Concrete Stamp Process Development
Background
During my employment with Toronto Stamp Inc., the cost of producing concrete stamps through the usual sub-contractor nearly doubled. The concrete stamps are typically made from zinc through a sand casting process. A solution is needed to continue the production without sacrificing Toronto Stamp's profit margin.
First alternative: 3D printed pattern
The first potential solution that was considered was using the company's FDM 3D printer to create the pattern to be used for sand casting, thereby reducing tooling cost. However, the rough surface finish of the FDM prints causes sand to become stuck on the pattern. Several print smoothing techniques were experimented with, all were too time consuming and did not produce a good enough surface finish. A resin-based printing process was considered but abandoned due to cost and print size limitations.
Second alternative: CNC routed pattern
The second alternative solution was to use one of the company's CNC router to produce the pattern out of plywood. This produced an adequate pattern for the purpose of sand casting. However it was determined that the cost of sand casting would still be too high even with the reduced tooling cost.
Solution: CNC routed concrete stamp
It was soon realized that the routers are capable of machining aluminium, and therefore a concrete stamp could be produced straight from machining a block of aluminium. After a few trial runs, the feeds and speeds are optimized and the process was deemed a success. Several challenges had to be overcome before the process was implemented. First, the workholding problem was addressed. Then, an efficient toolpath creation process was established. Each stamp would take up to two hours of machining time, but this problem was mitigated with work scheduling.
Result
The new, entirely in-house process of producing concrete stamps allowed the company to produce a superior product while maintaining its original price. The new process also resulted in significantly reduced turnaround time and increased profit margins for Toronto Stamp.