Experimental Investigation of Dimensional Precision of Deep Drawn Cups Using Direct Polymer Additive Tooling

Abstract

While deep drawing of sheet metals is economical at high volumes, it can be very costly for manufacturing prototypes, mainly due to high tooling costs. Additively manufactured polymer tools have the potential to be more cost-efficient for small series, but they are softer and thus less resilient than conventional steel tools. This work aimed to study the dimensional precision of such tools using a standard cup geometry. Tools were printed with FFF using two different materials, PLA and CF-PA. A test series of 20 parts was drawn from each tool. Afterwards, the dimensional precisions of the drawn parts were analyzed using an optical measuring system. The achieved dimensional accuracy of the first drawn cup using the PLA toolset was 1.98 mm, which was further improved to 1.04 mm by altering shrinkage and springback allowances. The repeatability of the deep drawing process for the CF-reinforced PA tool was 0.17 mm during 20 drawing operations and better than that of the PLA tool (1.17 mm). To conclude, deep drawing of standard cups is doable using direct polymer additive tooling with a dimensional accuracy of 1.04 mm, which can be further improved by refining allowances incorporated to the CAD model being printed.