CAPP System Design for the Surhard Material Tool

Surhard is a hard cutting tool material used for tooling that has to hold an edge under load. In a planning database it is treated as a material class, not a single grade. Each record carries hardness range, abrasive behavior, recommended tool geometry, and the feed and speed window that the shop has proven on its own machines.

The reason to give it its own class is that the rules change. Hard tool material moves the constraint from chip evacuation to tool wear. A generic steel record will output a feed rate that burns the edge in ten minutes, so the class has to carry its own numbers.

Three fields do most of the work: hardness band, abrasive index, and whether the feature is a form cut or a plain cut. Get those wrong and every downstream decision drifts. Get them right and the sequence almost writes itself.

The first layer is the part model. It reads features from the CAD file or from a manual entry form: holes, pockets, faces, threads, tolerances, surface finish. Only features the shop can actually cut should be offered, otherwise the planner generates operations nobody can run.

The second layer is the knowledge base. It holds machine capability, tool library, fixture options, and the cutting data for each material class. This is the layer that shops own and nobody else can copy. Build it from your own tool life records, not from a supplier catalog.

The third layer is the decision engine. It matches features to operations, orders them, and assigns machines. Rules can be simple: hard material first for roughing, stress relief before finishing, inspection after any tight tolerance. A rule set of forty to sixty entries covers most tool work.

The output is a route sheet plus setup notes. If the planner cannot explain why it chose an operation, engineers will not trust it, so keep a reason code on every step.

Speed and feed for hard tool material sit in a narrow window. On a 12 mm carbide end mill in Surhard-class stock, a starting point of 45–70 m/min surface speed and 0.03–0.06 mm per tooth keeps the edge alive, with air blast or minimum quantity lubrication rather than flood coolant.

Depth of cut is the variable most often set too high. For roughing, 0.5–1.0 mm radial and up to 1.5 mm axial works on a rigid setup. On a long tool or a thin wall, halve it and raise the speed instead.

Finishing follows the tolerance, not the material. Holding ±0.005 mm on a hard tool insert usually means a separate finishing pass with a fresh edge, and inspection between roughing and finishing when the part will move after stock removal.

Let the engine pick a range, not a single number. A fixed value in the database becomes wrong the moment a machine is swapped or a holder changes.

Tool life data is the usual failure point. Nobody records it, so the knowledge base fills with catalog values that do not match the shop floor. Start by logging edge changes on one hard-material job for a month.

The second break is scope creep. A planner that tries to handle sheet metal, turning, and five-axis milling at once never finishes. Pick one process family, get it running, then add the next.

The third is trust. If the generated plan is wrong twice, engineers go back to paper. Publish the rule set, let them edit it, and log every override. Those overrides are the best data you will ever get.

Integration with the machine is optional at the start. Exporting a route sheet and a tool list to the operator is enough for most shops under fifty employees.