Additive manufacturing can be an alternative process for making parts once made through traditional machining. For example, Wilson Tool International produces a line of oil reservoirs made for its QuickTap tapping tool. Tapping tools are a core part of the punch press products, helping to eliminate secondary operations in sheet metal manufacturing. They are used to tap up to 200 holes per minute while maintaining thread quality. A tapping tool consists of the tap itself, a motor, and an oil reservoir.
The parts were previously made using cold-rolled steel that was punched and formed into seven to nine components that were then welded together. Wilson Tool International offers six reservoir designs, which vary based on the type of punch press they are used in. Each tank went through a rigorous testing process to ensure the reservoir did not leak from the welded seams when subjected to pressurization. The entire process was time intensive and the production cost was high.
In addition, with six variations of the reservoir, the company needed to keep high inventory levels to ensure on time delivery to customers. One drawback of high inventory, though, was the risk of part obsolescence.
Several options were tried before settling on additive manufacturing. One option was a fully machined reservoir made from aircraft grade aluminum. Blow molding was also investigated, but the tooling cost for the different parts would only drive up the part price and the quality of the product was not acceptable. Most of the options did not meet Wilson Tool’s cost and lead-time goals.
So, the engineers turned to additive manufacturing. They found that the Carbon Digital Light Synthesis technology could replace steel punching. The result was not only a suitable tapping tool, but they saved at least 60% in costs, and 50% in leadtime. In addition, the additive design contributed to better operator safety.
The proof of concept part from Carbon had to meet the functional requirements of holding oil, interfacing with off-the-shelf tubing, and providing sufficient impact absorption. Print results had to be repeatable.
The first print in Carbon’s RPU (rigid polyurethane) 70 material met all criteria, demonstrating that it was printable, functional, and up to 60% less expensive per part. The parts’ lead-time was cut by up to 50% and did not pose the destructive hazard that the metal ones did when they were not installed properly.
The engineers moved to validate the design broadly. They went through five different design iterations in three months, ensuring the suitability of the Carbon Digital Light Synthesis technology and optimizing the design for printability, adding mechanical rigidity with an internal lattice, and integrating a signature surface finish. They also added part numbers and branded elements to the part files. For the largest tanks, they added an internal lattice structure for additional mechanical rigidity (Figure 2). The parts were also validated for both thermal and chemical stability, as the engineers were concerned about low temperatures (0°F) and exposure to naphtha for cleaning.
When RPU 70 passed all of the tests, they qualified the oil reservoir parts for production, broadly implementing the new material across their reservoirs (Figure 3). The savings on these parts means lower prices, shorter lead times and better, safer parts for consumers.