Redefining Rocket Motor Tooling with 3D Printing

Transforming the tooling process to accelerate rocket motor development.

One of the most famous rocket motors ever designed almost didn't get off the ground. Engineers developing the Apollo Saturn V's F-1 rocket engines were perplexed by a problem causing their engines to explode on the test stand. Only when the team devised a new approach - a new way of thinking - to the standard design of the fuel injector system did they achieve combustion stability and success, ultimately allowing humanity to reach the moon.

Fast-forward sixty years, and another rocket motor developer, Northrop Grumman, is taking a similar fresh-approach mindset to overcome challenging production obstacles. This time, the problem is the excessive lead-time within the tooling supply chain, which puts excessive drag on new rocket motor development. Rather than accept the status quo, the team at Northrop Grumman forged a new path and used additive manufacturing (AM) to replace the metal tooling causing the delays in new development. The result was a dramatic reduction in tooling production time and the creation of a new rocket motor in less than a year.

Supply Chain Disruptions Drive Delays

Northrop Grumman Propulsion Systems has a rich history of solid rocket motor development, providing lift capability for defense, civil, and commercial rocket applications for over 60 years. The Northrop Grumman team there even provided rocket motors for the Apollo moon missions. Success at this level relies on innovation and a healthy supply chain to meet the technical, cost, and schedule challenges that face any product development program. But supply chains are fragile, a fact underscored by the COVID pandemic, although that's not the only cause. Political tensions, trade wars, and similar geopolitical challenges are constant threats to stable supply chains, highlighting the value of on-shoring or near-shoring strategies. Specific to rocket motor development, one of the weak links is the procurement of new tooling used to mold the solid rocket propellant inside the motor casing to meet mission objectives. For Northrop Grumman, the aforementioned supply chain realities can push out tooling lead times for over a year for some projects.

Chase Smaellie, Northrop Grumman tooling engineer, is all too familiar with procurement delays that impact project plans: "During COVID, lots of different suppliers were shut down, and we really struggled, and still struggle, getting in large forgings, castings and weldments. It takes much longer than it should to get some of these larger tools into the company."

The ramifications of supply chain disruptions go beyond time-related delays. As any manufacturer knows, production pauses mean the product gets to market later rather than sooner. In a competitive industry, this can ultimately result in missed business opportunities. Process delays hamper the ability to react swiftly to changing market conditions, new customer requirements, or emerging trends. They also negatively impact delivery schedules, leading to unmet customer expectations, erosion of the company's dependability, and lost sales.