make up for it.
- A matched set directly shortens machine make-ready time.
What stripping does
The stripping tool removes from the sheet the waste left around the product after the cut. Pins in the upper tool push the waste down, openings in the lower tool let it fall, and the product stays suspended in the sheet on its nicks. Window openings, small inner waste pieces and narrow strips snag on the product if they are not supported correctly.
Good stripping design removes the need for hand stripping and lets the machine run at a steady speed. The design is derived from the cutting die drawing: unless waste regions, bridge widths and nick positions are planned together with the cut, stripping cannot be corrected afterwards.
- It keeps inner waste from snagging on the product.
- It removes the need for hand stripping and operator intervention.
- On high-volume work it saves seconds on every stroke.
Why blanking matters
Blanking takes the stripped blanks out of the sheet and lowers them onto the pallet in straight columns. On multi-up or delicate work, collecting the blanks unmixed and with unmarked edges depends on this station; a grid window that is tight to the product contour rubs the edge, one that is too wide lets the blank turn as it drops and the column leans.
Poor blanking design comes back as crushed edges, mixed stacks or machine stoppages. The pusher contact points are distributed symmetrically over the blank; a pusher acting from one side turns the blank, and over a long run that turn becomes a visible drift on top of the pallet.
- It keeps the stack orderly; columns stay straight and countable.
- It reduces the risk of crushed and chewed edges.
- It lets blanks reach the filling line without jamming.
What is needed before a quote
For a BOBST job, alongside the drawing, the machine model or sheet format, number of positions and layout, material and grammage, expected speed and stacking requirement are needed. If the model is unknown, the board size and a dimensioned photo of an existing die do the same job.
A photo of the old set is the fastest reference for nick pattern and pin placement on the new build. Reviewing waste gaps and product layout at quote stage reduces surprises in production; when the stripping and blanking requirement is stated in the first message, the set is designed for it from the start.
- Machine model and sheet size are shared in the first message.
- Number of positions, layout and stacking requirement are stated.
- A photo of the old set or die is sent where one exists.
Quote details we clarify together
When the file, material, quantity and deadline are clear, the quote conversation moves faster and with less back-and-forth.
- Current revision file
- Material and quantity details
- Critical dimensions or production notes
- Deadline expectation and delivery preference
