Lubricants for large-scale die-casting

The emergence of larger and more complex die-cast parts calls for novel lubricants that support the latest generation of die-casting machinery.

“The expanding scope of automotive emissions regulations is pressuring automakers and their suppliers, one result of which is designers and manufacturers’ focus on ‘light-weighting’ new vehicles. Their goal is to reduce overall vehicle weight to improve fuel economy and range by introducing a growing number of hybrid and electric vehicles,” says Mark Cross, the global business development director for die-casting at Quaker Houghton.

“To achieve overall vehicle-weight reduction, engineers are adopting a range of materials and production techniques to create lighter components for powertrains, drivetrains, and structural systems. This use of new materials – including aluminium, carbon fibre composites, high-strength steel, magnesium and titanium brings a need to re-think traditional manufacturing and assembly processes and embrace new technologies and techniques.”

The model Y Tesla replaces 70 underbody parts with one casting

“For die-casting in particular, engineers must consider how to improve product quality and productivity for large and complex parts. Alongside this, production costs need to fall, the total cost of ownership needs to be reduced, and the environmental impact of the die-casting process must be lowered.”

A shift towards larger die-cast parts
“The automotive industry is no stranger to automation, with many production lines already embracing Industry 4.0 standards. Physical and digital processes are increasingly intertwined as they aim to create smarter, more efficient production sequences. And still the pressure is on to combine production efficiency with those lighter materials.”

“Die-casting of course is a critical manufacturing process for the auto industry, to form parts such as engine blocks and transmission cases. Now, the technique is being adapted to cast one-piece structural parts like shock towers and torque bars, supporting those light-weighting goals. Tesla has drawn much attention for its stated goal of producing a unitary, die-cast underbody structure to replace a combination of multiple welded and stamped components. This requires using the world’s largest die-casting machine to produce such a large casting – a change that could revolutionise automotive design and production.”

“The benefits of die-casting are well known to automakers: it’s a quick and relatively economical process that offers the repeatability required by mass production, meaning identical parts can be produced from one mould.”

“The move toward engineering a vehicle structure from a smaller number of large die-cast parts rather than high volumes of smaller parts reduces production complexity and offers significantly reduced costs. Casting larger parts stands to remove as many as 70 steps from a more traditional production process, and while the benefits are clear the casting of larger parts brings complexity to the die-casting process.”

“To avoid compromising quality and increasing costs in the manufacture of large, complex components, specifying the correct die lubricant technology is essential to ensure an adequate release lubricant film is formed over the die surface.”

“As die tools increase in size and complexity, they become increasing difficult to lubricate using conventional water-based lubricant systems. Ensuring lubricant reaches all parts of the complex tool to prevent casting failure is a significant challenge, not easily overcome.”

Lack of penetration of the lubricant spray into areas such as ribs, coupled with the low film forming capabilities of water-based lubricants is a real challenge for die-casters. Additionally, the spray heads used to apply water-based lubricants are simply too large, bulky, and inflexible to deploy lubricant successfully to all areas of the die face.

“For an industry looking to cast larger components and maintain product quality, improve productivity, and reduce costs, water-free electrostatic lubricant systems like Quaker Houghton’s like Lubrolene provide a solution. Such systems combine a high-power release agent, free from the drawback of conventional lubricants, coupled with a compact low weight spray system.”

“Switching from traditional water-based lubricants to a water-free electrostatic solution allows die-casters to produce larger components with higher process temperatures, while meeting the challenges of maintaining product quality, improving productivity, and reducing costs.”