STEEL RULE DIE
Steel-rule die, also known as cookie cutter dies, are used for cutting sheet metal and softer webs, such as plastics, wood, cork, felt, fabrics, and paperboard. The cutting surface of the die is the edge of hardened steel strips, known as steel rule. These steel rules are usually located using saw or laser-cut grooves in plywood. In some cases, to reduce the manufacturing costs, the grooves for the steel rule are cut in a CNC router using a small diameter milling tool.
The mating die can be a flat piece of hardwood or steel, a male shape that matches the workpiece profile, or it can have a matching groove that allows the rule to nest into. See below a steel rule pressed into wooden board with grooves to create a die.
Rubber strips are wedged in with the steel rule to act as the stripper plate; the rubber compresses on the down-stroke and on the up-stroke it pushes the workpiece out of the die
The main advantage of steel-rule dies is the low cost to make them, as compared to solid dies; however, they are not as robust as solid dies, so they’re usually only used for short production runs.
Here the snow flake (shown in the left) is cut out on paper from a steel rule die (show in in the right)
Here is an example of a die which is used to cut cardboard sheets and create bending lines at the same time
Some other examples for cardboard box cutting
As an exercise to make a steel rule die you can do the following: Let us make a steel rule die as shown in the figure below:
Make a cad model as shown below:
The above dxf has the following:
1. It has 4 bridges. These 4 bridges are for the notches in the steel rule to sit in it. Note down the bridge length and gap between bridges. You can see the notches in the steel rule shown below.
Note: Here we have used plastic strapping material instead of a steel rule.
2. A center hole for fixing the handle.
3. An outer cutout path.
- Cut the DXF in CNC mc in 6mm or 12mm thick plywood.
- The design path should be cut using minimal dia end mill in a CNC router ( ~ 0.7mm or 1mm ).
- The outer profile can be cut with the same 1mm tool for easy setup or if needed you can change to a larger dia end mill for cutting outer path.
- Larger the diameter, the faster you can cut. Also the risk of breakage is minimal.
Suggested project variants:
You can try the following variants:
1) Make a SRD for your college name or LOGO.
2) Adapt the SRD design to cut soft materials like paper, cardboard.
3) Visit local packaging industry and study how they fabricate steel SRD, How the base is cut, How the Steel rule is bent, What is manufacturing cost, time etc.
For information regarding bending the steel rule, go through the following videos: