THE CUSTOMER

PUNCH Torino is a leading European R&D and engineering facility for the development of internal combustion engines and propulsion systems. Located in Torino, Italy, it began operation in 2005 as a spin-off of GM’s divestiture of the Fiat-GM powertrain joint venture. Under GM’s ownership, it grew from 80 to over 700 employees from 12 nations. In 2020, it became part of Belgium’s PUNCH Group.

Since then, it has continued to support GM and a growing roster of manufacturers and startups in diverse technology projects that include gasoline, diesel and hydrogen engines, generator sets, transmissions, additive manufacturing and collaboration software.

THE CHALLENGE

PUNCH Torino builds a variety of prototype engines for its clients and develops and tests new components for existing engine designs. During the build process, engineers must install a timing chain that connects the engine’s crankshaft to a pair of camshafts. When they rotate, lobes along their length open and close the valves of each cylinder to let fuel and air into them at the right time.

As the timing chain sprocket is tightened, the camshafts must be kept completely stationary in a defined position to guarantee the perfect synchronization of the timing system when the engine is running. If the camshafts aren’t locked in place, the valves may open and close at the wrong times, damaging or destroying the engine.

To prevent the camshafts from moving, PUNCH Torino’s engineers have designed fork-like camshaft locking tools, built out of Onyx with fiber reinforcement. During the tightening process, the tools must withstand torque up to 120-newton meters and must not allow any degrees of rotation, according to Valerio Ametrano, senior pre-production engineer.

The camshaft locking tools are currently built using a Markforged X7 using Onyx with carbon fiber reinforcement. Each one takes approximately 18 hours to print, he estimates.

If a locking tool breaks during this critical tightening process, the torque on the camshaft will cause it to rotate out of position. The team would then need to loosen or remove the timing chain, re-secure the camshafts and begin the tightening process again. Waiting for a new locking tool to be printed could delay the team by a day or more, especially if it caused them to miss a build window for a new engine.

During the engine design process, engineers often make frequent, small design changes to engine components, especially during the early stages of engine development. Each time, the team must tweak the design of the camshaft locking tools and print new ones. Often, the engineering team may test multiple camshaft designs at the same time. Each one requires a slightly different tool design.

In the past, the process of designing camshaft locking tools required a lot of trial-and-error work. There wasn’t an accurate way to predict if a tool would be stiff enough and strong enough to withstand the torque loads placed on them. They had no way of knowing if a design change to the locking tool could compromise its structural integrity. Also, because FEA analysis isn’t designed for 3D-printed parts, the team had to make many assumptions and approximations to design jigs that met all of their requirements.

THE SOLUTION

PUNCH Torino was able to gain some major efficiencies using Simulation from Markforged. Prior to using it, a new camshaft configuration could require printing and testing up to eight jig designs to get their configuration exactly right, Ametrano recalls. For example, a change in geometry or dimensions (lobe, length, diameter, etc.) of the camshaft may have required a slightly different fork shape to hold it in place. But the revised locking tool design didn’t quite conform to the shape of the shaft and allowed for too much camshaft rotation. So, the team often had to print multiple iterations of tools until they landed on a configuration that worked just right.

After they started to use Simulation for Markforged, they were able to reduce the average number of locking tool design iterations from eight to three, at least at first. According to Ametrano, when the team was first learning to use the new simulation tool, they went through some trial and error to correctly characterize the boundary conditions, force modulus and deformation the locking tool was exposed to. Now that they have this data dialed in, they can usually simulate and print a typical locking tool in a single iteration, he points out.

He estimates that Simulation for Markforged not only saves the team an average of 18 hours per jig but also the engineering time required to modify the part designs; this is now managed within the software. In addition, it frees up a significant amount of printer time that was previously dedicated to producing multiple iterations of camshaft locking tools.

Ametrano first validates the part in Simulation and then uses the software to optimize the print settings and the placement of carbon fiber. He often experiments with several configurations of manually-placed fiber, comparing the estimated deflection and safety factor of each one. Using Simulation, he can see in a matter of minutes how different fiber layouts affect the part performance. This allows him to identify the best-performing configuration for printing quickly and easily.

During the early stages of engine development, engineers sometimes make frequent changes to camshaft designs. If the changes are minor, the team modifies the design of the camshaft locking tool, while keeping the previous use case in Simulation for Markforged to verify that it will still have the required strength. If design engineers make major changes to the camshaft designs, the team must redesign the locking tool and re-do the simulation based on the new design.

Engine builds require the PUNCH Torino team to gather a large number of components and tools in one place so they can assemble up to eight or ten of them within a limited time window. Simulation from Markforged helps ensure that the camshaft locking tools are correctly configured and ready to use when they’re needed. A poorly configured tool can break under pressure, delaying an engine build for a day or more, Ametrano emphasizes.

THE FUTURE

In addition to designing and prototyping engines for different worldwide OEM automakers, PUNCH Torino sells its 3D printing expertise to several industrial and technology clients. A logical next step is to use Simulation from Markforged to help streamline the design optimization and build process for their parts. Because this tool is so powerful and affordable, the PUNCH Torino team believes it can save them a lot of time and help them deliver better parts to its clients.

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