While machining processes dominate metal removal for automotive parts manufacturing, trends toward smaller pieces with higher form and finish tolerances are leading manufacturers to consider alternatives. Advances in abrasive grinding materials and processes have made the technology more suited to a range of manufacturing applications.
Cost savings can come from many places – reduced capital expenditure, consumable tooling, logistics, and cycle time. In particular, creep-feed and peel grinding have applications suited to motor vehicle production. The following are examples of customers replacing machining processes with abrasive grinding.
The Affolter AF110plus gear-hobbing center features quick changeover with minimum down-time and several automation options. It supports worm-screw power skiving, a high-speed cutting technique for gear components.
The machine’s CNC control includes step-by-step software programming and the ability to network machines to download programs from a PC or server.
Nearly every new engine in a car for the past decade has featured some version of computer-controlled valve or cam timing to improve fuel efficiency, boost power, and better manage emissions systems. That shift has been a major boon to powder metallurgy (PM) service companies such as NetShape Technologies Inc. Headquartered in Floyds Knob, Indiana, with four manufacturing facilities in North America and two in China, NetShape has grown to supply precision powertrain components to a variety of manufacturers.
“For variable valve timing/variable cam timing (VVT/VCT) components, PM was the original design-of-choice technology because of our ability to form the complex features required with little to no machining,” says John von Arx, NetShape market segment leader for automotive. “With the move to VVT/VCT systems, automakers went away from gerotor-style engine oil pumps to variable-vane pumps, which again, PM is the technology of choice.”
In addition to VVT/VCT parts and variable-vane pump components, NetShape provides camshaft and crankshaft engine sprockets and camshaft assembly components. Von Arx adds that industry trends should have PM parts making up a greater portion of vehicle engines in the future, although the total weight of such parts shipped will fall as automakers continue to shift from V-8 and V-6 engines to 4-cylinder models. PM producers also have an opportunity to provide more transmission components as 7-, 8-, 9-, and 10-speed automatics replace 4-speed and 5-speed models.
As powertrain orders have increased, von Arx says PM companies have invested heavily in new technologies. NetShape has developed a material solution that has properties close to 8620 hardened steel – HP-1, high performance.
“Previously, there was not a viable solution from the PM industry to replace machined, hardened 8620 steel components,” von Arx says. “This will allow us to engage with automotive customers with a solution that combines the net forming capabilities NetShape provides with a material solution that could replace 8620.”
Klüberalfa RM 93-101, a PFPE-based surface finishing gel, mitigates creaking and squeaking noises in moving polymer components. Compatible with a wide range of plastics and elastomers, Klüberalfa RM 93-101 is applied in thin, transparent layers that do not disrupt the aesthetics of the part to which it is adhered, such as door seals and dashboards.
Adding an iris scanner to a car’s rearview mirror enables biometric identification of authorized vehicle users. When tied into other vehicle systems, the scanner can allow authorized users to start the car and personalize setup by automatically adjusting mirrors, steering wheel, seat position, music favorites, and GPS locations.
Discretely integrated into an automatic-dimming rearview mirror and related windscreen mount, the scanner is in the driver’s line of sight upon entering the car. It provides a consistent feature location across vehicle platforms and can share other electronic components.
Despite the growing sophistication of digital design tools, if you go into any automotive design studio, you’ll still see clay models. While more products are starting in the virtual world, eventually designers need to touch, feel, and see physical representations of their work. The challenge is bridging the digital and physical design worlds. Several companies offer mills that can cut clay blocks into representations of 3D digital models. However, if designers alter the clay – adding more weight to one feature, carving a bit away from another – those changes don’t flow back to the virtual design. Some studios use hand-held scanners or coordinate measuring machines (CMMs) to capture those changes, but each can be a time-consuming process.
Drew Shemenski, president of metrology equipment supplier Wenzel America Ltd., in Wixom, Michigan, says the solution is a closed-loop system that can create the clay models and capture changes that designers make. Wenzel equipment achieves that by combining clay milling capabilities, with the scanning and measurement tools of a CMM. So, the same machine can convert a raw blank of clay into a representation of a physical design, then capture any changes made to that model.
“There are two types of milling for clay models – CMM-based or traditional. With a traditional mill, it’s always been a one-way process. You’re translating the 3D digital design into a physical representation,” Shemenski says. “By adding a CMM to that, it becomes a two-way process. You create that physical model from the digital design, but then you can capture changes to that clay model.”
He adds that the clay design tools came out of Wenzel’s CMM business. The company had been selling CMMs to design studios, and on a visit, engineers talked to designers about the challenges they faced. Setting up a clay model for scanning was a challenge, often requiring designers to move the clay model onto special fixtures – a step that risked damaging fine details that had been painstakingly carved into the designs.
The initial goal of adding the milling head was to eliminate those setup steps. Engineers achieved that by developing a high-precision milling head, then beefing up motors, drives, and power systems in the CMM so they could handle the weight and energy draw from the milling equipment. Engineers then added features to software tools to create the digital-to-physical-to-digital pathways.
The value of the system became clear to designers very quickly, Shemenski says. That two-way path between digital and physical designs allows studios to quickly move one version of a product to the next. Because of the investments needed to produce a new vehicle line, design studios tend to tweak every component to make sure it’s ideal before going into production.
“The average consumer has no idea how many iterations of every car, or every part of a car, designers go through before production. Our systems let companies go through iteration after iteration faster,” Shemenski explains.
Keeping clay models on the same fixtures as they move from milling to hand alterations to scanning eliminates risk of damage and time-consuming, hand-scanning of features. The CMM producer has created several milling machines for European automotive design studios, and it offers them in North America. So far, the bulk of interest in the U.S. has come from recreational vehicle, commercial truck, all-terrain vehicle (ATV), and industrial equipment producers, Shemenski says. Those manufacturers face ergonomic design challenges, so the ability to quickly go through multiple design stages is attractive.
To further improve this iterative cycle, Wenzel has launched Wenzel DesignTec. This new division is adding to its product offering with a new line of Studio Mills that will increase the speed and capability of clay milling, while maintaining the ease of scanning and measurement in a single flexible package.
“Clay models are still essential to design, whether you’re talking about cars, motorcycles, or ATVs. Most people buy vehicles emotionally, so designers need to excite people,” Shemenski says. “Working only digitally, you lose some of that emotion. There’s no replacement for touching and seeing a part in the physical world.”
Additive technologies, such as 3D printing, are also gaining popularity in design studios for their ability to translate digital files into physical objects, and Shemenski expects sales of those systems to continue to grow. However, 3D-printed iterations still have a major drawback.
“You’re dealing with something that’s not easy to change in the physical world. You can carve away some material, but it’s very hard to do that without damaging other features,” Shemenski explains. “And you can’t add to it easily. You can’t just take more clay and mold it into the design to get a feel for the design change.”